CN222459853U

CN222459853U - Overlapping type heat pump system

Info

Publication number: CN222459853U
Application number: CN202421274433.1U
Authority: CN
Inventors: 祝建军; 丛辉; 李强; 陈见兴; 朱海涛; 孟庆超; 程振军; 刘玉君; 冯胜健
Original assignee: Qingdao Hisense Hitachi Air Conditioning System Co Ltd
Current assignee: Qingdao Hisense Hitachi Air Conditioning System Co Ltd
Priority date: 2024-06-05
Filing date: 2024-06-05
Publication date: 2025-02-11
Anticipated expiration: 2034-06-05

Abstract

The utility model discloses an overlapping heat pump system which comprises a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a first compressor and a second compressor, wherein the first heat exchanger is arranged in an outdoor environment and exchanges heat through an outdoor fan, the second heat exchanger comprises a first passage and a second passage, the first heat exchanger and the first passage are used for exchanging heat between a refrigerant in the first passage and a refrigerant in the second passage, the third heat exchanger and a liquid heat exchange medium are arranged in a heat exchange mode, the second heat exchanger and the second passage and the third heat exchanger form a second cycle, the fourth heat exchanger and the liquid heat exchange medium are arranged in a heat exchange mode and form a third cycle with the first heat exchanger and the first compressor, the first cycle and the second cycle are in linkage heating operation or the third cycle operation, and the third cycle operation can be used for refrigerating or heating. The utility model realizes the efficient operation of the system with medium and small compression ratio, efficient defrosting and no increase of the power of the outdoor fan, and saves energy and cost.

Description

Overlapping type heat pump system

Technical Field

The utility model relates to the technical field of air conditioning, in particular to a cascade heat pump system.

Background

In order to realize efficient heating or refrigerating of the air source heat pump under a larger ratio of condensing pressure to evaporating pressure, an overlapping heat pump circulation technology is adopted in the prior art to improve the operation performance of the air source heat pump under a large compression ratio. Specifically, the heat produced by the air source heat pump unit comes from the condenser of the high temperature section heat pump unit, and the low temperature section air source heat pump is only associated with the high temperature section heat pump evaporator to provide a heat source for the high temperature section.

In the prior art, a pipeline and a heat exchanger which can be directly communicated with a high-temperature section condenser are additionally arranged at a low-temperature section, so that when the environment temperature is higher, the heat exchanger additionally arranged at the low-temperature section directly forms a heat pump circulation system with the high-temperature section condenser, and the heating high-efficiency operation with a medium compression ratio or a small compression ratio is performed.

When the cascade air source heat pump with the structure is used for defrosting, the high-temperature section circulation and the low-temperature section circulation operate simultaneously to defrost the low-temperature section evaporator, the system is complex in control and low in efficiency, or the additionally arranged low-temperature Duan Huanre device is directly communicated with the high-temperature section condenser to perform single-cycle refrigeration operation, the additionally arranged low-temperature Duan Huanre device is used for defrosting and heating the low-temperature Duan Huanre device, the problems of asynchronous defrosting and low efficiency exist, namely, the additionally arranged low-temperature Duan Huanre device needs special installation to enable the low-temperature Duan Huanre device to uniformly defrost. In addition, the low-temperature Duan Huanre device is additionally arranged to increase the volume of the outdoor heat exchanger, fan power adaptation is required to be increased, the occupied space is larger, and the cost is increased.

The above information disclosed in this background section is only for enhancement of understanding of the background section of the application and therefore it may not form the prior art that is already known to those of ordinary skill in the art.

Disclosure of Invention

Aiming at the problems of low efficiency of small compression ratio and low defrosting efficiency of the cascade heat pump system in the background technology, the utility model provides the cascade heat pump system which can realize high-efficiency operation, high-efficiency defrosting with low cost and energy conservation with high efficiency of small compression ratio.

In order to achieve the aim of the utility model, the utility model is realized by adopting the following technical scheme:

an overlapping heat pump system comprises a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a first compressor and a second compressor;

the first heat exchanger is arranged in an outdoor environment and exchanges heat with the outdoor environment through an outdoor fan;

The second heat exchanger comprises a first passage and a second passage, and is used for exchanging heat between the refrigerant in the first passage and the refrigerant in the second passage;

the first compressor is connected with the first heat exchanger and the first passage through pipelines to form a first cycle;

the third heat exchanger is arranged in heat exchange with the liquid heat exchange medium;

The second compressor is connected with the second passage and the third heat exchanger through pipelines to form a second cycle;

The fourth heat exchanger is in heat exchange arrangement with the liquid heat exchange medium, is connected with the first heat exchanger and the first compressor through pipelines to form a third cycle, and the first cycle, the second cycle and the third cycle are linked to perform heating operation or the third cycle operation, and the third cycle operation can perform refrigeration or heating.

