阅读说明：本技术 热压缩与机械压缩并联的两级压缩复合制冷系统及其方法 (Two-stage compression composite refrigeration system with parallel thermal compression and mechanical compression and method thereof ) 是由 李泽宇 王蕊婷 于 2020-10-28 设计创作，主要内容包括：本发明公开了一种热压缩与机械压缩并联的两级压缩复合制冷系统及其方法；集热器与蓄热水箱、第一热水泵、发生器依次相连；蓄热水箱与第二热水泵、集热器依次相连；发生器与精馏器、冷凝器吸收循环侧、第一节流阀依次相连；第一节流阀分别与过冷器、级间冷却器相连；过冷器、级间冷却器与流量调节阀、吸收器、溶液泵、精馏器、溶液热交换器依次相连；冷凝器压缩循环侧与过冷器、蒸发器、第一级压缩机、空气冷却器、级间冷却器、第二级压缩机依次相连；蒸发器与冷冻水泵、供冷用户端依次相连；本系统通过热压缩与两级机械压缩相结合不仅增强了太阳能制冷效率,又提高了单位太阳能消耗的压缩功节约量,还显著降低了压缩机排气温度。(The invention discloses a two-stage compression composite refrigeration system with parallel thermal compression and mechanical compression and a method thereof; the heat collector is connected with the heat storage water tank, the first hot water pump and the generator in sequence; the heat storage water tank is connected with the second hot water pump and the heat collector in sequence; the generator is connected with the rectifier, the absorption cycle side of the condenser and the first throttle valve in sequence; the first throttle valve is respectively connected with the subcooler and the interstage cooler; the subcooler and the interstage cooler are sequentially connected with the flow regulating valve, the absorber, the solution pump, the rectifier and the solution heat exchanger; the compression cycle side of the condenser is sequentially connected with the subcooler, the evaporator, the first-stage compressor, the air cooler, the interstage cooler and the second-stage compressor; the evaporator is connected with the chilled water pump and the cooling user end in sequence; the system not only enhances the solar refrigeration efficiency, but also improves the compression work saving amount consumed by unit solar energy and also obviously reduces the exhaust temperature of the compressor by combining the thermal compression and the two-stage mechanical compression.)

1. A two-stage compression composite refrigeration system with parallel thermal compression and mechanical compression, which is characterized in that,

this two-stage compression composite refrigeration system includes: the system comprises a solar water heating system, an absorption refrigeration subsystem and a two-stage compression refrigeration subsystem;

the solar water heating system comprises a solar heat collector (1), a heat storage water tank (2), a first hot water pump (3) and a second hot water pump (4) which are connected through pipelines; wherein, the water outlet of the solar heat collector (1) is connected with the water inlet (201) of the heat storage water tank (2) through a pipeline; a water outlet (202) of the heat storage water tank (2) is communicated with the first hot water pump (3) through a pipeline; a hot water outlet of the first hot water pump (3) is connected to a hot water inlet of the generator (5) through a pipeline; a hot water outlet of the generator (5) is connected with a return water inlet (203) of the heat storage water tank (2) through a pipeline; a return water outlet (204) of the heat storage water tank (2) is sequentially connected with a second hot water pump (4) and a water inlet of the solar heat collector (1);

the absorption refrigeration subsystem comprises a generator (5), a rectifier (6), a condenser (7), a first throttle valve (8), an interstage cooler (9), a subcooler (10), an absorber (11), a solution pump (12), a solution heat exchanger (13) and a flow regulating valve (22) which are connected through pipelines; the refrigerant side outlet of the generator (5) is connected with the inlet of the rectifier (6); a refrigerant side outlet of the rectifier (6) is connected with a refrigerant side inlet of the condenser (7); a solution outlet (601) of the rectifier (6) is connected with a reflux inlet (501) of the generator (5); an outlet (701) on the side of the absorption cycle refrigerant of the condenser (7) is divided into two branches after passing through a first throttling valve (8): one branch is connected with the interstage cooler (9) after passing through the subcooler (10), and the other branch is directly connected with the interstage cooler (9); an absorption cycle side outlet (901) of the interstage cooler (9) is connected with a refrigerant side inlet of the absorber (11) through a regulating valve (22); a concentrated solution outlet of the absorber (11) is connected with a concentrated solution inlet of the rectifier (6) through a solution pump (12); a concentrated solution outlet (602) of the rectifier (6) is connected with a low-temperature side inlet of the solution heat exchanger (13); the low-temperature side outlet of the solution heat exchanger (13) is connected with a concentrated solution inlet (502) of the generator (5); the dilute solution outlet of the generator (5) is connected with the high-temperature side inlet of the solution heat exchanger (13); the high-temperature side outlet of the solution heat exchanger (13) is connected with the solution inlet of the absorber (11);

