Composite solution heat exchanger with pre-cooler and refrigeration system and process thereof

Abstract

The application belongs to the technical field of absorption refrigeration, and particularly relates to a composite solution heat exchanger with a precooler and a refrigeration system and process thereof. The composite precooled heat exchanger comprises a shell, a GAX heat exchanger and a precooler. The GAX heat exchanger and the precooler are both horizontally arranged in the shell. A partition plate is fixedly arranged in the shell to separate the GAX heat exchanger and the precooler. A through opening is arranged between the top of the partition plate and the inner wall of the shell. The absorption refrigeration system comprises a generator, a condenser, an evaporator, an absorber, a lean-rich liquid heat exchanger and a GVX heat exchanger. The lean-rich liquid heat exchanger utilizes the composite precooled heat exchanger. The shell structure can solve the problem of refrigerant leakage of the lean-rich liquid heat exchanger. The precooler is arranged in the shell, and the liquid refrigerant in the shell can be used to cool the precooler. The leaked refrigerant of the lean-rich liquid heat exchanger can be absorbed, and the overall safety of the device is improved.

Description

Technical Field

[0001] This invention relates to the field of absorption refrigeration technology, and in particular to a composite solution heat exchanger with a precooler, its refrigeration system, and process. Background Technology

[0002] Absorption refrigeration systems utilize low-grade waste heat to drive a thermodynamic working fluid, achieving refrigeration through a phase change of the working fluid (such as ammonia). The main equipment includes a generator, condenser, evaporator, absorber, and solution pump. The generator primarily uses low-grade waste heat to heat a mixed solution (rich in refrigerant) of a certain concentration, delivered from the absorber by the solution pump. This causes most of the low-boiling-point refrigerant in the rich solution to desorb, becoming a high-pressure gaseous refrigerant that enters the condenser. There, it is cooled by circulating water into a high-pressure liquid refrigerant. The high-pressure liquid refrigerant then passes through an expansion valve to depressurize into a low-pressure, saturated gaseous refrigerant. This low-pressure gaseous refrigerant enters the evaporator, where it absorbs heat from the medium to be cooled and vaporizes into a low-pressure gaseous refrigerant, which then enters the absorber. The high-pressure lean liquid remaining in the generator after the generation process is reduced to low-pressure lean liquid by the pressure reducing valve and enters the absorber, where it mixes and absorbs with the low-pressure gaseous refrigerant coming out of the evaporator, restoring it to its original concentration and becoming room-temperature rich liquid. The room-temperature rich liquid is pressurized by the solution pump and sent back to the generator to continue the cycle.

[0003] The patent with publication number "CN108148555B" discloses a deep refrigeration method driven by a refrigerant and residual heat. The deep refrigeration system includes an absorber, a generator, a condenser, and an evaporator. The rich solution output of the absorber is connected to the rich solution input of the generator via a rich solution pipeline, and a solution pump is installed on the rich solution pipeline. The lean solution output of the generator is connected to the lean solution input of the absorber via a lean solution pipeline, forming a solution loop. A throttling valve is installed on the lean solution pipeline. The ammonia output of the generator is connected to the ammonia input of the condenser via a high-temperature ammonia pipeline. The ammonia liquid output of the condenser is connected to the ammonia liquid input of the evaporator via an ammonia liquid pipeline, and a pressure reducing valve is installed on the ammonia liquid pipeline. The ammonia gas output of the condenser is connected to the ammonia input of the absorber via a low-temperature ammonia gas pipeline, forming an ammonia loop.

[0004] In practical applications, lean and rich liquid heat exchangers adopt plate heat exchanger structures. The corrugated design on the surface of the plates of the plate heat exchanger can create strong turbulence in the medium within the flow channel, which greatly improves the heat transfer coefficient. Moreover, the hot and cold media flow in opposite directions, resulting in high temperature difference utilization and higher heat exchange efficiency. However, plate heat exchangers are prone to refrigerant leakage due to problems such as stress impact, poor welding quality, inadequate sealing structure design, corrosion and aging of metal materials, which pose certain safety hazards and urgently need to be addressed. Summary of the Invention

[0005] 1. Technical problems to be solved

[0006] The purpose of this invention is to solve the problem of refrigerant leakage in existing plate-type rich and lean liquid heat exchangers due to poor welding quality, inadequate sealing structure design, metal corrosion and aging, etc., and to propose a composite solution heat exchanger with a precooler, as well as its refrigeration system and process.

