阅读说明：本技术 一种与喷射器耦合的复叠制冷循环系统及过冷方法 (Cascade refrigeration cycle system coupled with ejector and supercooling method ) 是由 杨启超 迟卫凯 陈晓楠 王朋 刘广彬 赵远扬 李连生 于 2021-09-18 设计创作，主要内容包括：本发明属于冷冻冷藏和制冷技术领域,具体涉及一种与喷射器耦合的复叠制冷循环系统及过冷方法,包括冷凝器和过冷器,冷凝器和过冷器均连接喷射器,喷射器的出口依次连接气液分离器和第二膨胀阀,第二膨胀阀与过冷器入口相连通；冷凝器的出口还连接第一膨胀阀,第一膨胀阀依次连接冷凝蒸发器、高压级压缩机,高压级压缩机与冷凝器相连通。冷凝器出口的制冷剂液体分为两路,其中一路进入喷射器与流经过冷器后进入喷射器的高温级制冷剂混合,然后进入气液分离器,气体进入高压级压缩机进行压缩,液体流经第二膨胀阀进入过冷器完成制冷循环。该制冷循环系统能够提高复叠制冷循环系统的效率,可实现有效过冷,提高系统性能系数。(The invention belongs to the technical field of freezing, refrigeration and refrigeration, and particularly relates to a cascade refrigeration cycle system coupled with an ejector and a supercooling method, wherein the cascade refrigeration cycle system comprises a condenser and a subcooler, the condenser and the subcooler are both connected with the ejector, an outlet of the ejector is sequentially connected with a gas-liquid separator and a second expansion valve, and the second expansion valve is communicated with an inlet of the subcooler; the outlet of the condenser is also connected with a first expansion valve, the first expansion valve is sequentially connected with a condensation evaporator and a high-pressure stage compressor, and the high-pressure stage compressor is communicated with the condenser. The refrigerant liquid at the outlet of the condenser is divided into two paths, wherein one path of the refrigerant liquid enters the ejector to be mixed with the high-temperature-level refrigerant flowing through the subcooler and then enters the gas-liquid separator, the gas enters the high-pressure-level compressor to be compressed, and the liquid enters the subcooler through the second expansion valve to complete the refrigeration cycle. The refrigerating cycle system can improve the efficiency of the cascade refrigerating cycle system, can realize effective supercooling, and improves the performance coefficient of the system.)

1. A cascade refrigeration cycle system coupled with an ejector is characterized by comprising a condenser and a subcooler, wherein the condenser and the subcooler are both connected with the ejector, the outlet of the ejector is sequentially connected with a gas-liquid separator and a second expansion valve, and the second expansion valve is communicated with the inlet of the subcooler; the outlet of the condenser is also connected with a first expansion valve, the first expansion valve is sequentially connected with a condensation evaporator and a high-pressure stage compressor, and the high-pressure stage compressor is communicated with the condenser.

2. The refrigeration cycle system as claimed in claim 1, wherein an outlet of the subcooler is connected to the low-pressure stage expansion valve, the evaporator, the low-pressure stage compressor, and the condensing evaporator in sequence, and then connected to an inlet of the subcooler to form a cycle.

3. The refrigeration cycle system as set forth in claim 1, wherein the refrigerant of said ejector is introduced into said gas-liquid separator, the gas separated from said gas-liquid separator is introduced into a high-pressure stage compressor for compression, and the liquid is introduced into a subcooler through a second expansion valve.

4. A supercooling method of a refrigerating cycle system according to any one of claims 1 to 3, wherein a refrigerant liquid at an outlet of the condenser is divided into two paths, and one path enters the condensing evaporator through the first expansion valve to be evaporated into a gas and then enters the high pressure stage compressor to complete a refrigerating cycle; the other path of the refrigerant enters the ejector to be mixed with the refrigerant flowing through the subcooler and then enters the gas-liquid separator, the gas at the outlet of the gas-liquid separator enters the high-pressure stage compressor to be compressed, and the liquid flows through the second expansion valve and enters the subcooler to complete the other path of refrigeration cycle.

Technical Field

The invention belongs to the technical field of freezing refrigeration and refrigeration, and particularly relates to a cascade refrigeration cycle system coupled with an ejector and a supercooling method.

Background

The supercooling technology is one of effective measures for improving the performance of a refrigeration system and a circulating system thereof, and in a cascade refrigeration system, the supercooling degree of a low-temperature stage is improved, so that the refrigerating capacity of unit refrigerant flow of low-pressure stage circulation is improved, and the system performance can be obviously improved.

Generally, a supercooling technology can be realized by arranging a subcooler, a plate economizer, mechanical supercooling, thermoelectric supercooling and the like, the subcooler is arranged by increasing the heat exchange area of a condenser on the basis of the condenser, the supercooling effect is influenced by the temperature of a cooling water inlet, the supercooling effect is limited by the evaporation temperature of a high-temperature stage in a cascade refrigeration system, the refrigerant of the low-temperature stage cannot be subcooled below the evaporation temperature of the high-temperature stage through an evaporation condenser, and the condensation evaporator has heat exchange temperature difference, namely the evaporation temperature of the high-temperature stage is lower than the condensation temperature of the low-temperature stage, so the supercooling effect is limited. The mechanical supercooling method is to arrange a subcooler at the outlet of the condenser, the cold energy of the subcooler is provided by a single refrigeration cycle and can be generally provided by a conventional vapor compression refrigeration system, an absorption refrigeration system or a thermoelectric refrigeration system and other systems, and extra parts are added in the method, so that the system is more complex.

