CN108759138A - The operation method and system of not exclusively cooling refrigeration system among second throttle - Google Patents

Abstract

The invention discloses an operation method and system of a secondary throttling intermediate incomplete cooling refrigeration system, and aims to provide a method and system for defrosting a low-temperature evaporator by using a heat pump cycle of a low-pressure compressor. There are medium-temperature evaporators and low-temperature evaporators in each low-pressure stage unit, the medium-temperature evaporator is used to realize medium-temperature refrigeration, and the low-temperature evaporator is used to realize low-temperature refrigeration or defrosting. When there is a low-temperature evaporator that needs to be defrosted, the low-pressure stage compressor that realizes the defrosting function is converted into a high-pressure stage compressor through valve switching, and the low-temperature compressor in the low-pressure stage unit that realizes the defrosting function absorbs energy from the cooling function. The medium-pressure superheated steam of the low-pressure stage compressor is compressed and condensed to heat the low-temperature evaporator to be defrosted to achieve defrosting. The invention adopts the heat pump cycle of the low-pressure compressor to defrost the low-temperature evaporator, has small temperature fluctuation, high defrosting efficiency, and can provide cooling capacity between the refrigerating room and the freezing room.

Description

Operation method and system of secondary throttling intermediate incomplete cooling refrigeration system

technical field

The present invention relates to the technical field of refrigeration, and more specifically relates to an operation method and refrigeration system of a secondary throttling intermediate incomplete cooling refrigeration system with a medium temperature evaporator and adopting heat pump defrosting.

Background technique

In cold storage, when the cooling surface of the heat exchanger is covered by frost, if it is not removed in time, the accumulated frost will reduce the suction temperature of the compressor, increase the exhaust temperature, block the air passage, reduce the heat transfer area, and reduce the air flow rate. The flow resistance increases significantly, the heat transfer efficiency decreases sharply, and the operating performance of the refrigeration device decreases. The quality of the defrosting effect is also the key to give full play to the equipment capacity of the cold storage, reduce the cost of overhaul, save electricity and ensure the quality of food.

The existing defrosting methods for evaporators in cold storage mainly include: electric heating method, water spraying method, reverse cycle defrosting method, etc. Among them, the electric heating method and the water spraying method are used to defrost the frost layer by external heating, and the frost melts from the outside to the inside, so the heat of defrosting is actually much larger than the theoretical value. It has many functions and high operating cost. Considering safety, stability and energy saving, it is rarely used now. The heat of the reverse cycle defrosting method comes from the outdoor environment and the power consumption of the compressor. By changing the connection mode of the four-way reversing valve, the flow direction of the working medium in the entire refrigeration system is temporarily changed, and then the heat transfer direction is changed, so that the evaporator It is converted into a condenser to heat the evaporator to achieve the defrosting effect, but at this time the refrigeration cycle stops during defrosting, and all evaporators cannot continue to cool. The reverse cycle defrosting method has high defrosting efficiency, energy saving and reliability. However, this defrosting method is only suitable for a single-stage compression refrigeration system with a simple structure. The entire refrigeration system runs in reverse, and all evaporators in the cold storage are switched to condensers. Due to the large temperature difference between the surface temperature of the evaporator and the temperature inside the cold storage, the defrosting time is long, and the temperature fluctuations in the cold storage are large, which will cause food dryness. Consumption, resulting in economic losses. Therefore, orderly and efficient defrosting of the evaporator is necessary for the two-stage compression system to maintain high-efficiency operation.

At present, the effective defrosting method in the two-stage compression refrigeration system is the single-stage compression heat pump cycle method, that is, in the original two-stage compression refrigeration system, the pipeline connecting the inlet and outlet of the evaporator is divided into a refrigeration branch and a defrosting branch. The defrosting pipeline at the inlet of the evaporator is connected to the exhaust end of the high-pressure compressor or the low-pressure compressor, and the outlet of the evaporator is connected to a gas-liquid separator with a large volume. When the evaporator needs cooling, the cooling branch is connected to the evaporator by switching the valve, and the evaporator is cooled. When the evaporator needs defrosting, the defrosting branch is connected to the evaporator by switching the valve to defrost the evaporator. Since this defrosting method runs a single-stage compression heat pump cycle during defrosting, when the two-stage compression refrigeration cycle is converted to a single-stage compression heat pump defrosting cycle, the pressure difference of the compressors participating in the single-stage compression heat pump cycle defrosting increases greatly. It will cause impact on the compressor and damage the compressor, and the temperature of the working medium entering the evaporator for this single-stage compression heat pump defrosting cycle is low, the defrosting speed is slow, and the time for heat diffusion around the evaporator is long, resulting in a high defrosting efficiency. In addition, when defrosting the evaporator, a large amount of liquid working fluid condensed by the evaporator flows into the gas-liquid separator. After long-term accumulation, these liquid working fluids are easily sucked by the low-pressure stage compressor, forming a wet compression of the compressor. Cause compressor damage, resulting in economic losses.

In addition, the existing cold storage generally can only achieve a single cooling temperature, and provides the cooling capacity of the cold storage room or the freezing room according to the needs of use, which is inconvenient to use.

Contents of the invention

The purpose of the present invention is to aim at the technical defects existing in the prior art, and to provide a low-pressure stage compressor heat pump cycle to defrost the gear of the low-temperature evaporator, avoid temperature fluctuations, have high defrosting efficiency, and can improve the stability of the compressor. The operation method of the secondary throttling intermediate incomplete cooling refrigeration system.

Another object of the present invention is to provide a two-stage compression refrigeration system with high defrosting efficiency, small temperature fluctuation, stable operation, and at the same time, it can provide secondary throttling and incomplete cooling between the refrigeration room and the freezing room.

The technical scheme adopted for realizing the purpose of the present invention is:

An operation method of a secondary throttling intermediate incomplete cooling refrigeration system, in which a medium-temperature evaporator and a low-temperature evaporator are arranged in each low-pressure stage unit, the medium-temperature evaporator is used to realize medium-temperature refrigeration, and the low-temperature evaporator is used to realize low-temperature Refrigeration or defrosting, the operation method includes the following steps: when all low-pressure stage units realize the refrigeration function, the medium-temperature evaporator evaporates the medium-pressure saturated liquid working medium into medium-pressure saturated vapor to realize medium-temperature refrigeration; the low-temperature evaporator The evaporator evaporates the low-pressure liquid working medium into low-pressure steam to realize low-temperature refrigeration; when there is a low-temperature evaporator that needs defrosting, the low-pressure stage compressor that realizes the defrosting function is converted into a high-pressure stage compressor through valve switching to realize the defrosting function The low-temperature compressor in the low-pressure stage unit absorbs the medium-pressure superheated vapor from the low-pressure stage compressor of the low-pressure stage unit that realizes the refrigeration function, or absorbs the mixed hot gas from the intercooler and the low-pressure stage compressor that realizes the refrigeration function, and is compressed Finally, it is sent to the low-temperature evaporator to be defrosted, and the low-temperature evaporator is condensed and heated to realize defrosting, and the low-temperature evaporator in the low-pressure stage unit that realizes the cooling function still realizes the cooling function; after the defrosting is completed, the defrosting function is realized The low-pressure stage unit realizes the refrigeration function by switching the valve.

A secondary throttling intermediate incomplete cooling refrigeration system using heat pump defrosting to realize the above operation method, including a high-pressure stage compressor unit, a condenser, a first throttle valve, an intercooler, and multiple low-pressure stage units; each The low-pressure stage unit includes a low-pressure stage compressor, a first four-way reversing valve, a second throttle valve, a low-temperature evaporator, a medium-temperature evaporator, a first one-way valve, and a second one-way valve; the low-pressure stage compressor The suction end of the compressor is connected to the fourth interface of the first four-way reversing valve, the exhaust end of the low-pressure stage compressor is connected to the second interface of the first four-way reversing valve, and the first four-way reversing valve The third port of a four-way reversing valve is respectively connected to the inlet of the first one-way valve and the outlet of the second one-way valve, and the first port of the first four-way reversing valve passes through the cryogenic The evaporator is connected to the first interface of the second throttle valve; the first interfaces of the medium temperature evaporator are connected in parallel and connected to the air inlet of the intercooler, and the first interface of the second throttle valve The two ports and the second port of the medium temperature evaporator are connected in parallel to the liquid outlet of the intercooler, the outlet of the first one-way valve, the inlet of the second one-way valve and the The suction end of the high-pressure stage compressor unit is connected in parallel and connected to the air outlet of the intercooler; the exhaust end of the high-pressure stage compressor unit passes through the condenser, the first throttle valve and the intercooler. Inlet connection.