the two-stage compression refrigeration subsystem comprises an evaporator (15), a first-stage compressor (16), an air cooler (17), an interstage cooler (9), a second-stage compressor (18), a condenser (7), a subcooler (10), a second throttle valve (14) and a chilled water pump (19) which are connected through pipelines; a compression cycle refrigerant side outlet (702) of the condenser (7) is connected with an inlet of the subcooler (10); the outlet of the subcooler (10) is connected with the inlet of the evaporator (15) through a second throttling valve (14); the outlet of the evaporator (15) is connected with the air inlet of the first-stage compressor (16); the exhaust port of the first stage compressor (16) is connected with the air inlet of the inter-stage cooler (9) through an air cooler (17); the outlet (902) of the inter-stage cooler (9) is connected with the air inlet of the second-stage compressor (18); the discharge port of the second stage compressor (18) is connected with the refrigerant side outlet of the absorption subsystem rectifier (6) in front of the refrigerant side inlet of the condenser (7);

the inlet end of the chilled water of the evaporator (15) is connected with the outlet end (20) of a cooling user through a chilled water pump (19) by a pipeline, and the inlet end (21) of the cooling user is connected with the outlet end of the chilled water of the evaporator (15).

2. A two-stage compression compound refrigeration system with thermal compression and mechanical compression in parallel as claimed in claim 1, wherein: the solar heat collector (1) is a groove type solar heat collector.

3. A two-stage compression compound refrigeration system with thermal compression and mechanical compression in parallel as claimed in claim 2, wherein: the absorption refrigeration subsystem is an ammonia absorption refrigeration system.

4. A two-stage compression compound refrigeration system with thermal compression and mechanical compression in parallel as claimed in claim 2, wherein: the compression refrigeration subsystem is an ammonia compression refrigeration system.

5. A two-stage compression compound refrigeration system with thermal compression and mechanical compression in parallel as claimed in claim 2, wherein: the first-stage compressor (16) and the second-stage compressor (18) are variable-frequency compressors.

6. A two-stage compression compound refrigeration system with thermal compression and mechanical compression in parallel as claimed in claim 2, wherein: the subcooler (10) is a plate heat exchanger or a shell-and-tube heat exchanger.

7. A method of operating a two-stage compression compound refrigeration system with thermal compression in parallel with mechanical compression as set forth in any of claims 1 to 6, characterized by comprising the steps of:

the solar hot water operation step:

when the solar radiation intensity reaches the set starting condition of the heat collector (1), starting the second hot water pump (4), sending water stored in the heat storage water tank (2) into the heat collector (1), collecting solar energy to heat hot water, and then enabling the hot water to enter the heat storage water tank (2) for storage;

an absorption cycle operation step:

starting the first hot water pump (3), the first throttle valve (8), the solution pump (12) and the flow regulating valve (22) to enable the circulation to be in a working state;

the first hot water pump (3) conveys hot water at the temperature of about 110-115 ℃ stored in the heat storage water tank (2) to the generator (5), ammonia water solution in the generator (5) is heated by the hot water to be vaporized, the vaporized ammonia vapor enters the rectifier (6) to be rectified, the ammonia vapor led out from the rectifier (6) is cooled by cooling water in the condenser (7) at the temperature of 40-45 ℃ to condense the ammonia vapor into liquid ammonia, the liquid ammonia is throttled by the first throttle valve (8) and divided into two branches, one branch is conveyed to the subcooler (10) and is subjected to heat absorption and evaporation at the temperature of 6-8 ℃, the cooled ammonia vapor is introduced into the cooler (9), the other branch is conveyed to the interstage cooler (9) to be subjected to heat absorption and evaporation at the temperature of 6-8 ℃, the evaporated ammonia vapor enters the absorber (11) and is absorbed by dilute solution with the concentration of 0.3-0.4 flowing out of the generator (5) through the solution heat exchanger (13), the heat generated in the absorption process is taken away by cooling water, the concentration of the absorbed dilute solution is increased to 0.4-0.5, then the dilute solution enters a rectifier (6) under the drive of a solution pump (12), the heat generated in the dilute solution is absorbed in the rectifier (6) and then enters a solution heat exchanger (13), the concentrated solution at the low-temperature side is heated by the dilute solution at the high-temperature side and then enters a generator (5), and the continuous cycle work is realized;