In some specific embodiments, the system further comprises a first controllable valve, a second controllable valve, a third controllable valve, a fourth controllable valve, a fifth controllable valve and a first throttling element, wherein the first compressor comprises a first exhaust port and a first air suction port;

The first exhaust port is connected with one end of the first passage through the first controllable valve, one end of the fourth heat exchanger through the second controllable valve and one end of the first heat exchanger through the third controllable valve; the first air suction port is connected with one end of the first heat exchanger through the fourth controllable valve, and is connected with one end of the fourth heat exchanger through the fifth controllable valve;

The other end of the first heat exchanger is connected with the other end of the first passage and the other end of the fourth heat exchanger through the first throttling piece.

In some specific embodiments, the heat exchanger further comprises a first check valve connected in series on a pipeline between the other end of the first heat exchanger and the other end of the first passage, and the first passage is communicated with the first heat exchanger.

In some specific embodiments, the cooling medium circulating pump is connected with the first throttling element in parallel, and two ends of the cooling medium circulating pump are respectively connected with two ends of the first throttling element through pipelines;

The refrigerant circulating pump, the first heat exchanger, the third controllable valve, the first controllable valve and the first passage form a fourth circulation which operates in linkage with the second circulation.

In some specific embodiments, the refrigerant circulating pump further comprises a second one-way valve, wherein two ends of the second one-way valve are respectively connected with two ends of the first throttling element after being connected with the refrigerant circulating pump in series through a pipeline;

The second one-way valve is positioned between the refrigerant circulating pump and the first heat exchanger, is connected with the liquid outlet and is communicated with the first heat exchanger from the liquid outlet.

In some specific embodiments, a gas-liquid separator is also included, comprising an inlet, an outlet;

the inlet is connected with one end of the fourth controllable valve, which is far away from the first heat exchanger, and one end of the fifth controllable valve, which is far away from the fourth heat exchanger, and the outlet is connected with the first air suction port.

In some specific embodiments, the system further comprises a four-way valve, a first controllable valve, a second controllable valve and a first throttling element, wherein the four-way valve comprises a first port, a second port, a third port and a fourth port;

The first port is connected with the first exhaust port, the second port is connected with the first air suction port, the third port is connected with one end of the first passage through the first controllable valve and one end of the fourth heat exchanger through the second controllable valve, and the fourth port is connected with one end of the first heat exchanger;

In some specific embodiments, the second compressor further comprises a second throttling element, wherein the second compressor comprises a second exhaust port and a second air suction port which are respectively connected with one end of the third heat exchanger and one end of the second passage;

The second throttling piece is a one-way throttling valve, and the third heat exchanger throttles the second passage.

In some specific embodiments, the third heat exchanger and the fourth heat exchanger are integrally provided as a fifth heat exchanger;

The fifth heat exchanger includes a third passage, a fourth passage for the second cycle, the third cycle, respectively.

The cascade heat pump system is characterized in that a fourth heat exchanger is additionally arranged on the side of a high-temperature condenser and forms a third cycle with a first compressor and the first heat exchanger, when the first heat exchanger needs defrosting, the third cycle works in a refrigeration state to form single-stage compression refrigeration to defrost the first heat exchanger, firstly, the fourth heat exchanger exchanges heat with a liquid heat exchange medium, the heat exchange efficiency is high, the evaporation efficiency is high, the defrosting efficiency of the first heat exchanger is improved, secondly, the first heat exchanger is used as a condenser to directly defrost the first heat exchanger through the refrigeration of the third cycle, defrosting is balanced and high in efficiency, and the defrosting efficiency is high to reduce the influence of defrosting on system heat supply. And the fourth heat exchanger is in heat exchange arrangement with the liquid heat exchange medium, the volume of the heat exchanger is smaller than that of the air-cooled heat exchanger, the occupied space is reduced, the power of an outdoor fan is not increased, and the cost is reduced.

Other features and advantages of the present utility model will become apparent upon review of the detailed description of the utility model in conjunction with the drawings.

Drawings

In order to more clearly illustrate the embodiments of the present utility model or the technical solutions of the prior art, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it will be obvious that the drawings in the following description are some embodiments of the present utility model, and that other drawings can be obtained according to these drawings without inventive effort to a person skilled in the art.

FIG. 1 is a schematic diagram of a system architecture according to an embodiment;

FIG. 2 is a schematic diagram of a system architecture according to an embodiment;

FIG. 3 is a schematic diagram of a system architecture according to an embodiment;

FIG. 4 is a schematic diagram of a system architecture according to an embodiment;

FIG. 5 is a schematic diagram of a system architecture according to an embodiment;

FIG. 6 is a schematic diagram of a system architecture according to an embodiment;

FIG. 7 is a schematic diagram of a system architecture according to an embodiment;

FIG. 8 is a control flow diagram according to an embodiment;

FIG. 9 is a control flow diagram according to an embodiment;

Fig. 10 is a control flow diagram according to an embodiment.