A secondary throttling intermediate incomplete cooling refrigeration system using heat pump defrosting to realize the above operation method, including a high-pressure stage compressor unit, a condenser, a first throttle valve, an intercooler, and multiple low-pressure stage units; each The low-pressure stage unit includes a low-pressure stage compressor, a first four-way reversing valve, a second four-way reversing valve, a second throttle valve, a low-temperature evaporator, a medium-temperature evaporator, a first one-way valve, and a second one-way valve. The suction end of the low-pressure stage compressor is connected to the fourth interface of the first four-way reversing valve, and the exhaust end of the low-pressure stage compressor is connected to the fourth port of the first four-way reversing valve. The second interface is connected, the third interface of the first four-way reversing valve is respectively connected with the inlet of the first one-way valve and the outlet of the second one-way valve, and the first four-way reversing valve The first port of the low-temperature evaporator is connected to the first port of the second throttle valve, and the second port of the second throttle valve is connected to the second port of the second four-way reversing valve The first interface of the medium temperature evaporator is connected in parallel with the air inlet of the intercooler, and the second interface of the medium temperature evaporator is connected with the third interface of the second four-way reversing valve , the first port and the fourth port of the second four-way reversing valve are connected in parallel to the liquid outlet of the intercooler; the outlet of the first one-way valve, the second one-way The inlet of the valve and the suction end of the high-pressure stage compressor unit are connected in parallel to the air outlet of the intercooler; the exhaust end of the high-pressure stage compressor unit passes through the condenser and the first throttle valve Connect with the liquid inlet of the intercooler.

A secondary throttling intermediate incomplete cooling refrigeration system using heat pump defrosting to realize the above operation method, including a high-pressure stage compressor unit, a condenser, a first throttle valve, an intercooler, a two-way valve, and multiple low-pressure stages unit; each of the low-pressure stage units includes a low-pressure stage compressor, a first four-way reversing valve, a second throttle valve, a low-temperature evaporator, a medium-temperature evaporator, a first one-way valve, and a second one-way valve; The suction end of the low-pressure stage compressor is connected to the fourth interface of the first four-way reversing valve, and the exhaust end of the low-pressure stage compressor is connected to the second interface of the first four-way reversing valve , the third port of the first four-way reversing valve is respectively connected to the inlet of the first one-way valve and the outlet of the second one-way valve, and the first port of the first four-way reversing valve The low-temperature evaporator is connected to the first port of the second throttle valve; the first port of the medium-temperature evaporator is connected in parallel to the air inlet of the intercooler, and the second throttle valve The second interface of the flow valve and the second interface of the medium temperature evaporator are connected in parallel to the liquid outlet of the intercooler, the outlet of the first check valve, the outlet of the second check valve The inlet and the suction end of the high-pressure stage compressor unit are connected in parallel and then connected to the gas outlet of the intercooler through the two-way valve; the exhaust end of the high-pressure stage compressor unit passes through the condenser, the first A throttling valve is connected with the liquid inlet of the intercooler.

A secondary throttling intermediate incomplete cooling refrigeration system using heat pump defrosting to realize the above operation method, including a high-pressure stage compressor unit, a condenser, a first throttle valve, an intercooler, a two-way valve, and multiple low-pressure stages unit; each of the low-pressure stage units includes a low-pressure stage compressor, a first four-way reversing valve, a second four-way reversing valve, a second throttle valve, a low-temperature evaporator, a medium-temperature evaporator, and a first one-way valve and the second one-way valve; the suction end of the low-pressure stage compressor is connected to the fourth interface of the first four-way reversing valve, and the exhaust end of the low-pressure stage compressor is connected to the first four-way The second interface of the reversing valve is connected, and the third interface of the first four-way reversing valve is respectively connected with the inlet of the first one-way valve and the outlet of the second one-way valve. The first port leading to the reversing valve is connected to the first port of the second throttle valve through the low-temperature evaporator, and the second port of the second throttle valve is connected to the second port of the second four-way reversing valve. The second interface is connected; the first interface of the medium temperature evaporator is connected in parallel to the air inlet of the intercooler, and the second interface of the medium temperature evaporator is connected to the second four-way reversing valve. The third interface is connected, and the first interface and the fourth interface of the second four-way reversing valve are connected in parallel to the liquid outlet of the intercooler; the outlet of the first one-way valve, the outlet of the The inlet of the second one-way valve and the suction end of the high-pressure stage compressor unit are connected together in parallel and then connected with the gas outlet of the intercooler through the two-way valve; the exhaust end of the high-pressure stage compressor unit is connected through the The condenser and the first throttle valve are connected to the liquid inlet of the intercooler.

The high-pressure stage compressor unit includes one or more high-pressure stage compressors, and the specific number is determined according to the operating conditions of the refrigeration system. When multiple high-pressure stage compressors are used, the suction port of each high-pressure stage compressor Parallel connection serves as the suction end of the high-pressure stage compressor unit, and the exhaust port of each of the high-pressure stage compressors is connected in parallel as the exhaust end of the high-pressure stage compressor unit.

The number of the low-voltage stage units is at least three.

Compared with prior art, the beneficial effect of the present invention is:

1. In the operation method of the refrigeration system of the present invention, the switching between the cooling mode and the defrosting mode of the low-pressure stage unit is realized by switching the valve. In the defrosting mode, the low-pressure stage compressor that realizes the defrosting function is converted into a high-pressure stage compressor to operate, and the low-temperature compressor in the low-pressure stage unit that realizes the defrosting function absorbs the medium-pressure superheat from the low-pressure stage compressor that realizes the cooling function Steam or mixed vapor from the intercooler and the refrigeration low-pressure stage compressor realizes the reverse cycle defrosting of the low-pressure stage unit. The cycle during defrosting and the cycle during refrigeration are both two-stage compression cycles, thereby forming a dynamic refrigeration system. The temperature fluctuation is small, the defrosting efficiency is high, and the energy is saved. At the same time, the compressor can run stably, which improves the service life of the system.

2. In the refrigeration system of the present invention, when there is a low-temperature evaporator in the low-pressure unit for defrosting, switching between the refrigeration and defrosting modes of the low-pressure unit is realized by switching the valve. In the defrosting mode, the low-pressure defrosting function is realized. The two-stage compressor is converted into a high-pressure compressor to run, and the defrosting cycle and the refrigeration cycle are two-stage compression cycles, thereby forming a dynamic refrigeration system, which is more flexible and convenient to use, high in defrosting efficiency, and saves energy.

3. In the refrigeration system of the present invention, when the evaporator in the low-pressure stage unit is defrosting, the low-pressure stage compressor is converted into a high-pressure stage compressor to operate, and the defrosting cycle of the low-pressure stage unit works between the intermediate pressure and high pressure. When the unit changes from a refrigeration cycle to a defrosting cycle, the pressure difference between the suction and discharge of the compressor in the low-pressure stage unit changes less, and the heat dissipation of the compressor is better, which is beneficial to protect the compressor and increase the service life of the compressor.

4. In the refrigeration system of the present invention, the heat source for the defrosting of the evaporator in the low-pressure stage unit is the input work of the evaporator and the compressor in the refrigeration low-pressure stage unit. The heat supply during defrosting is sufficient and unrestricted, and can be fully Defrost, the defrosting efficiency is higher, and it is more suitable for large-scale two-stage compression refrigeration systems.

5. In the refrigeration system of the present invention, the heat pump cycle of the low-pressure stage compressor is used to defrost the gear of the low-temperature evaporator. The lubricating oil of the compressor returns to the oil evenly, the wear degree of the high and low pressure compressors is even, the system is simple and the efficiency is high. Compared with the refrigeration system with a separate defrosting evaporator and a separate defrosting branch, the structure is simpler and the initial investment of the system is reduced.

