A condensing heat refrigeration drive device and its multi-stage evaporator refrigeration system

Abstract

The present invention discloses a condensation heat refrigeration driving device and a multi-stage evaporator refrigeration system thereof. A refrigerant pump is connected to the outlet of the loop body condenser. The outlet of the refrigerant pump is connected to a first evaporative condenser for heating and vaporizing the liquid refrigerant. The first evaporative condenser is provided with a low-temperature heat exchange channel for the liquid refrigerant to flow through. The low-temperature heat exchange channel is connected to the return port of the loop body condenser. A first condensation row pipe for exchanging heat with the liquid refrigerant is arranged in the low-temperature heat exchange channel. Both ends of the first condensation row pipe are circularly connected to a low-temperature evaporation loop. A low-temperature evaporator is arranged on the low-temperature evaporation loop. The first condensation row pipe is connected to the outlet side of the low-temperature evaporator. Using low-grade condensation heat to bear part of the cooling load reduces the cooling load burden of the voltage compression refrigeration system, reduces the waste heat input to the outside, and can quickly discharge a large amount of heat generated by the low-temperature evaporation loop, enabling the low-temperature evaporation loop refrigeration system to operate stably and efficiently for a long time.

Description

Technical Field

[0001] The present invention relates to the technical field of refrigeration systems, and particularly to a condensing heat refrigeration driving device and a multi-stage evaporator refrigeration system thereof. Background Art

[0002] With the improvement of people's living standards, people have a higher pursuit of comfort, resulting in a rapid increase in the use of air conditioners. However, most of today's air conditioners are voltage compression refrigeration. Due to the huge power consumption of the compressor, it not only brings great pressure to the power plant during the day, but also poses a huge safety hazard to the environment. However, jet refrigeration can avoid the above problems. Jet refrigeration is a refrigeration technology driven by thermal energy, which can make full use of solar energy, industrial waste heat, geothermal energy and other low-grade heat sources; it has the advantages of simple structure, few moving parts, low operation and maintenance costs, etc.; its working medium can be green and environmentally friendly natural substances such as carbon dioxide, water, and hydrocarbons, which fully conforms to the development theme of green environmental protection. However, its disadvantage is that the existence of mixing loss, wall friction and shock loss inside the ejector makes the compression ratio small, and it can only operate under the conditions of higher evaporation temperature and lower condensation temperature. Therefore, this system is restricted by the evaporation temperature and condensation temperature and cannot be widely used. Therefore, on the basis of jet refrigeration, through effective energy-saving measures, the evaporation temperature of the system is greatly reduced and the condensation temperature is increased, so as to offset part of the adverse effects caused by the low compression ratio of the ejector, thereby effectively expanding the application space of the jet refrigeration system. While large voltage compression refrigeration cold storages bear huge cooling loads, they release a large amount of waste heat, which enters the atmosphere, resulting in an increase in the global surface temperature, intensifying the greenhouse effect, causing global warming, wasting this part of low-grade heat and polluting the environment. Therefore, efficiently utilizing this part of waste heat has important energy-saving and environmental protection significance. According to the different refrigeration environments required by different foods, large cold storages should simultaneously have multiple types of environments, namely high temperature, medium temperature, and low temperature environments, corresponding to fresh-keeping, refrigeration, and freezing functions respectively. Therefore, reasonably designing three evaporators with significantly different evaporation temperatures is of great significance for promoting the application of such systems.

[0003] Furthermore, most of the existing cold storages rely on voltage compression refrigeration, which not only requires a huge initial investment in equipment but also consumes a large amount of electric energy during operation; and most of the existing voltage compression refrigeration cold storages directly discharge a large amount of condensing heat into the outdoor atmosphere through air cooling or water cooling methods, resulting in an increase in the global surface temperature, intensifying the greenhouse effect, causing global warming, reducing the heat exchange capacity at the condenser end, wasting this part of low-grade heat, and polluting the atmospheric environment; moreover, although there are still some low-grade heat-driven refrigeration systems with multiple evaporators, the difference in evaporation temperature between the evaporators is not obvious, or to achieve a lower evaporation temperature, a large irreversible loss is taken as the price, and this method cannot make the low-grade heat-driven refrigeration system operate stably and efficiently.