The reference numerals are given to the figures,

F. The outdoor fan, H1, the first heat exchanger, H2, the second heat exchanger, H21, the first passage, H22, the second passage, H3, the third heat exchanger, H4, the fourth heat exchanger, H5, the fifth heat exchanger, H51, the third passage, H52, the fourth passage, S1, the first controllable valve, S2, the second controllable valve, S3, the third controllable valve, S4, the fourth controllable valve, S5, the fifth controllable valve, C1, the first compressor, C2, the second compressor, the Y, the gas-liquid separator, V1, the first throttling element, V2, the second throttling element, V3, the first one-way valve, V4, the second one-way valve, V5, the one-way valve, the P, the circulating pump, V, the four-way valve, 1, the first port, 2, the second port, the 3, the third port, the 4 and the fourth port.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

In the description of the present application, it should be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present application, unless otherwise indicated, the meaning of "a plurality" is two or more.

In the description of the present application, unless explicitly stated or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected, mechanically connected, electrically connected, directly connected, indirectly connected via an intervening medium, or in communication between two elements. The specific meaning of the above terms in the present application will be understood in specific cases by those of ordinary skill in the art.

The following disclosure provides many different embodiments, or examples, for implementing different features of the utility model. In order to simplify the present disclosure, components and arrangements of specific examples are described below. They are, of course, merely examples and are not intended to limit the utility model. Furthermore, the present utility model may repeat reference numerals and/or letters in the various examples, which are for the purpose of brevity and clarity, and which do not themselves indicate the relationship between the various embodiments and/or arrangements discussed. In addition, the present utility model provides examples of various specific processes and materials, but one of ordinary skill in the art will recognize the application of other processes and/or the use of other materials.

[ Air conditioner principle ]

The air conditioner performs a refrigerating cycle of the air conditioner by using a compressor, a condenser, an expansion valve, and an evaporator. The refrigeration cycle includes a series of processes involving compression, condensation, expansion, and evaporation, and refrigerating or heating an indoor space.

The low-temperature low-pressure refrigerant enters the compressor, the compressor compresses the refrigerant gas into a high-temperature high-pressure state, and the compressed refrigerant gas is discharged. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and heat is released to the surrounding environment through the condensation process.

The expansion valve expands the liquid-phase refrigerant in a high-temperature and high-pressure state formed by condensation in the condenser into a low-pressure liquid-phase refrigerant. The evaporator evaporates the refrigerant expanded in the expansion valve and returns the refrigerant gas in a low-temperature and low-pressure state to the compressor. The evaporator may achieve a cooling effect by exchanging heat with a material to be cooled using latent heat of evaporation of a refrigerant. The air conditioner may adjust the temperature of the indoor space throughout the cycle.

An outdoor unit of an air conditioner refers to a portion of a refrigeration cycle including a compressor and an outdoor heat exchanger, an indoor unit of the air conditioner includes an indoor heat exchanger, and an expansion valve may be provided in the indoor unit or the outdoor unit.

The indoor heat exchanger and the outdoor heat exchanger function as a condenser or an evaporator. When the indoor heat exchanger is used as a condenser, the air conditioner is used as a heater of a heating mode, and when the indoor heat exchanger is used as an evaporator, the air conditioner is used as a cooler of a cooling mode.

[ Present application ]

In some specific embodiments, referring to fig. 1, 2, 3, 4, 6, 7, 8, the cascade heat pump system includes a first heat exchanger H1, a second heat exchanger H2, a third heat exchanger H3, a fourth heat exchanger H4, a first compressor C1, a second compressor C2, a first temperature sensor, a controller.

The first heat exchanger H1 is of a fin type and is arranged in an outdoor environment, and exchanges heat with the outdoor environment through an outdoor fan F.

The second heat exchanger H2 includes a first path H21 and a second path H22, and exchanges heat between the refrigerant in the first path H21 and the refrigerant in the second path H22, and simultaneously completes condensation or evaporation of the refrigerant in the first path H21 and evaporation or condensation of the refrigerant in the second path H22.

The first compressor C1 is connected to the first passage H21 of the first heat exchanger H1 and the second heat exchanger H2 through a pipeline to form a first cycle, which can realize a heating operation in which the first passage H21 is a condenser. That is, the first passage H21 functions as a condenser and the first heat exchanger H1 functions as an evaporator during the first cycle operation.

The third heat exchanger H3 is arranged for exchanging heat with the liquid heat exchange medium, for example, the liquid heat exchange medium is water, and the third heat exchanger H3 is arranged in the water tank and exchanges heat with the water in the water tank.

The second compressor C2 is connected with the second passage H22 of the second heat exchanger H2 and the third heat exchanger H3 through pipelines to form a second cycle, and the second cycle can realize heating operation of the third heat exchanger H3 as a condenser. That is, the third heat exchanger H3 functions as a condenser and the second path H22 functions as an evaporator in the second cycle operation. I.e. the third heat exchanger H3, effects heating of the water provided by the user, i.e. a heating source providing hot water to the user.