6. The defrosting of the low-temperature evaporator in the refrigeration system of the present invention adopts the reverse cycle heat pump defrosting method, heating from the inside of the frost layer, and the frost is easy to fall off from the cooling surface, so the actual defrosting heat is much smaller than the theoretical value. At the same time, the frost layer melts from the inside to the outside, and no water vapor escapes to the outside of the evaporator at the initial stage of defrosting. Only when the frost melts and falls off, the heat on the rib tube radiates outward, but at this time the defrosting stage tends to end, so the heat exchange with the storage and surrounding enclosure structures is small, and the defrosting efficiency is relatively high.

7. In the refrigeration system of the present invention, the number of high-pressure stage compressors is not limited, and the number of low-pressure stage units is at least three. According to different working conditions and different cooling capacity requirements, high and low pressure stage variable flow cycles can be realized, matching out Optimal capacity ratio between high and low pressure stages.

8. The refrigerating system of the present invention can produce cooling capacity at two evaporation temperatures at the same time, and is especially suitable for use in a cold storage system to simultaneously provide cooling capacity for a refrigerated room and a freezing room.

9. In the refrigeration system of the present invention, when there is defrosting of the low-temperature evaporator of the low-pressure unit, the heat source for the defrosting of the low-temperature evaporator of the defrosting low-pressure unit is the medium-pressure superheated gas, that is, the middle and low pressure stage of the defrosting low-pressure unit The compressor directly sucks medium-pressure steam with high superheat from the exhaust end of the low-pressure stage compressor of the refrigeration low-pressure stage unit, and the high-pressure working medium discharged from the low-pressure stage compressor of the defrosting low-pressure stage unit has a higher temperature and enters the defrosting low-pressure stage unit The working fluid temperature of the low-temperature evaporator is higher, the defrosting effect is better, and the defrosting speed is faster.

Description of drawings

Fig. 1 shows the structural principle diagram of the non-flooded type of hot gas defrosting in Embodiment 1 of the present invention, which adopts heat pump defrosting, has a secondary throttling and incomplete cooling of a medium temperature evaporator, and a two-stage compression refrigeration system;

Fig. 2 is a structural schematic diagram of a two-stage compression refrigeration system with secondary throttling and incomplete cooling in the middle of a medium-temperature evaporator with a heat pump defrosting of a hot gas defrosting flooded type according to Embodiment 2 of the present invention;

Figure 3 shows the non-flooded type high-temperature hot gas defrosting in Example 3 of the present invention, using the high-temperature hot gas discharged from the low-pressure stage compressor to defrost, and having a medium-temperature evaporator with secondary throttling and intermediate incomplete cooling. Two-stage compression refrigeration Structural schematic diagram of the system;

Figure 4 shows the flooded type of high-temperature hot gas defrosting in Example 4 of the present invention, using the high-temperature hot gas discharged from the low-pressure stage compressor to defrost, and a two-stage compression refrigeration system with a medium-temperature evaporator, secondary throttling, and incomplete cooling in the middle Schematic diagram of the structure;

Figure 5 shows a schematic diagram of the intercooler interface.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

The key points of the design of the present invention are: a low-pressure stage compressor is connected with a low-temperature evaporator. When defrosting, the low-pressure stage compressor becomes a high-pressure stage compressor through valve switching, and the original high-pressure stage compressor is partially or completely shut down, so that The medium-pressure steam working medium is sucked by the low-pressure defrosting compressor, and the defrosting evaporator is converted into a two-stage compression condenser, which is defrosted one by one (or in groups). After defrosting, each evaporator is refrigerated by switching valves. Specific technical solutions such as:

In the operation method of the secondary throttling intermediate incomplete cooling refrigeration system of the present invention, a medium-temperature evaporator and a low-temperature evaporator are arranged in each low-pressure stage unit, the medium-temperature evaporator is used to realize medium-temperature refrigeration, and the low-temperature evaporator is used to realize Low-temperature refrigeration or defrosting, the operation method includes the following steps: when all low-pressure stage units realize the refrigeration function, the medium-temperature evaporator evaporates the medium-pressure saturated liquid working medium into medium-pressure saturated vapor to realize medium-temperature refrigeration; the low-temperature The evaporator evaporates the low-pressure liquid working medium into low-pressure steam to realize low-temperature refrigeration; when there is a low-temperature evaporator that needs defrosting, the low-pressure stage compressor that realizes the defrosting function is converted into a high-pressure stage compressor through valve switching to realize defrosting The low-temperature compressor in the low-pressure stage unit of the function absorbs the medium-pressure superheated vapor from the low-pressure stage compressor that realizes the refrigeration function, or absorbs the mixed hot gas from the intercooler and the low-pressure stage compressor that realizes the refrigeration function, and sends it into the The low-temperature evaporator to be defrosted is condensed and heated to realize defrosting, and the low-temperature evaporator in the low-pressure stage unit that realizes the cooling function still realizes the cooling function; after the defrosting is completed, the low-pressure stage unit that realizes the defrosting function passes through The valve is switched to realize the refrigeration function; when there are multiple low-temperature evaporators that need to be defrosted, the defrosting is realized through gear shifting.

In the present invention, the number of high-pressure stage compressors in the high-pressure stage compressor unit is one or more, and the number of low-pressure stage units is at least three. When the number of high-pressure stage compressors is one and the number of low-pressure stage units is three, the high-pressure stage compressors need to be shut down to achieve reverse cycle defrosting. The attached picture shows that the high-pressure stage compressor unit contains 2 high-pressure stage compressors and 4 low-pressure stage units. If both high-pressure stage compressors are shut down when one low-pressure stage unit is defrosting, the operating ratio of high and low pressure stage is 1: 3. If one high-pressure stage compressor runs and the other stops when a low-pressure stage unit is defrosting, the operating ratio of high and low pressure stages is 2:3. If there are 3 high-pressure stage compressors and 6 low-pressure stage units in the high-pressure stage compressor unit, during defrosting, there will be more types of high- and low-pressure stage operation ratios. During the defrosting process, whether the high-pressure stage compressor is shut down or partially shut down is determined according to the ratio of the high- and low-stage compressors, specific working conditions, and defrosting quality.

When the low-temperature evaporator 6-1 in the low-pressure stage unit needs to be defrosted, the original high-pressure stage compressor is partially or completely shut down, so that the medium-pressure vapor working medium is sucked by the low-pressure stage compressor for defrosting. When the low-temperature evaporator 6-1 in multiple low-pressure stage units needs to be defrosted, the gear defrosting method is adopted, that is, the low-temperature evaporator 6-1 in a defrosting low-pressure stage unit is immediately switched to refrigeration after defrosting. The low-pressure level unit defrosts the low-temperature evaporators 6-1 of other low-pressure level units, and defrosts the multiple low-temperature evaporators 6-1 one by one. After all the low-temperature evaporators 6-1 are defrosted, all The low-pressure stage unit is converted into a refrigeration low-pressure stage unit, and the high-pressure stage compressor 1-2 is turned on.

Operation method of the present invention can be realized by following refrigeration system:

The present invention adopts the heat pump defrosting secondary throttling intermediate incomplete cooling refrigeration system with a medium temperature evaporator. The state of medium pressure working fluid is divided into flooded liquid supply type and non-flooded liquid supply type. Among them, the dryness of the working fluid entering the low temperature evaporator and the medium temperature evaporator in the flooded liquid supply type system is low, the heat exchange efficiency is high, and the heat exchanger area required for the low temperature evaporator and the medium temperature evaporator is small. The system structure of the non-flooded liquid supply type is simple, with fewer components and lower cost.

In the refrigeration system with secondary throttling and incomplete cooling in the middle of the medium-temperature evaporator that adopts heat pump defrosting in the present invention, when there is a medium-low temperature evaporator in a low-pressure unit for defrosting, the low-pressure stage of the low-pressure unit is compressed by switching the valve. The machine sucks medium-pressure superheated steam from the intercooler, and can also suck medium-pressure superheated steam that is not cooled by the intercooler. When the medium-pressure superheated steam with a higher degree of superheat is sucked and not mixed with the medium-pressure saturated steam coming out of the cooling outlet of the intercooler, the medium-pressure superheated steam is sucked into and compressed by the low-pressure compressor of the defrosting low-pressure stage unit to discharge higher-temperature hot gas , the temperature of the working medium entering the low-temperature evaporator of the defrosting low-pressure stage unit is higher, the defrosting effect is better, and the defrosting speed is faster. When the low-temperature evaporators of all low-pressure units do not need defrosting, the high-pressure compressor sucks in the medium-pressure saturated vapor cooled by the intercooler through valve switching, and the medium-pressure saturated vapor is sucked and compressed by the high-pressure compressor to discharge hot gas The temperature is low, the condensation effect is good, and the refrigeration efficiency is high.

