An ejector-type cascade refrigeration cycle system suitable for air liquefaction

Abstract

The application discloses an ejector type cascade refrigeration cycle system suitable for air liquefaction, which mainly comprises a compressor, a condenser, a regenerative heat exchanger, an expansion valve, a three-way control valve, a sight glass, a medium-temperature evaporator, a low-temperature evaporator and an ejector and the like. The outlet of the compressor is connected with the inlet of the condenser, the outlet of the condenser exchanges heat with the output of the ejector through the regenerative heat exchanger, and then passes through the first-stage expansion valve, and then is divided into two streams through the three-way control valve, one stream enters the high-pressure inlet of the ejector after passing through the medium-temperature evaporator, and the other stream passes through the second-stage expansion valve and the sight glass and then passes through the low-temperature evaporator, and then returns to the low-pressure suction inlet of the ejector, and the outlet of the ejector returns to the compressor through the regenerative heat exchanger, the pressure energy in the decompression is recovered to drive the second-stage refrigeration cycle by using the suction effect of the ejector, and two-stage cooling of air is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of new energy storage and refrigeration technology, more particularly, to an ejector type cascade refrigeration cycle system suitable for air liquefaction. BACKGROUND

[0002] In recent years, with the increasingly prominent traditional energy crisis and the growing voice of reducing carbon emissions, new energy storage concepts have developed rapidly, which use new working fluids, technical principles or equipment to efficiently convert, store and use energy. One important application direction includes liquefied air energy storage, which requires a low-temperature environment provided by a refrigeration cycle to liquefy air.

[0003] Traditional refrigeration cycles mainly include basic processes such as compression, condensation, throttling and evaporation. When the temperature to be achieved is not too low, a single-stage cycle can meet the working requirements. However, when an extremely low temperature environment needs to be built and gas needs to be deeply cooled and liquefied, it is difficult to achieve this through a single-stage refrigeration cycle. One design idea is to use a cascade refrigeration method to cool the cooled substance using a multi-stage refrigeration cycle, which can further improve the refrigeration efficiency while reducing the cooling difficulty. The throttling energy loss in the commonly used throttling valve in traditional refrigeration schemes is large, and an expander is often used instead in large-scale gas liquefaction systems, which has higher refrigeration efficiency and is more suitable for large-scale centralized energy storage. However, the device is large in size and complex in structure, which has certain limitations. For small and medium-sized distributed energy storage liquefaction work requirements, it is necessary to consider how to improve the working effect of cascade refrigeration, improve the energy efficiency characteristics, and use small and efficient devices to reduce energy loss. SUMMARY

[0004] Therefore, the present application provides an ejector type cascade refrigeration cycle system suitable for air liquefaction, which is suitable for small and medium-sized distributed liquefaction energy storage requirements, and the specific technical scheme is as follows:

[0005] An ejector type cascade refrigeration cycle system suitable for air liquefaction is composed of a compressor, a condenser, a regenerative heat exchanger, a first-stage expansion valve, a three-way control valve, a second-stage expansion valve, a sight glass, a medium-temperature evaporator, a low-temperature evaporator and an ejector, which constitutes a first-stage refrigeration cycle and a second-stage refrigeration cycle, and sequentially cools air through the medium-temperature evaporator and the low-temperature evaporator.

[0006] The first-stage refrigeration cycle is sequentially connected by a compressor, a condenser, a regenerative heat exchanger, a first-stage expansion valve, a three-way control valve, a medium-temperature evaporator and an ejector, the outlet of the compressor is connected with the inlet of the condenser, the outlet of the condenser is connected with the hot end inlet of the regenerative heat exchanger, the cold end inlet of the regenerative heat exchanger is connected with the medium-pressure outlet of the ejector, the cold end and the hot end working medium exchange heat in the regenerative heat exchanger, the hot end outlet of the regenerative heat exchanger is connected with the inlet of the first-stage expansion valve, the cold end outlet of the regenerative heat exchanger is connected with the inlet of the compressor, the outlet of the first-stage expansion valve is connected with the inlet of the three-way control valve, the left outlet of the three-way control valve is connected with the cold end inlet of the medium-temperature evaporator, and the cold end outlet of the medium-temperature evaporator is connected with the high-pressure inlet of the ejector;

[0007] The second-stage refrigeration cycle is composed of the three-way control valve, a second-stage expansion valve, a sight glass, a low-temperature evaporator and the ejector, the right outlet of the three-way control valve is connected with the inlet of the second-stage expansion valve, the outlet of the second-stage expansion valve is connected with the inlet of the sight glass, the outlet of the sight glass is connected with the cold end inlet of the low-temperature evaporator, and the cold end outlet of the low-temperature evaporator is connected with the low-pressure inlet of the ejector.

