CN108709333A - The operation method and system of refrigeration system completely cooling among second throttle - Google Patents

Abstract

The invention discloses an operation method and system of a refrigeration system with secondary throttling and complete cooling in the middle, and aims to provide a method and system for defrosting gear blocks of 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. The method is: when there is a low-temperature evaporator that needs defrosting, through The valve is switched, and 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 working fluid from the low-pressure stage compressor that realizes the refrigeration function, and condenses after compression The low-temperature evaporator to be defrosted is heated to achieve defrosting. When there are multiple low-temperature evaporators that need to be defrosted, the defrosting is realized through gear shifting. In the present invention, both the defrosting cycle and the refrigeration cycle are two-stage compression cycles, the temperature fluctuation of the cold storage is small, the structure is simple, and the efficiency is high.

Description

Operation method and system of refrigeration system with secondary throttling and intermediate complete cooling

technical field

The invention relates to the technical field of refrigeration, and more specifically relates to an operation method and a refrigeration system of a two-stage compression refrigeration system with secondary throttling and complete cooling in the middle of a medium-temperature evaporator that adopts 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 operates a single-stage compression heat pump cycle during defrosting, when the two-stage compression refrigeration cycle is converted to a single-unit compression heat pump defrosting cycle, the working pressure difference of the compressor participating in the single-stage compression heat pump cycle defrosting increases sharply, which will cause Impact on the compressor, damage the compressor, and this single-stage compression heat pump defrosting cycle enters the evaporator for defrosting, the temperature of the working medium is low, the defrosting speed is slow, and the time for heat diffusion around the evaporator is long, resulting in a decrease in 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, resulting in 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 solve the technical defects existing in the prior art, and provide an operation method of a refrigeration system with high defrosting efficiency, small temperature fluctuation, and long-term stable operation of the compressor with secondary throttling and complete cooling in the middle.

Another object of the present invention is to provide a heat pump cycle to defrost the low-temperature evaporator gear, with small temperature fluctuations and stable operation. At the same time, it can provide the cooling capacity of the refrigerating room and the freezing room with secondary throttling and intermediate complete cooling. Two-stage compression refrigeration system.

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

A method for operating a refrigeration system with secondary throttling and intermediate complete cooling, 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-pressure stage compressor in the low-pressure stage unit absorbs the medium-pressure superheated vapor from the low-pressure stage compressor that realizes the refrigeration function or the medium-pressure saturated vapor from the intercooler, and sends it to the low-temperature evaporator to be defrosted after being compressed , condensing and heating the low-temperature evaporator to realize defrosting, and the low-temperature evaporator in the low-pressure stage unit that realizes the refrigeration function still realizes the refrigeration function; Refrigeration function; when there are multiple low-temperature evaporators that need defrosting, the defrosting is realized through gear shifting.

A refrigerating system with heat pump defrosting, secondary throttling and intermediate complete cooling for realizing the above operating method, including a high-pressure stage compressor unit, a condenser, a first throttle valve, an intercooler, and multiple sets of 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 low temperature The evaporator is connected to the first port of the second throttle valve, and in multiple groups of the low-pressure stage units, the second port of the second throttle valve is connected in parallel with the second port of the medium temperature evaporator together and connected with the liquid outlet of the intercooler, the first port of the medium temperature evaporator is connected in parallel and connected with the first air inlet of the intercooler, the outlet of the first check valve connected in parallel with the second air inlet of the intercooler, the inlet of the second check valve is connected in parallel and connected with the suction end of the high-pressure stage compressor unit and the inlet of the intercooler respectively. The gas outlet is connected; 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 throttle valve.

The high-pressure stage compressor unit includes one or more high-pressure stage compressors. When multiple high-pressure stage compressors are used, the suction port of each high-pressure stage compressor is connected in parallel as the suction port of the high-pressure stage compressor unit. The exhaust port of each high-pressure stage compressor 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.