Divided into embodiment 1, 2 and embodiment 3, 4 according to the difference of the inhaled medium-pressure working medium. Wherein, embodiment 1 and embodiment 2 are the technical schemes of inhaling the medium-pressure superheated working medium flowing out from the refrigeration low-pressure stage unit and the medium-pressure saturated steam mixed steam coming out from the cooling outlet of the intercooler during defrosting, embodiment 3 and Embodiment 4 selects to inhale medium-pressure steam with a higher degree of superheat that is not mixed with the medium-pressure saturated steam from the cooling outlet of the intercooler by closing the two-way valve 8. The defrosting effect is better with mixed medium pressure steam.

Example 1

The structure schematic diagram of the non-full liquid type of hot gas defrosting adopting heat pump defrosting and secondary throttling intermediate incomplete cooling refrigeration system is shown in Figure 2, including high-pressure stage compressor unit, condenser 5, first throttle valve 4 -1. Intercooler 3 and multiple low-pressure stage units. In this embodiment, the high-pressure stage compressor unit includes one or more high-pressure stage compressors 1-2. When multiple high-pressure stage compressors are used, the suction port of each high-pressure stage compressor 1-2 Parallel connection is used as the suction end of the high-pressure stage compressor unit, and the exhaust port of each of the high-pressure stage compressors 1-2 is connected in parallel as the exhaust end of the high-pressure stage compressor unit. Each of the low-pressure stage units includes a low-pressure stage compressor 1-1, a first four-way reversing valve 2-1, a second throttle valve 4-2, a low-temperature evaporator 6-1, a medium-temperature evaporator 6-2, The first one-way valve 7-1 and the second one-way valve 7-2. The suction end of the low-pressure stage compressor 1-1 is connected to the fourth port of the first four-way reversing valve 2-1, and the exhaust end of the low-pressure stage compressor 1-1 is connected to the first port of the first four-way reversing valve 2-1. The second interface of the four-way reversing valve 2-1 is connected, and the third interface of the first four-way reversing valve 2-1 is respectively connected with the inlet of the first one-way valve 7-1 and the second one-way valve. connected to the outlet of the valve 7-2, and the first port of the first four-way reversing valve 2-1 is connected to the first port of the second throttle valve 4-2 via the low-temperature evaporator 6-1 ; The first interface of the medium temperature evaporator 6-2 is connected in parallel and connected with the air inlet 3-1 of the intercooler 3, the second interface of the second throttle valve 4-2 and the The second interface of the medium temperature evaporator 6-2 is connected in parallel with the liquid outlet 3-4 of the intercooler 3, the outlet of the first check valve 7-1, the outlet of the second check valve The inlet of 7-2 and the suction end of the high-pressure stage compressor unit are connected in parallel to the gas outlet 3-2 of the intercooler 3 . The exhaust end of the high-pressure stage compressor unit is connected to the liquid inlet 3-3 of the intercooler 3 via the condenser 5 and the first throttle valve 4-1.

The low-pressure stage unit can be used in a refrigeration cycle or a defrosting cycle. When used in a refrigeration cycle, it works in a low-pressure stage system with two-stage compression, that is, the low-temperature evaporator in the low-pressure stage unit is refrigerated, and is defined as a refrigeration low-pressure stage unit. When it is used in the defrosting cycle, it works in the high-pressure stage system with two-stage compression, that is, the low-temperature evaporator in the low-pressure stage unit defrosts, which is defined as the defrosting low-pressure stage unit.

When the low-temperature evaporator in the low-pressure stage unit does not need defrosting, all the low-pressure stage units are used for the refrigeration cycle, that is, all the low-pressure stage units are refrigeration low-pressure stage units. The first port of the first four-way reversing valve 2-1 in the refrigeration low-pressure stage unit is connected to the fourth port, and the second port is connected to the third port. The thermodynamic process of the secondary throttling intermediate incomplete cooling two-stage compression refrigeration cycle with a medium-temperature evaporator is as follows: the low-pressure stage compressor 1-1 in the refrigeration low-pressure stage unit passes through the first four-way reversing valve 2-1 from the Low-pressure steam is inhaled in the low-temperature evaporator 6-1, and the low-pressure steam becomes medium-pressure superheated steam after being compressed and boosted by the low-pressure stage compressor 1-1, and the steam passes through the first four-way reversing valve 2-1 and The first one-way valve 7-1 mixes with the saturated medium-pressure steam coming out of the gas outlet 3-2 of the intercooler 3, and the mixed medium-pressure superheated steam with a lower degree of superheat is inhaled by the high-pressure stage compressor unit, and the steam After being compressed and boosted by the high-pressure stage compressor 1-2 in the high-pressure stage compressor unit, it becomes high-pressure superheated steam, and then it is discharged into the condenser 5 to be condensed into a high-pressure liquid, and the high-pressure liquid passes through the first throttle valve 4 -1 throttling and decompression into medium-pressure wet vapor enters the intercooler 3 through the liquid inlet 3-3 of the intercooler 3 . A part of the medium-pressure liquid working fluid in the intercooler 3 evaporates and absorbs heat, cooling the medium-pressure superheated vapor coming in from the air inlet 3-1 of the intercooler 3 . The medium-pressure saturated liquid working medium coming out of the liquid outlet 3-4 of the intercooler 3 is divided into two paths, and one medium-pressure saturated liquid working medium enters the medium-temperature evaporator 6-2 to evaporate and absorb the medium-temperature cold storage heat, resulting in a medium-temperature refrigeration phenomenon, the medium-pressure saturated vapor from the medium-temperature evaporator 6-2 returns to the intercooler 3 through the air inlet 3-1 of the intercooler 3; The medium-pressure saturated liquid working fluid coming out of the liquid outlet 3-4 of the intercooler 3 is throttled and depressurized by the second throttle valve 4-2 to become a low-pressure wet vapor and enter the low-temperature evaporator 6-1 to evaporate. Absorb the heat in the low-temperature cold storage to generate low-temperature refrigeration, and the low-pressure steam coming out of the low-temperature evaporator 6-1 returns to the low-pressure stage compressor 1-1 through the first four-way reversing valve 2-1 The suction end completes a two-stage compression refrigeration cycle with a secondary throttling intermediate incomplete cooling with a medium temperature evaporator.

When there is a low-temperature evaporator in a low-pressure unit that needs to be defrosted, the corresponding low-pressure unit is a defrosting low-pressure unit, and the remaining low-pressure units are refrigeration low-pressure units. The first port of the first four-way reversing valve 2-1 in the defrosting low-pressure stage unit is connected to the second port, the third port is connected to the fourth port, and the first four-way reversing valve in the refrigeration low-pressure stage unit The first port of the valve 2-1 is connected to the fourth port, and the second port is connected to the third port. On the basis of the thermal process of the secondary throttling intermediate incomplete cooling two-stage compression refrigeration cycle with a medium temperature evaporator, the thermal process of defrosting the low-temperature evaporator in the defrosting low-pressure stage unit is as follows: from the air outlet 3 of the intercooler -2 The medium-pressure saturated steam mixed with the medium-pressure superheated steam discharged from the exhaust end of the low-pressure stage compressor in the low-pressure stage unit of the refrigeration unit becomes the medium-pressure superheated steam with a small superheated degree and is defrosted The low-pressure stage compressor 1-1 in the low-pressure stage unit is inhaled through the first four-way reversing valve 2-1 and the second one-way valve 7-2, and the vapor is compressed by the low-pressure stage compressor 1-1 After boosting, it becomes high-pressure superheated steam, which is discharged into the low-temperature evaporator 6-1 to be condensed, and the low-temperature evaporator 6-1 is heated to cause the defrosting phenomenon of the low-temperature evaporator 6-1, which is condensed into The high-pressure liquid working medium is throttled and depressurized by the second throttle valve 4-2 to become a medium-pressure wet vapor and mixed with the medium-pressure liquid coming out of the liquid outlet 3-4 of the intercooler 3 to form a wet vapor Entering the medium temperature evaporator 6-2 and the second throttle valve 4-2 in the refrigeration low-pressure stage unit, and completing the secondary throttling intermediate of the medium temperature evaporator using the low-pressure stage compressor heat pump cycle defrosting is incomplete Cooling two-stage compression refrigeration cycle.

