CN111435016A - Radiation convection type heat exchanger and air conditioner with same - Google Patents

Abstract

The present invention relates to a radiant convection heat exchanger and an air conditioner having the same. Specifically, the radiation convection heat exchanger includes: a radiation heat exchange part, the radiation heat exchange part is in the shape of a cylinder with both ends open, and is configured to absorb heat or cold from its inner wall and radiate heat or cold outward from its outer wall. and a convective heat exchange portion, disposed inside the radiation heat exchange portion, configured to generate heat or cold, and to transfer the heat or cold to the air flowing through the inside of the radiation heat exchange, and to transfer the heat or cold the inner wall surface of the radiation heat exchange part; and the convection heat exchange part includes a refrigerant pipeline, and the refrigerant pipeline has a main inlet pipe, a main outlet pipe and a plurality of refrigerant channels extending along the axial direction of the radiation heat exchange part; each refrigerant channel One end is communicated with the main inlet pipe, and the other end is communicated with the main outlet pipe, so that a plurality of refrigerant passages are connected in parallel. On the premise of ensuring the heating or cooling capacity, it can reduce the blowing sensation of the human body and increase the thermal comfort of the human body.

Description

Radiant convection heat exchanger and air conditioner having the same

technical field

The invention relates to the field of refrigeration and heating, in particular to a radiation convection heat exchanger and an air conditioner having the same.

Background technique

The heat exchanger of the existing air conditioner mainly heats or cools the air in the form of forced convection heat exchange, and then transfers the heat or cold to the room or the human body. Thermal comfort, especially when higher heating or cooling capacity is required, the high wind blowing from the heat exchanger of the air conditioner can easily cause thermal discomfort to the human body.

SUMMARY OF THE INVENTION

The purpose of the first aspect of the present invention is to overcome at least one defect of the existing heat exchanger, and to provide a radiation convection heat exchanger, which can significantly reduce the thermal discomfort of the human body when exchanging heat with the human body or room.

The object of the second aspect of the present invention is to provide an air conditioner having the above-mentioned radiation convection heat exchanger.

According to the first aspect of the present invention, the present invention proposes a radiation convection heat exchanger, which includes:

a radiant heat exchange part, the radiant heat exchange part having a cylindrical shape with both ends open, configured to absorb heat or cold from its inner wall and to radiate heat or cold outward from its outer wall; and

The convection heat exchange part is arranged inside the radiation heat exchange part, and is configured to generate heat or cold energy, transfer the heat or cold energy to the air flowing through the inside of the radiation heat exchange part, and transfer the heat or cold energy transferred to the inner wall surface of the radiation heat exchange part; and

The convection heat exchange part includes a refrigerant pipeline, and the refrigerant pipeline has a general inlet pipe, a general outlet pipe and a plurality of refrigerant passages extending along the axial direction of the radiation heat exchange part;

One end of each of the refrigerant passages is communicated with the general inlet pipe, and the other end is communicated with the general outlet pipe, so that a plurality of the refrigerant passages are connected in parallel.

Optionally, the refrigerant pipeline includes a plurality of heat exchange plates; each of the heat exchange plates has a first edge and a second edge extending along the axial direction of the radiation heat exchange portion; the first edge arranged in the middle of the inner space of the radiation heat exchange part, the second edge is connected to the inner wall surface of the radiation heat exchange part; a plurality of the heat exchange plates are arranged in sequence along the circumferential direction of the radiation heat exchange part ;and

Each of the heat exchange plates has at least one of the refrigerant passages.

Optionally, a plurality of heat dissipation fins arranged in sequence along the radial direction of the radiation heat exchange portion is disposed between every two adjacent heat exchange plates;

Each of the heat dissipation fins has an arc shape that is arched toward the radially outer side of the radiation heat exchange portion.

Optionally, each of the heat exchange plates is disposed intersecting the radial direction of the radiation heat exchange portion toward the second edge of the heat exchange plate; or

Each of the heat exchange plates extends in the axial direction of the radiation heat exchange portion, and extends in the radial direction of the radiation heat exchange portion.