The fourth heat exchanger H4 is arranged in a heat exchange manner with the liquid heat exchange medium, for example, the liquid heat exchange medium is water, and the fourth heat exchanger H4 is arranged in the water tank and exchanges heat with the water in the water tank. The fourth heat exchanger H4 is connected with the first heat exchanger H1 and the first compressor C1 through pipelines to form a third cycle, and the heating operation of the fourth heat exchanger H4 as a condenser can be realized. That is, in the third cycle heating operation, the fourth heat exchanger H4 serves as a condenser, and the first heat exchanger H1 serves as an evaporator.

The first cycle and the second cycle are linked to perform heating operation in a first operation mode, namely two-stage compression heating operation, and the third cycle is linked to perform heating operation in a second operation mode.

The first temperature sensor is used for detecting the ambient temperature.

The controller is connected with the first temperature sensor and is used for acquiring the ambient temperature.

The controller of the system is configured to set a target temperature S100 for heating, acquire an ambient temperature in a circulating manner, calculate a difference S200 between the target temperature and the ambient temperature, and determine to operate the first operation mode or the second operation mode according to the difference S300 between the target temperature and the ambient temperature.

According to the cascade heat pump system, the required heating amount of the system is judged through the difference value between the target temperature and the ambient temperature, and the first operation mode with high heating amount or the second operation mode with low heating amount is selected according to the required heating amount, so that the heating load of the system is matched with the required heating amount, the running stability of the system is improved, and the energy efficiency of the system is improved.

In addition, the third heat exchanger H3 and the fourth heat exchanger H4 are both in heat exchange arrangement with the liquid heat exchange medium, and the fin type heat exchanger which is relatively air-cooled can be arranged to be smaller in size, namely, compared with the prior art, the heat exchanger of the cascade heat pump system in the second operation mode of realizing single-stage compression heating is reduced in size, the occupied area is reduced, the power of the outdoor fan F is not required to be increased, and the cost is reduced.

Of course, the first cycle and the second cycle can also realize linkage refrigeration to realize double-stage compression refrigeration with high compression ratio, and the third cycle can also realize refrigeration operation.

In some specific embodiments, referring to fig. 1 and 8, the cascade heat pump system further comprises a first controllable valve S1, a second controllable valve S2, and a first throttle V1, and the first compressor C1 comprises a first discharge port and a first suction port.

The first air outlet is connected with one end of a first passage H21 through a first controllable valve S1, is connected with one end of a fourth heat exchanger H4 through a second controllable valve S2, and the first air suction port is connected with one end of the first heat exchanger H1.

The other end of the first heat exchanger H1 is connected with the other end of the first passage H21 and the other end of the fourth heat exchanger H4 through a first throttling piece V1.

The system is operated in the first operation mode by controlling the first controllable valve S1 to be communicated, the second controllable valve S2 to be cut off, the first compressor C1 to operate and the second compressor C2 to operate, namely, when the system judges that the first operation mode needs to operate, the first controllable valve S1 is controlled to be communicated, the second controllable valve S2 to be cut off, and the first compressor C1 and the second compressor C2 to operate.

The system is operated in the second operation mode by controlling the second controllable valve S2 to be communicated, the first controllable valve S1 to be cut off, the first compressor C1 to operate and the second compressor C2 to stop operating, namely, when the system judges that the second operation mode needs to be operated, the second controllable valve S2 is controlled to be communicated, the first controllable valve S1 to be cut off, the first compressor C1 to operate and the second compressor C2 to stop operating.

The cascade heat pump system of the embodiment realizes the switching between the first operation mode and the second operation mode by arranging the first controllable valve S1 and the second controllable valve S2, and is simple and reliable and high in efficiency.

In some specific embodiments, referring to fig. 3, 7, 8, and 9, the cascade heat pump system further includes a refrigerant circulation pump P and a third controllable valve S3.

The two ends of the refrigerant circulating pump P are respectively connected with the two ends of the first throttling element V1 through pipelines, the two ends of the third controllable valve S3 are respectively connected with the first exhaust port and one end of the first heat exchanger H1 to form a fourth circulation consisting of the first heat exchanger H1, the first passage H21 and the refrigerant circulating pump P, and the refrigerant in the fourth circulation is not compressed by the compressor and is only used as a heat exchange medium.

The fourth cycle and the second cycle are operated in a linkage mode to be in a third operation mode. That is, in the third operation mode, the refrigerant circulation pump P is controlled to operate, the third controllable valve S3 and the first controllable valve S1 are controlled to communicate with each other, the second controllable valve is controlled to be closed, the refrigerant in the fourth cycle is caused to circulate, the refrigerant that does not pass through the compressor is caused to exchange heat with the external environment in the first heat exchanger H1, and the refrigerant in the second passage H22 is caused to exchange heat in the first passage H21. The second circulation heating operation, the second passage H22 as an evaporator and the third heat exchanger H3 as a condenser.