[0008] Compared with the traditional refrigeration system, the present application uses the ejector and the expansion valve to realize the refrigeration in different temperature zones, recovers the pressure energy in the refrigerant by using the ejector, simplifies the equipment structure, improves the control flexibility of the refrigeration temperature and optimizes the energy consumption level of the system.

[0009] Preferably, the ejector has three interfaces, i.e., a high-pressure inlet, a low-pressure inlet and a medium-pressure outlet, the fluid entering the high-pressure inlet mixes with the fluid at the low-pressure inlet after being injected by the high-pressure inlet and then flows out from the medium-pressure outlet.

[0010] The present application discloses an ejector type staged refrigeration cycle system suitable for air liquefaction, which mainly comprises a compressor, a condenser, a regenerative heat exchanger, an expansion valve, a three-way control valve, a sight glass, a medium-temperature evaporator, a low-temperature evaporator and an ejector. BRIEF DESCRIPTION OF DRAWINGS

[0011] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only constitute a part of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained based on the provided drawings without creative labor.

[0012] Figure 1 A schematic diagram of an ejector-type cascade refrigeration cycle system suitable for air liquefaction.

[0013] Reference signs:

[0014] 1-compressor, 2-condenser, 3-heat recovery heat exchanger, 4-first stage expansion valve, 5-three-way control valve, 6-second stage expansion valve, 7-liquid level indicator, 8-medium temperature evaporator, 9-low temperature evaporator, 10-ejector. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments only constitute a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0016] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0017] Embodiment:

[0018] As shown in the drawings, Figure 1 The present application provides an ejector-type cascade refrigeration cycle system suitable for air liquefaction, which is composed of a compressor 1, a condenser 2, a heat recovery heat exchanger 3, a first stage expansion valve 4, a three-way control valve 5, a second stage expansion valve 6, a liquid level indicator 7, a medium temperature evaporator 8, a low temperature evaporator 9 and an ejector 10, which constitutes a first stage refrigeration cycle and a second stage refrigeration cycle, and sequentially cools air through the medium temperature evaporator 8 and the low temperature evaporator 9. Among them, Figure 1 The thick line represents the air flow path, and the other lines represent the refrigeration flow path.

[0019] Specifically,

[0020] The first stage refrigeration cycle is formed by compressor 1, condenser 2, regenerative heat exchanger 3, first stage expansion valve 4, three-way control valve 5, medium-temperature evaporator 8 and ejector 10 connected in sequence, the outlet of compressor 1 is connected with the inlet of condenser 2, the outlet of condenser 2 is connected with the hot end inlet of regenerative heat exchanger 3, the cold end inlet of regenerative heat exchanger 3 is connected with the medium-pressure outlet of ejector 10, the cold end and hot end working medium exchange heat in regenerative heat exchanger 3, the hot end outlet of regenerative heat exchanger 3 is connected with the inlet of first stage expansion valve 4, the cold end outlet of regenerative heat exchanger 3 is connected with the inlet of compressor 1, the outlet of first stage expansion valve 4 is connected with the inlet of three-way control valve 5, the left outlet of three-way control valve 5 is connected with the cold end inlet of medium-temperature evaporator 8, the cold end outlet of medium-temperature evaporator 8 is connected with the high-pressure inlet of ejector 10;

[0021] The second stage refrigeration cycle is formed by three-way control valve 5, second stage expansion valve 6, sight glass 7, low-temperature evaporator 9 and ejector 10, the right outlet of three-way control valve 5 is connected with the inlet of second stage expansion valve 6, the outlet of second stage expansion valve 6 is connected with the inlet of sight glass 7, the outlet of sight glass 7 is connected with the cold end inlet of low-temperature evaporator 9, the cold end outlet of low-temperature evaporator 9 is connected with the low-pressure inlet of ejector 10.