Optionally, along the direction from the corresponding first edge to the second edge, two of the plurality of heat dissipation fins between every two adjacent heat exchange plates are adjacent to the heat dissipation The space between the fins has a plurality of distance values, and the plurality of distance values become smaller in turn;

Each of the heat exchange plates has a plurality of the refrigerant channels, and in each of the heat exchange plates, in the direction from the first edge to the second edge, the plurality of the refrigerant channels are arranged in sequence, The interval between two adjacent refrigerant channels has a plurality of interval values; from the direction of the first edge to the second edge, the plurality of interval values decrease in turn; and

From the direction of the first edge to the second edge, the ratio between the number of the refrigerant channels and the number of the heat dissipation fins is 4/5 to 10/1.

Optionally, one end of each of the heat exchange plates is provided with a collector inlet pipe, and the other end is provided with a collector outlet pipe;

Each of the header inlet pipes communicates with the header inlet pipes and the refrigerant passages on the corresponding heat exchange plates;

Each of the headers communicates with the header and the refrigerant passages on the corresponding heat exchange plates.

Optionally, the refrigerant pipeline includes a plurality of cylindrical structures arranged coaxially, and each of the cylindrical structures is arranged coaxially with the radiation heat exchange part;

The cylindrical structure includes at least one heat exchange cylinder, and one or more refrigerant passages are provided on the cylinder wall of each of the heat exchange cylinders.

Optionally, a fin layer is provided between the outermost cylindrical structure and the inner wall surface of the radiation heat exchange part; or, the outer wall surface of the outermost cylindrical structure and the inner wall surface of the radiation heat exchange part. The wall surface is integrally formed or contacted;

A fin layer is disposed between every two adjacent cylindrical structures, and each fin layer has a plurality of heat dissipation fins uniformly distributed along the circumferential direction of the radiation heat exchange portion; and each The heat dissipation fins extend in the axial direction of the radiation heat exchange portion.

Optionally, the convection heat exchange part is an integral piece, and is formed by extrusion process; or,

The convective heat exchange portion and the radiation heat exchange portion are integrally formed as an integral piece, and are formed by an extrusion process.

According to the second aspect of the present invention, the present invention further provides an air conditioner comprising an evaporator and a condenser, wherein the evaporator and/or the condenser adopts any one of the above-mentioned radiation convection heat exchangers.

In the radiation convection heat exchanger and the air conditioner of the present invention, because of the radiation heat exchange part and the convection heat exchange part, the cylindrical radiant plate bears a part of the heating or cooling load, and can ensure the heating or cooling capacity under the premise of ensuring the heating or cooling capacity. It reduces the blowing sensation of the human body and increases the thermal comfort of the human body; especially when heating in winter, the radiant heat transfer can significantly increase the thermal comfort of the human body.

The above and other objects, advantages and features of the present invention will be more apparent to those skilled in the art from the following detailed description of the specific embodiments of the present invention in conjunction with the accompanying drawings.

Description of drawings

Hereinafter, some specific embodiments of the present invention will be described in detail by way of example and not limitation with reference to the accompanying drawings. The same reference numbers in the figures designate the same or similar parts or parts. It will be understood by those skilled in the art that the drawings are not necessarily to scale. In the attached picture:

1 is a schematic structural diagram of a radiation convection heat exchanger according to an embodiment of the present invention;

Figure 2 is a schematic cross-sectional view of a radiant convection heat exchanger according to one embodiment of the present invention;

3 is a schematic cross-sectional view of a radiant convection heat exchanger according to one embodiment of the present invention;

Figure 4 is a schematic cross-sectional view of a radiant convection heat exchanger according to one embodiment of the present invention;

5 is a schematic cross-sectional view of a radiant convection heat exchanger according to one embodiment of the present invention.

Detailed ways

Figure 1 is a schematic cross-sectional view of a radiant convection heat exchanger according to one embodiment of the present invention. As shown in FIG. 1 and referring to FIGS. 2 to 5 , an embodiment of the present invention provides a radiation convection heat exchanger, which includes a radiation heat exchange part 20 and a convection heat exchange part 30 . The radiation heat exchange portion 20 has a cylindrical shape with both ends open, and is configured to absorb heat or cooling from its inner wall and radiate heat or cooling outward from its outer wall. For example, the outer contour of the cross section of the radiation heat exchange part 20 is a circle, a semicircle, a square or a fan shape. The convection heat exchange part 30 is disposed inside the radiation heat exchange part 20, and is configured to generate heat or cold energy, and transfer the heat or cold energy to the air flowing through the inner side of the radiation heat exchange part 20, and to transfer the heat or cold energy to the air passing through the inner side of the radiation heat exchange part 20. The inner wall surface of the radiation heat exchange part 20 . The radiation heat exchange part 20 is located on the outer shell surface of the radiation convection heat exchanger, and can be directly used as the outer shell.

