CN106091489B

CN106091489B - Vertical double-falling-film heat exchanger and absorption heat pump

Info

Publication number: CN106091489B
Application number: CN201610621008.9A
Authority: CN
Inventors: 苏庆泉
Original assignee: Beijing Lianliyuan Technology Co Ltd
Current assignee: Hunan chemical chain Technology Co., Ltd
Priority date: 2016-08-01
Filing date: 2016-08-01
Publication date: 2020-03-27
Anticipated expiration: 2036-08-01
Also published as: CN106091489A

Abstract

The invention discloses a vertical double-falling-film heat exchanger and an absorption heat pump, wherein the vertical double-falling-film heat exchanger comprises a heat exchange tube, an upper end plate of the heat exchange tube and a lower end plate of the heat exchange tube; the first fluid guide chamber is positioned above the upper end plate of the heat exchange tube, and a first fluid in the first fluid guide chamber flows into the heat exchange tube from the upper end of the heat exchange tube and forms an internal falling film on the inner wall of the heat exchange tube; the first fluid receiver is positioned below the lower end plate of the heat exchange tube and is used for receiving a first fluid flowing out of the heat exchange tube; the second fluid introduction chamber is positioned below the upper end plate of the heat exchange tube, and the second fluid forms an outer falling film on the outer wall of the heat exchange tube; and the second fluid receiving chamber is positioned above the lower end plate of the heat exchange tube and is used for containing a second fluid flowing down the heat exchange tube. The heat exchanger has good heat exchange effect, compact structure and small volume, and combines the advantages of less power consumption, small volume, small occupied area and low manufacturing cost of the heat exchanger absorption heat pump.

Description

Vertical double-falling-film heat exchanger and absorption heat pump

Technical Field

The invention relates to the technical field of heat pumps in thermal engineering, in particular to a vertical double-falling-film heat exchanger and an absorption heat pump.

Background

The absorption heat pump comprises an absorption refrigeration system, a first-class absorption heat pump system, a second-class absorption heat pump system and other absorption heat pumps in other forms, is a circulating system which uses heat as a driving force to pump heat from a low-temperature heat source to a high-temperature heat source, is an effective device for recycling low-grade heat energy, and has double functions of saving energy and protecting the environment. As shown in fig. 1, an absorption heat pump system generally includes an evaporator 100, an absorber 200, a generator 300, a condenser 400, a heat exchanger, piping, and a shield pump. The evaporator 100 is communicated with the absorber 200 through a first working medium steam passage 700, the generator 300 is communicated with the condenser 400 through a second working medium steam passage 800, the evaporation heat exchanger 102 of the evaporator 100 is arranged inside a container body of the evaporator 100, the absorption heat exchanger 202 of the absorber 200 is arranged inside a container body of the absorber 200, the generation heat exchanger 302 of the generator 300 is arranged inside a container body of the generator 300, and the condensation heat exchanger 402 of the condenser 400 is arranged inside a container body of the condenser 400. According to the temperature difference between the inlet and the outlet of the heat exchanger, the adopted heat sources are divided into a variable temperature heat source and a constant temperature heat source, and the heat exchange temperature difference of less than 3 ℃ can be regarded as the constant temperature heat source. The absorption heat pump mainly adopts a variable temperature heat source. The evaporation heat exchanger 102, the absorption heat exchanger 202, the generation heat exchanger 302 and the condensation heat exchanger 402 of the existing absorption heat pump only form falling films of working media or absorption solution on the outer pipe wall of the heat exchange pipe due to the adoption of the horizontally installed heat exchange pipe, but cannot form falling films of evaporation heat media, absorption heat media, generation heat media and condensation heat media on the inner pipe wall of the heat exchange pipe, so that the heat exchange effect is poor, and the power consumption required by heat medium circulation is large. Meanwhile, the existing absorption heat pump adopting the horizontal heat exchange tube has large volume due to small heat exchange intensity, and occupies large area due to the fact that only the horizontal box body design can be adopted.

Disclosure of Invention

In view of this, the embodiment of the present invention provides a vertical double-falling film heat exchanger, and mainly aims to improve a heat exchange effect, reduce power consumption, reduce a volume, and reduce a floor area.

In order to achieve the purpose, the invention mainly provides the following technical scheme:

in one aspect, an embodiment of the present invention provides a vertical double-falling film heat exchanger, including:

the heat exchange tube, the upper end plate of the heat exchange tube and the lower end plate of the heat exchange tube;

the first fluid guide chamber is positioned above the upper end plate of the heat exchange tube, and a first fluid in the first fluid guide chamber flows into the heat exchange tube from the upper end of the heat exchange tube and forms an internal falling film on the inner wall of the heat exchange tube;

the first fluid receiver is positioned below the lower end plate of the heat exchange tube and used for containing a first fluid flowing out of the heat exchange tube;

the second fluid introduction chamber is positioned below the upper end plate of the heat exchange tube;

and the second fluid receiving chamber is positioned above the lower end plate of the heat exchange tube and is used for containing a second fluid flowing down the heat exchange tube.

Preferably, the heat exchange tube penetrates through the second fluid introduction chamber to be communicated with the first fluid introduction chamber, the top plate of the second fluid introduction chamber is an upper end plate of the heat exchange tube, the bottom plate of the heat exchange tube is a liquid distribution pore plate, the liquid distribution pore plate is provided with liquid distribution holes for the heat exchange tube to penetrate through, the aperture of the liquid distribution holes is larger than the outer diameter of the heat exchange tube, a gap is formed between the outer wall surface of the heat exchange tube and the liquid distribution pore plate, the second fluid in the second fluid introduction chamber flows out through the gap, and an outer falling film is formed on the outer wall surface of the heat exchange tube;

preferably, the liquid distribution hole plate is provided with at least two convex parts extending along the radial direction of the liquid distribution hole on the circumference of each liquid distribution hole for positioning the heat exchange tube.

Preferably, the convex portions are uniformly distributed on the circumferential line of the liquid distribution hole.

On the other hand, the embodiment of the invention provides an absorption heat pump, which comprises an evaporator, an absorber, a generator and a condenser, wherein the evaporator and the absorber are communicated through a first working medium steam channel, the condenser and the generator are communicated through a second working medium steam channel, the generator and the absorber are communicated through a first solution circulating pipeline and a second solution circulating pipeline, the first solution circulating pipeline conveys an absorption solution from the generator to the absorber, the second solution circulating pipeline conveys the absorption solution from the absorber to the generator, the first solution circulating pipeline and the second solution circulating pipeline are provided with solution heat exchangers, the absorption solution conveyed in the first solution circulating pipeline and the second solution circulating pipeline carries out heat exchange through the solution heat exchangers, the evaporator and the condenser are connected through the working medium pipelines, the working medium pipelines convey the working medium in the condenser to the evaporator, the evaporator comprises an evaporation heat exchanger, the absorber comprises an absorption heat exchanger, the generator comprises a generation heat exchanger, the condenser comprises a condensation heat exchanger, wherein at least one of the evaporation heat exchanger, the absorption heat exchanger, the generation heat exchanger and the condensation heat exchanger adopts the vertical double-falling film heat exchanger in the embodiment.

Preferably, the evaporation heat exchanger is the vertical double-falling-film heat exchanger, and the evaporation heat exchanger is arranged in an evaporation chamber of the evaporator, wherein

The first fluid in the evaporation heat exchanger is a working medium, and the second fluid is an evaporation heat medium;

a first fluid introduction chamber above the upper end plate of the heat exchange tube is connected with a first fluid receiver below the lower end plate of the heat exchange tube through a working medium circulation pipeline, and the first fluid introduction chamber is connected with a condenser through a working medium pipeline;

the working medium circulating pipeline is provided with a working medium circulating pump, the working medium circulating pump conveys the working medium in the first fluid receiver to the first fluid introducing chamber, and preferably, the first fluid introducing chamber is internally provided with a first fluid spraying device. The working medium flowing out of the first fluid introduction chamber flows downwards along the inner wall surface of the heat exchange tube to form an internal falling film; the evaporation heat medium led into the chamber by the second fluid flows downwards along the outer wall surface of the heat exchange tube to form an outer falling film, the working medium and the evaporation heat medium exchange heat through the heat exchange tube, part of the working medium is heated and evaporated into steam, the working medium steam flows into the absorber through the first working medium steam channel, and the liquid working medium flows into the first fluid receiver.

For the case that the evaporation heat medium is steam, preferably, the evaporator may enlarge the gap between the outer wall surface of the heat exchange tube and the liquid distribution pore plate, or the evaporator may not be provided with the liquid distribution pore plate, and the evaporation heat medium is condensed on the outer wall surface of the heat exchange tube to form an outer falling film of the liquid evaporation heat medium.