A refrigerating system with secondary throttling and intermediate complete cooling for realizing the above-mentioned operating method, comprising a high-pressure stage compressor unit, a condenser, a first throttle valve, an intercooler, and multiple sets of low-pressure stage units; each of the low-pressure stage units It 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 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 is The low-temperature evaporator is connected to the first port of the second throttle valve, the second port of the second throttle valve is connected to the second port of the second four-way reversing valve, and the medium-temperature evaporator The second port of the evaporator is connected to the third port of the second four-way reversing valve. In multiple groups of the low-pressure stage units, the first ports of the medium-temperature evaporator are connected in parallel and connected with the intercooler The first air inlet of the second four-way reversing valve is connected in parallel with the fourth interface and connected with the liquid outlet of the intercooler; the outlet of the first one-way valve connected in parallel and connected with the second air inlet of the intercooler, the inlet of the second check valve is connected in parallel and connected with the suction end of the high-pressure stage compressor unit and the inlet of the intercooler respectively The gas outlet is connected; 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 throttle valve.

A refrigerating system with secondary throttling and intermediate complete cooling to realize the above operating method, including a high-pressure stage compressor unit, a condenser, a first throttle valve, an intercooler, a third four-way reversing valve, and multiple low-pressure stage units ; Each 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, and the low-pressure stage 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 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 passes through the The low-temperature evaporator is connected to the first port of the second throttle valve; in multiple groups of the low-pressure stage units, the first ports of the medium-temperature evaporator are connected in parallel and connected to the first inlet port of the intercooler The second port of the second throttle valve is connected in parallel with the second port of the medium temperature evaporator and connected with the liquid outlet of the intercooler, and the outlet of the first one-way valve is connected in parallel together and connected with the second interface of the third four-way reversing valve, the inlet of the second one-way valve is connected in parallel and connected with the suction end of the high-pressure stage compressor unit and with the third and four-way reversing valve respectively. The third port of the reversing valve is connected, the first port of the third four-way reversing valve is connected with the second air inlet of the intercooler, and the fourth port of the third four-way reversing valve It is connected with the air outlet of the intercooler; the exhaust end of the high-pressure stage compressor unit is connected with the liquid inlet of the intercooler through the condenser and the first throttle valve.

A refrigerating system with secondary throttling and intermediate complete cooling for realizing the above-mentioned operating method, including a high-pressure stage compressor unit, a condenser, a first throttle valve, a third four-way reversing valve, an intercooler, 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 port 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. 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 of 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 first port of the second four-way reversing valve. Two interfaces are connected; the first interface of the medium temperature evaporator is connected in parallel and connected with the first air inlet of the intercooler, and the other end of the medium temperature evaporator is connected with the second four-way reversing valve. The third interface is connected, the first interface and the fourth interface of the second four-way reversing valve are connected in parallel and connected with the liquid outlet of the intercooler; the outlets of the first one-way valve are connected in parallel and connected to the second interface of the third four-way reversing valve, the inlets of the second one-way valve are connected in parallel and are respectively reversed with the suction end of the high-pressure stage compressor unit and the third four-way reversing valve. The third port of the valve is connected, the first port of the third four-way reversing valve is connected to the second air inlet of the intercooler, the fourth port of the third four-way reversing valve is connected to the intermediate The air outlet of the cooler is connected; the exhaust end of the high-pressure stage compressor unit is connected with the liquid inlet of the intercooler through the condenser and the first throttle valve.

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 medium-pressure saturated vapor from the intercooler is compressed to realize 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 system without temperature fluctuations. Small size, high defrosting efficiency, saving energy. At the same time, the compressor can run stably, which improves the service life of the system.

2. The present invention adopts a heat pump defrosting refrigeration system with secondary throttling and intermediate complete cooling of a medium-temperature evaporator. When there is a low-pressure unit with a low-temperature evaporator for defrosting, the cooling and defrosting of the low-pressure 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. The defrosting cycle and the refrigeration cycle are both two-stage compression cycles, thereby forming a dynamic refrigeration system. It is flexible and convenient, has high defrosting efficiency and saves energy.

3. The medium- and low-pressure stage compressor of the low-pressure stage unit of the refrigeration system defrosting of the present invention can suck the medium-pressure superheated steam that is not cooled by the intercooler, and the medium-pressure superheated steam is sucked and compressed by the low-pressure compressor of the defrosting low-pressure stage unit. The high-temperature hot gas enters the low-temperature evaporator of the defrosting low-pressure unit at a higher temperature, and 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.

4. 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 medium pressure and high pressure, and the low-pressure stage unit When the refrigeration cycle is transformed into 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.