And judging whether to operate the first operation mode, the second operation mode or the third operation mode according to the difference value of the target temperature and the ambient temperature.

Specifically, when the system judges that the third operation mode is operated, the first controllable valve S1 and the third controllable valve S3 are controlled to be communicated, the second controllable valve S2 is controlled to be cut off, the first compressor C1 is controlled to stop operation, and the refrigerant circulating pump P and the second compressor C2 are controlled to operate.

The cascade heat pump system of the embodiment controls the third operation mode by setting the third controllable valve S3 and the refrigerant circulating pump P so that the refrigerating capacity is between the first operation mode and the second operation mode. And the running mode of execution is determined by judging the difference value of the target temperature and the ambient temperature, so that the running automation degree of the system is improved.

In some specific embodiments, referring to fig. 1, 2, 3, 4, 5, 6, and 7, the liquid heat exchange medium is water for providing hot water to a user or using hot water for heating a target object or space, and the target temperature is a target water temperature, which may be automatically obtained according to an ambient temperature.

The target temperature is in a linear relationship with the ambient temperature. That is, the target temperature is equal to the sum of the product of the first coefficient and the ambient temperature and the second coefficient. The first coefficient and the second coefficient can be set according to different requirements of different application scenes.

The cascade heat pump system of the embodiment improves the automation degree and the intelligent degree of the system operation through the automatic generation of the target temperature.

In some specific embodiments, referring to fig. 8 and 9, a first temperature threshold and a second temperature threshold smaller than the first temperature threshold are set to obtain a target temperature S101, an ambient temperature is circularly obtained, a difference between the target temperature and the ambient temperature S200 is calculated, the difference between the target temperature and the ambient temperature is compared with the first temperature threshold and the second temperature threshold, the first operation mode S401 is operated when the difference between the target temperature and the ambient temperature is not smaller than the first temperature threshold S301, the second operation mode S402 is operated when the difference between the target temperature and the ambient temperature is not larger than the second temperature threshold S302, and the third operation mode S403 is operated when the difference between the target temperature and the ambient temperature is between the second temperature threshold and the first temperature threshold.

In some specific embodiments, the first temperature threshold and the second temperature threshold are range values, the switching from the first operation mode to the third operation mode and the switching from the third operation mode to the second operation mode are respectively performed at the minimum value of the first temperature threshold and the second temperature threshold, and the switching from the second operation mode to the third operation mode and the switching from the third operation mode to the first operation mode are respectively performed at the maximum value of the first temperature threshold and the second temperature threshold.

That is, when the system is operating in the first operating mode and the difference between the target temperature and the ambient temperature is not greater than the minimum value of the first temperature threshold, the system transitions to the third operating mode and, if the difference between the target temperature and the ambient temperature is not greater than the minimum value of the second temperature threshold, the system transitions to the second operating mode.

And when the system operates in the third operation mode and the difference between the target temperature and the ambient temperature is not greater than the minimum value of the second temperature threshold, the system is switched to the second operation mode, and if the difference between the target temperature and the ambient temperature is not less than the maximum value of the first temperature threshold, the system is switched to the first operation mode.

When the system operates in the second operation mode and the difference between the target temperature and the ambient temperature is not smaller than the maximum value of the second temperature threshold, the system is converted into the third operation mode, and when the difference between the target temperature and the ambient temperature is not smaller than the maximum value of the first temperature threshold, the system is converted into the first operation mode.

In the cascade heat pump system of the embodiment, the return difference control of switching between the system operation modes is realized by setting the first temperature threshold value and the second temperature threshold value as range values, so that the frequency of switching the system operation modes is reduced, and the stability and the reliability of the system operation are improved.

In some specific embodiments, the first temperature threshold and the second temperature threshold are point values, and the switching between the first operation mode and the third operation mode and the switching between the second operation mode and the third operation mode are controlled by adopting a fixed return difference.

The method comprises the steps of setting a return difference of a first temperature threshold value and a return difference of a second temperature threshold value, switching from a first operation mode to a third operation mode and switching from the third operation mode to the second operation mode when a difference between a target temperature and an ambient temperature is not smaller than a sum of the first temperature threshold value, the second temperature threshold value and the return difference, and switching from the second operation mode to the third operation mode and from the third operation mode to the first operation mode when the difference between the target temperature and the ambient temperature is not larger than the difference between the first temperature threshold value, the second temperature threshold value and the return difference.

The cascade heat pump system of the embodiment reduces the frequency of switching the operation modes of the system by setting the return difference to control the return difference of the operation modes to be switched, and improves the stability and the reliability of the operation of the system.