When the radiant convection heat exchanger in the embodiment of the present invention is in operation, the convection heat exchange part 30 generates heat or cold energy, performs heat exchange with the air inside the radiant heat exchange part 20 , and exchanges heat with the inner wall of the radiant heat exchange part 20 . Heat exchange is performed, and the air after heat exchange can flow out of the radiation heat exchange part 20 to keep warm or cool the room or the human body. Cool down. The cylindrical radiant panel bears a part of the heating or cooling load, which can reduce the blowing sensation of the human body and increase the thermal comfort of the human body on the premise of ensuring the heating or cooling capacity; especially in winter heating, the radiation heat transfer can significantly increase the human body. Thermal comfort.

In particular, as shown in FIGS. 1 and 2 , the convection heat exchange unit 30 includes a refrigerant pipe and heat dissipation fins 33 provided on the refrigerant pipe. The refrigerant pipeline has a general inlet pipe 35 , a general outlet pipe and a plurality of refrigerant passages extending along the axial direction of the radiation heat exchange portion 20 . One end of each refrigerant passage is communicated with the main inlet pipe 35, and the other end is communicated with the main outlet pipe, so that a plurality of refrigerant passages are connected in parallel. It has high heat exchange uniformity and low flow resistance. Each heat dissipation fin 33 is provided with one or more heat dissipation holes. For example, the refrigerant pipeline includes a plurality of circular straight pipes, and each circular straight pipe extends along the axial direction of the radiation heat exchange portion 20, which has the above-mentioned refrigerant passages; there are a plurality of heat dissipation fins 33, which are installed on the plurality of circular straight pipes. Tube. That is, the convection heat exchange part 30 is a conventional fin-and-tube heat exchanger.

In some preferred embodiments of the present invention, as shown in FIG. 1 to FIG. 3 , the refrigerant pipeline includes a plurality of heat exchange plates 31 , and each heat exchange plate 31 is provided with one or more refrigerant passages 32 . The plurality of heat dissipation fins 33 are attached to the plurality of heat exchange plates 31 .

Further, each heat exchange plate 31 has a first edge and a second edge extending in the axial direction of the radiation heat exchange portion 20 . The first edge is disposed in the middle of the inner space of the radiation heat exchange portion 20 , and the second edge is connected to the inner wall surface of the radiation heat exchange portion 20 . The plurality of heat exchange plates 31 are uniformly distributed along the circumferential direction of the radiation heat exchange portion 20 . For example, in some embodiments, each heat exchange plate 31 extends in the axial direction of the radiation heat exchange portion 20 and extends in the radial direction of the radiation heat exchange portion 20 , as shown in FIG. 2 . In other embodiments, each heat exchange plate 31 is disposed intersecting with the radial direction of the radiation heat exchange portion 20 toward the second edge of the heat exchange plate 31 , as shown in FIG. 3 .

In some embodiments of the present invention, a plurality of heat dissipation fins 33 arranged in sequence along the radial direction of the radiation heat exchange portion 20 are disposed between every two adjacent heat exchange plates 31 . The plurality of refrigerant passages 32 in each heat exchange plate 31 are sequentially arranged in the direction from the first edge to the second edge.

Along the radial direction of the radiation heat exchange portion 20, the interval between the two adjacent heat dissipation fins 33 among the plurality of heat dissipation fins 33 between each two adjacent heat exchange plates 31 has a plurality of distance values, In order to make the arrangement density of the plurality of heat dissipation fins 33 different. For example, along the radial direction of the radiation heat exchange portion 20 , the distance values become smaller in sequence, that is, the arrangement of the heat dissipation fins 33 is first sparse and then dense.

Specifically, the plurality of heat dissipation fins 33 between every two adjacent heat exchange plates 31 are arranged into multiple groups, each group of heat dissipation fins 33 has at least two heat dissipation fins 33 , and each group of heat dissipation fins 33 has at least two heat dissipation fins 33 . The distance between every two adjacent heat-dissipating fins 33 is equal to one of the above-mentioned distance values, so that the interval between the heat-dissipating fins 33 between every two adjacent heat-exchange plates 31 has multiple distance values. Groups can share one heat dissipation fin 33 , that is, use one common heat dissipation fin 33 for grouping.