Preferably, the absorption heat exchanger is the vertical double-falling-film heat exchanger, and the absorption heat exchanger is arranged in an absorption chamber of the absorber, wherein

The first fluid in the absorption heat exchanger is absorption solution, and the second fluid is absorption heating medium;

a first fluid introduction chamber above the upper end plate of the heat exchange tube is connected with a generator through a first absorption solution circulating pipeline;

the first fluid outlet chamber below the lower end plate of the heat exchange tube is connected with the generator through a second solution circulating pipeline;

a liquid distribution pore plate is arranged below the upper end plate of the heat exchange tube, and an absorption cavity between the upper end plate of the heat exchange tube and the liquid distribution pore plate forms a second fluid introduction chamber;

a cavity between the lower end plate of the heat exchange tube and the liquid distribution pore plate forms a second fluid receiving chamber;

the second fluid receiving chamber is connected with an absorption heat medium leading-in pipeline and an absorption heat medium leading-out pipeline, the absorption heat medium leading-in pipeline inputs the absorption heat medium into the second fluid receiving chamber, the second fluid receiving chamber is connected with the second fluid leading-in chamber through an absorption heat medium circulating pipeline, an absorption heat medium circulating pump is arranged on the absorption heat medium circulating pipeline, the absorption heat medium circulating pump conveys the absorption heat medium in the second fluid receiving chamber to the second fluid leading-in chamber, the absorption heat medium flows out through a gap between the outer wall surface of the heat exchange tube and the liquid distribution pore plate, and an outer falling film is formed on the outer wall of the heat exchange tube;

the absorption solution in the first fluid introduction chamber flows downwards along the inner wall surface of the heat exchange tube to form an inner falling film, simultaneously absorbs working medium steam generated in the evaporator and releases high-temperature absorption heat, the absorption solution and the absorption heat medium exchange heat through the heat exchange tube, and the absorption heat medium absorbing the high-temperature absorption heat is output through the absorption heat medium guide-out pipeline. Preferably, the first fluid introducing chamber is provided with a first fluid spraying device.

Preferably, in the case where part of the absorption heat medium is evaporated to the absorption heat medium vapor in the heat exchange, the absorption heat medium introduction pipe is installed below the second fluid lead-out chamber and the absorption heat medium lead-out pipe is installed above the second fluid lead-out chamber; in the case where the absorption heat medium vapor is not generated, the absorption heat medium introduction pipe is installed in the second fluid introduction chamber and the absorption heat medium discharge pipe is installed below the second fluid discharge chamber, and in this case, the absorber may not be provided with the absorption heat medium circulation pipe and the absorption heat medium circulation pump.

Preferably, the evaporator and the absorber share a vertical container, the evaporator is located above the container, and the absorber is located below the container. Preferably, the vertical container shared by the evaporator and the absorber is a vertical cylindrical container.

Preferably, the generating heat exchanger is the vertical double-falling-film heat exchanger, and the generating heat exchanger is arranged in a generating chamber of the generator, wherein

The first fluid in the generating heat exchanger is absorption solution, and the second fluid is generating heat medium;

a first fluid introduction chamber above the upper end plate of the heat exchange tube is connected with the absorber through a first absorption solution circulating pipeline;

the first fluid outlet chamber below the lower end plate of the heat exchange tube is connected with the absorber through a second solution circulating pipeline;

a liquid distribution pore plate is arranged below the upper end plate of the heat exchange tube, and a cavity between the upper end plate of the heat exchange tube and the liquid distribution pore plate forms a second fluid introduction chamber;

the generating heat medium leading-in pipeline is connected with the second fluid leading-in chamber, the generating heat medium leading-out pipeline is connected with the second fluid receiving chamber, the generating heat medium flows out through a gap between the outer wall surface of the heat exchange tube and the liquid distribution pore plate, and an outer falling film is formed on the outer wall of the heat exchange tube. For the case that the generated heating medium is steam, preferably, the generator can enlarge the gap between the outer wall surface of the heat exchange tube and the liquid distribution pore plate, or the liquid distribution pore plate is not arranged, and the evaporation heating medium is condensed on the outer wall surface of the heat exchange tube to form an outer falling film of the liquid evaporation heating medium;

the absorption solution in the first fluid introduction chamber flows downwards along the inner wall surface of the heat exchange tube to form an internal falling film, meanwhile, the absorption solution and the generation heat medium exchange heat through the heat exchange tube, part of the working medium in the absorption solution is heated and evaporated into working medium steam, and the steam working medium flows into the condenser through the second steam working medium channel.

Preferably, the condensing heat exchanger is the vertical double-falling-film heat exchanger, and the condensing heat exchanger is arranged in a condensing chamber of the condenser, wherein

The first fluid in the condensing heat exchanger is working medium steam, and the second fluid is a condensing heat medium;

a first fluid introduction chamber is arranged below the lower end plate of the heat exchange tube, a first fluid receiver is also arranged below the lower end plate of the heat exchange tube, and the first fluid receiver is connected with the evaporator through a working medium circulation pipeline;

the condensation heat medium guiding pipeline is connected with the second fluid guiding chamber, the condensation heat medium guiding pipeline is connected with the second fluid receiving chamber, the condensation heat medium flows out through a gap between the outer wall surface of the heat exchange tube and the liquid distribution pore plate, and an outer falling film is formed on the outer wall of the heat exchange tube;

the first fluid flowing into the heat exchange tube from the first fluid introduction chamber exchanges heat with the condensation heating medium through the heat exchange tube, and the first fluid is condensed and flows downwards along the inner wall surface of the heat exchange tube to form an inner falling film.

Preferably, the generator and the condenser share a single vertical vessel, the condenser being located above the vessel and the generator being located below the vessel. Preferably, the vertical container shared by the generator and the condenser is a vertical cylindrical container.

Preferably, at most three of the evaporation heat exchanger, the absorption heat exchanger, the generation heat exchanger and the condensation heat exchanger adopt the vertical double-falling-film heat exchanger in the embodiment, and the rest of the heat exchangers are arranged externally.

Preferably, the generator comprises an absorption solution flash evaporation chamber and a second absorption solution spraying device, the second absorbs solution spray piping, second absorption solution spray pump and emergence heat exchanger, the outside of absorption solution flash chamber is located to the emergence heat exchanger, upper portion in the absorption solution flash chamber is equipped with second absorption solution spray set, second absorption solution spray set is connected with the second absorption solution spray piping of locating absorption solution flash chamber outside, second absorption solution spray piping carries the absorption solution in the absorption solution flash chamber to second absorption solution spray set and sprays, be equipped with second absorption solution spray pump on the second absorption solution spray piping, second absorption solution spray piping is connected with the cold fluid side that takes place the heat exchanger, the heat medium pipeline that takes place of heat source is connected with the hot fluid side that takes place the heat exchanger.

Preferably, the generator further comprises a solid-liquid separation device, when the absorbent in the absorbent solution in the absorption solution flash chamber of the generator is crystallized, the solid-liquid separation device separates the absorption solution into two parts including absorbent crystals and absorbent crystals, wherein the absorbent solution without absorbent crystals is conveyed to the second absorption solution spraying device through the second absorption solution spraying pipeline, and the absorbent solution with absorbent crystals is conveyed into the absorber through the first solution circulating pipeline.

Preferably, the solid-liquid separation apparatus includes:

the liquid baffle plate is connected with the inner wall surface of the container body of the generator forming the absorption solution flash evaporation chamber, an interlayer is formed between the liquid baffle plate and the inner wall surface of the absorption solution flash evaporation chamber of the generator, and the absorption solution in the absorption solution flash evaporation chamber enters the interlayer from an interlayer inlet at the lower end of the liquid baffle plate;

an overflow tank formed on the outer wall surface of the container body of the generator for containing the absorption solution overflowing from the interlayer;

the overflow port is arranged on the side wall of the container body of the generator and is communicated with the interlayer and the overflow groove;

the second absorption solution spraying pipeline is communicated with the overflow groove, and the first solution circulating pipeline is communicated with the bottom of the absorption solution flash evaporation chamber; wherein

When the absorbent of the absorption solution is crystallized, the absorbent crystal falls to the bottom of the generator along the liquid baffle and the inner wall surface of the container body of the generator, the absorbent crystal falling to the bottom is conveyed to the absorber along with the absorption solution through the first solution circulating pipeline, the absorption solution enters the interlayer from the lower end of the liquid baffle, the absorption solution without the absorbent crystal at the upper part in the interlayer enters the overflow groove from the overflow port, and is conveyed to the second absorption solution spraying device through the second absorption solution spraying pipeline.

Preferably, the cross section of the lower part of the absorption solution flash chamber of the generator is gradually reduced to form a funnel shape, and the liquid baffle plate is obliquely arranged.

Preferably, the absorption heat pump is a second-type absorption heat pump, a throttle valve is arranged on the second solution circulating pipeline, and the throttle valve is arranged between the absorber and the solution heat exchanger. Thereby avoiding the crystallization blockage of the throttle valve caused by the temperature reduction of the absorption solution.

The absorption heat pump is a second-type absorption heat pump, a throttle valve is arranged on the second solution circulating pipeline, and the throttle valve is arranged between the absorber and the solution heat exchanger. Thereby avoiding the crystallization blockage of the throttle valve caused by the temperature reduction of the absorption solution.

Preferably, the evaporation heat exchanger is externally arranged as follows, the evaporator comprises an evaporation chamber, an evaporation heat exchanger, a working medium spray pipeline, a working medium spray pump and a working medium spray device, the evaporation heat exchanger is arranged outside the evaporation chamber, the evaporation heat exchanger and the working medium spray pump are arranged on the working medium spray pipeline, the working medium spray pump arranged on the working medium spray pipeline sends working medium in the evaporation chamber to the working medium spray device after heat exchange through the evaporation heat exchanger by the working medium spray pipeline, the working medium spray device sprays the working medium in the evaporation chamber, the evaporation chamber is a flash evaporation chamber, and the working medium is flashed into steam in the evaporation chamber.