In some specific embodiments, the return difference of the first temperature threshold is equal to the return difference of the second temperature threshold.

In some embodiments, the first temperature threshold is equal to a difference between the target temperature and the ambient temperature when the energy efficiency of the unit in the first mode of operation is equal to the energy efficiency of the unit in the third mode of operation, and the second temperature threshold is equal to a difference between the target temperature and the ambient temperature when the energy efficiency of the unit in the second mode of operation is equal to the energy efficiency of the unit in the third mode of operation.

The energy efficiency of the unit in the first operation mode is equal to the ratio of the unit heating amount to the sum of the outdoor fan F power, the first compressor C1 power and the second compressor C2 power, the energy efficiency of the unit in the second operation mode is equal to the ratio of the unit heating amount to the sum of the outdoor fan F power and the first compressor C1 power, and the energy efficiency of the unit in the third operation mode is equal to the ratio of the unit heating amount to the sum of the second compressor C2 power and the refrigerant circulating pump P power.

The first temperature threshold and the second temperature threshold may be obtained experimentally. The system respectively operates a first operation mode, a second operation mode and a third operation mode of set parameters, respectively calculates the energy efficiency of the unit and the corresponding difference value of the target temperature and the environment temperature, and obtains the difference value of the target temperature and the environment temperature when the energy efficiency of the unit in the first operation mode is equal to the energy efficiency of the unit in the third operation mode, and the difference value of the target temperature and the environment temperature when the energy efficiency of the unit in the second operation mode is equal to the energy efficiency of the unit in the third operation mode.

In some specific embodiments, referring to fig. 2, 3, 6, 7, and 10, the cascade heat pump system further includes a second temperature sensor, a fourth controllable valve S4, and a fifth controllable valve S5.

The second temperature sensor is disposed on the first heat exchanger H1 for detecting an evaporation temperature.

The first air suction port is connected with one end of the first heat exchanger H1 through a fourth controllable valve S4, and is connected with one end of the fourth heat exchanger H4 through a fifth controllable valve S5.

The defrosting control method comprises the steps of presetting a defrosting temperature threshold S500, circularly obtaining the ambient temperature and the evaporating temperature during heating operation in a first operation mode and a second operation mode, calculating the difference S600 between the ambient temperature and the evaporating temperature, controlling the third controllable valve S3 and the fifth controllable valve S5 to be communicated when the difference S700 between the ambient temperature and the evaporating temperature is not smaller than the defrosting temperature threshold, controlling the first controllable valve S1, the second controllable valve S2 and the fourth controllable valve S4 to be cut off, controlling the first compressor C1 to operate, controlling the second compressor C2 to stop operating, and operating the fourth operation mode S800 of the third circulation to defrost the first heat exchanger H1.

When the first cycle and the third cycle are in heating operation, the first controllable valve S1 and the fourth controllable valve S4 are controlled to be communicated, the second controllable valve S2, the third controllable valve S3 and the fifth controllable valve S5 are controlled to be cut off, the first compressor C1 and the second compressor C2 are controlled to operate, or the second controllable valve S2 and the fourth controllable valve S4 are controlled to be communicated, the first controllable valve S1, the third controllable valve S3 and the fifth controllable valve S5 are controlled to be cut off, and the first compressor C1 is controlled to operate and the second compressor C2 is controlled to stop operating.

According to the cascade heat pump system, the third circulation of the cascade heat pump system is enabled to work in a refrigerating state, namely, in a fourth operation mode through control of the first controllable valve S1, the second controllable valve S2, the third controllable valve S3, the fourth controllable valve S4 and the fifth controllable valve S5, single-stage compression refrigeration is formed to defrost the first heat exchanger H1, firstly, the fourth heat exchanger H4 exchanges heat with a liquid heat exchange medium, the heat exchange efficiency is high, the evaporation efficiency is high, the defrosting efficiency of the first heat exchanger is improved, secondly, the first heat exchanger H1 is enabled to serve as a condenser to directly defrost, defrosting is balanced and efficient, and the influence of frosting on system heat supply can be further reduced. And the fourth heat exchanger H4 is in heat exchange arrangement with the liquid heat exchange medium, the volume of the heat exchanger is smaller than that of the air-cooled heat exchanger, the occupied space is reduced, the power of the outdoor fan F is not increased, the cost is reduced, and the energy is saved.

In some specific embodiments, referring to fig. 1, 2, 3, 4, 5, 6, 7, the cascade heat pump system further comprises a first check valve V3.

The first check valve V3 is connected in series to a pipeline connected to the other end of the first heat exchanger H1 and the other end of the first passage H21, and is communicated with the first heat exchanger H1 through the first passage H21. That is, the other end of the first heat exchanger H1 is connected to the other end of the first passage H21 through a first check valve V3 and a pipe, and the first check valve V3 is communicated from the other end of the first passage H21 to the other end of the first heat exchanger H1. The other end of the first heat exchanger H1 is connected with one end of a first one-way valve V3 through a pipeline, the other end of the first one-way valve V3 is connected with the other end of a first passage H21 through a pipeline, and the first one-way valve V3 is communicated from the other end of the first passage H21 to the other end of the first heat exchanger H1.