In each heat exchange plate 31, in the direction from the first edge to the second edge, a plurality of refrigerant passages 32 are arranged in sequence, and the interval between two adjacent refrigerant passages 32 has one or more spacing values. Multiple spacing values decrease in turn. The plurality of refrigerant passages 32 on each heat exchange plate 31 are arranged in multiple groups, each group of refrigerant passages 32 has at least two refrigerant passages 32, and the distance between every two adjacent refrigerant passages 32 in each group of refrigerant passages 32 is equal to One of the above-mentioned spacing values, so that the interval between the refrigerant channels 32 on each heat exchange plate 31 has multiple spacing values, and adjacent two groups can share one refrigerant channel 32, that is, use a common refrigerant channel 32 for grouping.

In the direction from the first edge to the second edge, the ratio between the number of refrigerant channels 32 and the number of heat dissipation fins 33 is 4/5 to 10/1, preferably 1/1 to 10/1. Each of the radiating fins 33 has an arc shape that is arched toward the outside of the radiation heat exchange portion 20 . The cross-sectional profile of each refrigerant passage 32 is rectangular or circular or other regular or irregular shapes. The hydraulic radius of each refrigerant passage 32 is 0.1-10 mm; the number of refrigerant passages 32 on each heat exchange plate 31 is 10-50. The number of heat exchange plates 31 is 4 to 50. In some embodiments of the present invention, in the direction from the first edge to the second edge, the distance between two adjacent refrigerant passages 32 is one, that is, the plurality of refrigerant passages 32 are arranged at equal intervals. The distance between two adjacent heat dissipation fins 33 among the plurality of heat dissipation fins 33 between every two adjacent heat exchange plates 31 is one, that is, the distance between every two adjacent heat exchange plates 31 is one. The heat dissipation fins 33 are arranged at equal intervals.

In other preferred embodiments of the present invention, as shown in FIG. 4 and FIG. 5 , the refrigerant pipeline of the convection heat exchange part 30 includes one or more cylindrical structures arranged coaxially, and each cylindrical structure is connected to The radiation heat exchange part 20 is arranged coaxially. The cylindrical structure includes at least one heat exchange drum 36 , and one or more refrigerant channels 37 are provided on the drum wall of each heat exchange drum 36 .

Further, the cylindrical structure may further include at least one support cylinder, each support cylinder is disposed between two adjacent heat exchange cylinders 36, or disposed inside the innermost heat exchange cylinder 36, or disposed at the outermost heat exchange cylinder 36. between the heat cylinder 36 and the radiation heat exchange part 20 .

In order to facilitate heat transfer between the convection heat exchange portion 30 and the radiation heat exchange portion 20 , in some embodiments, a fin layer is provided between the outermost cylindrical structure and the inner wall surface of the radiation heat exchange portion 20 . In other embodiments, the outer wall surface of the outermost cylindrical structure and the inner wall surface of the radiation heat exchange part 20 are integrally formed or contacted against each other. The outermost cylindrical structure is preferably a heat exchange cylinder 36 .

In some embodiments of the present invention, there are multiple cylindrical structures, a fin layer is also disposed between every two adjacent cylindrical structures, and each fin layer has a plurality of fin layers along the circumference of the radiation heat exchange portion 20 . The heat dissipation fins 33 are uniformly distributed in the direction. And each heat dissipation fin 33 extends along the axial direction of the radiation heat exchange portion 20 to define a plurality of airflow channels extending along the axial direction of the radiation heat exchange portion 20 .

In some embodiments of the present invention, there are preferably at least two fin layers. In every two adjacent fin layers, the height of the radiating fins 33 on the outer side extending in the radial direction of the radiation heat exchange portion 20 is greater than that of the radiating fins 33 on the inner side extending in the radial direction of the radiation heat exchange portion 20 the height of. The wall thickness of each radiating fin 33 is 0.2-1 mm, and the distance between every two adjacent radiating fins 33 in each fin layer is 0.5-10 mm. Further, the heat dissipation fins 33 may be integrally formed with the corresponding cylindrical structures on the inner side, and the outer side may be in contact with the corresponding cylindrical structures on the outer side.