Disclosure of Invention

The invention aims to solve the problems in the prior art, provides a cascade refrigeration cycle system coupled with an ejector and a supercooling method, and provides a cycle and supercooling method for applying the ejector to the cascade refrigeration system, so that the efficiency of the cascade refrigeration cycle system can be improved.

The technical scheme of the invention is as follows:

a cascade refrigeration cycle system coupled with an ejector comprises a condenser and a subcooler, wherein the condenser and the subcooler are both connected with the ejector, the outlet of the ejector is sequentially connected with a gas-liquid separator and a second expansion valve, and the second expansion valve is communicated with the inlet of the subcooler; the outlet of the condenser is also connected with a first expansion valve, the first expansion valve is sequentially connected with a condensation evaporator and a high-pressure stage compressor, and the high-pressure stage compressor is communicated with the condenser.

The conventional cascade refrigeration system consists of a high-temperature-stage refrigeration system and a low-temperature-stage refrigeration system, namely a low-temperature-stage refrigeration cycle consisting of a low-pressure-stage compressor, a condensing evaporator, a low-pressure-stage expansion valve and an evaporator and a high-temperature-stage refrigeration cycle consisting of a high-pressure-stage compressor, a condenser, a first expansion valve and a condensing evaporator. On the basis, the invention provides a method for providing supercooling through high-temperature stage circulation so as to improve the supercooling degree of refrigerant liquid from a condensation evaporator in low-temperature circulation, thereby improving the refrigerating capacity of unit refrigerant flow of the low-temperature stage circulation and improving the total coefficient of performance (COP) of the system.

Furthermore, one path of outlet of the subcooler is sequentially connected with the low-pressure stage expansion valve, the evaporator, the low-pressure stage compressor and the condensation evaporator, and then is connected into one path of inlet of the subcooler to form circulation.

Further, the refrigerant of the ejector enters the gas-liquid separator, the gas separated from the gas-liquid separator enters the high-pressure stage compressor for compression, and the liquid flows through the second expansion valve and enters the subcooler.

The supercooling method of the refrigeration cycle system specifically comprises the following steps: refrigerant liquid at the outlet of the condenser is divided into two paths, wherein one path of refrigerant liquid enters the condensation evaporator through the first expansion valve and is evaporated into gas, and then enters the high-pressure stage compressor to complete one path of refrigeration cycle; the other path of the refrigerant enters the ejector to be mixed with the refrigerant flowing through the subcooler and then enters the gas-liquid separator, the gas at the outlet of the gas-liquid separator enters the high-pressure stage compressor to be compressed, and the liquid flows through the second expansion valve and enters the subcooler to complete the other path of refrigeration cycle.

The invention has the beneficial effects that:

(1) the invention can improve the efficiency of the cascade refrigeration cycle system by providing a circulation and supercooling method which uses the ejector in the cascade refrigeration system; the scheme of adopting the ejector can realize effective supercooling of low-temperature-level circulation, improve the coefficient of performance of the system, and the added ejector is a static part and has reliable performance.

(2) The refrigeration cycle system provided by the invention can improve the supercooling degree, reduce the total power consumption of the system and obviously improve the COP and COP of the systemEfficiency.

(3) The refrigeration cycle system provided by the invention can effectively reduce the exhaust temperature of the high-temperature compressor and improve NH₃Excessive compressor discharge temperature.

Drawings

FIG. 1 is a schematic view of a refrigeration cycle system provided by the present invention;

FIG. 2 is a pressure-enthalpy diagram of the operation of the refrigeration cycle system provided by the present invention;

in the above figures, 1, a low-pressure stage compressor; 2. a condensing evaporator; 3. a subcooler; 4. a low-pressure stage expansion valve; 5. an evaporator; 6. a high pressure stage compressor; 7. a condenser; 8. a first expansion valve; 9. an ejector; 9a, an injector nozzle; 9b, an injector mixing chamber; 9c, ejector plenum; 10. a gas-liquid separator; 11. a second expansion valve.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

For a further understanding of the invention, reference will now be made to the following description taken in conjunction with the accompanying drawings and examples.

As shown in fig. 1, the present embodiment relates to a cascade refrigeration cycle system coupled to an ejector, which includes a condenser 7, an outlet of the condenser 7 is respectively connected to a first expansion valve 8 and an ejector 9, the first expansion valve 8 is sequentially communicated with a condensation evaporator 2 and a high-pressure stage compressor 6, and then returns to the condenser 7 to form a circulation. The refrigeration cycle system also comprises a subcooler 3, wherein the subcooler 3 is sequentially connected with a low-pressure stage expansion valve 4, an evaporator 5, a low-pressure stage compressor 1 and a condensation evaporator 2, and then is connected into one inlet of the subcooler 3 to form circulation.