5. The present invention adopts a heat pump defrosting secondary throttling intermediate complete cooling refrigeration system with a medium-temperature evaporator, and the defrosting heat of the evaporator in the low-pressure unit comes from the input of the evaporator and the compressor in the low-pressure unit of refrigeration The heat supply during defrosting is sufficient and unrestricted, so it can fully defrost, and the defrosting efficiency is higher, and it is more suitable for large-scale two-stage compression refrigeration systems.

6. 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 stage compressors is uniform, and the wear degree of the high and low pressure stage compressors is uniform. The system is simple and efficient. 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.

7. The present invention adopts heat pump defrosting and has a medium-temperature evaporator with secondary throttling and complete cooling in the middle. The low-temperature evaporator defrosting 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.

8. The present invention adopts heat pump defrosting and has a secondary throttling intermediate complete cooling refrigeration system with a medium temperature evaporator. , Different cooling capacity requirements, realize the variable flow cycle of high and low pressure stages, and match the best capacity ratio between high and low pressure stages.

9. The secondary throttling intermediate complete cooling refrigeration system with a medium-temperature evaporator using heat pump defrosting in the present invention can simultaneously produce cooling capacity at two evaporation temperatures, and is especially suitable for use in a cold storage system to provide both a refrigerating room and a freezing room of cooling.

10. The present invention adopts high-temperature hot gas defrosting secondary throttling intermediate complete cooling refrigeration system with medium-temperature evaporator When there is a low-pressure stage unit for defrosting the low-temperature evaporator, the heat source for defrosting the low-pressure stage unit low-temperature evaporator defrosting It is medium pressure superheated gas. That is, the medium and low-pressure stage compressor of the defrosting low-pressure stage unit directly sucks the 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 temperature of the high-pressure working medium discharged from the low-pressure stage compressor of the defrosting low-pressure stage unit is higher. High, the temperature of the working fluid 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.

Description of drawings

Fig. 1 shows the structural principle diagram of the non-full liquid type secondary throttling intermediate complete cooling refrigeration system of the hot gas defrosting of embodiment 1 of the present invention;

Fig. 2 shows the structural principle diagram of the refrigeration system with full liquid type secondary throttling and complete cooling in the middle of hot gas defrosting according to Embodiment 2 of the present invention;

Fig. 3 is a structural schematic diagram of a non-flooded secondary throttling intermediate complete cooling refrigeration system for high-temperature hot gas defrosting in Embodiment 3 of the present invention;

Fig. 4 shows the structural principle diagram of the refrigeration system with full liquid type secondary throttling and intermediate complete cooling for high temperature hot gas defrosting in embodiment 4 of the present invention;

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 can be partially shut down or completely shut down. The medium-pressure superheated vapor from the low-pressure stage compressor that realizes the refrigeration function or the medium-pressure saturated vapor from the intercooler is sucked by the low-pressure stage compressor for defrosting, and enters the low-temperature evaporator to be defrosted after being compressed. The evaporator is converted to a two-stage compression condenser. One by one (or group) defrosting, after defrosting, each evaporator is refrigerated by switching valves. Specific technical solutions such as:

In the operation method of the refrigeration system with secondary throttling and complete cooling in the middle 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-pressure stage 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 the medium-pressure saturated vapor from the intercooler, and sends it to the low-temperature evaporation to be defrosted after being compressed 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 refrigeration function still realizes the refrigeration function; after the defrosting is completed, the low-pressure stage unit that realizes the defrosting function switches through the valve to realize refrigeration. Function. When there are multiple low-temperature evaporators that need defrosting, 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.

In the refrigerating system with secondary throttling intermediate complete cooling of the medium-temperature evaporator that adopts heat pump defrosting in the present invention, when there is a medium-low temperature evaporator defrosting in the low-pressure stage unit, according to the front and medium temperature of the second throttle valve of the low-pressure stage unit of the refrigeration The state of medium-pressure working medium in the evaporator is divided into full liquid supply type and non-full 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. At the same time, in the refrigeration system of the present invention, the corresponding low-pressure stage compressor during defrosting can suck medium-pressure saturated vapor from the intercooler, or can suck medium-pressure higher superheated vapor that is not cooled by the intercooler. In Embodiment 1 and Embodiment 2, the low-temperature compressor in the low-pressure stage unit that realizes the defrosting function absorbs the medium-pressure saturated vapor from the intercooler and realizes defrosting after being compressed; in Embodiment 3 and Embodiment 4, realizes defrosting The low-temperature compressor in the low-pressure stage unit of the frosting function absorbs the steam with a higher superheated degree at medium pressure from the low-pressure stage compressor that realizes the refrigeration function, and defrosts after being compressed. The medium-pressure superheated steam is inhaled and compressed by the low-pressure compressor of the defrosting low-pressure stage unit to discharge higher-temperature hot gas, and the working medium entering the low-temperature evaporator of the defrosting low-pressure stage unit has a higher temperature, better defrosting effect, and faster defrosting speed .