[0004] Furthermore, the patent with the publication number CN106679226A discloses "a dual-evaporator ejector refrigeration system constructed by a two-stage ejector". This system realizes the refrigeration cycle through two-stage ejection and dual evaporators. Through two-stage ejection, the refrigerant flowing out of the evaporator can be efficiently entrained. However, there are no pre-cooling measures before throttling for both evaporators, resulting in a small difference in the evaporation temperatures of the two evaporators. The patent with the publication number CN204202234U discloses "a solar-driven ejector refrigeration system". This system pre-cools the refrigerant entering the evaporator before throttling. The cold source uses the low-temperature refrigerant that has been cooled and depressurized through an additional throttle valve, achieving the effect of pre-cooling the evaporator before throttling. However, it creates the cold source at the cost of losing the pressure at the condenser outlet, resulting in a large throttling loss in the system. Summary of the Invention

[0005] The object of the present invention is to provide a condensing heat refrigeration driving device and its multi-stage evaporator refrigeration system to solve the problems existing in the above-mentioned prior art. By using low-grade condensing heat to bear part of the cooling load, the cooling load burden of the vapor compression refrigeration system is reduced. At the same time, the waste heat input to the outside is reduced, and a large amount of heat generated by the low-temperature evaporation loop can be quickly discharged, enabling the low-temperature evaporation loop refrigeration system to operate stably and efficiently for a long time.

[0006] To achieve the above object, the present invention provides the following solution: The present invention provides a condensing heat refrigeration driving device, including a pressurizing and heating loop. A loop body condenser storing liquid refrigerant is provided on the pressurizing and heating loop, and a refrigeration working medium pump for pressurizing the liquid refrigerant is provided. The refrigeration working medium pump is connected to the outlet of the loop body condenser. The outlet of the refrigeration working medium pump is connected to a first evaporative condenser for heating and vaporizing the liquid refrigerant. The first evaporative condenser is provided with a low-temperature heat exchange channel for the liquid refrigerant to flow through, and the low-temperature heat exchange channel is connected to the return port of the loop body condenser. A first condensing row pipe for exchanging heat with the liquid refrigerant is provided in the low-temperature heat exchange channel. Both ends of the first condensing row pipe extend out of the low-temperature heat exchange channel and are connected in a cycle to a low-temperature evaporation loop. A low-temperature evaporator is provided on the low-temperature evaporation loop, and the first condensing row pipe is connected to the outlet side of the low-temperature evaporator.

[0007] Preferably, a second evaporative condenser is connected between the first evaporative condenser and the loop body condenser. The second evaporative condenser is provided with a high-temperature heat exchange channel for the liquid refrigerant to flow through. A second condensing row pipe for exchanging heat with the liquid refrigerant is provided in the high-temperature heat exchange channel. Both ends of the second condensing row pipe extend out of the high-temperature heat exchange channel and are connected in a cycle to an industrial waste heat pipeline.

[0008] A multi-stage evaporator refrigeration system is also provided, which includes the pressurized heating loop for condensing heat recovery and the low-temperature evaporation loop supporting it. The low-temperature evaporation loop is circularly connected at both ends of the first condensation row pipe, and a fourth throttle valve, a low-temperature evaporator, and a compressor are sequentially arranged on the low-temperature evaporation loop along the refrigerant flow direction. A first subcooling mechanism for subcooling the refrigerant is arranged between the fourth throttle valve and the first condensation row pipe.

[0009] Preferably, it further includes an intermediate-temperature evaporation loop circularly connected to the loop body condenser. A first throttle valve, a second throttle valve, and an intermediate-temperature evaporator are sequentially arranged on the intermediate-temperature evaporation loop along the refrigerant flow direction. A gas-liquid separator for separating the refrigerant into gas and liquid is arranged between the first throttle valve and the second throttle valve. The second throttle valve is connected to the liquid outlet of the gas-liquid separator, and the gas outlet of the gas-liquid separator is connected to the reflux port of the loop body condenser.

[0010] Preferably, it further includes a high-temperature evaporation loop circularly connected to the loop body condenser. A third throttle valve and a high-temperature evaporator are sequentially arranged on the high-temperature evaporation loop along the refrigerant flow direction. A second subcooling mechanism for subcooling the refrigerant is connected between the third throttle valve and the outlet of the loop body condenser.

[0011] Preferably, the second subcooling mechanism is a first plate heat exchanger. A first heat exchange channel for gaseous refrigerant to flow through is arranged in the first plate heat exchanger. The first heat exchange channel is connected between the gas outlet of the gas-liquid separator and the reflux port of the loop body condenser. A first heat exchange pipeline for exchanging heat with the gaseous refrigerant is arranged in the first heat exchange channel. The first heat exchange pipeline is connected between the outlet of the loop body condenser and the third throttle valve.

[0012] Preferably, the first subcooling mechanism is a second plate heat exchanger. A second heat exchange channel for gaseous refrigerant to flow through is arranged in the second plate heat exchanger. The second heat exchange channel is connected between the outlet of the high-temperature evaporator and the reflux port of the loop body condenser, and the outlet of the first heat exchange channel is synchronously connected to the inlet of the second heat exchange channel. A second heat exchange pipeline for exchanging heat with the gaseous refrigerant is arranged in the second heat exchange channel. The second heat exchange pipeline is connected between the first condensation row pipe and the fourth throttle valve.

[0013] Preferably, a mixing pipeline for isobarically mixing gaseous refrigerant is arranged between the high-temperature evaporator and the second heat exchange channel, and the outlet of the first heat exchange channel is connected to the mixing pipeline.