[0007] 2. Technical Solution

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A composite solution heat exchanger with a precooler includes a shell, a GAX heat exchanger, and a precooler. The GAX heat exchanger and the precooler are both horizontally arranged inside the shell. A partition is fixedly installed inside the shell to separate the GAX heat exchanger and the precooler. An opening is provided between the top of the partition and the inner wall of the shell for the passage of gaseous refrigerant. A high-pressure liquid refrigerant inlet and a high-pressure gaseous refrigerant outlet are respectively provided on the top of the shell near the precooler end.

[0010] The top of the GAX heat exchanger is provided with a rich solution inlet and a high-pressure lean solution outlet for introducing rich solution and exporting high-pressure lean solution, respectively. The bottom of the GAX heat exchanger is provided with a rich solution outlet and a high-pressure lean solution inlet for exporting rich solution and introducing high-pressure lean solution, respectively.

[0011] The precooler is provided with a precooling inlet and a precooling outlet on one side. The precooling inlet is connected to the high-pressure lean solution outlet through a conduit, which is used to introduce the high-pressure lean solution into the precooler.

[0012] Preferably, a level gauge is installed at one end of the housing near the high-pressure liquid refrigerant inlet to monitor the level of the high-pressure liquid refrigerant inside the housing.

[0013] Preferably, the level gauge is one of a radio frequency admittance level gauge, a cable-guided wave radar level gauge, or a magnetostrictive level gauge.

[0014] Preferably, a liquid refrigerant collection bag is provided at the bottom of the shell near the GAX heat exchanger, and a collection pipe is fixedly connected to the bottom of the liquid refrigerant collection bag, with a control valve provided on the collection pipe; a connecting pipe is fixedly connected to the bottom of the shell near the precooler, with a manual valve provided on the connecting pipe.

[0015] Preferably, the precooler is one of a plate precooler, a shell precooler, or a spiral wound precooler.

[0016] This invention also proposes an operation method for a composite solution heat exchanger with a precooler, which includes the following steps using the aforementioned composite precooling heat exchanger:

[0017] S1: High-pressure liquid refrigerant is introduced into one side of the precooler through the high-pressure liquid refrigerant inlet, so that the precooler is completely immersed in the high-pressure liquid refrigerant. At the same time, the high-pressure liquid refrigerant is partially vaporized into high-pressure gaseous refrigerant under the heat exchange effect of the precooler. The high-pressure gaseous refrigerant first enters the GAX heat exchanger side through the port. When the pressure inside the shell is balanced, the high-pressure gaseous refrigerant exits through the high-pressure gaseous refrigerant outlet.

[0018] S2: Then, the rich solution and the high-pressure lean solution are introduced through the rich solution inlet and the high-pressure lean solution inlet, respectively. The rich solution and the high-pressure lean solution exchange heat in the GAX heat exchanger. After heat exchange, the rich solution and the high-pressure lean solution are discharged through the rich solution outlet and the high-pressure lean solution outlet, respectively.

[0019] S3: The high-pressure lean solution discharged from the high-pressure lean solution outlet enters the precooler through the precooling inlet and is precooled by the precooler. The precooled high-pressure lean solution is then discharged through the precooling outlet.

[0020] This invention also proposes a refrigeration system, including a generator, a condenser, an evaporator, an absorber, a lean-rich liquid heat exchanger, and a GVX heat exchanger. The lean-rich liquid heat exchanger utilizes the aforementioned composite pre-cooling heat exchanger. The inlet of the generator is connected to a rich solution outlet, a collection pipe, and a connecting pipe, respectively. The outlet of the generator is connected to a high-pressure lean solution inlet. The outlet of the absorber is connected to the rich solution inlet via a solution pump. The inlet of the absorber is connected to the pre-cooling outlet via a first expansion valve. The outlet of the condenser is connected to a high-pressure liquid refrigerant inlet and the GVX heat exchanger, respectively. The outlet of the generator and the high-pressure gaseous refrigerant outlet are both connected to the inlet of the condenser. The outlet of the GVX heat exchanger is connected to the inlet of the evaporator via a second expansion valve.