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

Example 1

The structural schematic diagram of the full-liquid secondary throttling intermediate complete cooling refrigeration system for hot gas defrosting of the present invention is shown in Figure 1, including a high-pressure stage compressor unit, a condenser 5, a first throttle valve 4-1, an intermediate cooling Device 3 and multiple sets of low-voltage 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. The low-pressure stage units can be used for refrigeration cycle or defrosting cycle, and 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, 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 first The fourth interface of the four-way reversing 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 The third interface of the four-way reversing 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 The first interface of 2-1 is connected to the first interface of the second throttle valve through the low-temperature evaporator 6-1. In multiple groups of the low-pressure stage units, the second throttle valve 4- The second interface of 2 is connected in parallel with the second interface of the medium temperature evaporator 6-2 and connected with the liquid outlet of the intercooler 3, and the first interface of the medium temperature evaporator 6-2 is connected in parallel And connected with the first air inlet of the intercooler 3, the outlets of the first one-way valve 7-1 are connected in parallel and then connected with the second air inlet of the intercooler 3, the first The inlets of the two one-way valves 7-2 are connected in parallel and connected with the suction end of the high-pressure compressor unit and the gas outlet of the intercooler 3 respectively; the exhaust end of the high-pressure compressor unit passes through the The condenser 5 and the first throttle valve 4-1 are connected to the liquid inlet of the intercooler 3 .

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 realize the refrigeration function. In the low-pressure stage unit that realizes the refrigeration function, the first port of the first four-way reversing valve 2-1 is connected to the fourth port, and the second port of the first four-way reversing valve 2-1 is connected to the third port . The thermodynamic process of the secondary throttling intermediate complete cooling two-stage compression refrigeration cycle with a medium-temperature evaporator is as follows: in the low-pressure stage unit that realizes the refrigeration function, the low-pressure stage compressor 1-1 passes through the first four-way reversing valve 2-1 The low-pressure steam is sucked from the low-temperature evaporator 6-1, and the working medium is compressed and boosted by the low-pressure stage compressor 1-1 to become a medium-pressure superheated steam, and then passes through the first four-way reversing valve 2- 1. The first check valve 7-1 and the second air inlet 3-2 of the intercooler 3 are discharged into the intercooler 3 for cooling. The high-pressure stage compressor unit sucks medium-pressure saturated steam from the air outlet 3-3 of the intercooler 3, and the steam is compressed and boosted by the high-pressure stage compressor unit to become high-pressure superheated steam and then discharged into the condenser 5 The medium is condensed into a high-pressure liquid, and the liquid is throttled and depressurized by the first throttle valve 4-1 to become a medium-pressure wet vapor and enters the intercooler through the liquid inlet 3-4 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 second air inlet 3-2 of the intercooler. The medium-pressure saturated liquid working medium flowing out from the liquid outlet 3-5 of the intercooler is divided into two parts, and a part of the medium-pressure saturated liquid working medium flowing out from the liquid outlet 3-5 of the intercooler enters the medium-temperature Evaporate in the evaporator 6-2, absorb the heat in the medium-temperature cold storage, and produce a medium-temperature refrigeration phenomenon, and the medium-pressure saturated vapor from the medium-temperature evaporator 6-2 passes through the first air inlet 3- of the intercooler 3 1 Returning to the intercooler, another part of the medium-pressure saturated liquid working medium flowing out from the liquid outlet 3-5 of the intercooler is throttled and reduced by the second throttle valve 4-2 to become a low-pressure wet The steam enters the low-temperature evaporator 6-1 to evaporate, absorbs the heat in the low-temperature cold storage, and produces a low-temperature refrigeration phenomenon. The low-pressure steam coming out of the low-temperature evaporator 6-1 passes through the first 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 complete cooling with a medium-temperature evaporator.