Example 2

The structural diagram of the flooded type of hot gas defrosting adopting heat pump defrosting secondary throttling intermediate incomplete cooling refrigeration system is shown in Figure 2, including high-pressure stage compressor unit, condenser 5, first throttle valve 4- 1. Intercooler 3 and multiple low-pressure stage units. In this embodiment, the high-pressure stage compressor unit includes one or more high-pressure stage compressors 1-2. When multiple high-pressure stage compressors 1-2 are used, each of the high-pressure stage compressors 1-2 The suction port is connected in parallel as the suction end of the high-pressure stage compressor unit, and the exhaust port of each of the high-pressure stage compressors 1-2 is connected in parallel as the exhaust end of the high-pressure stage compressor unit. Each of the low-pressure stage units includes a low-pressure stage compressor 1-1, a first four-way reversing valve 2-1, a second four-way reversing valve 2-2, a second throttle valve 4-2, and a low-temperature evaporator 6-1. Medium temperature evaporator 6-2, first one-way valve 7-1 and second one-way valve 7-2. The suction end of the low-pressure stage compressor 1-1 is connected to the fourth port of the first four-way reversing valve 2-1, and the exhaust end of the low-pressure stage compressor 1-1 is connected to the first port of the first four-way reversing valve 2-1. The second interface of the four-way reversing valve 2-1 is connected, and the third interface of the first four-way reversing valve 2-1 is respectively connected with the inlet of the first one-way valve 7-1 and the second one-way valve. connected to the outlet of the valve 7-2, and the first port of the first four-way reversing valve 2-1 is connected to the first port of the second throttle valve 4-2 via the low-temperature evaporator 6-1 , the second port of the second throttle valve 4-2 is connected to the second port of the second four-way reversing valve 2-2; the first port of the medium temperature evaporator 6-2 is connected in parallel It is connected with the air inlet 3-1 of the intercooler 3, the second interface of the medium temperature evaporator 6-2 is connected with the third interface of the second four-way reversing valve 2-2, and the first The first port and the fourth port of the two-way reversing valve 2-2 are connected in parallel to the liquid outlet 3-4 of the intercooler 3; the outlet of the first one-way valve 7-1, The inlet of the second one-way valve 7-2 and the suction end of the high-pressure stage compressor unit are connected in parallel to the air outlet 3-2 of the intercooler 3; the exhaust port of the high-pressure stage compressor unit The gas end is connected to the liquid inlet 3-3 of the intercooler 3 via the condenser 5 and the first throttle valve 4-1.

The low-pressure stage unit can be used in a refrigeration cycle or a defrosting cycle. When used in a refrigeration cycle, it works in a low-pressure stage system with two-stage compression, that is, the low-temperature evaporator in the low-pressure stage unit is refrigerated, and is defined as a refrigeration low-pressure stage unit. When it is used in the defrosting cycle, it works in the high-pressure stage system with two-stage compression, that is, the low-temperature evaporator in the low-pressure stage unit defrosts, which is defined as the defrosting low-pressure stage unit.

When the low-temperature evaporator in the low-pressure stage unit does not need defrosting, all the low-pressure stage units are used for the refrigeration cycle, that is, all the low-pressure stage units are refrigeration low-pressure stage units. The first port of the first four-way reversing valve 2-1 in the refrigeration low-pressure unit is connected to the fourth port, the second port is connected to the third port, and the second port of the second four-way reversing valve 2-2 One interface is connected with the second interface, and the third interface is connected with the fourth interface. The thermodynamic process of the two-stage compression refrigeration cycle with secondary throttling and intermediate incomplete cooling with a medium-temperature evaporator 6-2 is as follows: the low-pressure stage compressor 1-1 of the refrigeration low-pressure stage unit passes through the first four-way reversing valve 2-1 The low-pressure steam is inhaled from the low-temperature evaporator 6-1, and the first steam is compressed and boosted by the low-pressure stage compressor 1-1 to become a medium-pressure superheated steam, and the medium-pressure superheated steam is passed through the first four-way exchange The direction valve 2-1 and the first one-way valve 7-1 are mixed with the saturated medium-pressure steam coming out from the gas outlet 3-2 of the intercooler 3; The suction end of the high-pressure compressor unit is inhaled, and the medium-pressure superheated steam is compressed and boosted by the high-pressure compressor 1-2 in the high-pressure compressor unit to become high-pressure superheated steam and then discharged into the condenser 5 for condensation It is a high-pressure liquid; the high-pressure liquid flowing out from the condenser 5 is throttled and depressurized by the first throttle valve 4-1 to become a medium-pressure wet vapor through the liquid inlet 3-3 of the intercooler 3 and enters the Intercooler 3. A part of the medium-pressure liquid working fluid in the intercooler 3 evaporates and absorbs heat, cooling the medium-pressure superheated vapor coming in from the air inlet 3-1 of the intercooler 3 . The medium-pressure saturated liquid working medium coming out of the liquid outlet 3-4 of the intercooler 3 is divided into two paths, one medium-pressure saturated liquid working medium enters the medium-temperature evaporator 6 through the second four-way reversing valve 2-2 -2 to evaporate, absorb the heat in the medium-temperature cold storage, and produce medium-temperature refrigeration phenomenon, and the medium-pressure saturated vapor from the medium-temperature evaporator 6-2 returns to the Intercooler 3; the medium-pressure saturated liquid working fluid coming out of the liquid outlet 3-4 of the other part of the intercooler 3 passes through the second four-way reversing valve 2-2 and the second throttle valve 4-2 The low-pressure steam enters the low-temperature evaporator 6-1 to evaporate, absorbs the heat in the low-temperature cold storage, and produces low-temperature refrigeration. The low-pressure steam coming out of the low-temperature evaporator 6-1 passes through the first A four-way reversing valve 2-1 returns to the suction end of the low-pressure stage compressor 1-1 to complete a two-stage compression refrigeration cycle with secondary throttling and intermediate incomplete cooling with a medium-temperature evaporator.

When there is a low-temperature evaporator in a low-pressure unit that needs to be defrosted, the corresponding low-pressure unit is a defrosting low-pressure unit, and the remaining low-pressure units are refrigeration low-pressure units. The first port of the first four-way reversing valve 2-1 in the defrosting low-pressure stage unit is connected to the second port, the third port is connected to the fourth port, and the second four-way reversing valve 2-2 first The interface is connected to the fourth interface, and the second interface is connected to the third interface. The connection ports of the first four-way reversing valve 2-1 and the second four-way reversing valve 2-2 in the refrigeration low-pressure stage unit remain unchanged. On the basis of the thermal process of the secondary throttling intermediate incomplete cooling two-stage compression refrigeration cycle with a medium temperature evaporator, the thermal process of defrosting the low-temperature evaporator in the defrosting low-pressure stage unit is as follows: from the air outlet 3 of the intercooler -2 The medium-pressure saturated steam mixed with the medium-pressure superheated steam discharged from the exhaust end of the low-pressure stage compressor in the low-pressure stage unit of the refrigeration unit becomes the medium-pressure superheated steam with a small superheated degree and is defrosted The low-pressure stage compressor 1-1 in the low-pressure stage unit is inhaled through the first four-way reversing valve 2-1 and the second one-way valve 7-2, and the vapor is compressed by the low-pressure stage compressor 1-1 After boosting, it becomes high-pressure superheated steam, which is discharged into the low-temperature evaporator 6-1 to be condensed, and the low-temperature evaporator 6-1 is heated to cause the defrosting phenomenon of the low-temperature evaporator 6-1, which is condensed into The high-pressure liquid working medium is throttled and depressurized by the second throttle valve 4-2 to become medium-pressure wet steam, and the medium-pressure wet steam enters the medium-temperature evaporator 6-2 through the second four-way reversing valve 2-2 Evaporation, completing the two-stage compression refrigeration cycle with secondary throttling and incomplete cooling in the middle with a medium-temperature evaporator using a low-pressure stage compressor heat pump cycle defrosting.