[0021] Preferably, a solenoid valve is provided between the liquid outlet of the condenser and the high-pressure liquid refrigerant inlet, for controlling the flow rate of the high-pressure liquid refrigerant according to the liquid level signal monitored by the level gauge.

[0022] This invention also proposes a refrigeration process utilizing the aforementioned refrigeration system, comprising the following steps:

[0023] Step 1: After the rich liquid is heated by the heat source in the generator, it produces a high-pressure lean solution and a high-pressure gaseous refrigerant. The high-pressure lean solution enters the composite pre-cooling heat exchanger through the high-pressure lean solution inlet, and the high-pressure gaseous refrigerant enters the condenser.

[0024] Step 2: The high-pressure gaseous refrigerant exchanges heat in the condenser and liquefies into high-pressure liquid refrigerant. Then, part of the high-pressure liquid refrigerant is introduced into the composite precooling heat exchanger through the high-pressure liquid refrigerant inlet, and the remaining high-pressure liquid refrigerant is introduced into the GVX heat exchanger for heat exchange.

[0025] Step 3: After heat exchange, the high-pressure liquid refrigerant is depressurized to low-pressure liquid refrigerant through the expansion valve. The low-pressure liquid refrigerant enters the evaporator to absorb heat and cool, and then vaporizes into low-pressure gaseous refrigerant. The low-pressure gaseous refrigerant is then introduced into the absorber after heat exchange through the GVX heat exchanger.

[0026] Step 4: Simultaneously, the high-pressure lean solution after heat exchange is introduced into the expansion valve through the high-pressure lean solution outlet, where it is depressurized to a low-pressure lean solution and enters the absorber. The low-pressure lean solution absorbs the low-pressure gaseous refrigerant in the absorber and forms a rich solution. The rich solution is then introduced into the composite pre-cooling heat exchanger by the solution pump for heat exchange and then enters the generator for circulation.

[0027] 3. Beneficial effects

[0028] Compared with the prior art, the advantages of this invention are:

[0029] (1) In this invention, by setting up a shell structure, the lean and rich liquid heat exchanger can be provided with leak protection. At the same time, by placing the precooler inside the shell, the liquid refrigerant inside the shell can be used to cool the precooler and absorb the refrigerant leaked from the lean and rich liquid heat exchanger, thereby effectively improving the overall safety of the device.

[0030] (2) In this invention, by setting a partition, the GAX heat exchanger and the precooler are separated. The high-pressure liquid refrigerant at the precooler can be vaporized into high-pressure gaseous refrigerant and enter the side of the GAX heat exchanger through the port, and form a pressure balance with the interior of the GAX heat exchanger to prevent refrigerant leakage in the GAX heat exchanger.

[0031] (3) In this invention, the liquid level gauge can dynamically monitor the liquid level of the high-pressure liquid refrigerant on the precooler side and send the monitoring signal to the control system. The control system controls the opening and closing of the solenoid valve according to the monitoring data of the liquid level gauge, thereby realizing the control of the flow rate of the high-pressure liquid refrigerant. The liquid refrigerant collection bag can collect the liquid refrigerant on the GAX heat exchanger side and introduce it into the generator for circulation. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the internal structure of a composite solution heat exchanger with a precooler proposed in Embodiment 1 of the present invention;

[0033] Figure 2This is a side view of a composite solution heat exchanger with a precooler proposed in Embodiment 1 of the present invention;

[0034] Figure 3 This is a schematic diagram of the working process of a composite solution heat exchanger with a precooler proposed in Embodiment 2 of the present invention;

[0035] Figure 4 This is a schematic diagram of the working process of a refrigeration system proposed in Embodiment 3 of the present invention.

