Heat power driven refrigeration system and method based on series-parallel structure and multiple reheat

Abstract

The application discloses a heat work driving type refrigeration system with heat and mechanical compression in parallel and multiple heat recovery and a method thereof; an evaporator is sequentially connected with a first-stage compressor and a heat recovery device; the heat recovery device is connected with a gas-liquid separator and an absorber; the gas-liquid separator is connected with a second-stage compressor, the heat recovery device and a condenser; the condenser is connected with a first throttling valve and the gas-liquid separator; the condenser is connected with the gas-liquid separator, a second throttling valve and the evaporator; the absorber is connected with a solution pump, a heat recovery cycle side of the heat recovery device and a generator; one side of the generator is sequentially connected with a third throttling valve of the heat recovery cycle side of the heat recovery device and the absorber, and the other side of the generator is connected with the heat recovery device and the condenser. In the system, the heat and mechanical compressors have parallel connection characteristics at a high-pressure stage, and are connected in series at a low-pressure stage, and the exhaust heat of three compression processes is compactly recovered and utilized in heat compression through a multiple flow heat recovery device, so that the heat consumption is significantly reduced and the matching of the system with a small and medium-sized heat source is improved.

Description

Technical Field

[0001] This invention relates to refrigeration systems, and more particularly to a heat-driven refrigeration system and method based on a hybrid structure and multiple regenerative processes. Background Technology

[0002] Reducing the energy consumption of cold storage refrigeration systems plays a vital role in the sustainable development of the cold chain logistics industry.

[0003] Two-stage and cascade systems based on dual mechanical compression processes are currently the main refrigeration devices for cold storage.

[0004] Because low-grade heat energy at around 100℃ is widely present in nature and industrial processes, applying a heat-driven refrigeration system and replacing one stage of mechanical compression with a thermodynamic compression process will effectively reduce the energy consumption of cold storage.

[0005] Traditional thermodynamic refrigeration systems are mainly based on two-stage and cascade cycles. Their energy-saving mechanism is to reduce the mechanical compression pressure ratio by using thermodynamic compression, thereby saving mechanical work.

[0006] In engineering applications, most heat sources are small to medium scale. At this time, the huge heat consumption of the refrigeration system and the insufficient heating capacity of the heat source constitute a prominent contradiction. During operation, the unit will quickly degenerate into a single-stage cycle driven by mechanical work, resulting in an increase in mechanical compression pressure ratio and a significant increase in mechanical energy and compressor exhaust temperature.

[0007] Furthermore, the exhaust temperature of mechanical compressors is subject to an upper threshold constraint, which means that the system evaporation temperature can only be increased to prevent it from failing, but this in turn affects the reliability of the cold storage. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings and deficiencies of the prior art and to provide a heat-driven refrigeration system and method based on a hybrid structure and multiple regeneration.

[0009] This invention is achieved through the following technical solution:

[0010] A thermodynamic and mechanical compression hybrid and multiple regenerative thermodynamic refrigeration system includes: a two-stage compression refrigeration subsystem and an absorption refrigeration subsystem;

[0011] The two-stage compression refrigeration subsystem includes: an evaporator 1, a first-stage compressor 2, a gas-liquid separator 4, a second-stage compressor 6, a condenser 7, a first throttle valve 8, and a second throttle valve 9, all connected by pipelines.

[0012] The refrigerant outlet of the evaporator 1 is connected to the inlet of the first-stage compressor 2; the exhaust port of the first-stage compressor 2 is divided into two branches after passing through the outlet 301 of the regenerator 3; one branch is connected to the refrigerant side inlet of the absorber 5; the other branch is connected to the inlet of the gas-liquid separator 4; the first outlet 401 of the gas-liquid separator 4 is connected to the inlet of the second-stage compressor 6; the exhaust port of the second-stage compressor 6 is connected to the refrigerant inlet of the condenser 7 after passing through the regenerator 3; the refrigerant outlet of the condenser 7 is divided into two branches; one branch is directly connected to the inlet 402 of the gas-liquid separator 4; the other branch is connected to the inlet 403 of the gas-liquid separator 4 through the first throttle valve 8; the second outlet 404 of the gas-liquid separator 4 is connected to the refrigerant inlet of the evaporator 1 through the second throttle valve 9.