Example 3

The schematic diagram of the non-flooded type of high-temperature hot gas defrosting in the present invention adopts the secondary throttling intermediate incomplete cooling refrigeration system of heat pump defrosting as shown in Figure 3, including high-pressure stage compressor unit, condenser 5, first throttle valve 4 -1. Intercooler 3, two-way valve 8 and multiple low-pressure stage units. In this embodiment, the high-pressure stage compressor unit includes one or more high-pressure stage compressors 1-2. When multiple high-pressure stage compressors are used, the suction port of each high-pressure stage compressor 1-2 Parallel connection is used as the suction end of the high-pressure stage compressor unit, and the exhaust port of each of the high-pressure stage compressors 1-2 is connected in parallel as the exhaust end of the high-pressure stage compressor unit. Each of the low-pressure stage units includes a low-pressure stage compressor 1-1, a first four-way reversing valve 2-1, a second throttle valve 4-2, a low-temperature evaporator 6-1, a medium-temperature evaporator 6-2, The first one-way valve 7-1 and the second one-way valve 7-2; the suction end of the low-pressure stage compressor 1-1 is connected to the fourth interface of the first four-way reversing valve 2-1, The exhaust end of the low-pressure stage compressor 1-1 is connected to the second port of the first four-way reversing valve 2-1, and the third port of the first four-way reversing valve 2-1 is respectively connected to The inlet of the first one-way valve 7-1 is connected to the outlet of the second one-way valve 7-2, and the first interface of the first four-way reversing valve 2-1 passes through the low-temperature evaporator 6 -1 is connected to the first port of the second throttle valve 4-2; the first port of the medium temperature evaporator 6-2 is connected in parallel to the air inlet 3-1 of the intercooler 3 , the second port of the second throttle valve 4-2 and the second port of the medium temperature evaporator 6-2 are connected in parallel to the liquid outlet 3-4 of the intercooler 3, the The outlet of the first one-way valve 7-1, the inlet of the second one-way valve 7-2 and the suction end of the high-pressure stage compressor unit are connected in parallel and pass through the two-way valve 8 and the intercooler. The gas outlet 3-2 of the device 3 is connected; the exhaust end of the high-pressure stage compressor unit is connected to the liquid inlet 3-3 of the intercooler 3 through the condenser 5 and the first throttle valve 4-1 .

The low-pressure stage unit can be used in a refrigeration cycle or a defrosting cycle. When used in a refrigeration cycle, it works in a low-pressure stage system with two-stage compression, that is, the low-temperature evaporator in the low-pressure stage unit is refrigerated, and is defined as a refrigeration low-pressure stage unit. When it is used in the defrosting cycle, it works in the high-pressure stage system with two-stage compression, that is, the low-temperature evaporator in the low-pressure stage unit defrosts, which is defined as the defrosting low-pressure stage unit.

When the low-temperature evaporator in the low-pressure stage unit does not need defrosting, all the low-pressure stage units are used for the refrigeration cycle, that is, all the low-pressure stage units are refrigeration low-pressure stage units. In the refrigeration low-pressure stage unit, the first port of the first four-way reversing valve 2-1 is connected to the fourth port, the second port is connected to the third port, and the two-way valve 8 is opened. The thermodynamic process of the secondary throttling intermediate incomplete cooling two-stage compression refrigeration cycle with a medium-temperature evaporator is as follows: the low-pressure stage compressor 1-1 in the refrigeration low-pressure stage unit passes through the first four-way reversing valve 2-1 from the The low-pressure steam is sucked into the low-temperature evaporator 6-1, and the steam is compressed and boosted by the low-pressure stage compressor 1-1 to become medium-pressure superheated steam, and the medium-pressure superheated steam passes through the first four-way reversing valve 2-1 1. The first one-way valve 7-1 is mixed with the saturated medium-pressure steam flowing out from the gas outlet 3-2 of the intercooler 3 through the two-way valve 8; mixed into medium-pressure superheated steam with a smaller degree of superheat Inhaled by the suction end of the high-pressure compressor unit, the steam is compressed and boosted by the high-pressure compressor 1-2 in the high-pressure compressor unit to become high-pressure superheated steam, and then discharged into the condenser 5 to be condensed into High-pressure liquid, the high-pressure liquid is throttled and depressurized by the first throttle valve 4-1 to become medium-pressure wet vapor and enters the intercooler 3 through the liquid inlet 3-3 of the intercooler 3 . A part of the medium-pressure liquid working medium in the intercooler 3 evaporates and absorbs heat, and cools the medium-pressure superheated vapor coming in from the air inlet 3-1 of the intercooler 3 . The medium-pressure saturated liquid working medium flowing out of the liquid outlet 3-4 of the intercooler 3 is divided into two paths: one medium-pressure saturated liquid working medium enters the medium-temperature evaporator 6-2 to evaporate, absorbing the medium-temperature cold storage heat, resulting in medium-temperature refrigeration phenomenon, the medium-pressure saturated vapor from the medium-temperature evaporator 6-2 returns to the intercooler 3 through the air inlet 3-1 of the intercooler 3; the other part of the intermediate The medium-pressure saturated liquid working medium coming out of the liquid outlet of the cooler 3 is throttled and depressurized by the second throttle valve 4-2 to become a low-pressure wet vapor, enters the low-temperature evaporator 6-1 to evaporate, and is absorbed in the low-temperature cold storage. The heat of the low-temperature refrigeration phenomenon is generated, and the low-pressure steam coming out of the low-temperature evaporator 6-1 returns to the suction end of the low-pressure stage compressor 1-1 through the first four-way reversing valve 2-1 , to complete the two-stage compression refrigeration cycle with secondary throttling and intermediate incomplete cooling with a medium-temperature evaporator.

When there is a low-temperature evaporator in a low-pressure unit that needs to be defrosted, the corresponding low-pressure unit is a defrosting low-pressure unit, and the remaining low-pressure units are refrigeration low-pressure units. The first port of the first four-way reversing valve 2-1 in the defrosting low-pressure stage unit is connected to the second port, the third port is connected to the fourth port, and the first four-way reversing valve in the refrigeration low-pressure stage unit The connection relationship of 2-1 remains unchanged, and the two-way valve 8 is closed. On the basis of the thermodynamic process of the secondary throttling intermediate incomplete cooling two-stage compression refrigeration cycle with a medium temperature evaporator, the defrosting thermal process of the low-temperature evaporator in the defrosting low-pressure stage unit is as follows: The low-pressure stage compressor 1-1 sucks superheat from the exhaust end of the low-pressure stage compressor 1-1 of the refrigeration low-pressure stage unit through the first four-way reversing valve 2-1 and the second one-way valve 7-2. Larger medium-pressure steam, after being compressed and boosted by the low-pressure stage compressor 1-1, the steam becomes high-pressure superheated steam, which is discharged into the low-temperature evaporator 6-1 for condensation, and the low-temperature evaporator 6-1 is heated , the defrosting phenomenon of the low-temperature evaporator 6-1 is generated, and the condensed high-pressure liquid working medium is throttled and depressurized by the second throttle valve 4-2 to become a medium-pressure wet vapor and cooled from the intermediate The medium-pressure liquid coming out of the liquid outlet 3-4 of the device 3 is mixed, and mixed into wet vapor, which enters the medium-temperature evaporator 6-2 and the second throttle valve 4-2 in the low-pressure stage unit of the refrigeration unit, and completes the use of low-pressure Two-stage compression refrigeration cycle with secondary throttling and incomplete cooling in the middle of medium-temperature evaporator for defrosting of high-temperature hot gas discharged from the first-stage compressor.