[0036] In the diagram: 1. Shell; 2. GAX heat exchanger; 3. Precooler; 4. Baffle; 5. Port; 6. High-pressure liquid refrigerant inlet; 7. High-pressure gaseous refrigerant outlet; 8. Rich solution inlet; 9. High-pressure lean solution outlet; 10. Rich solution outlet; 11. High-pressure lean solution inlet; 12. Precooling inlet; 13. Precooling outlet; 14. Conduit; 15. Level gauge; 16. Liquid refrigerant collection bag; 17. Collection pipe; 18. Control valve; 19. Connecting pipe; 20. Manual valve; 21. Support ring plate. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0038] Example 1:

[0039] Reference Figure 1-2 A composite solution heat exchanger with a precooler includes a shell 1, a GAX heat exchanger 2, and a precooler 3. The GAX heat exchanger 2 and the precooler 3 are both horizontally arranged inside the shell 1, forming an integrated structure that can effectively reduce the volume of the refrigeration equipment. The shell 1 is provided with multiple support ring plates 21 corresponding to the GAX heat exchanger 2 and the precooler 3, respectively, for supporting the GAX heat exchanger 2 and the precooler 3. The shell 1 includes a shell and tube boxes at both ends. The shell and the tube boxes at both ends are connected by flanges to facilitate maintenance of the GAX heat exchanger 2 and the precooler 3.

[0040] In this embodiment, a liquid refrigerant collection pack 16 is provided at the bottom of the shell 1 near the GAX heat exchanger side for collecting the liquid refrigerant formed on the GAX heat exchanger side. A collection pipe 17 is fixedly connected to the bottom of the liquid refrigerant collection pack 16 for introducing the liquid refrigerant into the generator. A control valve 18 is provided on the collection pipe 17 for controlling the amount of liquid refrigerant discharged. A connecting pipe 19 is fixedly connected to the bottom of the shell 1 near the precooler side for introducing the rich solution generated by the precooler leakage into the generator. A hand valve 20 is provided on the connecting pipe 19 for controlling the liquid flow rate in the connecting pipe 19.

[0041] In this embodiment, a partition 4 is fixedly installed inside the shell 1 to separate the GAX heat exchanger 2 and the precooler 3. High-pressure liquid refrigerant can enter the GAX heat exchanger side. A passage 5 is provided between the top of the partition 4 and the inner wall of the shell 1 for the passage of gaseous refrigerant to enter the GAX heat exchanger side and balance the internal pressure of the entire shell 1. It can also form a pressure balance with the inside of the GAX heat exchanger to prevent refrigerant leakage inside the GAX heat exchanger.

[0042] In this embodiment, the top of the shell 1 near the precooler 3 is provided with a high-pressure liquid refrigerant inlet 6 and a high-pressure gaseous refrigerant outlet 7, which are used to introduce the high-pressure liquid refrigerant in the condenser into the shell 1, absorb the heat of the precooler, vaporize it into high-pressure gaseous refrigerant, and reintroduce the high-pressure gaseous refrigerant formed in the shell 1 into the condenser for cooling.

[0043] In this embodiment, a level gauge 15 is installed at one end of the housing 1 near the high-pressure liquid refrigerant inlet 6 to monitor the level of the high-pressure liquid refrigerant inside the housing 1. The level gauge 15 is one of a radio frequency admittance level gauge, a cable-type guided wave radar level gauge, or a magnetostrictive level gauge.

[0044] In this embodiment, the top of the GAX heat exchanger 2 is provided with a rich solution inlet 8 and a high-pressure lean solution outlet 9. The rich solution inlet 8 is used to introduce the rich solution generated by the absorber, and the high-pressure lean solution outlet 9 is used to introduce the high-pressure lean solution after heat exchange into the precooler 3. The bottom of the GAX heat exchanger 2 is provided with a rich solution outlet 10 and a high-pressure lean solution inlet 11, which are used to export the rich solution and import the high-pressure lean solution.

[0045] In this embodiment, a precooling inlet 12 and a precooling outlet 13 are respectively provided on one side of the precooler 3. The precooling inlet 12 is used to introduce the high-pressure lean solution into the precooler 3 for precooling. The precooling outlet 13 can introduce the cooled high-pressure lean solution into the first expansion valve to reduce the pressure. The precooling inlet 12 is connected to the high-pressure lean solution outlet 9 through a conduit 14, which is used to introduce the high-pressure lean solution in the GAX heat exchanger 2 into the precooler 3 for precooling and cooling. The precooler 3 is one of a plate precooler, a shell precooler, or a spiral wound precooler, so that the precooler 3 can be completely immersed in the refrigerant, thereby improving the heat exchange effect of the precooler.