when the sunlight or the illumination radiation is strong, a flow control valve (22) of the interstage cooler (9) is adjusted, the flow of the working medium entering the absorber is increased, and the power consumption of the second-stage compression is reduced;

when no sunlight or weak illumination radiation exists, the temperature in the heat storage water tank (2) is low and cannot drive the absorption cycle to work, and the first hot water pump (3), the first throttle valve (8), the solution pump (12) and the flow regulating valve (22) are closed, so that the absorption cycle is in a stop working state;

and (3) two-stage compression cycle operation steps:

starting a second throttle valve (14), a first stage compressor (16) and a second stage compressor (18) to enable the two-stage compression cycle to be in a working state;

the ammonia vapor from the condenser (7) is cooled in a subcooler (10), throttled by a second throttle valve (14), evaporated in an evaporator (15) and generated cold at-18 to-20 ℃ to meet the user requirements, the evaporated ammonia vapor enters a first-stage compressor (16) for compression, the ammonia vapor at 75 to 80 ℃ from the exhaust port of the compressor is cooled to 45 to 50 ℃ by an air cooler (17), cooled to 10 to 13 ℃ by an interstage cooler (9), cooled and sent to a second-stage compressor (18) for recompression, the compressed ammonia vapor at 106 to 110 ℃ is mixed with the ammonia vapor generated by a rectifier (6) and then enters the condenser (7), and the steps are repeated in such a circulating way and work continuously.

Technical Field

The invention relates to a refrigeration system, in particular to a two-stage compression composite refrigeration system with parallel thermal compression and mechanical compression and a method thereof.

Background

Along with the improvement of the living standard of people, the demand of the refrigeration house is rapidly increased, the energy consumption of the refrigeration system is a main component part of the energy consumption of the refrigeration house, and the reduction of the energy consumption of the refrigeration system is favorable for the sustainable development of the refrigeration house and cold chain logistics. A large number of researches show that the energy consumption of the system can be obviously reduced by applying the solar refrigeration technology to the refrigeration house.

At present, although a composite refrigeration system based on absorption-supercooling compression cycle and cascade cycle has a certain energy-saving effect when applied to a refrigeration house, the composite refrigeration system has the following defects: (1) the ratio of the refrigerating capacity of the absorption sub-cycle to the refrigerating capacity of the compression sub-cycle is low, so that difficulty is brought to the maximization of combining the time-of-use electricity price to improve the energy-saving benefit, and the exhaust temperature of the compressor is high due to the high pressure ratio; (2) the latter has a low ratio of compression work saving to solar energy consumption, thereby significantly reducing the energy saving of the system.

Disclosure of Invention

The invention aims to overcome the defects and shortcomings of the prior art and provides a two-stage compression composite refrigeration system with parallel thermal compression and mechanical compression and a method thereof. The system not only enhances the solar refrigeration efficiency, but also improves the compression work saving amount consumed by unit solar energy and also obviously reduces the exhaust temperature of the compressor by combining the thermal compression and the two-stage mechanical compression.