[0014] Preferably, the loop body condenser is equipped with a first ejector. A first ejecting section communicating between the high-temperature heat exchange channel and the loop body condenser is provided on the first ejector. A first diversion section is bypassed beside the inlet of the first ejecting section, and the first diversion section is communicated with the outlet of the second heat exchange channel.

[0015] Preferably, the loop body condenser is further equipped with a second ejector. A second ejecting section communicating between the first ejecting section and the loop body condenser is provided on the second ejector. A second diversion section is bypassed beside the inlet of the second ejecting section, and the second diversion section is communicated with the outlet of the medium-temperature evaporator.

[0016] The present invention has achieved the following technical effects compared with the prior art:

[0017] First, the refrigerant pump is connected to the outlet of the loop body condenser. The outlet of the refrigerant pump is connected to a primary evaporative condenser for heating and vaporizing the liquid refrigerant. The primary evaporative condenser is provided with a low-temperature heat exchange channel for the liquid refrigerant to flow through, and the low-temperature heat exchange channel is communicated with the return port of the loop body condenser. A first condensing row pipe for exchanging heat with the liquid refrigerant is provided in the low-temperature heat exchange channel. Both ends of the first condensing row pipe extend out of the low-temperature heat exchange channel and are connected in a cycle on the low-temperature evaporation loop. A low-temperature evaporator is provided on the low-temperature evaporation loop. The first condensing row pipe is connected to the outlet side of the low-temperature evaporator. Among them, the high-pressure liquid refrigerant coming out of the refrigerant pump is evenly sprayed on the first condensing row pipe. The first condensing row pipe is connected to the low-temperature evaporation loop. The refrigerant passing through the low-temperature evaporator is in a gaseous state and flows into the first condensing row pipe. After the high-pressure liquid exchanges heat with the first condensing row pipe, it evaporates and absorbs heat to become a high-temperature and high-pressure gas. The gaseous refrigerant in the first condensing row pipe condenses into a liquid refrigerant after exchanging heat with the high-pressure liquid refrigerant and then flows back into the low-temperature evaporator. The primary evaporative condenser belongs to a closed cooling mechanism and does not contact the air. At the same time, it also takes away the heat of the condensing end of the low-temperature evaporation loop. Further, compared with a complete voltage compression refrigeration system, the present invention uses low-grade condensing heat to bear part of the cooling load, reducing the cooling load burden of the voltage compression refrigeration system and reducing the waste heat input to the outside. It not only saves energy but also reduces the harm to the environment. Compared with traditional air-cooled and water-cooled voltage compression refrigeration systems, the condenser of the low-temperature evaporation loop in the present invention uses a primary evaporative condenser, which is also the low-temperature generator of the low-grade heat-driven pressurized heating loop, enabling a large amount of heat generated by the low-temperature evaporation loop to be quickly discharged, enabling the low-temperature evaporation loop refrigeration system to operate stably and efficiently for a long time. At the same time, the primary evaporative condenser of the condensing heat-driven refrigeration system can quickly generate a high-temperature and lossless heat source.

[0018] Second, a secondary evaporative condenser is connected between the primary evaporative condenser and the loop body condenser. The secondary evaporative condenser is provided with a high-temperature heat exchange channel for the circulation of liquid refrigerant. A second condensing pipe for exchanging heat with the liquid refrigerant is arranged in the high-temperature heat exchange channel. Both ends of the second condensing pipe extend out of the high-temperature heat exchange channel and are connected in a cycle to the industrial waste heat pipeline. The industrial waste heat is utilized in combination with the condensation heat to drive the refrigeration system to undertake part of the cooling load, further reducing the cooling load burden of the vapor compression refrigeration system, saving energy, and reducing the harm to the environment.

[0019] Third, a low-temperature evaporation loop is connected in a cycle to both ends of the first condensing pipe. A fourth throttle valve, a low-temperature evaporator, and a compressor are sequentially arranged on the low-temperature evaporation loop along the direction of refrigerant flow. A first subcooling mechanism for subcooling the refrigerant is arranged between the fourth throttle valve and the first condensing pipe. The refrigerant before throttling of the low-temperature evaporator is cooled through the first subcooling mechanism to achieve the purpose of subcooling before throttling, creating a relatively low evaporation temperature for the low-temperature evaporator and realizing the refrigeration function.