[0046] In this embodiment, by setting up a shell structure, leakage protection can be provided for the lean and rich liquid heat exchanger. At the same time, by placing the precooler inside the shell, the liquid refrigerant inside the shell can be used to cool the precooler and absorb the refrigerant leaking from the lean and rich liquid heat exchanger, thereby effectively improving the overall safety of the device.

[0047] Example 2:

[0048] In this embodiment, refer to Figure 3 An operating method for a composite solution heat exchanger with a precooler, utilizing the composite precooling heat exchanger proposed in Example 1, includes the following steps:

[0049] S1: High-pressure liquid refrigerant is introduced into one side of the precooler 3 through the high-pressure liquid refrigerant inlet 6, so that the precooler 3 is completely immersed in the high-pressure liquid refrigerant. At the same time, the high-pressure liquid refrigerant is partially vaporized into high-pressure gaseous refrigerant under the heat exchange effect of the precooler 3. The high-pressure gaseous refrigerant first enters the side of the GAX heat exchanger 2 through the port 5. After the pressure inside the shell 1 is balanced, the high-pressure gaseous refrigerant exits through the high-pressure gaseous refrigerant outlet 7.

[0050] S2: Then, the rich solution and the high pressure lean solution are introduced through the rich solution inlet 8 and the high pressure lean solution inlet 11, respectively. The rich solution and the high pressure lean solution exchange heat in the GAX heat exchanger 2. After heat exchange, the rich solution and the high pressure lean solution are discharged through the rich solution outlet 10 and the high pressure lean solution outlet 9, respectively.

[0051] S3: The high-pressure lean solution discharged from the high-pressure lean solution outlet 9 enters the precooler 3 through the precooling inlet 12 and is precooled by the precooler 3. The precooled high-pressure lean solution is discharged through the precooling outlet 13.

[0052] Example 3:

[0053] In this embodiment, refer to Figure 4 A refrigeration system includes a generator, a condenser, an evaporator, an absorber, a lean-rich liquid heat exchanger, and a GVX heat exchanger. The lean-rich liquid heat exchanger utilizes the composite pre-cooling heat exchanger in Example 1. The inlet end of the generator is connected to the rich solution outlet 10, the collection pipe 17, and the connecting pipe 19, respectively, for introducing the rich solution in the GAX heat exchanger into the generator. The outlet end of the generator is connected to the high-pressure lean solution inlet 11, for introducing the high-pressure lean solution generated in the generator into the GAX heat exchanger 2, where it exchanges heat with the rich solution discharged from the absorber.

[0054] In this embodiment, the liquid outlet of the absorber is connected to the rich solution inlet 8 via a solution pump to pressurize the high-pressure rich solution discharged from the absorber and introduce it into the GAX heat exchanger 2. The liquid inlet of the absorber is connected to the precooling liquid outlet 13 via a first expansion valve to depressurize the high-pressure lean solution discharged from the precooler 3, reducing the impact of the lean solution on the absorber. The liquid outlet of the condenser is connected to the high-pressure liquid refrigerant inlet 6 and the GVX heat exchanger, respectively, to introduce part of the high-pressure liquid refrigerant into the shell 1 to absorb heat and cool the precooler. Most of the high-pressure liquid refrigerant enters the GVX heat exchanger and exchanges heat with the low-pressure gaseous refrigerant discharged from the evaporator. A solenoid valve is provided between the liquid outlet of the condenser and the high-pressure liquid refrigerant inlet 6 to control the flow rate of the high-pressure liquid refrigerant according to the liquid level signal monitored by the level gauge 15.

[0055] In this embodiment, the gas outlet of the generator and the high-pressure gaseous refrigerant outlet 7 are both connected to the gas inlet of the condenser. The liquid outlet of the GVX heat exchanger is connected to the liquid inlet of the evaporator through a second expansion valve. The second expansion valve can reduce the pressure of the high-pressure liquid refrigerant discharged from the GVX heat exchanger.