The invention is realized by the following technical scheme:

a two-stage compression compound refrigeration system with thermal compression in parallel with mechanical compression, the two-stage compression compound refrigeration system comprising: the system comprises a solar water heating system, an absorption refrigeration subsystem and a two-stage compression refrigeration subsystem;

the solar water heating system comprises a solar heat collector 1, a heat storage water tank 2, a first hot water pump 3 and a second hot water pump 4 which are connected through pipelines; wherein, the water outlet of the solar heat collector 1 is connected with the water inlet 201 of the heat storage water tank 2 through a pipeline; the water outlet 202 of the heat storage water tank 2 is communicated with the first hot water pump 3 through a pipeline; a hot water outlet of the first hot water pump 3 is connected to a hot water inlet of the generator 5 through a pipeline; the hot water outlet of the generator 5 is connected with the return water inlet 203 of the heat storage water tank 2 through a pipeline; a return water outlet 204 of the heat storage water tank 2 is sequentially connected with a second hot water pump 4 and a water inlet of the solar heat collector 1;

the absorption refrigeration subsystem comprises a generator 5, a rectifier 6, a condenser 7, a first throttle valve 8, an interstage cooler 9, a subcooler 10, an absorber 11, a solution pump 12, a solution heat exchanger 13 and a flow regulating valve 22 which are connected through pipelines; the refrigerant side outlet of the generator 5 is connected with the inlet of the rectifier 6; a refrigerant side outlet of the rectifier 6 is connected with a refrigerant side inlet of the condenser 7; a solution outlet 601 of the rectifier 6 is connected with a reflux inlet 501 of the generator 5; the refrigerant side outlet 701 of the absorption cycle of the condenser 7 is divided into two branches after passing through the first throttle valve 8: one branch is connected with the interstage cooler 9 after passing through the subcooler 10, and the other branch is directly connected with the interstage cooler 9; the absorption cycle side outlet 901 of the interstage cooler 9 is connected to the refrigerant side inlet of the absorber 11 through a regulating valve 22; a concentrated solution outlet of the absorber 11 is connected with a concentrated solution inlet of the rectifier 6 through a solution pump 12; the concentrated solution outlet 602 of the rectifier 6 is connected with the low-temperature side inlet of the solution heat exchanger 13; the low-temperature side outlet of the solution heat exchanger 13 is connected with the concentrated solution inlet 502 of the generator 5; the dilute solution outlet of the generator 5 is connected with the high-temperature side inlet of the solution heat exchanger 13; the high-temperature side outlet of the solution heat exchanger 13 is connected with the solution inlet of the absorber 11;

the two-stage compression refrigeration subsystem comprises an evaporator 15, a first-stage compressor 16, an air cooler 17, an interstage cooler 9, a second-stage compressor 18, a condenser 7, a subcooler 10, a second throttle valve 14 and a chilled water pump 19 which are connected through pipelines; a compression cycle refrigerant side outlet 702 of the condenser 7 is connected to an inlet of the subcooler 10; the outlet of the subcooler 10 is connected to the inlet of the evaporator 15 through a second throttle valve 14; the outlet of the evaporator 15 is connected with the air inlet of the first-stage compressor 16; the discharge port of the first stage compressor 16 is connected to the intake port of the inter-stage cooler 9 through an air cooler 17; an outlet 902 of the intercooler 9 is connected to an intake of the second stage compressor 18; the discharge of the second stage compressor 18 is connected to the refrigerant side outlet of the absorption subsystem rectifier 6 before the refrigerant side inlet of the condenser 7;

the inlet end of the chilled water of the evaporator 15 is connected with the outlet end 20 of the cooling user through a chilled water pump 19 by a pipeline, and the inlet end 21 of the cooling user is connected with the outlet end of the chilled water of the evaporator 15.

The solar heat collector 1 is a trough type solar heat collector.

The absorption refrigeration subsystem is an ammonia absorption refrigeration system.

The compression refrigeration subsystem is an ammonia compression refrigeration system.

The first-stage compressor 16 and the second-stage compressor 18 are variable frequency compressors.

The subcooler 10 is a plate heat exchanger or a shell-and-tube heat exchanger.

The advantages of the invention are mainly embodied in that: (1) the ratio of the compression work saving amount to the solar energy consumption amount is higher in all working conditions, and the system performance is obviously improved; (2) the exhaust temperature of the compressor is avoided from being higher; and (3) the absorption sub-cycle refrigerating capacity is simultaneously used as the supercooling capacity of the compression sub-cycle and the interstage refrigerating capacity of the first-stage compression exhaust, so that the ratio of the absorption sub-cycle refrigerating capacity to the compression sub-cycle refrigerating capacity is improved, and the time-of-use electricity price is favorably combined to improve the energy-saving benefit.