When the low-temperature evaporator in the low-pressure stage unit needs defrosting, the corresponding low-pressure stage unit realizes the defrosting function, and the remaining low-pressure stage units realize the refrigeration function. The thermodynamic cycle process of the low-pressure stage unit that realizes the refrigeration function remains unchanged. In the low-pressure stage unit realizing the defrosting function, the first port of the first four-way reversing valve 2-1 is connected to the second port, and the third port is connected to the fourth port. In the low-pressure stage unit that realizes the refrigeration function, the first port of the first four-way reversing valve 2-1 is connected to the fourth port, and the second port is connected to the third port, so that in the low-pressure stage unit that realizes the defrosting function The low-pressure stage compressor is converted into a high-pressure stage compressor. In the low-pressure stage unit that realizes the defrosting function, the defrosting thermodynamic process of the low-temperature evaporator 6-1 is as follows: the low-pressure stage compressor 1-1 passes through the first four-way reversing valve 2-1 and the second The second one-way valve 7-2 sucks medium-pressure saturated steam from the air outlet 3-3 of the intercooler, and the steam becomes high-pressure superheated steam after being compressed and boosted by the low-pressure stage compressor 1-1 and passes through the first four-way The reversing valve 2-1 enters the low-temperature evaporator 6-1 to condense, heats the low-temperature evaporator 6-1, and realizes the defrosting of the low-temperature evaporator 6-1, and the condensed high-pressure liquid working fluid passes through the The second throttling valve 4-2 throttling and depressurizing becomes medium-pressure wet vapor and mixes with the medium-pressure liquid flowing out from the liquid outlet 3-5 of the intercooler, and the mixed wet vapor enters into all low-pressure stage units correspondingly In the medium-temperature evaporator 6-2 and the second throttle valve 4-2 corresponding to the low-pressure stage unit that realizes the refrigeration function, the secondary throttling intermediate complete cooling with the medium-temperature evaporator that uses the low-pressure stage compressor heat pump cycle defrosting is completed Two-stage compression refrigeration cycle.

Example 2

The structural schematic diagram of the full-liquid secondary throttling intermediate complete cooling refrigeration system for hot gas defrosting of the present invention is shown in Figure 2, including a high-pressure stage compressor unit, a condenser 5, a first throttle valve 4-1, an intermediate cooling Device 3 and multiple sets of low-voltage 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. The low-pressure stage units can be used for refrigeration cycle or defrosting cycle, and 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. The second throttle valve 4-2, the low-temperature evaporator 6-1, the medium-temperature evaporator 6-2, the first one-way valve 7-1 and the second one-way valve 7-2, the low-pressure stage compressor 1 The suction end of -1 is connected to the fourth interface 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 four-way reversing valve 2-1 1, the third interface of the first four-way reversing valve 2-1 is respectively connected to the inlet of the first one-way valve 7-1 and the outlet of the second one-way valve 7-2 connected, 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, and the second throttle valve The second port of the valve 4-2 is connected to the second port of the second four-way reversing valve 2-2, and the second port of the medium temperature evaporator 6-2 is connected to the second port of the second four-way reversing valve 2-2. -2 to the third interface connection, in multiple groups of the low-pressure stage units, the first interface of the medium temperature evaporator 6-2 is connected in parallel and connected to the first air inlet 3-1 of the intercooler 3 connected, the first port of the second four-way reversing valve 2-2 is connected in parallel with the fourth port and connected with the liquid outlet 3-5 of the intercooler 3; the first one-way valve 7 -1 outlets are connected in parallel and connected with the second air inlet 3-2 of the intercooler 3, and the inlets of the second one-way valve 7-2 are connected in parallel and respectively connected with the high-pressure stage compressor unit The suction end of the intercooler 3 is connected to the air outlet 3-3 of the intercooler 3; the exhaust end of the high-pressure stage compressor unit is connected to the intercooler through the condenser 5 and the first throttle valve 4-1 The liquid inlet 3-4 of 3 is connected.