Example 4

The structural diagram of the flooded type of high-temperature hot gas defrosting using heat pump defrosting and incomplete cooling in the middle of the secondary throttling refrigeration system is shown in Figure 4, including a high-pressure compressor unit, a condenser 5, and a first throttle valve 4. -1. Intercooler 3, two-way valve 8 and multiple low-pressure stage units. In this embodiment, the high-pressure stage compressor unit includes one or more high-pressure stage compressors 1-2. When multiple high-pressure stage compressors are used, the suction port of each high-pressure stage compressor 1-2 Parallel connection is used as the suction end of the high-pressure stage compressor unit, and the exhaust port of each of the high-pressure stage compressors 1-2 is connected in parallel as the exhaust end of the high-pressure stage compressor unit. Each of the low-pressure stage units includes a low-pressure stage compressor 1-1, a first four-way reversing valve 2-1, a second four-way reversing valve 2-2, a second throttle valve 4-2, and a low-temperature evaporator 6-1, medium temperature evaporator 6-2, first one-way valve 7-1 and second one-way valve 7-2; The fourth interface of the valve 2-1 is connected, the exhaust end of the low-pressure stage compressor 1-1 is connected with the second interface of the first four-way reversing valve 2-1, and the first four-way reversing valve The third interface of the one-way valve 2-1 is respectively connected with the inlet of the first one-way valve 7-1 and the outlet of the second one-way valve 7-2, and the first four-way reversing valve 2-1 The first port of the low temperature evaporator 6-1 is connected to the first port of the second throttle valve 4-2, and the second port of the second throttle valve 4-2 is connected to the second port of the second throttle valve 4-2. connected to the second interface of the reversing valve 2-2; the first interfaces of the medium temperature evaporator 6-2 are connected in parallel to the air inlet 3-1 of the intercooler 3, and the medium temperature evaporator The second port of 6-2 is connected to the third port of the second four-way reversing valve 2-2, and the first port and the fourth port of the second four-way reversing valve 2-2 are connected in parallel It is connected with the liquid outlet 3-4 of the intercooler 3; the outlet of the first one-way valve 7-1, the inlet of the second one-way valve 7-2 and the suction of the high-pressure stage compressor unit After the gas ends are connected in parallel, they are connected to the air outlet 3-2 of the intercooler through the two-way valve 8; -1 is connected with the liquid inlet 3-3 of the intercooler 3.

The low-pressure stage unit can be used in a refrigeration cycle or a defrosting cycle. When used in a refrigeration cycle, it works in a low-pressure stage system with two-stage compression, that is, the low-temperature evaporator in the low-pressure stage unit is refrigerated, and is defined as a refrigeration low-pressure stage unit. When it is used in the defrosting cycle, it works in the high-pressure stage system with two-stage compression, that is, the low-temperature evaporator in the low-pressure stage unit defrosts, which is defined as the defrosting low-pressure stage unit.

When the low-temperature evaporator in the low-pressure stage unit does not need defrosting, all the low-pressure stage units are used for the refrigeration cycle, that is, all the low-pressure stage units are refrigeration low-pressure stage units. The first port of the first four-way reversing valve 2-1 in the refrigeration low-pressure unit is connected to the fourth port, the second port is connected to the third port, and the second port of the second four-way reversing valve 2-2 One port is connected to the second port, the third port is connected to the fourth port, and the two-way valve 8 is opened. The thermodynamic process of the secondary throttling intermediate incomplete cooling two-stage compression refrigeration cycle with a medium-temperature evaporator is as follows: the low-pressure stage compressor 1-1 in the refrigeration low-pressure stage unit passes through the first four-way reversing valve 2-1 from the The low-pressure steam is sucked into the low-temperature evaporator 6-1, and the steam is compressed and boosted by the low-pressure stage compressor 1-1 to become a medium-pressure superheated steam, and the steam passes through the first four-way reversing valve 2-1, the first The one-way valve 7-1 is mixed with the saturated medium-pressure steam that flows out from the air outlet 3-2 of the intercooler 3 through the two-way valve 8; the medium-pressure superheated steam with a smaller degree of superheat is mixed by the The suction end of the high-pressure compressor unit is inhaled, and the steam is compressed and boosted by the high-pressure compressor 1-2 of the high-pressure compressor unit to become a high-pressure superheated steam, and then it is discharged into the condenser 5 to be condensed into a high-pressure liquid; The high-pressure liquid is throttled and depressurized by the first throttling valve 4-1 to become medium-pressure wet vapor and enters the intercooler 3 through the liquid inlet 3-3 of the intercooler 3 . A part of the medium-pressure liquid working fluid in the intercooler 3 evaporates and absorbs heat, cooling the medium-pressure superheated vapor coming in from the air inlet 3-1 of the intercooler 3 . The medium-pressure saturated liquid working medium flowing out of the liquid outlet 3-4 of the intercooler 3 is divided into two paths: one medium-pressure saturated liquid working medium enters the medium-temperature evaporator through the second four-way reversing valve 2-2 6-2 evaporates, absorbs the heat in the medium-temperature cold storage, and produces a medium-temperature refrigeration phenomenon, and the medium-pressure saturated vapor from the medium-temperature evaporator 6-2 returns to the storage medium through the air inlet 3-1 of the intercooler 3 The intercooler 3; the medium-pressure saturated liquid working fluid coming out of the liquid outlet of the other part of the intercooler 3 is throttled down by the second four-way reversing valve 2-2 and the second throttle valve 4-2. The low-pressure steam enters the low-temperature evaporator 6-1 to evaporate, absorbs the heat in the low-temperature cold storage, and produces low-temperature refrigeration. The low-pressure steam coming out of the low-temperature evaporator 6-1 passes through the first four The reversing valve 2-1 returns to the suction end of the low-pressure stage compressor 1-1 to complete a two-stage compression refrigeration cycle with secondary throttling and intermediate incomplete cooling with a medium temperature evaporator.

When there is a low-temperature evaporator in a low-pressure unit that needs to be defrosted, the corresponding low-pressure unit is a defrosting low-pressure unit, and the remaining low-pressure units are refrigeration low-pressure units. The two-way valve 8 is closed, the first port of the first four-way reversing valve 2-1 in the defrosting low-pressure stage unit is connected to the second port, the third port is connected to the fourth port, and the second four-way reversing valve The first port of the valve 2-2 is connected to the fourth port, and the second port is connected to the third port. The interface connection between the first four-way reversing valve 2-1 and the second four-way reversing valve 2-2 in the refrigeration low-pressure stage unit remains unchanged. On the basis of the thermodynamic process of the secondary throttling intermediate incomplete cooling two-stage compression refrigeration cycle with a medium temperature evaporator, the defrosting thermal process of the low-temperature evaporator in the defrosting low-pressure stage unit is as follows: described in the defrosting low-pressure stage unit The low-pressure stage compressor 1-1 sucks in from the exhaust end of the low-pressure stage compressor 1-1 of the refrigeration low-pressure stage unit through the first four-way reversing valve 2-1 and the second one-way valve 7-2. The medium-pressure steam with higher heat, after being compressed and boosted by the low-pressure stage compressor 1-1, the steam becomes high-pressure superheated steam, which is discharged into the low-temperature evaporator 6-1 for condensation, and the low-temperature evaporator 6- 1. The defrosting phenomenon of the low-temperature evaporator 6-1 occurs, and the condensed high-pressure liquid working medium is throttled and depressurized by the second throttle valve 4-2 to become a medium-pressure wet steam, and the wet steam passes through the second throttle valve 4-2. The two-way and four-way reversing valve 2-2 enters the medium-temperature evaporator 6-2 to evaporate, and completes the defrosting of the high-temperature hot gas discharged by the low-pressure stage compressor. The secondary throttling of the medium-temperature evaporator is used for incomplete cooling. Two-stage compression refrigeration cycle.

The low-pressure stage compressor and the high-pressure stage compressor are any one of a scroll compressor, a rotary compressor, a screw compressor and a piston compressor.

The condenser is an air-cooled condenser, a water-cooled condenser or an evaporative condenser.

The low-temperature evaporator and the medium-temperature evaporator are air-cooled or solution-cooled.

The intercooler is a plate heat exchanger, a casing heat exchanger or a shell and tube heat exchanger.

The first throttle valve and the second throttle valve are electronic expansion valves, thermal expansion valves, capillary tubes or orifice throttling devices.

The first one-way valve, the second one-way valve, the first four-way reversing valve and the second four-way reversing valve are prior art. In the system, two-way valves, hand valves, and three-way reversing valves can be used instead.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, these improvements and Retouching should also be regarded as the protection scope of the present invention.