The invention relates to an operation method of a two-stage compression composite refrigeration system with parallel thermal compression and mechanical compression, which comprises the following steps:

the solar hot water operation step:

when the solar radiation intensity reaches the set starting condition of the heat collector 1, starting the second hot water pump 4, sending the water stored in the heat storage water tank 2 to the heat collector 1, collecting solar energy to heat hot water, and then enabling the hot water to enter the heat storage water tank 2 for storage;

an absorption cycle operation step:

starting the first hot water pump 3, the first throttle valve 8, the solution pump 12 and the flow regulating valve 22 to enable the circulation to be in a working state;

the first hot water pump 3 conveys hot water at the temperature of about 110-115 ℃ stored in the heat storage water tank 2 to the generator 5, ammonia water solution in the generator 5 is heated by the hot water to be vaporized, vaporized ammonia vapor enters the rectifier 6 to be rectified, the ammonia vapor led out from the rectifier 6 is cooled by cooling water in the condenser 7 at the temperature of 40-45 ℃ to be condensed into liquid ammonia, the liquid ammonia is divided into two branches after throttling by the first throttle valve 8, one branch is conveyed to the subcooler 10 to absorb heat at the temperature of 6-8 ℃ for evaporation, the evaporated ammonia vapor is introduced into the interstage cooler 9, the other branch is conveyed to the interstage cooler 9 to absorb heat at the temperature of 6-8 ℃ for evaporation, the evaporated ammonia vapor enters the absorber 11 to be absorbed by dilute solution flowing out from the generator 5 and flowing through the solution heat exchanger 13, the concentration of 0.3-0.4, the heat generated in the absorption process is taken away by the cooling water, the concentration of the dilute solution after absorption is increased to 0.4-0.5, then enters the rectifier 6 under the driving of the solution pump 12, enters the solution heat exchanger 13 after absorbing the heat generated in the rectifier 6, and enters the generator 5 after the concentrated solution at the low temperature side is heated by the dilute solution at the high temperature side, thus continuously working circularly;

when the sunlight or the illumination radiation is strong, the flow control valve 22 of the interstage cooler 9 is adjusted, the flow of the working medium entering the absorber is increased, and the power consumption of the second-stage compression is reduced;

when no sunlight or weak illumination radiation exists, the temperature in the heat storage water tank 2 is low, and the absorption cycle cannot be driven to work, and the first hot water pump 3, the first throttle valve 8, the solution pump 12 and the flow regulating valve 22 are closed, so that the absorption cycle is in a stop working state;

and (3) two-stage compression cycle operation steps:

actuating the second throttle 14, the first stage compressor 16 and the second stage compressor 18 to place the two stage compression cycle in operation;

the ammonia vapor from the condenser 7 is cooled in a subcooler 10, throttled by a second throttle valve 14, evaporated in an evaporator 15 and generated cold at-18 to-20 ℃ to meet the user requirement, the evaporated ammonia vapor enters a first-stage compressor 16 for compression, the ammonia vapor at 75 to 80 ℃ from the exhaust port of the compressor is cooled to 45 to 50 ℃ by an air cooler 17, cooled to about 10 to 13 ℃ by an interstage cooler 9, cooled and sent to a second-stage compressor 18 for recompression, the compressed ammonia vapor at about 106 to 110 ℃ is mixed with the ammonia vapor generated by a rectifier 6 and then enters the condenser 7, and the steps are repeated in a circulating manner and continuously work.

Compared with the prior art, the invention has the following advantages and effects:

the invention overcomes the defects of the composite refrigeration mode based on absorption-supercooling compression cycle and overlapping cycle applied to the traditional refrigeration house, ensures that the ratio of the compression work saving amount to the solar energy consumption amount has higher level in all working conditions, obviously improves the system performance, simultaneously adopts a two-stage compression intercooling mode in the compression process, avoids overhigh exhaust temperature of the compressor, improves the ratio of the absorption and compression sub-cycle refrigeration amounts, and is favorable for better combining time-of-use electricity price and improving the energy-saving benefit.

Drawings

Fig. 1 is a schematic structural diagram of a two-stage compression composite refrigeration system with parallel thermal compression and mechanical compression according to the present invention.