The air flows in the airflow channel between the cooling fins 33, and the total number of the cooling fins 33 should meet the following requirements: the total outer surface of the cooling fins 33 should provide sufficient heat exchange surface for the heat exchange between the air and the refrigerant; The total number of rings in the sheet layer is preferably 1-20.

In some embodiments of the present invention, the plurality of refrigerant passages 37 in the wall of each heat exchange cylinder 36 are uniformly distributed along the circumferential direction of the heat exchange cylinder 36 . The cross-sections of the plurality of refrigerant passages 37 in the cylinder wall of each heat exchange cylinder 36 may include circles and polygons, and the polygons may be rectangular or approximately rectangular structures. The circumferential directions are arranged alternately in sequence. The hydraulic radius of each refrigerant passage 37 is 0.6-10 mm.

The cylindrical structure includes at least two heat exchange cylinders 36 . In every two adjacent heat exchange cylinders 36 , the height of each refrigerant passage on the outer heat exchange cylinder 36 extending in the radial direction of the radiation heat exchange portion 20 is greater than that of each refrigerant passage on the inner heat exchange cylinder 36 The height extending in the radial direction of the radiation heat exchange portion 20 .

In some embodiments of the present invention, the convection heat exchange portion 30 defines a central channel 38 extending in the axial direction of the radiation heat exchange portion 20 and located in the center of the space inside the radiation heat exchange portion 20 . The central channel 38 may be configured to circulate air or refrigerant. In other embodiments, both ends of the central channel 38 are provided with closed structures, and the central channel 38 can also be configured to be provided with fittings such as a shunt pipe. Each refrigerant channel 32/refrigerant channel 37 is preferably a microchannel tube. The heat exchange plate 31 , the heat exchange cylinder 36 , the support cylinder, and the radiation heat exchange portion 20 can all be made of copper or aluminum.

In some embodiments of the present invention, in order to facilitate processing and manufacturing, the convection heat exchange part 30 is formed by an extrusion process, that is, the convection heat exchange part is preferably an integral piece. Or, the whole formed by the convection heat exchange part 30 and the radiation heat exchange part 20 is formed by extrusion process. That is to say, the whole of the convection heat exchange part and the radiation heat exchange part 20 constitutes a one-piece workpiece. Extruded one-piece processed parts, the heat dissipation fins 33 are directly connected with the walls of the refrigerant passage 32/refrigerant passage 37, and belong to the same part, and there is no problem of contact thermal resistance between the two, which can significantly reduce the heat between the refrigerant and the air. Heat transfer thermal resistance, increase heat transfer performance.

In some embodiments of the present invention, one end of each heat exchange plate 31/heat exchange cylinder 36 is provided with a collector inlet pipe, and the other end is provided with a collector outlet pipe. Each header inlet pipe communicates with the header pipe 35 and the refrigerant passages on the corresponding heat exchange plate 31/heat exchange cylinder 36; each header outlet pipe communicates with the header outlet pipe and the refrigerant on the corresponding heat exchange plate 31/heat exchange barrel 36 aisle.

Embodiments of the present invention also provide an air conditioner, which may include a compressor, a condenser, a throttling device, and an evaporator. The evaporator and/or the condenser adopts the radiant convection heat exchanger in any of the above embodiments. Preferably, only the evaporator adopts the radiant convection heat exchanger in any of the above embodiments. Further, a fan may be provided at one end of the radiation heat exchange portion 20 to promote air to enter the inner side of the radiation heat exchange portion 20 to perform heat exchange with the convection heat exchange portion.

By now, those skilled in the art will recognize that, although various exemplary embodiments of the present invention have been illustrated and described in detail herein, the present invention may still be implemented in accordance with the present disclosure without departing from the spirit and scope of the present invention. The content directly determines or derives many other variations or modifications consistent with the principles of the invention. Accordingly, the scope of the present invention should be understood and deemed to cover all such other variations or modifications.