Claims (7)

1. A method for operating a secondary throttling intermediate incomplete cooling refrigeration system, characterized in that a medium-temperature evaporator and a low-temperature evaporator are set in each low-pressure stage unit, and the medium-temperature evaporator is used to realize medium-temperature refrigeration. The low-temperature evaporator is used to realize low-temperature refrigeration or defrosting. The operation method includes the following steps: when all low-pressure stage units realize the refrigeration function, the medium-temperature evaporator evaporates the medium-pressure saturated liquid working medium into medium-pressure saturated vapor to realize medium-temperature Refrigeration; the low-temperature evaporator evaporates the low-pressure liquid working medium into low-pressure steam to realize low-temperature refrigeration; when there is a low-temperature evaporator that needs defrosting, the low-pressure compressor that realizes the defrosting function is converted into a high-pressure compressor by switching the valve In operation, the cryogenic compressor in the low-pressure stage unit performing the defrosting function absorbs medium-pressure superheated vapor from the low-pressure stage compressor of the low-pressure stage unit performing the cooling function, or from the intercooler and the low-pressure stage compressor performing the cooling function The mixed hot gas is compressed and sent to the low-temperature evaporator to be defrosted, condensed and heated to realize defrosting, and the low-temperature evaporator in the low-pressure stage unit that realizes the refrigeration function still realizes the refrigeration function; Finally, the low-pressure stage unit that realizes the defrosting function realizes the cooling function through valve switching. 2. A secondary throttling intermediate incomplete cooling refrigeration system that adopts heat pump defrosting to realize the operation method described in claim 1 is characterized in that it includes a high-pressure stage compressor unit, a condenser, a first throttle valve, an intermediate A cooler and a plurality of low-pressure stage units; each of the low-pressure stage units includes a low-pressure stage compressor, a first four-way reversing valve, a second throttle valve, a low-temperature evaporator, a medium-temperature evaporator, a first one-way valve, and The second one-way valve; the suction end of the low-pressure stage compressor is connected to the fourth interface of the first four-way reversing valve, and the exhaust end of the low-pressure stage compressor is connected to the first four-way reversing valve connected to the second interface of the reversing valve, the third interface of the first four-way reversing valve is respectively connected to the inlet of the first one-way valve and the outlet of the second one-way valve, and the first four-way The first port of the reversing valve is connected to the first port of the second throttle valve through the low-temperature evaporator; the first port of the medium-temperature evaporator is connected in parallel and connected to the air inlet of the intercooler connected, the second port of the second throttle valve and the second port of the medium temperature evaporator are connected in parallel to the liquid outlet of the intercooler, the outlet of the first one-way valve, the The inlet of the second check valve and the suction end of the high-pressure stage compressor unit are connected in parallel to the gas outlet of the intercooler; the exhaust end of the high-pressure stage compressor unit passes through the condenser, the first A throttling valve is connected with the liquid inlet of the intercooler. 3. The secondary throttling intermediate incomplete cooling refrigeration system adopting heat pump defrosting according to claim 2, characterized in that, the high-pressure stage compressor unit includes one or more high-pressure stage compressors, and the specific number depends on the The operating conditions of the refrigeration system are determined. When multiple high-pressure compressors are used, the suction port of each high-pressure compressor is connected in parallel as the suction end of the high-pressure compressor unit, and each high-pressure compressor The exhaust ports of the compressors are connected in parallel as the exhaust end of the high-pressure stage compressor unit. 4. The refrigeration system with secondary throttling and intermediate incomplete cooling according to claim 2 or 3, characterized in that the number of said low-pressure stage units is at least three. 5. A secondary throttling intermediate incomplete cooling refrigeration system that adopts heat pump defrosting to realize the operation method described in claim 1 is characterized in that it includes a high-pressure stage compressor unit, a condenser, a first throttle valve, an intermediate A cooler and a plurality of low-pressure stage units; each of the low-pressure stage units includes a low-pressure stage compressor, a first four-way reversing valve, a second four-way reversing valve, a second throttle valve, a low-temperature evaporator, a medium-temperature evaporator device, a first one-way valve and a second one-way valve; the suction end of the low-pressure stage compressor is connected to the fourth interface of the first four-way reversing valve, and the exhaust end of the low-pressure stage compressor It is connected with the second interface of the first four-way reversing valve, and the third interface of the first four-way reversing valve is connected with the inlet of the first one-way valve and the outlet of the second one-way valve respectively. The first port of the first four-way reversing valve is connected to the first port of the second throttle valve through the low-temperature evaporator, and the second port of the second throttle valve is connected to the first port of the second throttle valve. The second interface of the two four-way reversing valve is connected; the first interface of the medium temperature evaporator is connected in parallel to the air inlet of the intercooler, and the second interface of the medium temperature evaporator is connected to the first interface of the intermediate temperature evaporator. The third port of the two four-way reversing valve is connected, and the first port and the fourth port of the second four-way reversing valve are connected in parallel to the liquid outlet of the intercooler; the first single The outlet of the valve, the inlet of the second one-way valve, and the suction end of the high-pressure stage compressor unit are connected in parallel to the air outlet of the intercooler; the exhaust end of the high-pressure stage compressor unit The first throttling valve is connected to the liquid inlet of the intercooler through the condenser. 6. A secondary throttling intermediate incomplete cooling refrigeration system that adopts heat pump defrosting to realize the operation method described in claim 1 is characterized in that it includes a high-pressure stage compressor unit, a condenser, a first throttle valve, an intermediate A cooler, a two-way valve, and a plurality of low-pressure stage units; each of the low-pressure stage units includes a low-pressure stage compressor, a first four-way reversing valve, a second throttle valve, a low-temperature evaporator, a medium-temperature evaporator, a first A one-way valve and a second one-way valve; the suction end of the low-pressure stage compressor is connected to the fourth interface of the first four-way reversing valve, and the exhaust end of the low-pressure stage compressor is connected to the fourth port of the first four-way reversing valve. The second interface of a four-way reversing valve is connected, and the third interface of the first four-way reversing valve is respectively connected with the inlet of the first one-way valve and the outlet of the second one-way valve. The first port of the first four-way reversing valve is connected to the first port of the second throttle valve through the low-temperature evaporator; the first port of the medium-temperature evaporator is connected in parallel with the intercooler The air inlet of the second throttle valve and the second interface of the medium temperature evaporator are connected in parallel to the liquid outlet of the intercooler, and the first one-way valve The outlet of the second one-way valve, the inlet of the second one-way valve, and the suction end of the high-pressure stage compressor unit are connected in parallel and then connected with the gas outlet of the intercooler through the two-way valve; the high-pressure stage compressor unit The exhaust end of the exhaust port is connected with the liquid inlet of the intercooler through the condenser and the first throttle valve. 7. A secondary throttling intermediate incomplete cooling refrigeration system that adopts heat pump defrosting to realize the operation method described in claim 1 is characterized in that it includes a high-pressure stage compressor unit, a condenser, a first throttle valve, an intermediate A cooler, a two-way valve, and a plurality of low-pressure stage units; each of the low-pressure stage units includes a low-pressure stage compressor, a first four-way reversing valve, a second four-way reversing valve, a second throttle valve, a low-temperature evaporation device, medium temperature evaporator, first one-way valve and second one-way valve; the suction end of the low-pressure stage compressor is connected to the fourth interface of the first four-way reversing valve, and the low-pressure stage compressor The exhaust end of the first four-way reversing valve is connected to the second port of the first four-way reversing valve, and the third port of the first four-way reversing valve is respectively connected to the inlet of the first one-way valve and the second one-way reversing valve. connected to the outlet of the valve, the first port of the first four-way reversing valve is connected to the first port of the second throttle valve through the low-temperature evaporator, and the second port of the second throttle valve It is connected with the second interface of the second four-way reversing valve; the first interface of the medium temperature evaporator is connected in parallel with the air inlet of the intercooler, and the second interface of the medium temperature evaporator It is connected with the third port of the second four-way reversing valve, and the first port and the fourth port of the second four-way reversing valve are connected in parallel and then connected with the liquid outlet of the intercooler; The outlet of the first one-way valve, the inlet of the second one-way valve and the suction end of the high-pressure stage compressor unit are connected in parallel and then connected to the gas outlet of the intercooler through the two-way valve; The exhaust end of the high-pressure stage compressor unit is connected to the liquid inlet of the intercooler through the condenser and the first throttling valve.