Detailed Description

The present invention will be described in further detail with reference to specific examples.

Examples

As shown in fig. 1. The invention discloses a two-stage compression composite refrigeration system with parallel thermal compression and mechanical compression, which comprises: the system comprises a solar water heating system, an absorption refrigeration subsystem and a two-stage compression refrigeration subsystem;

the solar water heating system comprises a solar heat collector 1, a heat storage water tank 2, a first hot water pump 3 and a second hot water pump 4 which are connected through pipelines; wherein, the water outlet of the solar heat collector 1 is connected with the water inlet 201 of the heat storage water tank 2 through a pipeline; the water outlet 202 of the heat storage water tank 2 is communicated with the first hot water pump 3 through a pipeline; a hot water outlet of the first hot water pump 3 is connected to a hot water inlet of the generator 5 through a pipeline; the hot water outlet of the generator 5 is connected with the return water inlet 203 of the heat storage water tank 2 through a pipeline; a return water outlet 204 of the heat storage water tank 2 is sequentially connected with a second hot water pump 4 and a water inlet of the solar heat collector 1;

the absorption refrigeration subsystem comprises a generator 5, a rectifier 6, a condenser 7, a first throttle valve 8, an interstage cooler 9, a subcooler 10, an absorber 11, a solution pump 12, a solution heat exchanger 13 and a flow regulating valve 22 which are connected through pipelines; the refrigerant side outlet of the generator 5 is connected with the inlet of the rectifier 6; a refrigerant side outlet of the rectifier 6 is connected with a refrigerant side inlet of the condenser 7; a solution outlet 601 of the rectifier 6 is connected with a reflux inlet 501 of the generator 5; the refrigerant side outlet 701 of the absorption cycle of the condenser 7 is divided into two branches after passing through the first throttle valve 8: one branch is connected with the interstage cooler 9 after passing through the subcooler 10, and the other branch is directly connected with the interstage cooler 9; the absorption cycle side outlet 901 of the interstage cooler 9 is connected to the refrigerant side inlet of the absorber 11 through a regulating valve 22; a concentrated solution outlet of the absorber 11 is connected with a concentrated solution inlet of the rectifier 6 through a solution pump 12; the concentrated solution outlet 602 of the rectifier 6 is connected with the low-temperature side inlet of the solution heat exchanger 13; the low-temperature side outlet of the solution heat exchanger 13 is connected with the concentrated solution inlet 502 of the generator 5; the dilute solution outlet of the generator 5 is connected with the high-temperature side inlet of the solution heat exchanger 13; the high-temperature side outlet of the solution heat exchanger 13 is connected with the solution inlet of the absorber 11;

the two-stage compression refrigeration subsystem comprises an evaporator 15, a first-stage compressor 16, an air cooler 17, an interstage cooler 9, a second-stage compressor 18, a condenser 7, a subcooler 10, a second throttle valve 14 and a chilled water pump 19 which are connected through pipelines; a compression cycle refrigerant side outlet 702 of the condenser 7 is connected to an inlet of the subcooler 10; the outlet of the subcooler 10 is connected to the inlet of the evaporator 15 through a second throttle valve 14; the outlet of the evaporator 15 is connected with the air inlet of the first-stage compressor 16; the discharge port of the first stage compressor 16 is connected to the intake port of the inter-stage cooler 9 through an air cooler 17; an outlet 902 of the intercooler 9 is connected to an intake of the second stage compressor 18; the discharge of the second stage compressor 18 is connected to the refrigerant side outlet of the absorption subsystem rectifier 6 before the refrigerant side inlet of the condenser 7;

the inlet end of the chilled water of the evaporator 15 is connected with the outlet end 20 of the cooling user through a chilled water pump 19 by a pipeline, and the inlet end 21 of the cooling user is connected with the outlet end of the chilled water of the evaporator 15.

The solar heat collector 1 is a trough type solar heat collector.

The absorption refrigeration subsystem is an ammonia absorption refrigeration system.

The compression refrigeration subsystem is an ammonia compression refrigeration system.

The first-stage compressor 16 and the second-stage compressor 18 are variable frequency compressors.

The subcooler 10 is a plate heat exchanger or a shell-and-tube heat exchanger.