[0013] The absorption refrigeration subsystem includes: an absorber 5, a solution pump 10, a regenerator 3, a generator 11, a third throttle valve 12, and a condenser 7 connected by pipelines;

[0014] The concentrated solution outlet of the absorber 5 is divided into two branches by the solution pump 10, which are respectively connected to the first low-temperature inlet 302 and the second low-temperature inlet 303 of the regenerator 3. The two outlets on the low-temperature side of the regenerator 3 are respectively connected to the first concentrated solution inlet 304 and the second concentrated solution inlet 305 of the generator 11. The first dilute solution outlet 1101 of the generator 11 is connected to the regenerator 3. The high-temperature side outlet 306 of the regenerator 3 is connected to the dilute solution inlet of the absorber 5 through the third throttle valve 12. The second dilute solution outlet 1102 of the generator 11 is connected to the refrigerant inlet of the condenser 7.

[0015] The compression refrigeration subsystem is an ammonia compression refrigeration system.

[0016] The absorption refrigeration subsystem is an ammonia absorption refrigeration system.

[0017] The first-stage compressor 2 and the second-stage compressor 6 are variable frequency compressors.

[0018] The operating method of the thermodynamic and mechanical compression hybrid and multiple regenerative thermodynamic refrigeration system of the present invention includes the following steps:

[0019] Two-stage compression cycle operation steps:

[0020] Start the first-stage compressor 2, the second-stage compressor 6, the first throttle valve 8 and the second throttle valve 9 to put the two-stage compression cycle into operation;

[0021] In evaporator 1, liquid ammonia evaporates and generates a cooling capacity of -40°C to meet user needs. The evaporated ammonia vapor enters the first-stage compressor 2 for compression. The ammonia vapor, at 75°C to 80°C, exiting the discharge port of the first-stage compressor 2, is first cooled by the concentrated solution on the low-temperature side of the absorption circulation pipeline in the regenerator 3. The cooled ammonia vapor is then divided into two branches. The ammonia vapor in the compression circulation branch enters the gas-liquid separator 4 for further cooling to -6.5°C. After cooling, it is sent to the second-stage compressor 6 for further compression, reaching 106°C to 110°C. Ammonia vapor at ℃ is mixed with ammonia vapor generated by generator 11 and then cooled by regenerator 3. The cooled ammonia vapor is further cooled by cooling water in condenser 7 at 40℃~45℃, causing the ammonia vapor to condense into liquid ammonia. The condensed liquid ammonia is divided into two branches. One branch is sent to gas-liquid separator 4 for further cooling and then enters evaporator 1 through second throttle valve 9. The other branch is sent to gas-liquid separator 4 through first throttle valve 8 and absorbs heat to evaporate at 6℃~8℃. After evaporation, it is fed into second-stage compressor 6. This cycle continues until the two-stage compression cycle is completed.

[0022] Absorption cycle operation steps:

[0023] Start the solution pump 10 and the third throttle valve 12 to put the absorption cycle into operation;

[0024] Ammonia vapor enters the first-stage compressor 2 for compression. The ammonia vapor, at 75°C to 80°C, exiting the compressor's exhaust port, is cooled by the concentrated solution on the low-temperature side of the absorption circulation pipeline in the regenerator 3. The cooled ammonia vapor is divided into two branches. The ammonia vapor in the absorption circulation branch enters the absorber 5 and is absorbed by the dilute solution with a concentration of 0.3 to 0.4 flowing from the generator 11 through the regenerator 3. The heat generated during the absorption process is carried away by cooling water. After absorption, the concentration of the diluted solution increases to 0.4 to 0.5. Subsequently, driven by the solution pump 10, it is divided into two branches and enters the regenerator 3. The concentrated solution on the low-temperature side is heated by the dilute solution on the high-temperature side and the ammonia vapor in the compression circulation pipeline before entering the generator 11. The ammonia solution in the generator 11 is heated by hot water and evaporates. The evaporated ammonia vapor mixes with the ammonia vapor generated by the second-stage compressor 6 and is cooled by the regenerator 3. The cooled ammonia vapor enters the condenser 7 and then returns to the absorber 5 through the compression circulation system. This cycle continues until the absorption cycle is completed.

[0025] During the absorption cycle operation, when the system input heat is insufficient to drive the absorption cycle, the solution pump 10 and the third throttle valve 12 are shut down, causing the absorption cycle to stop.

[0026] The inability to drive the input heat means that there is no input heat source or the heat source temperature is below 110°C under the conditions of evaporation temperature of -40°C and condensation temperature of 40°C.