Preferably, the absorption heat exchanger is externally arranged, and particularly, the absorber comprises an absorption chamber, an absorption heat exchanger and a first absorption solution spraying device, the absorption heat exchanger is arranged outside the absorption chamber, the absorption heat exchanger is a counter-flow heat exchanger, a first absorption solution spraying pipeline is arranged outside the absorption chamber, the absorption heat exchanger is arranged on a first absorption solution spraying pipeline which is connected with the absorption chamber and a first absorption solution spraying device, the first absorption solution spraying pipeline is provided with a first absorption solution spraying pump, the first absorption solution spraying pump sends the absorption solution in the absorption cavity to the first absorption solution spraying device after the heat exchange of the absorption heat exchanger through the first absorption solution spraying pipeline, the first absorption solution spraying device sprays absorption solution in the absorption chamber, and the absorption solution absorbs working medium steam in the evaporation chamber.

As preferred, the condensation heat exchanger is external specifically as follows, the condenser includes condensation cavity, condensation heat exchanger, condensation working medium spray set, condensation working medium spray line and condensation working medium spray pump, condensation working medium spray set locates in the condensation cavity, condensation working medium spray line locates the condensation cavity outside, condensation heat exchanger and condensation working medium spray pump locate on the condensation working medium spray line that is located the condensation cavity outside, condensation working medium spray pump carries the condensation working medium in with the condensation cavity behind the condensation heat exchanger to condensation working medium spray set by condensation working medium spray line, condensation working medium spray line with condensation heat exchanger's hot-fluid side is connected, and condensation heat exchanger's cold fluid side is connected with condensation heating medium pipeline.

Preferably, the heat source for generating the heat medium is industrial waste heat, geothermal heat, solar heat, or the like.

Preferably, the working medium is water; the absorbent is LiBr or LiNO₃LiCl and CaCl₂Any one or a mixture of two or more of them; the generating heating medium and the evaporating heating medium are saturated steam, wet steam, superheated steam or steam containing non-condensable gas, and the absorbing heating medium is water in a saturated state or a nearly saturated state.

Compared with the prior art, the invention has the beneficial effects that:

the heat exchanger provided by the embodiment of the invention is a novel vertical double-falling-film heat exchanger, and has the advantages of good heat exchange effect, small volume and compact structure. According to the invention, the heat exchanger is organically combined into the absorption heat pump, so that the absorption heat pump disclosed by the embodiment of the invention has the advantages of less power consumption, small volume, small occupied area and low manufacturing cost compared with the existing absorption heat pump.

Drawings

Fig. 1 is a schematic structural diagram of a second type absorption heat pump system in the prior art.

Fig. 2 is a schematic structural view of an absorption heat pump system according to embodiment 1 of the present invention.

Fig. 3 is a schematic structural view of an absorption heat pump system according to embodiment 2 of the present invention.

Fig. 4 is a schematic structural view of an absorption heat pump system according to embodiment 3 of the present invention.

Fig. 5 is a schematic structural view of an absorption heat pump system according to embodiment 4 of the present invention.

Fig. 6 is a schematic structural view of an absorption heat pump system according to embodiment 5 of the present invention.

FIG. 7 is a schematic structural diagram of a liquid distribution pore plate in an embodiment of the invention.

Detailed Description

The present invention will be described in further detail with reference to the following examples, which are not intended to limit the invention thereto. In the following description, different "one embodiment" or "an embodiment" refers to not necessarily the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

Fig. 2 is a schematic structural view of an absorption heat pump system according to embodiment 1 of the present invention. Fig. 3 is a schematic structural view of an absorption heat pump system according to embodiment 2 of the present invention. Fig. 4 is a schematic structural view of an absorption heat pump system according to embodiment 3 of the present invention. Fig. 5 is a schematic structural view of an absorption heat pump system according to embodiment 4 of the present invention. Fig. 6 is a schematic structural view of an absorption heat pump system according to embodiment 5 of the present invention. In each of the embodiments shown in fig. 2 to 6, a case where the vertical double-falling-film heat exchanger according to the embodiment of the present invention is used as a heat exchanger (including a generation heat exchanger, a condensation heat exchanger, an evaporation heat exchanger, and an absorption heat exchanger) is shown in fig. 2 to 6. Vertical two falling film heat exchangers includes:

a heat exchange tube 910, a heat exchange tube upper end plate 960 and a heat exchange tube lower end plate 970;

a first fluid introduction chamber 920 positioned above the heat exchange tube upper end plate 960, wherein the first fluid in the first fluid introduction chamber 920 flows into the heat exchange tube 910 from the upper end of the heat exchange tube 910, and forms an internal falling film on the inner wall of the heat exchange tube 910;

a first fluid receiver 930 positioned below the heat exchange tube lower end plate 970 for receiving a first fluid flowing out of the heat exchange tube 910;

a second fluid introduction chamber 940 positioned below the heat exchange tube upper end plate 960, wherein the second fluid in the second fluid introduction chamber 940 flows downwards on the outer wall surface of the heat exchange tube 910 to form an outer falling film;

and a second fluid receiving chamber 950 positioned above the lower end plate 970 of the heat exchange tube, the second fluid receiving chamber 950 being adapted to receive a second fluid flowing down along the outer wall surface of the heat exchange tube.

The vertical double-falling-film heat exchanger provided by the embodiment of the invention realizes double falling films inside and outside the heat exchange tube, and improves the heat exchange effect.

As a preferable example of the above embodiment, referring to fig. 2 to 7, fig. 7 is a schematic structural view of a liquid distribution orifice plate. In this embodiment, the heat exchange tube 910 passes through the second fluid introducing chamber 940 to communicate with the first fluid introducing chamber 920, the top plate of the second fluid introducing chamber 940 is an upper heat exchange tube end plate 960, the bottom plate is a liquid distribution pore plate 941, the liquid distribution pore plate 941 is provided with liquid distribution pores 942 for the heat exchange tube 910 to pass through, the pore diameter of the liquid distribution pores 942 is larger than the outer diameter of the heat exchange tube 910, a gap is formed between the outer wall surface of the heat exchange tube 910 and the liquid distribution pore plate, the second fluid in the second fluid introducing chamber 940 flows out through the gap, and an outer falling film is formed on the outer wall surface of the heat exchange tube 910. When this embodiment makes the second fluid flow down along the clearance that forms between heat exchange tube 910 and the liquid distribution orifice plate 941 through setting up liquid distribution orifice plate 941, forms outer falling liquid film better at the outer wall of heat exchange tube 910, has guaranteed the heat transfer effect, has improved heat exchange efficiency.

As a preferable example of the above embodiment, the liquid distribution hole plate 941 has at least two protrusions 943 extending in the radial direction of the liquid distribution holes 942 on the circumference of each liquid distribution hole 942 for positioning the heat exchange tube 910. The protrusion 943 can ensure the heat exchange tube 910 to be coaxial with the liquid distribution hole 942, and the assembly of the heat exchanger is easier. Further, the convex portions 943 are generally uniformly distributed on the circumferential line of the liquid distribution holes 942. Further, the number of the convex portions 943 is at least three, and if three convex portions 943 are provided, the three convex portions divide one circle of the liquid distribution hole into three equal parts. Of course, the protrusions 943 may take any suitable form other than the specific form of the above-described embodiment, as long as they can contact the outer wall surface of the heat exchange tube to position the heat exchange tube.

In another aspect, an embodiment of the present invention provides an absorption heat pump, and referring to fig. 2 to 6, the absorption heat pump includes an evaporator 100, an absorber 200, a generator 300, and a condenser 400; the evaporator 100 is communicated with the absorber 200 through a first working medium vapor passage 700, the condenser 400 is communicated with the generator 300 through a second working medium vapor passage 800, the generator 300 and the absorber 200 realize circulation of absorption solution through a solution circulation pipeline, wherein the absorption solution is conveyed from the generator 300 to the absorber 200 through the first solution circulation pipeline 510, the absorption solution is conveyed from the absorber 200 to the generator 300 through the second solution circulation pipeline 520, the solution heat exchanger 530 is arranged on the first solution circulation pipeline 510 and the second solution circulation pipeline 520, the absorption solution conveyed in the first solution circulation pipeline 510 and the second solution circulation pipeline 520 carries out heat exchange through the solution heat exchanger 530, the evaporator 100 is connected with the condenser 400 through the working medium pipeline 610, the working medium pipeline 610 conveys the working medium in the condenser 400 to the evaporator 100, the evaporator 100 comprises an evaporation heat exchanger 102, the absorber 200 comprises an absorption heat exchanger 202, the generator 300 comprises a generating heat exchanger 302 and the condenser 400 comprises a condensing heat exchanger 402, wherein at least one of the evaporating heat exchanger 102, the absorbing heat exchanger 202, the generating heat exchanger 302 and the condensing heat exchanger 402 is a vertical double falling film heat exchanger of the above-described embodiment.

After at least one of the evaporation heat exchanger 102, the absorption heat exchanger 202, the generation heat exchanger 302 and the condensation heat exchanger 402 provided by the embodiment of the invention adopts the vertical double-falling-film heat exchanger of the embodiment, the heat exchange effect can be improved, and the efficiency of the whole system can be improved.