[0056] Example 4:

[0057] In this embodiment, refer to Figure 4 A refrigeration process, utilizing the absorption refrigeration system in Example 3, includes the following steps:

[0058] Step 1: After the rich liquid is heated by the heat source in the generator, it produces a high-pressure lean solution and a high-pressure gaseous refrigerant. The high-pressure lean solution enters the composite pre-cooling heat exchanger through the high-pressure lean solution inlet 11, and the high-pressure gaseous refrigerant enters the condenser.

[0059] Step 2: The high-pressure gaseous refrigerant exchanges heat in the condenser and liquefies into high-pressure liquid refrigerant. Then, part of the high-pressure liquid refrigerant is introduced into the composite pre-cooling heat exchanger through the high-pressure liquid refrigerant inlet 6, and the remaining high-pressure liquid refrigerant is introduced into the GVX heat exchanger for heat exchange.

[0060] Step 3: After heat exchange, the high-pressure liquid refrigerant is depressurized to low-pressure liquid refrigerant through the expansion valve. The low-pressure liquid refrigerant enters the evaporator to absorb heat and cool, and then vaporizes into low-pressure gaseous refrigerant. The low-pressure gaseous refrigerant is then introduced into the absorber after heat exchange through the GVX heat exchanger.

[0061] Step 4: Simultaneously, the high-pressure lean solution after heat exchange is introduced into the expansion valve through the high-pressure lean solution outlet 9, where it is depressurized to a low-pressure lean solution and enters the absorber. The low-pressure lean solution absorbs the low-pressure gaseous refrigerant in the absorber and forms a rich solution. The rich solution is introduced into the composite pre-cooling heat exchanger through the solution pump for heat exchange and then enters the generator for circulation.

[0062] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A composite solution heat exchanger with a precooler, comprising a shell (1), a GAX heat exchanger (2), and a precooler (3), characterized in that, The GAX heat exchanger (2) and the precooler (3) are both horizontally arranged inside the shell (1). A partition (4) is fixedly installed inside the shell (1) to separate the GAX heat exchanger (2) and the precooler (3). A passage (5) is provided between the top of the partition (4) and the inner wall of the shell (1) for the passage of gaseous refrigerant. A high-pressure liquid refrigerant inlet (6) and a high-pressure gaseous refrigerant outlet (7) are respectively provided on the top of the shell (1) near the precooler (3). The top of the GAX heat exchanger (2) is provided with a rich solution inlet (8) and a high-pressure lean solution outlet (9) for introducing rich solution and exporting high-pressure lean solution. The bottom of the GAX heat exchanger (2) is provided with a rich solution outlet (10) and a high-pressure lean solution inlet (11) for exporting rich solution and introducing high-pressure lean solution. The precooler (3) is provided with a precooling inlet (12) and a precooling outlet (13) on one side. The precooling inlet (12) is connected to the high-pressure lean solution outlet (9) through a conduit (14) to introduce the high-pressure lean solution into the precooler (3). The bottom of the shell (1) near the GAX heat exchanger is provided with a liquid refrigerant collection bag (16). The bottom of the liquid refrigerant collection bag (16) is fixedly connected to a collection pipe (17). A control valve (18) is provided on the collection pipe (17). The bottom of the shell (1) near the precooler is fixedly connected to a connecting pipe (19). A hand valve (20) is provided on the connecting pipe (19).

2. A composite solution heat exchanger with a precooler according to claim 1, characterized in that, A level gauge (15) is installed at one end of the housing (1) near the high-pressure liquid refrigerant inlet (6) to monitor the level of the high-pressure liquid refrigerant inside the housing (1).

3. A composite solution heat exchanger with a precooler according to claim 2, characterized in that, The level gauge (15) is one of the following: radio frequency admittance level gauge, cable guided wave radar level gauge, or magnetostrictive level gauge.

4. A composite solution heat exchanger with a precooler according to claim 1, characterized in that, The precooler (3) is one of a plate precooler, a shell-and-tube precooler, or a spiral wound precooler.