[0027] Compared with the prior art, the present invention has the following advantages and effects:

[0028] Regardless of whether there is a heat input, the system always operates in a two-stage compression cycle, thus avoiding a series of problems such as performance degradation and reliability issues caused by the increase in mechanical compression pressure ratio when the heat source is exhausted.

[0029] This invention recovers and utilizes the exhaust waste heat from the three compression processes in a thermodynamic compressor by reheating, such as recovering sensible heat of about 40°C to 80°C, thereby significantly reducing heat consumption and improving the system's compatibility with small and medium-sized heat sources. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the thermodynamic and mechanical compression hybrid and multiple regenerative thermodynamic refrigeration system of the present invention. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to specific embodiments.

[0032] Example

[0033] like Figure 1 As shown. This invention discloses a thermo-work driven refrigeration system that combines thermo-compression and mechanical compression with multiple regenerative processes, comprising: a two-stage compression refrigeration subsystem and an absorption refrigeration subsystem;

[0034] The two-stage compression refrigeration subsystem includes: an evaporator 1, a first-stage compressor 2, a gas-liquid separator 4, a second-stage compressor 6, a condenser 7, a first throttle valve 8, and a second throttle valve 9, all connected by pipelines.

[0035] The refrigerant outlet of the evaporator 1 is connected to the inlet of the first-stage compressor 2; the exhaust port of the first-stage compressor 2 is divided into two branches after passing through the outlet 301 of the regenerator 3; one branch is connected to the refrigerant side inlet of the absorber 5; the other branch is connected to the inlet of the gas-liquid separator 4; the first outlet 401 of the gas-liquid separator 4 is connected to the inlet of the second-stage compressor 6; the exhaust port of the second-stage compressor 6 is connected to the refrigerant inlet of the condenser 7 after passing through the regenerator 3; the refrigerant outlet of the condenser 7 is divided into two branches; one branch is directly connected to the inlet 402 of the gas-liquid separator 4; the other branch is connected to the inlet 403 of the gas-liquid separator 4 through the first throttle valve 8; the second outlet 404 of the gas-liquid separator 4 is connected to the refrigerant inlet of the evaporator 1 through the second throttle valve 9.

[0036] The absorption refrigeration subsystem includes: an absorber 5, a solution pump 10, a regenerator 3, a generator 11, a third throttle valve 12, and a condenser 7 connected by pipelines;

[0037] The concentrated solution outlet of the absorber 5 is divided into two branches by the solution pump 10, which are respectively connected to the first low-temperature inlet 302 and the second low-temperature inlet 303 of the regenerator 3. The two outlets on the low-temperature side of the regenerator 3 are respectively connected to the first concentrated solution inlet 304 and the second concentrated solution inlet 305 of the generator 11. The first dilute solution outlet 1101 of the generator 11 is connected to the regenerator 3. The high-temperature side outlet 306 of the regenerator 3 is connected to the dilute solution inlet of the absorber 5 through the third throttle valve 12. The second dilute solution outlet 1102 of the generator 11 is connected to the refrigerant inlet of the condenser 7.

[0038] The compression refrigeration subsystem is an ammonia compression refrigeration system.

[0039] The absorption refrigeration subsystem is an ammonia absorption refrigeration system.

[0040] The first-stage compressor 2 and the second-stage compressor 6 are variable frequency compressors.

[0041] The operating method of the thermodynamic and mechanical compression hybrid and multiple regenerative thermodynamic refrigeration system of the present invention includes the following steps:

[0042] Two-stage compression cycle operation steps:

[0043] Start the first-stage compressor 2, the second-stage compressor 6, the first throttle valve 8 and the second throttle valve 9 to put the two-stage compression cycle into operation;

[0044] In evaporator 1, liquid ammonia evaporates and generates a cooling capacity of -40°C to meet user needs. The evaporated ammonia vapor enters the first-stage compressor 2 for compression. The ammonia vapor, at 75°C to 80°C, exiting the discharge port of the first-stage compressor 2, is first cooled by the concentrated solution on the low-temperature side of the absorption circulation pipeline in the regenerator 3. The cooled ammonia vapor is then divided into two branches. The ammonia vapor in the compression circulation branch enters the gas-liquid separator 4 for further cooling to -6.5°C. After cooling, it is sent to the second-stage compressor 6 for further compression, reaching 106°C to 110°C. Ammonia vapor at ℃ is mixed with ammonia vapor generated by generator 11 and then cooled by regenerator 3. The cooled ammonia vapor is further cooled by cooling water in condenser 7 at 40℃~45℃, causing the ammonia vapor to condense into liquid ammonia. The condensed liquid ammonia is divided into two branches. One branch is sent to gas-liquid separator 4 for further cooling and then enters evaporator 1 through second throttle valve 9. The other branch is sent to gas-liquid separator 4 through first throttle valve 8 and absorbs heat to evaporate at 6℃~8℃. After evaporation, it is fed into second-stage compressor 6. This cycle continues until the two-stage compression cycle is completed.