[0020] Fourth, a first throttle valve, a second throttle valve, and a medium-temperature evaporator are sequentially arranged on the medium-temperature evaporation loop along the direction of refrigerant flow. A gas-liquid separator for separating the refrigerant into gas and liquid is arranged between the first throttle valve and the second throttle valve. The second throttle valve is connected to the liquid outlet of the gas-liquid separator. The gas outlet of the gas-liquid separator is connected to the return port of the loop body condenser. Through the secondary throttling and gas-liquid separation technology, a relatively low evaporation temperature is created for the medium-temperature evaporator to realize the refrigeration function. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0022] Figure 1 It is a schematic diagram of the overall structure of the multi-stage evaporator refrigeration system of the present invention;

[0023] Figure 2 It is a cycle pressure-enthalpy diagram of the working process of the multi-stage evaporator refrigeration system of the present invention;

[0024] Among them, 101 - Loop body condenser; 102 - Refrigerant pump; 103 - Primary evaporative condenser; 104 - First ejector; 105 - Second ejector; 106 - First throttle valve; 107 - Gas - liquid separator; 108 - Second throttle valve; 109 - Medium - temperature evaporator; 110 - First plate heat exchanger; 111 - Third throttle valve; 112 - High - temperature evaporator; 113 - Second plate heat exchanger; 114 - Fourth throttle valve; 115 - Low - temperature evaporator; 116 - Compressor; 117 - Secondary evaporative condenser. Specific embodiments

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] The purpose of the present invention is to provide a condensation - heat refrigeration drive device and its multi - stage evaporator refrigeration system to solve the problems existing in the above - mentioned prior art. By using low - grade condensation heat to bear part of the cooling load, the cooling load burden of the vapor - compression refrigeration system is reduced, and at the same time, the waste heat input to the outside is reduced. Moreover, it can quickly discharge a large amount of heat generated by the low - temperature evaporation loop, enabling the low - temperature evaporation loop refrigeration system to operate stably and efficiently for a long time.

[0027] To make the above - mentioned objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0028] As Figures 1 to 2As shown in the figure, this embodiment provides a condensation heat refrigeration drive device, including a pressurization and heating loop. On the pressurization and heating loop, there is a loop body condenser 101 storing liquid refrigerant, and a refrigeration working medium pump 102 for pressurizing the liquid refrigerant. The refrigeration working medium pump 102 is connected to the outlet of the loop body condenser 101. The outlet of the refrigeration working medium pump 102 is connected to a first evaporative condenser 103 for heating and vaporizing the liquid refrigerant. The first evaporative condenser 103 is provided with a low-temperature heat exchange channel for the liquid refrigerant to flow through, and the low-temperature heat exchange channel is connected to the return port of the loop body condenser 101. Inside the low-temperature heat exchange channel, there is a first condensation row pipe for exchanging heat with the liquid refrigerant. Both ends of the first condensation row pipe extend out of the low-temperature heat exchange channel and are connected in a cycle on the low-temperature evaporation loop. On the low-temperature evaporation loop, there is a low-temperature evaporator 115. The first condensation row pipe is connected to the outlet side of the low-temperature evaporator 115. Among them, the high-pressure liquid refrigerant coming out of the refrigeration working medium pump 102 is evenly sprayed on the first condensation row pipe. The first condensation row pipe is connected to the low-temperature evaporation loop. The refrigerant passing through the low-temperature evaporator 115 is in a gaseous state and flows into the first condensation row pipe. After the high-pressure liquid exchanges heat with the first condensation row pipe, it evaporates and absorbs heat to become a high-temperature and high-pressure gas. The gaseous refrigerant in the first condensation row pipe condenses into a liquid refrigerant after exchanging heat with the high-pressure liquid refrigerant and then flows back into the low-temperature evaporator 115. The first evaporative condenser 103 belongs to a closed cooling mechanism and does not contact the air. At the same time, it also takes away the heat of the condensation end of the low-temperature evaporation loop. Further, compared with a complete voltage compression refrigeration system, the present invention uses low-grade condensation heat to bear part of the cooling load, reducing the cooling load burden of the voltage compression refrigeration system, and at the same time reducing the waste heat input to the outside. This not only saves energy but also reduces the harm to the environment. Compared with traditional air-cooled and water-cooled voltage compression refrigeration systems, in the present invention, the condenser of the low-temperature evaporation loop adopts the first evaporative condenser 103, which is also the low-temperature generator of the low-grade heat-driven pressurization and heating loop, enabling a large amount of heat generated by the low-temperature evaporation loop to be quickly discharged, improving the heat exchange capacity at the condenser end of the low-temperature evaporation loop and the refrigeration efficiency of the low-temperature evaporation loop, enabling the low-temperature evaporation loop refrigeration system to operate stably and efficiently for a long time. At the same time, the first evaporative condenser 103 of the condensation heat-driven refrigeration system can quickly generate a high-temperature and lossless heat source.