In the operation of the cascade heat pump system in the fourth operation mode of this embodiment, the first check valve V3 prevents the refrigerant flowing out from the other end of the first heat exchanger H1 or the other end of the fourth heat exchanger H4 from entering the first passage H21 to reduce the quality of the flowing refrigerant, ensure the quality of the refrigerant in the third cycle, and improve the heating and defrosting efficiency.

In some specific embodiments, referring to fig. 3, 6, and 7, the cascade heat pump system further includes a second check valve V4. The refrigerant circulating pump P comprises a liquid inlet and a liquid outlet.

The second check valve V4 and the refrigerant circulating pump P are connected in series through a pipeline, and then the two ends of the second check valve V4 and the two ends of the first throttling element V1 are respectively connected, are positioned between the refrigerant circulating pump P and the first heat exchanger H1, and are communicated with the first heat exchanger H1 through the refrigerant circulating pump P.

Namely, one end of the second one-way valve V4 is connected with the other end of the first heat exchanger H1 through a pipeline, the other end of the second one-way valve V4 is connected with a liquid outlet of the refrigerant circulating pump P, a liquid inlet of the refrigerant circulating pump P is connected with the other end of the first passage H21 or is connected with the other end of the first passage H21 through the first one-way valve V3, and the second one-way valve V4 is communicated from the liquid outlet of the refrigerant circulating pump P to the other end of the first heat exchanger H1.

In the cascade heat pump system of this embodiment, the second check valve V4 is provided to prevent the refrigerant from entering from the liquid outlet of the refrigerant circulating pump P and flowing out from the liquid inlet to reversely drive the refrigerant circulating pump P. The stability, reliability and safety of the system operation are ensured.

In some specific embodiments, referring to fig. 2, 3, 5, 6 and 7, the cascade heat pump system further comprises a gas-liquid separator Y, which includes an inlet and an outlet.

The inlet is connected with one end of the fourth controllable valve S4 far away from the first heat exchanger H1, one end of the fifth controllable valve S5 far away from the fourth heat exchanger H4, and the outlet is connected with the first air suction port.

Namely, the inlet is connected with one end of the first heat exchanger H1 through a fourth controllable valve S4, is connected with one end of the fourth heat exchanger H4 through a fifth controllable valve S5, and the outlet is connected with the first air suction port.

The first air suction port is connected with one end of a fourth controllable valve S4 and one end of a fifth valve through a gas-liquid separator Y, the other end of the fourth controllable valve S4 is connected with one end of a first heat exchanger H1, and the other end of the fifth controllable valve S5 is connected with one end of the fourth heat exchanger H4.

In some specific embodiments, referring to fig. 4, the cascade heat pump system includes a first heat exchanger H1, a second heat exchanger H2, a third heat exchanger H3, a fourth heat exchanger H4, a first compressor C1, a second compressor C2, a four-way valve V, a first controllable valve S1, a second controllable valve S2, and a first throttle V1.

The first heat exchanger H1 is disposed in an outdoor environment, and exchanges heat with the outdoor environment through the outdoor fan F.

The second heat exchanger H2 includes a first passage H21, a second passage H22 for exchanging heat between the refrigerant in the first passage H21 and the refrigerant in the second passage H22.

The first compressor C1 is connected to the first heat exchanger H1 and the first passage H21 through pipes to form a first cycle.

The third heat exchanger H3 is arranged in heat exchange with the liquid heat exchange medium.

The second compressor C2 is connected to the second passage H22 and the third heat exchanger H3 through pipes to form a second cycle.

The fourth heat exchanger H4 is in heat exchange arrangement with the liquid heat exchange medium, is connected with the first heat exchanger H1 and the first compressor C1 through pipelines to form a third cycle, and the first cycle and the second cycle are linked to perform heating operation or third cycle operation, and the third cycle operation can perform refrigeration or heating.

The four-way valve V comprises a first port 1, a second port 2, a third port 3 and a fourth port 4, and the first compressor C1 comprises a first exhaust port and a first air suction port.

The first exhaust port is connected with the first port 1, the second port 2 is connected with the first air suction port, the third port 3 is connected with one end of the first passage H21 through the first controllable valve S1 and one end of the fourth heat exchanger H4 through the second controllable valve S2, and the fourth port 4 is connected with one end of the first heat exchanger H1.

The cascade heat pump system of the embodiment realizes the heating operation of the first cycle, the heating operation of the third cycle or the cooling operation of the third cycle through the four-way valve V, the first controllable valve S1 and the second controllable valve S2.