[0045] Absorption cycle operation steps:

[0046] Start the solution pump 10 and the third throttle valve 12 to put the absorption cycle into operation;

[0047] Ammonia vapor enters the first-stage compressor 2 for compression. The ammonia vapor, at 75°C to 80°C, exits from the compressor exhaust port and is cooled by the concentrated solution on the low-temperature side of the absorption circulation pipeline in the regenerator 3. The cooled ammonia vapor is divided into two branches. The ammonia vapor in the absorption circulation branch enters the absorber 5 and is absorbed by the dilute solution with a concentration of 0.3 to 0.4 flowing from the generator 11 through the regenerator 3. The heat generated during the absorption process is carried away by cooling water. After absorption, the concentration of the diluted solution increases to 0.4 to 0.5. Subsequently, driven by the solution pump 10, it is divided into two branches and enters the regenerator 3. The concentrated solution on the low-temperature side is heated by the dilute solution on the high-temperature side and the ammonia vapor in the compression circulation pipeline before entering the generator 11. The ammonia solution in the generator 11 is heated by hot water and evaporates. The evaporated ammonia vapor mixes with the ammonia vapor generated by the second-stage compressor 6 and is cooled by the regenerator 3. The cooled ammonia vapor enters the condenser 7 and then returns to the absorber 5 through the compression circulation system. This cycle continues until the absorption cycle is completed.

[0048] During the absorption cycle operation, when the system input heat is insufficient to drive the absorption cycle, the solution pump 10 and the third throttle valve 12 are turned off, causing the absorption cycle to stop.

[0049] The inability to drive the input heat means that there is no input heat source or the heat source temperature is below 110°C under the conditions of evaporation temperature of -40°C and condensation temperature of 40°C.

[0050] As described above, the present invention can be implemented well.

[0051] The implementation of the present invention is not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A thermodynamic refrigeration system that combines thermodynamic compression and mechanical compression with multiple regenerative processes, characterized in that... include: Two-stage compression refrigeration subsystem, absorption refrigeration subsystem; The two-stage compression refrigeration subsystem includes: an evaporator (1) connected by pipelines, a first-stage compressor (2), a gas-liquid separator (4), a second-stage compressor (6), a condenser (7), a first throttle valve (8), and a second throttle valve (9); The refrigerant outlet of the evaporator (1) is connected to the inlet of the first-stage compressor (2); the exhaust port of the first-stage compressor (2) is divided into two branches after passing through the outlet (301) of the regenerator (3); one branch is connected to the refrigerant side inlet of the absorber (5); the other branch is connected to the inlet of the gas-liquid separator (4); the first outlet (401) of the gas-liquid separator (4) is connected to the inlet of the second-stage compressor (6); the exhaust port of the second-stage compressor (6) is connected to the refrigerant inlet of the condenser (7) after passing through the regenerator (3); the refrigerant outlet of the condenser (7) is divided into two branches; one branch is directly connected to the inlet (402) of the gas-liquid separator (4); the other branch is connected to the inlet (403) of the gas-liquid separator (4) through the first throttle valve (8); the second outlet (404) of the gas-liquid separator (4) is connected to the refrigerant inlet of the evaporator (1) through the second throttle valve (9); The absorption refrigeration subsystem includes: an absorber (5) connected by pipelines, a solution pump (10), a regenerator (3), a generator (11), a third throttle valve (12), and a condenser (7); The concentrated solution outlet of the absorber (5) is divided into two branches by the solution pump (10), which are respectively connected to the first low-temperature side inlet (302) and the second low-temperature side inlet (303) of the regenerator (3). The two outlets on the low-temperature side of the regenerator (3) are respectively connected to the first concentrated solution inlet (304) and the second concentrated solution inlet (305) of the generator (11). The first dilute solution outlet (1101) of the generator (11) is connected to the regenerator (3). The high-temperature side outlet (306) of the regenerator (3) is connected to the dilute solution inlet of the absorber (5) through the third throttle valve (12). The second dilute solution outlet (1102) of the generator (11) is connected to the refrigerant inlet of the condenser (7).