Flow valves and fluid pumps, etc., not mentioned in the above embodiments, necessary for circulation of the system, are known to those skilled in the art or are available from the prior art. As in the second type absorption heat pump (see fig. 2 to 5), a working medium pump 620 is disposed on the working medium pipeline 610, so as to transport the working medium from the condenser to the evaporator through the working medium pipeline 610; the first solution circulating pipe 510 is provided with an absorbing solution circulating pump 550, and the second solution circulating pipe 520 is provided with a throttle valve 540. For the first-type absorption heat pump system (see fig. 6) or the absorption refrigeration system, since the flow direction of the liquid in the external circulation pipeline is opposite to that of the second-type absorption heat pump, when the working medium pipeline 610 conveys the working medium from the condenser to the evaporator, the working medium pump 620 is not needed, and the working medium pipeline 610 is only provided with the working medium throttle valve 630; the throttle 540 and the absorbing solution circulating pump 550 need to be exchanged in position, that is, the throttle 540 is disposed on the first solution circulating pipe 510, and the absorbing solution circulating pump 550 is disposed on the second solution circulating pipe 520.

Fig. 2 shows an embodiment in which only the evaporator heat exchanger of the evaporator employs a vertical double falling film heat exchanger. As shown in fig. 2, the evaporation heat exchanger is the vertical double-falling-film heat exchanger, and the evaporation heat exchanger is arranged in an evaporation chamber of the evaporator, wherein

The first fluid in the evaporation heat exchanger 100 is a working medium, and the second fluid is an evaporation heat medium;

the first fluid introduction chamber 920 above the heat exchange tube upper end plate 960 is connected with the first fluid receiver 930 below the heat exchange tube lower end plate 970 through the working medium circulation pipeline 105, and the first fluid introduction chamber 920 is connected with the condenser 400 through the working medium pipeline 610;

the working medium circulation pipe 105 is provided with a working medium circulation pump 104, and the working medium circulation pump 104 conveys the working medium in the first fluid receiver 930 to the first fluid introduction chamber 920.

In the above embodiment, the first fluid introduction chamber 920 is preferably provided with the first fluid shower device 103. The working medium in the first fluid introduction chamber 920 flows downwards along the inner wall surface of the heat exchange tube 910 to form an internal falling film; the evaporation heat medium in the second fluid introduction chamber 940 flows downwards along the outer wall surface of the heat exchange tube 910 to form an outer falling film, the working medium and the evaporation heat medium perform heat exchange through the heat exchange tube 910, part of the working medium is heated and evaporated into steam, the working medium steam flows into the absorber 200 through the first working medium steam channel 700, and the liquid working medium flows into the first fluid receiver 930. The second fluid (the evaporation heat medium in this embodiment) is introduced into the second fluid introduction chamber 940 through the evaporation heat medium introduction pipe 11, and is then discharged from the second fluid receiving chamber 950 through the evaporation heat medium discharge pipe 12. The present embodiment is a form that the first fluid forms a falling mold on the inner wall surface of the heat exchange tube 910, and the second fluid forms a falling mold on the outer wall surface of the heat exchange tube 910, and of course, the first fluid and the second fluid can be exchanged according to specific situations, and the falling molds are respectively formed inside and outside the heat exchange tube.

In the case that the evaporation heat medium is steam, preferably, the evaporator 100 may enlarge a gap between the outer wall surface of the heat exchange tube 100 and the liquid distribution hole plate, or may not be provided with the liquid distribution plate, and the evaporation heat medium is condensed on the outer wall surface of the heat exchange tube to form an outer falling film of the liquid evaporation heat medium.

Fig. 3 is an embodiment in which the absorption heat exchanger of only the absorber 200 employs a vertical double falling film heat exchanger. As shown in fig. 3, the absorption heat exchanger is a vertical double-falling-film heat exchanger, and the absorption heat exchanger is arranged in an absorption chamber of the absorber, wherein

the first fluid introduction chamber 920 above the heat exchange tube upper end plate 960 is connected to the generator 300 through the first absorption solution circulation pipe 510;

a first fluid outlet chamber 930 below the lower end plate 970 of the heat exchange pipe is connected with the generator through a second solution circulation pipe 520;

a liquid distribution pore plate 941 is arranged below the upper end plate 960 of the heat exchange tube, and a second fluid introduction chamber 940 is formed in the absorption chamber 201 between the upper end plate 960 of the heat exchange tube and the liquid distribution pore plate 941;

the absorption chamber 201 between the lower end plate 970 of the heat exchange tube and the liquid distribution pore plate 941 forms a second fluid receiving chamber 950;

the second fluid receiving chamber 950 is connected with an absorption heat medium introducing pipeline 21 and an absorption heat medium leading-out pipeline 22, the absorption heat medium introducing pipeline 21 inputs the absorption heat medium into the second fluid receiving chamber 950, the second fluid receiving chamber 950 is connected with the second fluid leading-in chamber 940 through an absorption heat medium circulating pipeline 205, the absorption heat medium circulating pipeline 205 is provided with an absorption heat medium circulating pump 204, the absorption heat medium circulating pump 204 conveys the absorption heat medium in the second fluid receiving chamber 950 to the second fluid leading-in chamber 940, the absorption heat medium flows out through a gap between the outer wall surface of the heat exchange pipe 910 and a liquid distribution hole plate 941, and an outer falling film is formed on the outer wall of the heat exchange pipe 910;

the absorption solution in the first fluid introduction chamber 920 flows downwards along the inner wall surface of the heat exchange tube 910 to form an inner falling film, and simultaneously absorbs the working medium steam generated in the evaporator and releases high-temperature absorption heat, the absorption solution and the absorption heat medium exchange heat through the heat exchange tube, and the absorption heat medium absorbing the high-temperature absorption heat is output through the absorption heat medium discharge pipeline. Preferably, a first fluid spraying device 203 is disposed in the first fluid introducing chamber.

As a preferable mode of the above embodiment, in the case where part of the absorption heat medium is evaporated into the absorption heat medium vapor in the heat exchange, the absorption heat medium introduction pipe is installed below the second fluid lead-out chamber and the absorption heat medium lead-out pipe is installed above the second fluid lead-out chamber; in the case where the absorption heat medium vapor is not generated, the absorption heat medium introduction pipe is installed in the second fluid introduction chamber and the absorption heat medium discharge pipe is installed below the second fluid discharge chamber, and in this case, the absorber may not be provided with the absorption heat medium circulation pipe and the absorption heat medium circulation pump.

Preferably, the evaporator and the absorber share a vertical container, the evaporator is located above the vertical container, and the absorber is located below the vertical container. Preferably, the vertical container shared by the evaporator and the absorber is a vertical cylindrical container.

Fig. 4 shows an embodiment in which both the evaporating heat exchanger and the absorbing heat exchanger employ a vertical double falling film heat exchanger according to an embodiment of the present invention. For a detailed description, please refer to the description part of the embodiment in fig. 2 and fig. 3, which is not repeated herein.

Fig. 5 is an embodiment in which the evaporating heat exchanger, the absorbing heat exchanger and the condensing heat exchanger all employ the vertical double falling film heat exchanger of the embodiment of the present invention. Referring to the condensing heat exchanger part in fig. 5, the condensing heat exchanger is a vertical double-falling-film heat exchanger, and the condensing heat exchanger is arranged in a condensing chamber of the condenser, wherein

a first fluid introduction chamber 920 is arranged below the heat exchange tube lower end plate 970, a first fluid receiver 930 is further arranged below the heat exchange tube lower end plate 970, and the first fluid receiver 930 is connected with the evaporator 100 through a working medium circulation pipeline 610;

a liquid distribution pore plate 941 is arranged below the upper end plate 960 of the heat exchange tube, and a second fluid introduction chamber 940 is formed in a cavity between the upper end plate 960 of the heat exchange tube and the liquid distribution pore plate 941;

a second fluid receiving chamber 950 is formed by a cavity between the lower end plate 970 of the heat exchange tube and the liquid distribution pore plate 941;

the condensation heat medium leading-in pipeline 41 is connected with the second fluid leading-in chamber 940, the condensation heat medium leading-out pipeline 42 is connected with the second fluid receiving chamber 950, the condensation heat medium flows out through a gap between the outer wall surface of the heat exchange pipe 910 and the liquid distribution pore plate 941, and an outer falling film is formed on the outer wall of the heat exchange pipe 910;

the first fluid flowing into the heat exchange tubes from the first fluid introduction chamber 920 exchanges heat with the condensing heat medium through the heat exchange tubes, and the first fluid is condensed and flows downward along the inner wall surfaces of the heat exchange tubes to form an inner falling film.

Fig. 6 shows an embodiment in which the vertical double falling film heat exchanger according to an embodiment of the present invention is used for each of the evaporation heat exchanger, the absorption heat exchanger, the generation heat exchanger, and the condensation heat exchanger. The heat exchanger section occurs as seen in fig. 6. The generation heat exchanger is a vertical double-falling-film heat exchanger and is arranged in a generation chamber of the generator, wherein

the first fluid introduction chamber 920 above the heat exchange tube upper end plate 960 is connected to the absorber 200 through the first absorption solution circulation pipe 510;

a first fluid outlet chamber 930 below the lower end plate 970 of the heat exchange pipe is connected to the absorber 200 through a second solution circulation pipe 520;

the generation heat medium introduction pipe 31 is connected to the second fluid introduction chamber 940, the generation heat medium introduction pipe 32 is connected to the second fluid receiving chamber 950, and the generation heat medium flows out through a gap between the outer wall surface of the heat exchange pipe 910 and the liquid distribution hole plate 941, and forms an outer falling film on the outer wall of the heat exchange pipe 910. For the case that the generated heating medium is steam, preferably, the generator may enlarge the gap between the outer wall surface of the heat exchange tube 910 and the liquid distribution pore plate, or may not be provided with the liquid distribution plate 941, and the evaporation heating medium is condensed on the outer wall surface of the heat exchange tube to form an outer falling film of the liquid evaporation heating medium;

Of course, while the vertical double falling film heat exchanger of the above embodiment is used as part of the evaporation heat exchanger 102, the absorption heat exchanger 202, the generation heat exchanger 302 and the condensation heat exchanger 402, other parts of the absorption heat pump of the embodiment of the present invention may be used in the prior art, or may be modified to improve the efficiency of the whole system. As a preferred feature of the above embodiment, at most three of the evaporation heat exchanger, the absorption heat exchanger, the generation heat exchanger, and the condensation heat exchanger are the vertical double falling film heat exchanger described in the above embodiment, and the rest are externally disposed. In this embodiment, the vertical double-falling film heat exchanger in the above embodiment is not adopted, and a form in which the heat exchanger is externally arranged may be adopted. The details of the case where the evaporation heat exchanger 102, the absorption heat exchanger 202, the generation heat exchanger 302, or the condensation heat exchanger 402 is externally disposed (the vertical double falling film heat exchanger is not used) will be described below.