In some specific embodiments, a controller of the cascade heat pump system is connected with a first temperature sensor and a second temperature sensor to obtain the ambient temperature and the evaporation temperature, and the controller is connected with an outdoor fan F, a first compressor C1, a second compressor C2, a first controllable valve S1, a second controllable valve S2, a third controllable valve S3, a fourth controllable valve S4, a fifth controllable valve S5, a first throttling element V1, a second throttling element V2 and a refrigerant circulating pump P to control the actions according to control logic.

In some specific embodiments, a controller of the cascade heat pump system is connected with a first temperature sensor and a second temperature sensor to obtain the ambient temperature and the evaporation temperature, and the controller is connected with an outdoor fan F, a first compressor C1, a second compressor C2, a first controllable valve S1, a second controllable valve S2, a four-way valve V, a first throttling element V1 and a second throttling element V2 to control actions according to control logic.

In some specific embodiments, referring to fig. 4, the cascade heat pump system further comprises a gas-liquid separator Y comprising an inlet, an outlet.

The second port 2 is connected to the first suction port through the gas-liquid separator Y. I.e. the inlet is connected to the second port 2 and the outlet is connected to the first suction port.

In some specific embodiments, referring to fig. 1, 2, 3, 4, 5, 6, and 7, the cascade heat pump system further includes a second throttle V2, the second compressor C2 includes a second discharge port and a second suction port, which are respectively connected to one end of the third heat exchanger H3 and one end of the second passage H22, and the other end of the second passage H22 is connected to the other end of the third heat exchanger H3 through the second throttle V2.

The first throttle member V1 is a two-way throttle valve, the second throttle member V2 is a one-way throttle valve, and the third heat exchanger H3 throttles the second passage H22.

In some specific embodiments, referring to fig. 6 and 7, the first throttling element V1 may be connected by a check valve set V5 composed of four check valves to form a bridge, and the check valves are disposed on the bridge to implement a bidirectional throttling function.

In some specific embodiments, referring to fig. 3, 4, 5, and 6, the third heat exchanger H3 and the fourth heat exchanger H4 are integrally provided as a fifth heat exchanger H5.

The fifth heat exchanger H5 includes a third passage H51, a fourth passage H52 for the second cycle, and the third cycle, respectively.

According to the cascade heat pump system, the third heat exchanger H3 and the fourth heat exchanger H4 are integrally arranged, so that the volume of the heat exchangers of the cascade heat pump system is further reduced, the occupied space is reduced, and the cost is further reduced.

In the description of the above embodiments, particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing is merely illustrative of the present utility model, and the present utility model is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present utility model should be included in the scope of the present utility model. Therefore, the protection scope of the utility model is subject to the protection scope of the claims.

Claims

1. A cascade heat pump system, comprising:

the first heat exchanger is arranged in the outdoor environment and exchanges heat with the outdoor environment through the outdoor fan;

A second heat exchanger including a first passage, a second passage for exchanging heat between the refrigerant in the first passage and the refrigerant in the second passage;

A third heat exchanger arranged in heat exchange with the liquid heat exchange medium;

2. The cascade heat pump system of claim 1, further comprising a first controllable valve, a second controllable valve, a third controllable valve, a fourth controllable valve, a fifth controllable valve, a first throttle, wherein the first compressor comprises a first discharge port, a first suction port;

3. The cascade heat pump system of claim 2, further comprising a first check valve connected in series on a line between the other end of the first heat exchanger and the other end of the first passage, the first passage communicating to the first heat exchanger.

4. The cascade heat pump system of claim 3, further comprising a refrigerant circulation pump connected in parallel with the first throttling element, both ends of which are connected with both ends of the first throttling element through pipes, respectively;

5. The cascade heat pump system of claim 4, further comprising a second check valve connected in series with the refrigerant circulation pump through a pipe and having two ends respectively connected to two ends of the first throttle member;

6. The cascade heat pump system of claim 2, further comprising a gas-liquid separator comprising an inlet, an outlet;

7. The cascade heat pump system of claim 1, further comprising a four-way valve, a first controllable valve, a second controllable valve, a first throttle, the four-way valve comprising a first port, a second port, a third port, a fourth port, the first compressor comprising a first discharge port, a first suction port;

8. The cascade heat pump system of claim 7, further comprising a first check valve connected in series on a line between the other end of the first heat exchanger and the other end of the first passage, the first passage communicating to the first heat exchanger.

9. The cascade heat pump system according to any one of claims 2-8, further comprising a second throttle, wherein the second compressor comprises a second discharge port, a second suction port, which are respectively connected to one end of the third heat exchanger, one end of the second passage, and the other end of the second passage is connected to the other end of the third heat exchanger through the second throttle;

10. The cascade heat pump system according to any one of claims 1 to 8, characterized in that the third heat exchanger and the fourth heat exchanger are integrally provided as a fifth heat exchanger;