[0029] Among them, a secondary evaporative condenser 117 is connected between the primary evaporative condenser 103 and the loop body condenser 101. The secondary evaporative condenser 117 is provided with a high-temperature heat exchange channel for the liquid refrigerant to flow through. A second condensation row pipe for exchanging heat with the liquid refrigerant is arranged in the high-temperature heat exchange channel. Both ends of the second condensation row pipe extend out of the high-temperature heat exchange channel and are connected in a cycle on the industrial waste heat pipeline. The industrial waste heat is used in combination with the condensation heat to drive the refrigeration system to bear part of the cooling load, further reducing the cooling load burden of the voltage compression refrigeration system, saving energy, and reducing the harm to the environment. Moreover, since the temperature of the refrigerant that has recovered the condensation heat in the pressurization and heating loop is not high and cannot fully phase-change the refrigerant, a secondary evaporative condenser 117 is installed on the pressurization and heating loop after recovering the condensation heat as a high-temperature generator to supply heat using other low-grade and high-calorific value energy sources such as industrial waste heat, ensuring that the subsequent medium-temperature evaporator 109 and high-temperature evaporator 112 can refrigerate stably and efficiently, and also playing a role in saving energy and protecting the environment. Preferably, industrial waste heat and waste heat can also be replaced with solar energy, etc.

[0030] Furthermore, a multi-stage evaporator refrigeration system is also provided. The whole system consists of two subsystems, namely, a voltage compression refrigeration system and a low-grade heat-driven refrigeration system. The voltage compression refrigeration system has a low-temperature evaporation loop. The low-grade heat-driven refrigeration system includes a pressurization and heating loop, a medium-temperature evaporation loop, and a high-temperature evaporation loop. Among them, the pressurization and heating loop serving as a condensation heat refrigeration driving device is arranged in a supporting manner with the low-temperature evaporation loop. The low-temperature evaporation loop is connected in a cycle at both ends of the first condensation row pipe. And along the direction of the refrigerant flow on the low-temperature evaporation loop, a fourth throttle valve 114, a low-temperature evaporator 115, and a compressor 116 are sequentially arranged. A first subcooling mechanism for subcooling the refrigerant is arranged between the fourth throttle valve 114 and the first condensation row pipe. The refrigerant before throttling of the low-temperature evaporator 115 is cooled through the first subcooling mechanism to achieve the purpose of subcooling before throttling, that is, the saturated liquid refrigerant before throttling is subcooled, reducing the flashing gas generated during the throttling process of the refrigerant liquid, reducing the specific volume of the volume occupied by the flashing gas (i.e., reducing the so-called "dryness"), increasing the refrigerating capacity per unit mass, creating a relatively low evaporation temperature for the low-temperature evaporator 115, and realizing the refrigeration function.

[0031] As a preferred embodiment of the present invention, the medium-temperature evaporation loop is in circular communication with the loop body condenser 101. Along the refrigerant flow direction on the medium-temperature evaporation loop, a first throttle valve 106, a second throttle valve 108, and a medium-temperature evaporator 109 are sequentially provided. A gas-liquid separator 107 for separating the refrigerant into gas and liquid is provided between the first throttle valve 106 and the second throttle valve 108. The second throttle valve 108 is connected to the liquid outlet of the gas-liquid separator 107. The gas outlet of the gas-liquid separator 107 is connected to the reflux port of the loop body condenser 101. Through the secondary throttling and gas-liquid separation technology, that is, the saturated liquid refrigerant becomes a low-temperature and low-pressure wet steam after passing through the first throttle valve, and then the gas-liquid separation process is realized through the gas-liquid separator 107. Then, the saturated liquid refrigerant is drained and becomes a wet steam with a lower temperature and pressure after passing through the second throttle valve 108, so as to provide a lower evaporation temperature for the medium-temperature evaporator 109 and realize the refrigeration function.

[0032] As another preferred embodiment of the present invention, the high-temperature evaporation loop is in circular communication with the loop body condenser 101. Along the refrigerant flow direction on the high-temperature evaporation loop, a third throttle valve 111 and a high-temperature evaporator 112 are sequentially provided. A second subcooling mechanism for subcooling the refrigerant is connected between the third throttle valve 111 and the outlet of the loop body condenser 101. The second subcooling mechanism is used to cool the liquid before throttling of the high-temperature evaporator 112 to achieve the purpose of subcooling before throttling, create a low evaporation temperature for the high-temperature evaporator 112, and realize the fresh-keeping function.

[0033] Among them, the second subcooling mechanism is a first plate heat exchanger 110. A first heat exchange channel for the gaseous refrigerant to flow through is provided in the first plate heat exchanger 110. The first heat exchange channel is connected between the gas outlet of the gas-liquid separator 107 and the reflux port of the loop body condenser 101. A first heat exchange pipeline for exchanging heat with the gaseous refrigerant is provided in the first heat exchange channel. The first heat exchange pipeline is connected between the outlet of the loop body condenser 101 and the third throttle valve 111. Furthermore, the liquid before throttling of the high-temperature evaporator 112 is cooled through the first plate heat exchanger 110, and the heat of the gaseous refrigerant separated by the gas-liquid separator 107 is fully utilized, saving energy consumption and reducing the use cost.