Referring to fig. 3, the evaporator 100 includes an evaporation chamber 101, an evaporation heat exchanger 102, a working medium spray pipeline 105, a working medium spray pump 104 and a working medium spray device 103, the evaporation heat exchanger 102 is disposed outside the evaporation chamber 101, the evaporation heat exchanger 102 is a counter-flow heat exchanger, the working medium spray pipeline 105 is connected to a cold fluid side of the evaporation heat exchanger 102, the working medium spray pump 104 disposed on the working medium spray pipeline 105 transfers the working medium in the evaporation chamber 101 from the working medium spray pipeline 105 to the working medium spray device 103 after heat exchange by the evaporation heat exchanger 102, the working medium spray device 103 sprays the working medium in the evaporation chamber 101, the evaporation chamber 101 is a flash evaporation chamber, and the working medium is flashed into steam in the evaporation chamber 101.

The evaporator 100 of the embodiment of the present invention moves the evaporation heat exchanger 102 to the outside of the evaporation chamber 101, which can simplify the structure of the heat pump system and is more favorable for the case of using an absorption solution with high viscosity or containing absorbent crystals, thereby further improving the performance and the economical efficiency of the heat pump system. Particularly, for the absorption heat pump utilizing the variable-temperature low-temperature heat source, the working medium is quickly evaporated by combining spray flash evaporation, so that the external circulation flow of the working medium is reduced, and the power loss is reduced.

As a preference of the above embodiment, the container body forming the evaporation chamber 101 is cylindrical. In this embodiment, the container body of the evaporator 100 is cylindrical, which improves the pressure resistance of the evaporator 100, thereby improving the safety of the evaporator 100. In the prior art, as the evaporation heat exchanger 102 is internally arranged, in order to improve the heat exchange effect between the sprayed working medium and the evaporation heat exchanger 102, a shell and tube heat exchanger is required, and the container body of the evaporator 100 only can be in a cuboid shape, so that the pressure resistance is poor, and the safety is low.

Referring to fig. 2, fig. 2 shows an embodiment of an absorption heat pump system with an external absorption heat exchanger. The absorber 200 comprises an absorption chamber 201, an absorption heat exchanger 202 and a first absorption solution spraying device 203, the absorption heat exchanger 202 is arranged outside the absorption chamber 201, the absorption heat exchanger 202 is a counter-current heat exchanger, a first absorption solution spraying pipeline 205 is arranged outside the absorption chamber 201, the absorption heat exchanger 202 is arranged on the first absorption solution spraying pipeline 205, the first absorption solution spraying pipeline 205 is connected with the absorption chamber 201 and the first absorption solution spraying device 203, and a first absorption solution spraying pump 204 is arranged on the first absorption solution spraying pipeline 205. The first absorption solution spraying pump 204 transfers the absorption solution in the absorption chamber 201 from the first absorption solution spraying pipeline 205 to the first absorption solution spraying device 203 after heat exchange by the absorption heat exchanger 202, the first absorption solution spraying device 203 sprays the absorption solution in the absorption chamber 201, and the absorption solution absorbs the working medium vapor in the evaporation chamber. In this embodiment, on the basis of the external arrangement of the evaporation heat exchanger 102, the absorption heat exchanger 202 is also externally arranged, so that the heat and mass transfer process of the absorber part is enhanced, and the performance of the whole heat pump system is further improved. In the second type absorption heat pump, the first absorption solution spray pipe 205 is connected with the heat fluid side of the absorption heat exchanger 202, and the cold fluid side of the absorption heat exchanger 202 is connected with the absorption heat medium pipe.

As a preference of the above embodiment, the cross-section of the bottom of the absorption chamber 201 is gradually reduced. When the container body of the absorber 200 takes a cylindrical shape, the bottom of the absorption chamber 201 has an inverted conical shape. The liquid holding amount can be effectively reduced, so that the starting time of the system is shorter, the manufacturing cost is lower, and the pressure resistance and the corrosion resistance are higher.

As a preference of the above embodiment, the first solution circulation pipe 510 is connected to the first absorption solution spray device 203. In the present embodiment, on the basis of the above-described embodiments, the first solution circulation pipe 510 is connected to the first absorption solution spraying device 203, so that the absorption solution delivered by the first solution circulation pipe 510 and the absorption solution delivered by the first absorption solution spraying pipe 205 are mixed and delivered to the first absorption solution spraying device 203 for spraying. The power loss can be further reduced.

As a preference of the above embodiment, referring to fig. 2 to 6, wherein the evaporator 100 and the absorber 200 share the same container body, the container body is cylindrical, the upper part of the inner chamber of the container body forms the evaporation chamber 101 of the evaporator 100, and the lower part forms the absorption chamber 201 of the absorber 200. In this embodiment, the evaporator 100 and the absorber 200 share the same container body, and the container body is cylindrical, and has the characteristics of high pressure resistance and simple structure.

Preferably, the evaporation chamber 101 includes a first section and a second section, wherein the inner diameter of the first section is smaller than the inner diameter of the second section, the working medium receiver 106 is disposed in the second section, the working medium spraying device 103 is disposed in the first section, and the diameter of the working medium receiver 106 is greater than or equal to the inner diameter of the first section of the evaporation chamber. In the embodiment, two sections with different inner diameters are arranged, so that the sprayed working medium falls into the working medium receiver 106. In addition, the characteristic that the heat and mass transfer rate in the evaporation process is greater than that in the absorption process is utilized, so that the volume of the evaporation chamber is smaller than that of the absorption chamber, and the aims of reducing the installation space and reducing the material usage and cost are fulfilled.

Preferably, the lower end of the first section is provided with a working medium flow guiding structure 109, and the working medium flow guiding structure 109 guides the working medium on the inner wall of the first section into the working medium receiver 106. Through the arrangement of the working medium flow guide structure 109, all the working mediums sprayed on the inner wall of the first section can fall into the working medium receiver 106. The specific structure of the working medium flow guiding structure 109 is not limited, as long as the sprayed working medium is completely guided into the working medium receiver 106. The embodiment provides a simple structure, the working medium water conservancy diversion structure of easily making, this working medium water conservancy diversion structure is the working medium guide plate, and the working medium guide plate is formed by the lower extreme downwardly extending of first section, and the working medium guide plate stretches into the space of first section below. Thus, working medium on the inner wall of the first section can fall into the working medium receiver 106 along the working medium guide plate.

Preferably, the working medium pipeline 610 is connected with the working medium spraying device 103. The working medium delivered by the working medium pipeline 610 is mixed with the working medium delivered by the working medium spray pipeline 105 and then sprayed by the working medium spray device. Further reducing the flow in the working medium spraying pipeline 105, and saving more power than directly inputting the working medium into the evaporation chamber 101 through the working medium pipeline 610.

As a preference of the above embodiment, the solution heat exchangers 530 are provided on the first solution circulation pipe 510 and the second solution circulation pipe 520, and the absorption solutions transported in the first solution circulation pipe 510 and the second solution circulation pipe 520 are heat-exchanged by the solution heat exchangers 530. In this embodiment, the solution heat exchanger 530 is disposed on the solution circulation pipeline for circulation of the absorption solution between the absorber 200 and the generator 300, so that heat exchange of the absorption solution in the circulation process is realized, and the heat efficiency of the heat pump is further improved.

Preferably, in the above embodiment, the absorption solution circulation line is provided with a throttle valve 540, and the throttle valve 540 is provided between the absorber 200 and the solution heat exchanger 530. In the second type absorption heat pump system, the throttle valve 540 is disposed on the second solution circulation pipe 520. In the first type absorption heat pump system or the absorption refrigeration system, the throttling valve 540 is disposed on the first solution circulating pipe 510. Particularly, in the second type absorption heat pump, the present embodiment can prevent the throttle valve 540 from being blocked by crystallization due to temperature reduction. An outlet 531 of the solution heat exchanger 530 on the second solution circulation pipe 520 is disposed proximate to the generator 300. That is, the absorption solution sent from the second solution circulation line 520 is input to the generator 300 at a distance as short as possible after being output from the solution heat exchanger 530.