5. A method for operating a composite solution heat exchanger with a precooler, utilizing the composite solution heat exchanger as described in any one of claims 1-4, characterized in that, Includes the following steps: S1: High-pressure liquid refrigerant is introduced into one side of the precooler (3) through the high-pressure liquid refrigerant inlet (6), so that the precooler (3) is completely immersed in the high-pressure liquid refrigerant. At the same time, the high-pressure liquid refrigerant is partially vaporized into high-pressure gaseous refrigerant under the heat exchange effect of the precooler (3). The high-pressure gaseous refrigerant first enters the side of the GAX heat exchanger (2) through the port (5). When the pressure inside the shell (1) is balanced, the high-pressure gaseous refrigerant is discharged through the high-pressure gaseous refrigerant outlet (7). S2: Then, the rich solution and the high pressure lean solution are introduced through the rich solution inlet (8) and the high pressure lean solution inlet (11) respectively. The rich solution and the high pressure lean solution exchange heat in the GAX heat exchanger (2). After heat exchange, the rich solution and the high pressure lean solution are discharged through the rich solution outlet (10) and the high pressure lean solution outlet (9) respectively. S3: The high pressure lean solution discharged from the high pressure lean solution outlet (9) enters the precooler (3) through the precooling inlet (12) and is precooled by the precooler (3). The precooled high pressure lean solution is discharged through the precooling outlet (13).

6. A refrigeration system, comprising a generator, a condenser, an evaporator, an absorber, a lean-rich liquid heat exchanger, and a GVX heat exchanger, characterized in that, The lean and rich liquid heat exchanger utilizes the composite solution heat exchanger as described in any one of claims 1-4. The inlet end of the generator is connected to the rich solution outlet (10), the collection pipe (17), and the connecting pipe (19), respectively. The outlet end of the generator is connected to the high-pressure lean solution inlet (11). The outlet end of the absorber is connected to the rich solution inlet (8) via a solution pump. The inlet end of the absorber is connected to the pre-cooled outlet (13) via a first expansion valve. The outlet end of the condenser is connected to the high-pressure liquid refrigerant inlet (6) and the GVX heat exchanger, respectively. The outlet end of the generator and the high-pressure gaseous refrigerant outlet (7) are both connected to the inlet end of the condenser. The outlet end of the GVX heat exchanger is connected to the inlet end of the evaporator via a second expansion valve.

7. A refrigeration system according to claim 6, characterized in that, A solenoid valve is provided between the liquid outlet of the condenser and the high-pressure liquid refrigerant inlet (6) to control the flow rate of the high-pressure liquid refrigerant according to the liquid level signal monitored by the level gauge (15).

8. A refrigeration process, utilizing the refrigeration system as described in any one of claims 6-7, comprising the following steps: Step 1: After the rich liquid is heated by the heat source in the generator, a high-pressure lean solution and a high-pressure gaseous refrigerant are generated. The high-pressure lean solution enters the composite precooling heat exchanger through the high-pressure lean solution inlet (11), and the high-pressure gaseous refrigerant enters the condenser. Step 2: The high-pressure gaseous refrigerant exchanges heat in the condenser and liquefies into high-pressure liquid refrigerant. Then, part of the high-pressure liquid refrigerant is introduced into the composite precooling heat exchanger through the high-pressure liquid refrigerant inlet (6), and the remaining high-pressure liquid refrigerant is introduced into the GVX heat exchanger for heat exchange. Step 3: After heat exchange, the high-pressure liquid refrigerant is depressurized to low-pressure liquid refrigerant through the expansion valve. The low-pressure liquid refrigerant enters the evaporator to absorb heat and cool, and then vaporizes into low-pressure gaseous refrigerant. The low-pressure gaseous refrigerant is then introduced into the absorber after heat exchange through the GVX heat exchanger. Step 4: At the same time, the high-pressure lean solution after heat exchange is introduced into the expansion valve through the high-pressure lean solution outlet (9), and the pressure is reduced to low-pressure lean solution and enters the absorber. The low-pressure lean solution absorbs low-pressure gaseous refrigerant in the absorber and forms a rich solution. The rich solution is introduced into the composite pre-cooling heat exchanger through the solution pump for heat exchange and then enters the generator for circulation.

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