[0034] Moreover, the first subcooling mechanism is the second plate heat exchanger 113. A second heat exchange channel for the flow of gaseous refrigerant is provided in the second plate heat exchanger 113. The second heat exchange channel is connected between the outlet of the high-temperature evaporator 112 and the return port of the loop body condenser 101. And the outlet of the first heat exchange channel is synchronously connected to the inlet of the second heat exchange channel. A second heat exchange pipeline for exchanging heat with the gaseous refrigerant is provided in the second heat exchange channel. The second heat exchange pipeline is connected between the first condenser row pipe and the fourth throttle valve 114. Thus, the refrigerant before throttling of the low-temperature evaporator 115 is cooled by the second plate heat exchanger 113, making full use of the total heat of the gaseous refrigerant after heat exchange between the high-temperature evaporator 112 and the second plate heat exchanger 113, saving energy consumption and reducing the use cost.

[0035] Furthermore, a mixing pipeline for isobarically mixing the gaseous refrigerant is provided between the high-temperature evaporator 112 and the second heat exchange channel. The outlet of the first heat exchange channel is connected to the mixing pipeline, ensuring the isobaric mixing effect of the gaseous refrigerant flowing out of the second plate heat exchanger 113 and the high-temperature evaporator 112.

[0036] As a preferred embodiment of the present invention, the loop body condenser 101 is equipped with a first ejector 104. Preferably, the first ejector 104 adopts devices such as an ejector mixer or a Venturi tube. A first ejecting section connected between the high-temperature heat exchange channel and the loop body condenser 101 is provided on the first ejector 104. A first diversion section is bypassed at the inlet of the first ejecting section. The first diversion section is connected to the outlet of the second heat exchange channel. Compared with the voltage compression refrigeration system, the condensing heat refrigeration driving device in the present invention combines the refrigerant pump 102 and the first ejector 104, uses the high-pressure working flow to eject the low-pressure entrained flow, that is, uses the high-pressure refrigerant in the pressurized heating loop to divert the low-pressure refrigerant in the second heat exchange channel, that is, to eject the gaseous refrigerant heated by heat exchange with the second plate heat exchanger 113, replacing the original compressor, reducing the initial investment of the equipment and saving energy.

[0037] Furthermore, the loop body condenser 101 is also equipped with a second ejector 105. Preferably, the second ejector 105 adopts devices such as an ejector mixer or a Venturi tube. A second ejecting section connected between the first ejecting section and the loop body condenser 101 is provided on the second ejector 105. A second diversion section is bypassed at the inlet of the second ejecting section. The second diversion section is connected to the outlet of the medium-temperature evaporator 109. Compared with the voltage compression refrigeration system, on the basis of adopting the refrigerant pump 102 and the first ejector 104, the present invention further combines the second ejector 105, uses the high-pressure working flow to eject the low-pressure entrained flow, and the high-pressure refrigerant in the pressurized heating loop diverts the low-pressure refrigerant of the medium-temperature evaporator 109, replacing the original compressor, further reducing the initial investment of the equipment and saving energy.

[0038] Through two-stage injection, the system operates stably and efficiently. The first-stage ejector entrains the gaseous refrigerant from the second plate heat exchanger 113, which not only ensures the effect after the first throttling of the low-temperature evaporation loop but also ensures the subcooling effect before throttling of the high-temperature evaporation loop. The second-stage ejector entrains the gaseous refrigerant of the medium-temperature evaporator 109, greatly reducing the evaporation pressure of the medium-temperature evaporator 109 and enabling the refrigerant to evaporate and absorb heat at a lower temperature.

[0039] Through the rational combination of secondary throttling technology, gas-liquid separation technology, and plate heat exchange technology, the present invention achieves the purpose of effective subcooling before throttling, thereby designing three evaporators with significantly different evaporation temperatures.

[0040] Specifically in use, for the pressurization and heating loop: The liquid refrigerant flowing out from the loop body condenser 101 is first pressurized by the refrigerant pump 102, then heated by the first-stage evaporative condenser 103, then completely vaporized through the second-stage evaporative condenser 117, then entrains the gaseous refrigerant heated by heat exchange in the second plate heat exchanger 113 through the first ejector 104, then entrains the gaseous refrigerant from the medium-temperature evaporator 109 through the second ejector 105, and finally flows back to the loop body condenser 101 and then back to the condenser to complete the closed-loop conduction of the pressurization and heating loop.

[0041] For the low-temperature evaporation loop: The liquid refrigerant flowing out from the first condensation row of the first-stage evaporative condenser 103 is first subcooled by the mixed refrigerant from the high-temperature evaporator 112 of the second plate heat exchanger 113 and the outlet of the gas-liquid separator 107, then cooled and depressurized by the fourth throttle valve 114, then evaporated and absorbs heat through the low-temperature evaporator 115 to become gaseous refrigerant, then becomes high-temperature and high-pressure gas under the action of the compressor 116, and finally flows to the first condensation row of the first-stage evaporative condenser 103 to complete the closed loop of low-temperature evaporation.