As a preference for the above embodiment, reference is made to fig. 2 to 5, which show the case where the heat exchanger is externally positioned. In this embodiment, the generator 300 includes an absorption solution flash evaporation chamber 301, a generation heat exchanger 302 and a second absorption solution spraying device 303, the generation heat exchanger 302 is disposed outside the absorption solution flash evaporation chamber 301, a second absorption solution spraying device 303 is disposed on an upper portion inside the absorption solution flash evaporation chamber 301, the second absorption solution spraying device 303 is connected to a second absorption solution spraying pipeline 305 disposed outside the absorption solution flash evaporation chamber 301, the second absorption solution spraying pipeline 305 conveys the absorption solution inside the absorption solution flash evaporation chamber 301 to the second absorption solution spraying device 303 for spraying, a second absorption solution spraying pump 304 is disposed on the second absorption solution spraying pipeline 305, the second absorption solution spraying pipeline 305 is connected to a cold fluid side of the generation heat exchanger 302, and a generation heat medium pipeline of a heat source is connected to a hot fluid side of the generation heat exchanger 302.

In the generator 300 provided in this embodiment, the generation heat exchanger 302 is disposed outside the absorption solution flash chamber 301, and the absorption solution conveyed by the second absorption solution spraying pipeline 305 is subjected to heat exchange and temperature rise by the generation heat exchanger 302, and then conveyed to the second absorption solution spraying device 303 to be sprayed in the absorption solution flash chamber 301 of the generator 300. The principle of vacuum adiabatic flash is based on subjecting fine droplets of the absorption solution to vacuum adiabatic flash in an absorption solution flash chamber 301 within the generator 300. Compared with the cross-flow heat exchange tube in the prior art, the generation heat exchanger 302 in the embodiment adopts a counter-flow plate heat exchanger, and can realize complete counter-flow heat exchange, thereby improving the heat exchange strength and reducing the heat exchange temperature difference. The second-type absorption heat pump adopting the generator provided by the embodiment of the invention can adopt high-concentration absorption solution. Even if the absorption solution is evaporated, concentrated and cooled to supersaturate the absorbent and crystallize out crystal particles, since the generated fine crystal particles flow with the absorption solution, part of the crystals are transferred from the second absorption solution spray pipe 305 to the generation heat exchanger 302 and then dissolved by heat exchange. The problems that heat transfer and mass transfer are blocked due to crystallization of a heat exchange surface in the prior art do not exist. In addition, the second type absorption heat pump adopting the generator of the embodiment is suitable for adopting a low-temperature heat source with the variable-temperature heat source characteristic.

Referring to fig. 3 and 4, as a preferred embodiment, in order to further solve the problem of absorbent crystallization that may be caused by using a high-concentration absorbent solution, the generator 300 in the embodiment of the present invention further includes a solid-liquid separation device, and when the absorbent solution in the absorbent solution flash chamber 301 is crystallized, the solid-liquid separation device separates the absorbent solution into two parts including absorbent crystals and absorbent crystals, wherein the absorbent solution without absorbent crystals is delivered to the second absorbent solution spraying device 303 through the second absorbent solution spraying pipe 305, and the absorbent solution with absorbent crystals is delivered into the absorber 200 through the first solution circulating pipe 510. In this embodiment, the solid-liquid separation device is provided to separate the absorbent crystals in the absorbent solution, thereby further reducing the influence of the absorbent crystals on the operation of the generator 300. In addition, by arranging the solid-liquid separation device, the absorption solution which is output for spraying does not contain or contains less crystals, so that the absorption heat pump of the embodiment of the invention can adopt a generation heat source with lower temperature grade.

As a preferable example of the above embodiment, referring to fig. 3, in the present embodiment, the solid-liquid separation apparatus includes:

a liquid baffle 371 connected to the inner wall surface of the container body of the generator 300 forming the absorption solution flash chamber 301, an interlayer 374 formed between the liquid baffle 371 and the inner wall surface of the absorption solution flash chamber 301 of the generator 300, and the absorption solution in the absorption solution flash chamber 301 enters the interlayer from an interlayer inlet 375 at the lower end of the liquid baffle 371;

an overflow groove 373 formed on the outer wall surface of the container body of the generator 300 for receiving the absorption solution overflowing from the interlayer 374;

an overflow port 372 provided on the side wall of the container body of the generator 300, the overflow port 372 communicating the interlayer 374 and the overflow groove 373;

the second absorption solution spraying pipeline 305 is communicated with the overflow groove 373, and the first solution circulating pipeline 510 is communicated with the bottom of the absorption solution flash chamber 301; wherein

When the absorbent of the absorption solution is crystallized, the absorbent crystals fall downwards along the liquid baffle 371, when the absorbent crystals fall to the lower end of the liquid baffle 371, part of the absorbent crystals flow upwards along the interlayer along with the absorption solution, the absorbent crystals entering the interlayer fall again under the action of gravity and fall to the bottom of the generator 300 along the inner wall surface of the container body of the generator, the absorption solution in the interlayer realizes solid-liquid separation, the absorption solution on the upper part of the interlayer basically does not contain crystals, the absorbent crystals are conveyed to the absorber 200 along with the absorption solution through the first solution circulating pipeline 510, the absorption solution enters the interlayer from the lower end of the liquid baffle 371, the absorption solution on the upper part of the interlayer, which does not contain the absorbent crystals, enters the overflow channel 373 from the overflow port 372 and is conveyed to the second absorption solution spraying device 303 through the second absorption solution spraying pipeline 305. The solid-liquid separation device of the embodiment has a simple structure and a good separation effect. Carrying out solid-liquid separation on the absorption solution subjected to flash evaporation in the solid-liquid separation device, and then sending the absorption solution containing absorbent crystal particles to an absorber; since the absorbent crystal particles are fine and have fluidity, clogging of the absorption solution circulation pump 550, the first absorption solution spray device 203, and the first solution circulation pipe 510 is not caused; because the absorbent is crystallized at the lower temperature of the generator 300, namely at the lower solubility, and is dissolved at the higher temperature of the absorber 200, namely at the higher solubility, the absorber can use the absorption solution with the concentration higher than that of the absorption solution of the generator, even can use the saturation concentration at or close to the absorption temperature, thereby greatly improving the temperature grade of the industrial waste heat under the condition of the lower temperature grade of the generated heat source, facilitating the recycling, and bringing remarkable energy-saving effect and economic benefit to users. The liquid baffle 371 should be inclined to improve the separation effect.

As a preference of the above embodiment, referring to fig. 2 and 3, the absorption solution flashing chamber 301 of the generator 300 has a gradually decreasing cross-section in the lower part thereof in the shape of a funnel. The lower part of the absorption solution flash chamber 301 of the generator 300 is formed in a funnel shape (when the container body is cylindrical, the lower part of the absorption solution flash chamber 301 is formed in an inverted cone shape), and plays a certain role in the precipitation of absorbent crystals even if the liquid blocking plate 371 is not provided. In addition, the gradual reduction of the cross section of the lower part of the absorption solution flash chamber 301 can effectively reduce the liquid holding capacity, thereby leading to shorter start-up time of the system, lower manufacturing cost, higher compressive strength and higher corrosion resistance. Meanwhile, the absorbent crystals may be transferred to the first absorption solution spray device 203 in the absorber 200 from the first solution circulation pipe 510.

As a preferred embodiment, fig. 2 to 4 show the case that the condensing heat exchanger is externally arranged, referring to fig. 2 to 4, the condenser 400 includes a condensing chamber 401, a condensing heat exchanger 402, a condensing medium spray device 403, a condensing medium spray pipeline 405 and a condensing medium spray pump 404, the condensing medium spray device 403 is arranged in the condensing chamber 401, the condensing medium spray pipeline 405 is arranged outside the condensing chamber 401, the condensing heat exchanger 402 and the condensing medium spray pump 404 are arranged on the condensing medium spray pipeline 405, the condensing medium spray pump 404 conveys the condensing medium in the condensing chamber 401 from the condensing medium spray pipeline 405 to the condensing medium spray device 403 through the condensing heat exchanger 402, the condensing medium spray pipeline 405 is connected with the heat fluid side of the condensing heat exchanger 402, and the cold fluid side of the cooling heat exchanger 402 is connected with the condensing medium pipeline. In this embodiment, the condensing heat exchanger 402 is externally arranged, so that the working medium can perform countercurrent heat exchange in the condensing heat exchanger 402. The condensing heat exchanger 402 can adopt a detachable plate heat exchanger, complete countercurrent heat exchange is realized, the heat exchange effect is improved, and the heat exchanger is convenient to maintain for condensing heat media which easily cause scaling or blockage.

Preferably, the generator 300 and the condenser 400 share the same container body, the upper part of the chamber in the container body is a condensation chamber 401 of the condenser 400, the lower part of the inner chamber in the container body is an absorption solution flash evaporation chamber 301 of the generator 300, a condensed working medium receiver 406 is arranged at the lower part in the condensation chamber 401, a second working medium vapor channel 800 is formed between the outer wall of the condensed working medium receiver 406 and the inner wall of the container body, and the condensed working medium receiver 406 is connected with the working medium pipeline 610. The condensing heat exchanger of the condenser is connected with a condensing heat medium pipeline, and the condensing heat medium exchanges heat through the condensing heat exchanger to absorb the condensing heat of the working medium. The absorption solution sprayed by the second absorption solution spraying device 303 is flashed in the absorption solution flashing chamber 301, the evaporated working medium is condensed in the condensation chamber 401, the condensed working medium receiver 406 receives the liquid working medium formed by condensation of the working medium vapor, and the working medium pipeline 610 transmits the liquid working medium received by the condensed working medium receiver 406 to the evaporator 100. The condenser 400 and the generator 300 share one container body, and a condensation area is formed at the upper part in the container body, and a flash evaporation area is formed at the lower part in the container body, so that the performance is further improved, and the cost is reduced.