Claims (10)

1. A radiant convective heat exchanger comprising:

a radiant heat exchanging part having a cylindrical shape with both ends open, configured to absorb heat or cold from an inner wall surface thereof, and radiate the heat or cold outward from an outer wall surface thereof; and

a convection heat exchanging part disposed at an inner side of the radiation heat exchanging part, configured to generate heat or cold, and to transfer the heat or cold to air flowing through the inner side of the radiation heat exchanging part and to transfer the heat or cold to an inner wall surface of the radiation heat exchanging part; and is

The convection heat exchange part comprises a refrigerant pipeline, and the refrigerant pipeline is provided with a main inlet pipe, a main outlet pipe and a plurality of refrigerant channels extending along the axial direction of the radiation heat exchange part;

one end of each refrigerant channel is communicated with the main inlet pipe, and the other end of each refrigerant channel is communicated with the main outlet pipe, so that the refrigerant channels are connected in parallel.

2. Radiation convection heat exchanger of claim 1,

the refrigerant pipeline comprises a plurality of heat exchange plates; each heat exchange plate has a first edge and a second edge extending in an axial direction of the radiant heat exchange portion; the first edge is arranged in the middle of the space inside the radiation heat exchange part, and the second edge is connected to the inner wall surface of the radiation heat exchange part; the heat exchange plates are sequentially arranged along the circumferential direction of the radiation heat exchange part; and is

Each heat exchange plate is internally provided with at least one refrigerant channel.

3. Radiation convection heat exchanger of claim 2,

a plurality of radiating fins which are sequentially arranged along the radial direction of the radiation heat exchanging part are arranged between every two adjacent heat exchanging plates;

each radiating fin is in an arc shape which arches towards the radial outer side of the radiation heat exchange part.

4. Radiation convection heat exchanger of claim 2,

each heat exchange plate and the radial direction of the radiation heat exchange part facing to the second edge of the heat exchange plate are arranged in a crossed mode; or

Each heat exchange plate extends along the axial direction of the radiant heat exchange part and extends along the radial direction of the radiant heat exchange part.

5. A radiation convection heat exchanger as set forth in claim 3,

the interval between two adjacent heat dissipation fins in the plurality of heat dissipation fins between every two adjacent heat exchange plates along the direction from the corresponding first edge to the second edge has a plurality of distance values, and the plurality of distance values become smaller in sequence;

each heat exchange plate is internally provided with a plurality of refrigerant channels, the direction from the first edge to the second edge in each heat exchange plate is sequentially arranged, and the interval between two adjacent refrigerant channels has a plurality of interval numerical values; the first edge points to the second edge, and the plurality of spacing values become smaller in sequence; and is

The ratio of the number of the refrigerant channels to the number of the heat dissipation fins is 4/5 to 10/1 from the first edge to the second edge.

6. Radiation convection heat exchanger of claim 2,

one end of each heat exchange plate is provided with a collecting inlet pipe, and the other end of each heat exchange plate is provided with a collecting outlet pipe;

each collecting inlet pipe is communicated with the main inlet pipe and the refrigerant channel on the corresponding heat exchange plate;

each collecting outlet pipe is communicated with the total outlet pipe and the refrigerant channel on the corresponding heat exchange plate.

7. Radiation convection heat exchanger of claim 1,

the refrigerant pipeline comprises a plurality of coaxially arranged cylindrical structures, and each cylindrical structure is coaxially arranged with the radiation heat exchange part;

the cylindrical structure comprises at least one heat exchange cylinder, and one or more refrigerant channels are arranged on the wall of each heat exchange cylinder.

8. A radiation convection heat exchanger as set forth in claim 7,

a fin layer is arranged between the cylindrical structure at the outermost side and the inner wall surface of the radiation heat exchange part; or the outer wall surface of the outermost cylindrical structure and the inner wall surface of the radiation heat exchange part are integrally formed or abut against each other in a contact manner;

a fin layer is arranged between every two adjacent cylindrical structures, and each fin layer is provided with a plurality of radiating fins which are uniformly distributed along the circumferential direction of the radiation heat exchange part; and each radiating fin extends along the axial direction of the radiation heat exchanging part.

9. Radiation convection heat exchanger of claim 1,

the convection heat exchange part is an integrated workpiece and is formed by adopting an extrusion process; or the like, or, alternatively,

the whole formed by the convection heat exchange part and the radiation heat exchange part is an integrated workpiece and is formed by adopting an extrusion process.

10. An air conditioner comprises an evaporator and a condenser, and is characterized in that,

the evaporator and/or the condenser employ the radiation convection type heat exchanger as claimed in claims 1 to 9.

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