[0042] For the medium-temperature evaporation loop: The liquid refrigerant coming out from the loop body condenser 101 is first cooled and depressurized by the first throttle valve 106, then separated into gas and liquid parts by the gas-liquid separator 107, then the liquid refrigerant flowing out from the gas-liquid separator 107 is cooled and depressurized by the second throttle valve 108, then enters the medium-temperature evaporator 109 to evaporate and absorb heat to become gaseous refrigerant, and finally is entrained by the second ejector 105 and flows into the loop body condenser 101 to complete the closed loop of medium-temperature evaporation.

[0043] High-temperature evaporation loop: The liquid refrigerant coming out of the loop body condenser 101 first passes through the first plate heat exchanger 110 and is subcooled by the low-temperature gas from the gas-liquid separator 107, then passes through the third throttle valve 111 to reduce the temperature and pressure, then passes through the high-temperature evaporator 112 to evaporate and absorb heat and becomes gaseous refrigerant, then is isobarically mixed with the gaseous refrigerant flowing out of the gas-liquid separator 107, then flows through the second plate heat exchanger 113 and is ejected by the first ejector 104 to flow towards the second ejector 105, and finally flows towards the loop body condenser 101 to complete the high-temperature evaporation closed loop.

[0044] As Figure 2 shown, it is the pressure-enthalpy diagram of the refrigerant circulation process in the pressurization and heating loop, low-temperature evaporation loop, medium-temperature evaporation loop and high-temperature evaporation loop, representing the corresponding relationship between the pressure and enthalpy values of the state points. (Read the diagram according to each of the following circulation processes, and the numbers represent the state points where the refrigerant enters and exits each device in Figure 1 ); Pressurization and heating loop: 1 → 2 → 3 → 3'+5' → 6 → 6' → 6''+10' → 7 → 7' → 1; Low-temperature evaporation loop: 16 → 17 → 18 → 19 → 15 → 16; Medium-temperature evaporation loop: 1 → 8 → 8'+8'' → 9 → 10 → 10'+6'' → 7 → 7' → 1; High-temperature evaporation loop: 1 → 11 → 12 → 13+14 → 4 → 5 → 5'+3' → 6 → 6' → 6''+10' → 7 → 7' → 1.

[0045] Furthermore, the working principle of the ejector can also be reflected by the pressure-enthalpy diagram relationship. Taking the first ejector 104 as an example, the working condition 3 undergoes isentropic expansion to the working condition 3', the working condition 5 undergoes isentropic expansion to the working condition 5', the working conditions 3' and 5' are isobarically mixed to the working condition 6, and the working condition 6 undergoes isentropic compression to the working condition 6', realizing a complete ejection process. The ejection and compression processes are both approximately isentropic processes (reversible adiabatic).

[0046] The cold storages supporting the multi-stage evaporator refrigeration system are divided into: high-temperature cold storage (fresh storage), medium-temperature cold storage (refrigerated storage), low-temperature cold storage (frozen storage), and their refrigeration design temperatures, implementation methods and specific application fields are as follows:

[0047] High-temperature cold storage: The refrigeration design temperature is 5 - 15°C; In the condensation heat-driven refrigeration system, it is realized by the technology of subcooling before throttling and single throttling, that is, by using the high-temperature evaporation loop. The main application fields include fruit fresh storage, pharmaceutical fresh storage, chemical fresh storage, vegetable fresh storage, electronic raw material fresh storage, flower fresh storage, mushroom fresh storage, mushroom production workshop, low-temperature cold storage, meat fresh storage, beverage fresh storage, beer fresh storage, etc.

[0048] Medium-temperature cold storage: The designed refrigeration temperature is 5 to -5°C; in the condensation heat-driven refrigeration system, it is achieved through the secondary throttling and gas-liquid separation technology, that is, by using the medium-temperature evaporation loop; the main application fields include meat cold storage, ice cream cold storage, seafood cold storage, fish cold storage, ice storage, ice sculpture cold storage, pharmaceutical cold storage, chemical cold storage, etc.

[0049] Low-temperature cold storage: The designed refrigeration temperature is -18 to -25°C; in the voltage compression refrigeration system, it is achieved through subcooling before throttling and single throttling technology; that is, by using the low-temperature evaporation loop; the main application fields include meat freezer, fish freezer, pharmaceutical freezer, ice cream freezer, seafood freezer, chemical freezer, quick-freezing freezer, etc.

[0050] Adaptations made according to actual needs are all within the protection scope of the present invention.