In the case where the generator 300 and the condenser 400 share the same cylindrical container body, the condensing heat exchanger may be built-in or external. Wherein the condensing heat exchanger 402 is located above the condensed working medium receiver 406 when the condensing heat exchanger is built in. Working medium vapor generated in the absorption solution flash chamber 301 of the generator 300 is cooled by the condensing heat exchanger 402, condensed into a liquid state, and falls into the condensed working medium receiver 406.

When the condensing heat exchanger 402 is external, the condenser 400 includes a condensing chamber 401, the condensing heat exchanger 402, a condensed working medium spraying device 403, a condensed working medium spraying pipeline 405, a condensed working medium spraying pump 404 and a condensed working medium receiver 406, the condensed working medium spraying device 403 is arranged in the condensing chamber 401 and located above the condensed working medium receiver 406, and the condensed working medium spraying pipeline 405 is connected with the condensed working medium receiver 406. In this embodiment, the condensing heat exchanger 402 is disposed externally, so that the working medium can perform countercurrent heat exchange in the cooling heat exchanger 402.

Preferably, the condensation chamber 401 includes a first section and a second section, wherein the inner diameter of the first section is smaller than the inner diameter of the second section, the condensed working medium receiver 406 is disposed in the second section, the condensed working medium spray device 403 is disposed in the first section, and the diameter of the condensed working medium receiver 406 is greater than or equal to the inner diameter of the first section of the evaporation chamber. In this embodiment, by providing two sections with different inner diameters, the condensed working medium falls into the condensed working medium receiver 406. In addition, in the case where the condenser and the generator share one vessel, the inner diameter of the absorption solution flash chamber 301 coincides with the inner diameter of the second section of the condensation chamber 401. The characteristic that the heat and mass transfer rate in the condensation process is greater than that in the generation process is utilized, so that the volume of the condensation chamber is smaller than that of the flash evaporation chamber, and the aims of reducing the installation space and reducing the material usage and cost are fulfilled.

Preferably, the lower end of the first section of the condensation chamber 401 is provided with a condensed working medium guiding structure 409, and the condensed working medium guiding structure 409 guides the condensed working medium on the inner wall of the first section into the condensed working medium receiver 406. By arranging the condensed working medium diversion structure 409, the condensed working medium sprayed on the inner wall of the first section can fall into the condensed working medium receiver 406. The specific structure of the condensed working medium guiding structure 409 is not limited, as long as the sprayed working medium is completely guided into the condensed working medium receiver 406. The embodiment provides a simple structure, the condensing working medium water conservancy diversion structure of easily making, and this condensing working medium water conservancy diversion structure is the condensing working medium guide plate, and the condensing working medium guide plate is formed by the lower extreme downwardly extending of first section, and the space of condensing working medium guide plate below stretching into first section. In this way, the condensed working fluid on the inner wall of the first section may fall along the condensed working fluid guide plate into the condensed working fluid receiver 406.

The circulation method of the absorption heat pump of the embodiment of the invention comprises an evaporator link, an absorber link, a generator link and a condenser link, and the embodiments of the different heat pumps can be referred to at the same time, wherein

An evaporator step, wherein the working medium absorbs heat from the heating medium in the evaporation heat exchanger and is evaporated into working medium steam, and the working medium steam is conveyed into an absorber

The absorber link is used for absorbing the working medium steam generated by the evaporator and releasing high-temperature absorption heat, the absorption heat is taken as a high-temperature heat source and is output to the outside through the heat medium in the absorption heat exchanger, and the absorption solution in the absorber is conveyed into the generator;

in the generator link, after the absorption solution is heated by a heating generator of a generating heat exchanger, the working medium in the absorption solution is changed into steam, and the absorption solution after evaporation and concentration is conveyed to an absorber;

a condenser link, condensing the working medium steam generated by the generator and releasing condensation heat, wherein the condensation heat is taken away by cooling water in a condensation heat exchanger; liquid working media formed by condensation in the condenser are conveyed to the evaporator through a working medium pipeline;

wherein, at least one of the evaporation heat exchanger, the absorption heat exchanger, the generation heat exchanger and the condensation heat exchanger is the vertical double falling film heat exchanger described in the above embodiment.

On the basis of the above embodiment, when the vertical double falling film heat exchanger of the above embodiment is not adopted in the corresponding heat exchanger, the corresponding heat exchanger may be externally arranged.

As a preferred embodiment of the above embodiment, in combination with the embodiment in which the generation heat exchanger is externally disposed, in the generator link, the second absorption solution spraying device located at the upper part of the absorption solution flash evaporation chamber of the generator sprays the heated absorption solution, so that the fine liquid droplets of the absorption solution are subjected to vacuum adiabatic flash evaporation in the absorption solution flash evaporation chamber of the generator; the working medium steam generated by flash evaporation is conveyed to a condenser; absorbing the solution in the flash evaporation process to obtain evaporation concentration and cooling; the absorption solution after flash evaporation falls to the bottom of the absorption solution flash evaporation chamber, a part of the absorption solution enters a generation heat exchanger arranged outside the generator through a second absorption solution spray pump, heat of a generation heat source is absorbed through heat exchange between the generation heat exchanger and a generation heat medium, and the absorption solution after temperature rise is conveyed to a second absorption solution spray device; conveying a part of absorption solution to a first absorption solution spraying device in the absorber through a solution circulating pump for spraying;

the absorption heat pump circulation method provided by the embodiment of the invention heats the absorption solution outside the container body of the generator, can avoid heat transfer and mass transfer obstacles caused by crystallization of the absorbent on the heat exchange surface of the heat exchanger when the heat exchanger is built in, and is particularly beneficial to a second-class absorption heat pump working under the condition of high-concentration absorption solution. In addition, the generation heat exchanger of the embodiment of the invention can adopt a counter-flow heat exchanger, so that the variable-temperature generation heat source including water, hot air, heat conduction oil, superheated steam, steam containing non-condensable gas and the like can be more efficiently utilized. Particularly, the second type absorption heat pump can also work under the condition that the concentration of the absorption solution of the absorber is higher than that of the absorption solution of the generator, so that a lower-grade generation heat source can be utilized to obtain higher temperature grade improvement of industrial waste heat (including geothermal heat, solar heat and the like), and the industrial waste heat is more recycled, thereby bringing remarkable energy-saving effect and economic benefit to users. By making the supersaturated crystallized absorbent crystal particles fine and have fluidity, the invention can effectively overcome the problems of heat and mass transfer obstacles of a heat exchanger and blockage of pipelines and the like caused by absorbent crystallization in the prior second-type absorption heat pump.

Preferably, in combination with the embodiment in which the absorption heat exchanger is externally disposed in the absorption heat pump system, the absorber link is configured such that the absorption solution in the absorption chamber of the absorber is output through the first absorption solution spray pipe, the absorption solution conveyed by the first absorption solution spray pipe is subjected to heat exchange by the absorption heat exchanger and then conveyed to the first absorption solution spray device located in the absorption chamber of the absorber for spraying, the sprayed absorption solution absorbs the working medium vapor generated by the evaporator in the absorption chamber and releases high-temperature absorption heat, and the absorption heat is output to the outside through the absorption heat medium on the cold fluid side of the absorption heat exchanger.

As a preferable example of the above embodiment, the absorbing solution sent from the generator is sent to the first absorbing solution spraying device to be sprayed. The embodiment can further reduce the external circulation flow and reduce the power loss.

Preferably, in combination with the embodiment in which the evaporation heat exchanger is externally disposed in the absorption heat pump system, in the evaporator link, the working medium in the evaporation chamber of the evaporator is output via the working medium spray pipe, the working medium conveyed by the working medium spray pipe is subjected to heat exchange and heating by the evaporation heat exchanger and then conveyed to the working medium spray device located in the evaporation chamber of the evaporator for spraying, a part of the sprayed working medium is flashed in the evaporation chamber into working medium vapor, and the working medium vapor is conveyed to the absorber. Working medium in the evaporation chamber is output through a working medium spraying pipeline in the evaporation link, countercurrent heat exchange is carried out through an external evaporation heat exchanger, then the working medium is conveyed to a working medium spraying device located in the evaporation chamber to be sprayed, one part of the sprayed working medium is flashed into steam in the evaporation chamber, and the steam is conveyed to the absorption chamber through a first working medium steam channel under the strong absorption of absorption solution in the absorber to be absorbed by the absorption solution. Other parts of the cycle in this embodiment may be the same as in the prior art.

Preferably, in the embodiment, the condenser link is that the condensing working medium spraying pump conveys the condensing working medium in the condensing chamber to the condensing working medium spraying device from the condensing working medium spraying pipeline through the condensing heat exchanger, the condensing working medium is sprayed by the condensing working medium spraying device to condense the working medium steam generated by the generator and release condensing heat, and the condensing heat is taken away by the condensing heating medium in the condensing heat exchanger. This embodiment further enhances the heat and mass transfer process of the whole system.

Preferably, in the above embodiment, the heat absorbed by the working medium from the evaporation heat medium in the evaporation heat exchanger is industrial waste heat, geothermal heat, solar heat, or heat of an air conditioning refrigerant. The system and the method of the embodiment of the invention can adopt a lower-grade generation heat source to obtain larger temperature grade improvement of industrial waste heat (including geothermal heat, solar heat and the like), so that the system and the method are more convenient to recycle, and can bring remarkable energy-saving effect and economic benefit to users.