The advantages of the invention are mainly embodied in that: (1) the ratio of the compression work saving amount to the solar energy consumption amount is higher in all working conditions, and the system performance is obviously improved; (2) the exhaust temperature of the compressor is avoided from being higher; and (3) the absorption sub-cycle refrigerating capacity is simultaneously used as the supercooling capacity of the compression sub-cycle and the interstage refrigerating capacity of the first-stage compression exhaust, so that the ratio of the absorption sub-cycle refrigerating capacity to the compression sub-cycle refrigerating capacity is improved, and the time-of-use electricity price is favorably combined to improve the energy-saving benefit.

The operation of the two-stage compression composite refrigeration system with the parallel connection of the thermal compression and the mechanical compression is divided into the following steps:

the solar hot water operation step:

when the solar radiation intensity reaches the set starting condition of the heat collector 1, the second hot water pump 4 is started, water stored in the heat storage water tank 2 is sent to the heat collector 1, solar energy is collected to heat hot water, and the hot water enters the heat storage water tank 2 to be stored.

An absorption cycle operation step:

starting the first hot water pump 3, the first throttle valve 8, the solution pump 12 and the flow regulating valve 22 to enable the circulation to be in a working state;

the first hot water pump 3 conveys hot water stored in the heat storage water tank 2 and having the temperature of about 110-115 ℃ to the generator 5, ammonia water solution in the generator 5 is heated by the hot water to be vaporized, vaporized ammonia vapor enters the rectifier 6 to be rectified, the ammonia vapor led out from the rectifier 6 is cooled by cooling water in the condenser 7 at the temperature of 40-45 ℃ to be condensed into liquid ammonia, the liquid ammonia vapor is divided into two branches after throttling by the first throttle valve 8, one branch is conveyed to the subcooler 10 to absorb heat and evaporate at the temperature of 6-8 ℃, the branch is introduced into the interstage cooler 9 after being evaporated, the other branch is conveyed to the interstage cooler 9 to absorb heat and evaporate at the temperature of 6-8 ℃, the evaporated ammonia vapor enters the absorber 11 to be absorbed by dilute solution flowing out from the generator 5 and having the concentration of 0.3-0.4 through the solution heat exchanger 13, heat generated in the absorption process is taken away by the cooling water, the concentration of the dilute solution after being absorbed is increased to 0.4-0.5, then enters the rectifier 6 under the driving of the solution pump 12, enters the solution heat exchanger 13 after absorbing the heat generated in the rectifier 6, and enters the generator 5 after the concentrated solution at the low temperature side is heated by the dilute solution at the high temperature side, thus continuously working circularly;

when the sunlight or the illumination radiation is strong, the flow control valve 22 of the interstage cooler 9 is adjusted, the flow of the working medium entering the absorber is increased, and the power consumption of the second-stage compression is reduced;

when no sunlight or weak illumination radiation exists, the temperature in the heat storage water tank 2 is low, and the absorption cycle cannot be driven to work, and the first hot water pump 3, the first throttle valve 8, the solution pump 12 and the flow regulating valve 22 are closed, so that the absorption cycle is in a stop working state;

and (3) two-stage compression cycle operation steps:

actuating the second throttle 14, the first stage compressor 16 and the second stage compressor 18 to place the two stage compression cycle in operation;

the ammonia vapor from the condenser 7 is cooled in a subcooler 10, throttled by a second throttle valve 14, evaporated in an evaporator 15 and generated cold at-18 to-20 ℃ to meet the user requirement, the evaporated ammonia vapor enters a first-stage compressor 16 for compression, the ammonia vapor at 75 to 80 ℃ from the exhaust port of the compressor is cooled to 45 to 50 ℃ by an air cooler 17, cooled to 10 to 13 ℃ by an interstage cooler 9, cooled and sent to a second-stage compressor 18 for recompression, the compressed ammonia vapor at 106 to 110 ℃ is mixed with the ammonia vapor generated by a rectifier 6 and then enters the condenser 7, and the steps are repeated in a circulating manner and continuously work;

as described above, the present invention can be preferably realized.

The embodiments of the present invention are not limited to the above-described embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and they are included in the scope of the present invention.