When the low-temperature evaporators 6-1 in all the low-pressure stage units do not need defrosting, all the low-pressure stage units are used for the refrigeration cycle to realize the refrigeration function. In the low-pressure stage unit realizing the refrigeration function, 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 second four-way reversing valve 2-1 -2 The first interface is connected to the second interface, and the third interface is connected to the fourth interface. The thermodynamic process of the secondary throttling intermediate complete cooling two-stage compression refrigeration cycle with a medium-temperature evaporator is as follows: in the low-pressure stage unit that realizes the refrigeration function, the low-pressure stage compressor 1-1 passes through the first four-way reversing valve 2-1 The low-pressure steam is sucked from the low-temperature evaporator 6-1, and the working medium is compressed and boosted by the low-pressure stage compressor 1-1 to become a medium-pressure superheated steam, and then passes through the first four-way reversing valve 2- 1. The first check valve 7-1 and the second air inlet 3-2 of the intercooler 3 are discharged into the intercooler 3 for cooling; the high-pressure stage compressor 1-2 in the high-pressure stage compressor unit The medium-pressure saturated steam is inhaled from the air outlet 3-3 of the intercooler 3, and the steam is compressed and boosted by the high-pressure stage compressor 1-2 to become a high-pressure superheated steam, and then enters the condenser 5 to condense into a high-pressure liquid , the high-pressure liquid is throttled and decompressed by the first throttle valve 4-1 to become a medium-pressure wet vapor and enters the intercooler 3 through the liquid inlet 3-4 of the intercooler 3; the intercooler A part of the medium-pressure liquid working medium in the device 3 evaporates and absorbs heat, and cools the medium-pressure superheated vapor coming in from the second air inlet 3-2 of the intercooler 3. The medium-pressure saturated liquid working medium flowing out from the liquid outlet 3-5 of the intercooler 3 is divided into two parts, and a part of the 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 steam coming out of the medium-temperature evaporator 6-2 returns to the storage medium through the first air inlet 3-1 of the intercooler 3 The intercooler 3; the other part of the medium-pressure saturated liquid working fluid coming out of the liquid outlet 3-5 of the intercooler 3 enters the second throttle valve 4- through the second four-way reversing valve 2-2 2. The second throttling valve 4-2 reduces the pressure and turns it into low-pressure wet vapor, which enters the low-temperature evaporator 6-1 to evaporate, absorbs the heat in the low-temperature cold storage, and produces low-temperature refrigeration. From the low-temperature evaporator The low-pressure steam coming out of 6-1 returns to the suction end of the low-pressure stage compressor 1-1 through the first four-way reversing valve 2-1, and completes the secondary throttling and complete cooling of the middle temperature evaporator. stage compression refrigeration cycle.

When the low-temperature evaporator in a low-pressure unit needs to be defrosted, the corresponding low-pressure unit realizes the defrosting function, and the remaining low-pressure units realize the cooling function. The connection interface and thermodynamic cycle process of the first four-way reversing valve 2-1 and the second four-way reversing valve 2-2 in the low-pressure stage unit for realizing the refrigeration function remain unchanged. In the low-pressure stage unit for realizing the defrosting function, the first port of the first four-way reversing valve 2-1 is connected to the second port, the third port is connected to the fourth port, and the second four-way reversing valve 2-1 The first port of the valve 2-2 is connected to the fourth port, and the second port is connected to the third port, so that the low-pressure stage compressor in the low-pressure stage unit realizing the defrosting function is converted into a high-pressure stage compressor. The defrosting thermal process of the low-temperature evaporator in the low-pressure stage unit realizing the defrosting function is as follows: in the low-pressure stage unit realizing the defrosting function, the low-pressure stage compressor 1-1 passes through the first four-way reversing valve 2 -1 and the second one-way valve 7-2 suck medium-pressure saturated steam from the air outlet 3-3 of the intercooler 3, and the steam becomes high-pressure superheated steam after being compressed and boosted by the low-pressure stage compressor 1-1 It is discharged into the low-temperature evaporator 6-1 for condensation, and the low-temperature evaporator 6-1 is heated to cause the defrosting phenomenon of the low-temperature evaporator 6-1. The condensed high-pressure liquid working fluid passes through the second The second throttling valve 4-2 throttles and lowers the pressure to become medium-pressure wet steam, and the wet steam enters the medium-temperature evaporator 6-2 to evaporate through the second four-way reversing valve 2-2, and completes the heat pump cycle using a low-pressure compressor. Defrost, throttling, intercooled, two-stage compression refrigeration cycle with intermediate temperature evaporator.