[0022] Ejector 10 has three interfaces, a high-pressure inlet, a low-pressure inlet and a medium-pressure outlet, the low-pressure inlet is a low-pressure entraining inlet, the fluid entering the high-pressure inlet entrains and mixes with the fluid at the low-pressure inlet, and then flows out from the medium-pressure outlet.

[0023] When the system is running, the gaseous refrigerant compressed by compressor 1 becomes high-temperature and high-pressure state, is preliminarily cooled by condenser 2, and then further exchanges heat with the low-temperature refrigerant from the output of ejector 10 in regenerative heat exchanger 3. The cooled refrigerant is throttled and expanded by first stage expansion valve 4, and the pressure and temperature are significantly reduced, and then is divided into two paths by three-way control valve 5, one path is output from the left side to cool the input air to be cooled by medium-temperature heat exchanger 8, and the refrigerant output from medium-temperature heat exchanger 8 enters the high-pressure inlet of ejector 10; the other path is output from the right side to be throttled and expanded by second stage expansion valve 6 to reach a lower temperature and pressure, at this time the refrigerant has entered the gas-liquid two-phase mixed state, sight glass 7 can observe the liquid content in the refrigerant channel, and this branch further exchanges heat with the cooled air output from medium-temperature evaporator 8 by low-temperature evaporator 9 to cool it to a lower temperature, and then the refrigerant output from low-temperature evaporator 9 enters the low-pressure inlet of ejector 10, is entrained and mixed with the refrigerant of the high-pressure inlet after being output, and then is heated in regenerative heat exchanger 3 to return to compressor 1 to complete a complete working cycle.

[0024] The various embodiments described in this specification are presented for the purpose of illustration and description. Each of the embodiments described in this specification is presented as one or more exemplary embodiments. The various embodiments described in this specification can be combined with each other in any manner. Each of the embodiments described in this specification can be combined with other embodiments disclosed in the specification in any manner. The same or similar elements in the various embodiments are denoted by the same or similar reference numerals.

[0025] The above description of disclosed embodiments is intended to be illustrative and not restrictive. Many modifications and variations to the described embodiments will be apparent to those skilled in the art from this disclosure. The scope of the invention should be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and patents are incorporated herein by reference in their entirety.

Claims

1. An ejector staged refrigeration cycle system suitable for air liquefaction, characterized by, The first stage refrigeration cycle is composed of the compressor (1), the condenser (2), the regenerative heat exchanger (3), the first stage expansion valve (4), the three-way control valve (5), the medium temperature evaporator (8) and the ejector (10) connected in sequence, the outlet of the compressor (1) is connected with the inlet of the condenser (2), the outlet of the condenser (2) is connected with the hot end inlet of the regenerative heat exchanger (3), the cold end inlet of the regenerative heat exchanger (3) is connected with the medium pressure outlet of the ejector (10), the working medium in the cold end and the hot end exchanges heat in the regenerative heat exchanger (3), the hot end outlet of the regenerative heat exchanger (3) is connected with the inlet of the first stage expansion valve (4), the cold end outlet of the regenerative heat exchanger (3) is connected with the inlet of the compressor (1), the outlet of the first stage expansion valve (4) is connected with the inlet of the three-way control valve (5), the left outlet of the three-way control valve (5) is connected with the cold end inlet of the medium temperature evaporator (8), the cold end outlet of the medium temperature evaporator (8) is connected with the high pressure inlet of the ejector (10). The second stage refrigeration cycle is composed of the three-way control valve (5), the second stage expansion valve (6), the sight glass (7), the low temperature evaporator (9) and the ejector (10), the right outlet of the three-way control valve (5) is connected with the inlet of the second stage expansion valve (6), the outlet of the second stage expansion valve (6) is connected with the inlet of the sight glass (7), the outlet of the sight glass (7) is connected with the cold end inlet of the low temperature evaporator (9), the cold end outlet of the low temperature evaporator (9) is connected with the low pressure inlet of the ejector (10). The ejector (10) has three interfaces, a high pressure inlet, a low pressure inlet and a medium pressure outlet, the fluid entering the high pressure inlet mixes with the fluid at the low pressure inlet after being injected, and then flows out from the medium pressure outlet.

2. A system according to claim 1, wherein, ​

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