[0051] It should be noted that for those skilled in the art, obviously the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

[0052] Specific examples are used in the present invention to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A multi-stage evaporator refrigeration system, characterized in that, it includes a condensing heat refrigeration driving device, the condensing heat refrigeration driving device includes a pressurizing and heating loop, a loop body condenser storing liquid refrigerant is provided on the pressurizing and heating loop, a refrigeration working medium pump for pressurizing the liquid refrigerant, the refrigeration working medium pump is connected to the outlet of the loop body condenser, the outlet of the refrigeration working medium pump is connected to a first evaporative condenser for heating and vaporizing the liquid refrigerant, the first evaporative condenser is provided with a low-temperature heat exchange channel for the liquid refrigerant to flow through, and the low-temperature heat exchange channel is connected to the return port of the loop body condenser, a first condensing row of pipes for exchanging heat with the liquid refrigerant is provided in the low-temperature heat exchange channel, both ends of the first condensing row of pipes extend out of the low-temperature heat exchange channel and are connected in a cycle on a low-temperature evaporation loop, a low-temperature evaporator is provided on the low-temperature evaporation loop, and the first condensing row of pipes is connected to the outlet side of the low-temperature evaporator; a second evaporative condenser is connected between the first evaporative condenser and the loop body condenser, the second evaporative condenser is provided with a high-temperature heat exchange channel for the liquid refrigerant to flow through, a second condensing row of pipes for exchanging heat with the liquid refrigerant is provided in the high-temperature heat exchange channel, both ends of the second condensing row of pipes extend out of the high-temperature heat exchange channel and are connected in a cycle on an industrial waste heat pipeline; it further includes the pressurizing and heating loop for condensing heat recovery and its supporting low-temperature evaporation loop, the low-temperature evaporation loop is connected in a cycle at both ends of the first condensing row of pipes, and a fourth throttle valve, a low-temperature evaporator and a compressor are sequentially arranged on the low-temperature evaporation loop along the refrigerant flow direction, and a first subcooling mechanism for subcooling the refrigerant is provided between the fourth throttle valve and the first condensing row of pipes; it further includes an intermediate-temperature evaporation loop connected in a cycle with the loop body condenser, a first throttle valve, a second throttle valve and an intermediate-temperature evaporator are sequentially arranged on the intermediate-temperature evaporation loop along the refrigerant flow direction, a gas-liquid separator for separating the refrigerant into gas and liquid is provided between the first throttle valve and the second throttle valve, the second throttle valve is connected to the liquid outlet of the gas-liquid separator, and the gas outlet of the gas-liquid separator is connected to the return port of the loop body condenser.

2. The multi-stage evaporator refrigeration system according to claim 1, characterized in that, it further includes a high-temperature evaporation loop connected in a cycle with the loop body condenser, a third throttle valve and a high-temperature evaporator are sequentially arranged on the high-temperature evaporation loop along the refrigerant flow direction, and a second subcooling mechanism for subcooling the refrigerant is connected between the third throttle valve and the outlet of the loop body condenser.

3. The multi-stage evaporator refrigeration system according to claim 2, characterized in that, The second subcooling mechanism is a first plate heat exchanger. A first heat exchange channel for gaseous refrigerant to flow through is provided in the first plate heat exchanger. The first heat exchange channel is connected between the gas outlet of the gas-liquid separator and the return port of the loop body condenser. A first heat exchange pipeline for exchanging heat with the gaseous refrigerant is provided in the first heat exchange channel. The first heat exchange pipeline is connected between the outlet of the loop body condenser and the third throttle valve.

4. The multi-stage evaporator refrigeration system according to claim 3, characterized in that, The first subcooling mechanism is a second plate heat exchanger. A second heat exchange channel for gaseous refrigerant to flow through is provided in the second plate heat exchanger. The second heat exchange channel is connected between the outlet of the high-temperature evaporator and the return port of the loop body condenser, and the outlet of the first heat exchange channel is synchronously connected to the inlet of the second heat exchange channel. A second heat exchange pipeline for exchanging heat with the gaseous refrigerant is provided in the second heat exchange channel. The second heat exchange pipeline is connected between the first condenser row pipe and the fourth throttle valve.

5. The multi-stage evaporator refrigeration system according to claim 4, characterized in that, A mixing pipeline for isobarically mixing gaseous refrigerant is provided between the high-temperature evaporator and the second heat exchange channel. The outlet of the first heat exchange channel is connected to the mixing pipeline.

6. The multi-stage evaporator refrigeration system according to claim 5, characterized in that, The loop body condenser is equipped with a first ejector. A first ejecting section connected between the high-temperature heat exchange channel and the loop body condenser is provided on the first ejector. A first diversion section is bypassed at the inlet of the first ejecting section. The first diversion section is connected to the outlet of the second heat exchange channel.

7. The multi-stage evaporator refrigeration system according to claim 6, characterized in that, The loop body condenser is further equipped with a second ejector. A second ejecting section connected between the first ejecting section and the loop body condenser is provided on the second ejector. A second diversion section is bypassed at the inlet of the second ejecting section. The second diversion section is connected to the outlet of the medium-temperature evaporator.

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