2. The thermodynamic and mechanical compression hybrid and multiple regenerative thermodynamic refrigeration system according to claim 1, characterized in that: The compression refrigeration subsystem is an ammonia compression refrigeration system.

3. The thermodynamic and mechanical compression hybrid and multiple regenerative thermodynamic refrigeration system according to claim 1, characterized in that: The absorption refrigeration subsystem is an ammonia absorption refrigeration system.

4. The thermodynamic and mechanical compression hybrid and multiple regenerative thermodynamic refrigeration system according to claim 1, characterized in that: The first stage compressor (2) and the second stage compressor (6) are variable frequency compressors.

5. The method of operating the thermodynamic and mechanical compression hybrid and multiple regenerative thermodynamic refrigeration system according to any one of claims 1-4, characterized in that... Includes the following steps: Two-stage compression cycle operation steps: Start the first-stage compressor (2), the second-stage compressor (6), the first throttle valve (8) and the second throttle valve (9) to put the two-stage compression cycle into working condition; Liquid ammonia evaporates in the evaporator (1) and generates a cooling capacity of -40℃ to meet user needs. The evaporated ammonia vapor enters the first-stage compressor (2) for compression. The ammonia vapor at 75℃~80℃ exiting the exhaust port of the first-stage compressor (2) is first cooled by the concentrated solution on the low-temperature side of the absorption circulation pipeline in the regenerator (3). The cooled ammonia vapor is divided into two branches. The ammonia vapor in the compression circulation branch enters the gas-liquid separator (4) for further cooling to -6.5℃. After cooling, it is sent to the second-stage compressor (6) for compression again. After compression, the ammonia vapor reaches 106℃~110℃. After the ammonia vapor is mixed with the ammonia vapor generated by the generator (11), it is cooled by the regenerator (3). The cooled ammonia vapor is further cooled by the cooling water in the condenser (7) at 40℃~45℃, so that the ammonia vapor is condensed into liquid ammonia. The condensed liquid ammonia is divided into two branches. One branch is sent to the gas-liquid separator (4) to be cooled and enters the evaporator (1) through the second throttle valve (9). The other branch is sent to the gas-liquid separator (4) through the first throttle valve (8) and absorbs heat and evaporates at 6℃~8℃. After evaporation, it is fed into the second stage compressor (6). This cycle continues until the two-stage compression cycle is completed. Absorption cycle operation steps: Start the solution pump (10) and the third throttle valve (12) to put the absorption cycle into operation; Ammonia vapor is compressed in the first-stage compressor (2). The ammonia vapor at 75°C to 80°C exiting the compressor outlet is cooled by the concentrated solution on the low-temperature side of the absorption circulation pipeline in the regenerator (3). The cooled ammonia vapor is divided into two branches. The ammonia vapor in the absorption circulation branch enters the absorber (5) and is absorbed by the dilute solution with a concentration of 0.3 to 0.4 flowing out of the generator (11) and passing through the regenerator (3). The heat generated during the absorption process is carried away by cooling water. After absorption, the concentration of the diluted solution increases to 0.4 to 0.5, and then in the solution... Driven by the pump (10), the solution is divided into two branches and enters the regenerator (3). The concentrated solution on the low temperature side is heated by the dilute solution on the high temperature side and the ammonia vapor in the compression circulation pipeline and then enters the generator (11). The ammonia solution in the generator (11) is heated by hot water and evaporates. The evaporated ammonia vapor mixes with the ammonia vapor generated by the second stage compressor (6) and is cooled by the regenerator (3). The cooled ammonia vapor enters the condenser (7) and then returns to the absorber (5) through the compression circulation system. This cycle continues until the absorption cycle is completed.

6. The operating method of the thermodynamic and mechanical compression hybrid and multiple regenerative thermodynamic refrigeration system according to claim 5, characterized in that: During the absorption cycle operation, when the system input heat is insufficient to drive the absorption cycle, the solution pump (10) and the third throttle valve (12) are turned off, causing the absorption cycle to stop.

7. The operating method of the thermodynamic and mechanical compression hybrid and multiple regenerative thermodynamic refrigeration system according to claim 6, characterized in that: The inability to drive the input heat means that there is no input heat source or the heat source temperature is below 110°C under the conditions of evaporation temperature of -40°C and condensation temperature of 40°C.

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