Preferably, the absorption solution in the absorber is throttled by the throttle valve, enters the solution heat exchanger to exchange heat with the absorption solution from the generator, and is then conveyed to the generator.

As a preference of the above embodiment, the absorption solution is heat exchanged by a solution heat exchanger during circulation between the absorber and the generator.

Preferably, in the above embodiment, the generator is provided with a solid-liquid separation device, when the absorbent is supersaturated and crystallized to form fine and fluid crystal particles by evaporation concentration and cooling in the flash evaporation process, the absorbent in the generator is subjected to solid-liquid separation by the solid-liquid separation device, the absorbent containing the absorbent crystal particles is transported to the absorber by the solution circulation pump, and the absorbent containing no absorbent crystals is transported to the second absorbent spray device by the second absorbent spray pump, passed through the generator heat exchanger, and then transported to the second absorbent spray device.

Preferably, the working fluid used in the above embodiment is water, and the absorbent used may be selected from the group consisting of LiBr and LiNO₃LiCl and CaCl₂At least one of; the generation heating medium, the condensation heating medium, the evaporation heating medium and the absorption heating medium are liquid fluid or gaseous fluid, wherein the liquid fluid comprises water, aqueous solution, unfrozen liquid, heat transfer oil and the like, and the gaseous fluid comprises air, process gas, superheated steam, steam containing non-condensable gas and the like.

The evaporator 100, the absorber 200, the generator 300 and the condenser 400 in the embodiment of the invention can be used for both the second-type absorption heat pump and the first-type absorption heat pump.

The absorption heat pump and the circulation method provided by the embodiment of the invention can realize the working mode which cannot be realized by the existing second-class absorption heat pump. The generator of the second type of absorption heat pump operates at a point on a temperature curve of the saturated vapor pressure of the absorbent unsaturated solution, while the absorber operates at a point on a temperature curve of the saturated vapor pressure of the absorbent unsaturated solution at a concentration lower than a bleed range of the generator, and the temperature of the operating point of the absorber is higher than that of the operating point of the generator. In contrast, the generator of the absorption heat pump of the present invention operates at one point of the temperature curve of the saturated vapor pressure of the absorbent saturated solution at the absorbent saturation concentration, and the absorber operates at another point of the temperature curve of the saturated vapor pressure of the same saturated solution (or close to the curve), and the temperature of the absorber operating point is higher than the temperature of the generator operating point. The heat pump system of the present invention is operated under the condition that the concentration of the absorber absorption solution is higher than that of the generator absorption solution since the saturation solubility of the absorbent is larger as the temperature is higher. Therefore, the invention can utilize the lower grade heat source to obtain larger temperature grade promotion of the industrial waste heat (including geothermal heat, solar heat and the like), thereby being more convenient for recycling, and bringing remarkable energy-saving effect and economic benefit to users. In addition, in the embodiment of the invention, the supersaturated crystallized absorbent crystal particles are made to be fine and have fluidity, so that the problems of heat and mass transfer obstacles of a heat exchanger and blockage of pipelines and the like caused by absorbent crystallization in the conventional second-type absorption heat pump can be effectively solved.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims

1. An absorption heat pump comprises an evaporator, an absorber, a generator and a condenser, wherein the evaporator and the absorber are communicated through a first working medium steam channel, the condenser and the generator are communicated through a second working medium steam channel, the generator and the absorber are communicated through a first solution circulating pipeline and a second solution circulating pipeline, the first solution circulating pipeline conveys an absorption solution to the absorber from the generator, the second solution circulating pipeline conveys the absorption solution to the generator from the absorber, solution heat exchangers are arranged on the first solution circulating pipeline and the second solution circulating pipeline, the absorption solution conveyed in the first solution circulating pipeline and the second solution circulating pipeline carries out heat exchange through the solution heat exchangers, the evaporator and the condenser are connected through a working medium pipeline, and the working medium pipeline conveys the working medium in the condenser to the evaporator, the evaporator comprises an evaporation heat exchanger, the absorber comprises an absorption heat exchanger, the generator comprises a generation heat exchanger, the condenser comprises a condensation heat exchanger, the evaporator is characterized in that,

the generator comprises an absorption solution flash evaporation chamber, a generation heat exchanger and a second absorption solution spraying device, the generation heat exchanger is arranged outside the absorption solution flash evaporation chamber, the second absorption solution spraying device is arranged at the upper part in the absorption solution flash evaporation chamber and is connected with a second absorption solution spraying pipeline arranged outside the absorption solution flash evaporation chamber, the second absorption solution spraying pipeline conveys the absorption solution in the absorption solution flash evaporation chamber to the second absorption solution spraying device for spraying, a second absorption solution spraying pump is arranged on the second absorption solution spraying pipeline, the second absorption solution spraying pipeline is connected with the cold fluid side of the generation heat exchanger, and a generation heat medium pipeline of the generation heat source is connected with the hot fluid side of the generation heat exchanger 302;

the solid-liquid separation device separates the absorption solution into two parts including absorbent crystals and absorbent crystals when the absorbent in the absorption solution flash chamber is crystallized, wherein the absorption solution without the absorbent crystals is conveyed to the second absorption solution spraying device through a second absorption solution spraying pipeline, and the absorption solution with the absorbent crystals is conveyed into the absorber through a first solution circulating pipeline;

at least one of the evaporation heat exchanger, the absorption heat exchanger and the condensation heat exchanger adopts a vertical double-falling film heat exchanger, and the vertical double-falling film heat exchanger comprises:

the first fluid receiver is positioned below the lower end plate of the heat exchange tube and is used for receiving a first fluid flowing out of the heat exchange tube;

the second fluid introduction chamber is positioned below the upper end plate of the heat exchange tube, and the second fluid forms an outer falling film on the outer wall of the heat exchange tube;

2. An absorption heat pump according to claim 1, wherein the evaporation heat exchanger is the vertical double falling film heat exchanger, and the evaporation heat exchanger is disposed in an evaporation chamber of the evaporator, wherein

a working medium circulating pump is arranged on the working medium circulating pipeline, the working medium in the first fluid receiver is conveyed to the first fluid introducing chamber by the working medium circulating pump, and the working medium flows downwards along the inner wall surface of the heat exchange pipe to form an internal falling film; the evaporation heat medium led into the chamber by the second fluid flows downwards along the outer wall surface of the heat exchange tube to form an outer falling film, the working medium and the evaporation heat medium exchange heat through the heat exchange tube, part of the working medium is heated and evaporated into steam, the working medium steam flows into the absorber through the first working medium steam channel, and the liquid working medium flows into the first fluid receiver.

3. An absorption heat pump according to claim 1, wherein the absorption heat exchanger is the vertical double falling film heat exchanger, and the absorption heat exchanger is disposed in an absorption chamber of the absorber, wherein

the second fluid receiving chamber is connected with an absorption heat medium leading-in pipe and an absorption heat medium leading-out pipe, the absorption heat medium leading-in pipe inputs the absorption heat medium into the second fluid receiving chamber, the second fluid receiving chamber is connected with the second fluid leading-in chamber through an absorption heat medium circulating pipe, an absorption heat medium circulating pump is arranged on the absorption heat medium circulating pipe, the absorption heat medium circulating pump conveys the absorption heat medium in the second fluid receiving chamber to the second fluid leading-in chamber, the absorption heat medium flows out through a gap between the outer wall surface of the heat exchange pipe and the liquid distribution pore plate, and an outer falling film is formed on the outer wall of the heat exchange pipe;

the absorption solution in the first fluid introduction chamber flows downwards along the inner wall surface of the heat exchange tube to form an inner falling film, simultaneously absorbs working medium steam generated in the evaporator and releases high-temperature absorption heat, the absorption solution and the absorption heat medium exchange heat through the heat exchange tube, and the absorption heat medium absorbing the absorption heat is output through the absorption heat medium outlet pipeline.

4. An absorption heat pump according to claim 1, wherein the condensing heat exchanger is the vertical double falling film heat exchanger, and the condensing heat exchanger is disposed in a condensing chamber of a condenser, wherein

5. An absorption heat pump according to claim 1, wherein the evaporator and the absorber share a single vertical vessel, the evaporator being located above the vessel and the absorber being located below the vessel.

6. An absorption heat pump according to claim 1, wherein the generator and the condenser share a single vertical vessel, the condenser being located above the vessel and the generator being located below the vessel.

7. An absorption heat pump according to claim 1, wherein the heat exchange tube passes through the second fluid introduction chamber to communicate with the first fluid introduction chamber, the top plate of the second fluid introduction chamber is an upper end plate of the heat exchange tube, the bottom plate is a liquid distribution orifice plate, the liquid distribution orifice plate is provided with a liquid distribution orifice for the heat exchange tube to pass through, the diameter of the liquid distribution orifice is larger than the outer diameter of the heat exchange tube, a gap is formed between the outer wall surface of the heat exchange tube and the liquid distribution orifice plate, and the second fluid in the second fluid introduction chamber flows out through the gap and forms an outer falling film on the outer wall surface of the heat exchange tube.

8. An absorption heat pump according to claim 1, wherein the circumference of each liquid distribution hole of the liquid distribution hole plate comprises at least two protrusions extending along the radial direction of the liquid distribution hole, and the protrusions are used for positioning the heat exchange pipe.

9. An absorption heat pump according to claim 8, wherein the protrusions are evenly distributed over the circumference of the liquor distribution holes.