In one circulation, the subcooler 3 and the condenser 7 are both connected with the ejector 9, the outlet of the ejector 9 is sequentially connected with the gas-liquid separator 10 and the second expansion valve 11, one end of the second expansion valve 11 is connected with the gas-liquid separator 10, and the other end is communicated with the inlet of the subcooler 3. The refrigerant of the ejector 9 enters the gas-liquid separator 10 to be subjected to gas-liquid separation, the gas separated from the gas-liquid separator 10 enters the high-pressure stage compressor 6 to be compressed, and the liquid flows through the second expansion valve 11 to enter the subcooler 3.

The supercooling method of the cascade refrigeration cycle system coupled with the ejector specifically comprises the following steps: the refrigerant liquid from the condenser 7 is divided into two paths, one path of the refrigerant liquid enters the condensation evaporator 2 after being throttled by the first expansion valve 8 and is evaporated into gas, and then enters the high-pressure stage compressor 6; the other path of the mixed refrigerant enters the ejector 9 to be mixed with the high-temperature-stage refrigerant flowing through the subcooler 3 and then enters the gas-liquid separator 10, the gas enters the high-pressure-stage compressor 6 to be compressed, and the liquid flows through the second expansion valve 11 to enter the subcooler 3. The low-temperature refrigerant which is circulated out of the condensing evaporator 2 in the low-temperature stage is further cooled by the arrangement of the subcooler 3, namely, the subcooling degree of the low-temperature stage circulation is improved, and the system performance is improved. The pressure after passing through the second expansion valve 11 is lower than the pressure after passing through the first expansion valve 8, that is, for the high-temperature stage cycle, the evaporation temperature after passing through the second expansion valve 11 is lower than the evaporation temperature after passing through the first expansion valve 8, so as to ensure that the low temperature is used for cooling the low-pressure stage refrigerant, so that the refrigerant is subcooled.

That is, for the high temperature stage, the two-way throttling by the first expansion valve 8 and the second expansion valve 11 has provided different evaporation temperatures, the circuit passing through the first expansion valve 8 and the condensing evaporator 2 is mainly used for cooling the low temperature stage refrigerant gas into refrigerant liquid, and the circuit passing through the second expansion valve 11, the subcooler 3 and the ejector 9 is mainly used for providing subcooling for the low temperature stage circulation.

Example 1

In a specific embodiment, in the high-temperature stage, the saturated refrigerant liquid coming out of the condenser 7 is divided into two paths, one path of the saturated refrigerant liquid is throttled by the first expansion valve 8 and then enters the condensation evaporator 2 to be evaporated and absorb heat to be saturated refrigerant gas, so that the low-temperature stage refrigerant gas is condensed to be saturated refrigerant liquid, and then the saturated refrigerant gas enters the high-pressure stage compressor 6 to complete the cycle.

The other path of the refrigerant enters the ejector 9, is throttled and decompressed at an ejector nozzle 9a, is mixed with the saturated liquid refrigerant passing through the subcooler 3, is decompressed, then enters the gas-liquid separator 10, the saturated refrigerant gas coming out of the gas-liquid separator 10 enters the high-pressure stage compressor 6 for compression, and the saturated refrigerant liquid enters the subcooler 3 after passing through the second expansion valve 11 for throttling and decompression, is evaporated and absorbs heat to enable the low-temperature stage refrigerant liquid to be subcooled.

Refrigerant gas from the low-pressure stage compressor 1 at the low-temperature stage is condensed into saturated liquid by the condensing evaporator 2, then is changed into supercooled liquid by the cooler 3, and enters the evaporator 5 to evaporate and absorb heat after being throttled by the low-pressure stage expansion valve 4 to finish refrigeration.

Fig. 2 shows a pressure-enthalpy diagram of the refrigeration cycle system of the present invention, and 9a, 9b, and 9c respectively show a nozzle, a mixing chamber, and a pressure-expanding chamber of the ejector 9.

When calculating, the high-temperature stage condensation temperature is 35 ℃, the low-temperature stage condensation temperature is within the range of minus 55 ℃ to minus 35 ℃, the temperature difference delta T of the condensation evaporator 2 is 5 ℃, the supercooling degree is 2 ℃ to 10 ℃, the refrigerating capacity of the system is 100kW, the efficiency of the ejector nozzle 9a is 0.8, the mixing efficiency is 0.95, and the diffusion efficiency is 0.8.

As can be seen from the above table, the COP of the conventional cascade refrigeration system and the injection cascade refrigeration cycle system provided by the present invention and having the supercooling degree of 10 ℃ and 15 ℃ is calculated_MAXThe comparison shows that the COP increasing amplitudes of the refrigeration cycle system provided by the invention are respectively4.1 percent and 5.4 percent, and the effect is obvious.

Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that various changes, modifications and substitutions can be made without departing from the spirit and scope of the present invention. Any modification, equivalent replacement, or modification made within the spirit and principle of the present invention should be included in the protection scope of the present invention.