Example 3

The structural principle diagram of the non-flooded secondary throttling intermediate complete cooling refrigeration system for high-temperature hot gas defrosting in the present invention is shown in Figure 3, including a high-pressure stage compressor unit, a condenser 5, a first throttle valve 4-1, Intercooler 3, third four-way reversing valve 2-3 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. The low-pressure stage unit can be used for refrigeration cycle or defrosting cycle, and each low-pressure stage unit 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 device 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 first four-way The fourth interface of the reversing valve 2-1 is connected, the exhaust end of the low-pressure stage compressor 1-1 is connected to the second interface of the first four-way reversing valve 2-1, and the first four-way The third interface of the reversing 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- The first port of 1 is connected to the first port of the second throttle valve 4-2 through the low-temperature evaporator 6-1; among multiple sets of low-pressure stage units, the first port of the medium-temperature evaporator 6-2 One port is connected in parallel and connected with the first air inlet 3-1 of the intercooler 3, the second port of the second throttle valve 4-2 is connected with the second port of the medium temperature evaporator 6-2 The interfaces are connected in parallel and connected with the liquid outlet 3-5 of the intercooler 3, and the outlet of the first one-way valve 7-1 is connected in parallel and connected with the third four-way reversing valve 2-3 connected to the second interface of the second one-way valve 7-2, and the inlets of the second one-way valve 7-2 are connected in parallel and are respectively connected to the suction end of the high-pressure stage compressor unit and the third port of the third four-way reversing valve 2-3. Interface connection, the first interface of the third four-way reversing valve 2-3 is connected with the second air inlet 3-2 of the intercooler 3, the third four-way reversing valve 2-3 The fourth interface is connected to the air outlet 3-3 of the intercooler 3; the exhaust end of the high-pressure stage compressor unit is connected to the intercooler 3 through the condenser 5, the first throttle valve 4-1 The liquid inlet 3-4 is connected.

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 to realize the refrigeration function. The first port of the third four-way reversing valve 2-3 is connected to the second port, and the third port is connected to the fourth port. In the low-pressure stage unit realizing the refrigeration function, the first port of the first four-way reversing valve 2-1 is connected to the fourth port, and the second port is connected to the third port. The thermodynamic process of the secondary throttling intermediate complete cooling two-stage compression refrigeration cycle with a medium-temperature evaporator is as follows: in the low-pressure stage unit that realizes the refrigeration function, the low-pressure stage compressor 1-1 passes through the first four-way reversing valve 2-1 The low-pressure steam is sucked from the low-temperature evaporator 6-1, and the working medium is compressed and boosted by the low-pressure stage compressor 1-1 to become a medium-pressure superheated steam, and then passes through the first four-way reversing valve 2- 1. The first one-way valve 7-1, the third four-way reversing valve 2-3 and the second air inlet 3-2 of the intercooler 3 enter the intercooler 3 for cooling. The high-pressure stage compressor 1-2 in the high-pressure stage compressor unit sucks medium-pressure saturated steam from the gas outlet 3-3 of the intercooler 3 through the third four-way reversing valve 2-3, and the steam passes through the high-pressure Stage compressor 1-2 is compressed and boosted to become high-pressure superheated steam, and then enters the condenser 5 to be condensed into high-pressure liquid, and the high-pressure liquid is throttled and depressurized by the first throttle valve 4-1 to become medium-pressure wet steam Enter the intercooler 3 through the liquid inlet 3-4 of the intercooler 3; a part of the medium-pressure liquid working medium in the intercooler 3 evaporates and absorbs heat, and cools the second inlet of the intercooler 3 Medium-pressure superheated steam coming in from port 3-2. The medium-pressure saturated liquid working medium coming out of the liquid outlet 3-5 of the intercooler 3 is divided into two parts, and a part of the 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 medium-temperature refrigeration phenomenon, the medium-pressure saturated vapor from the medium-temperature evaporator 6-2 returns to the intercooler 3 through the first air inlet 3-1 of the intercooler 3; the other part The pressure-saturated liquid working medium 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, 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 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 secondary section with the medium-temperature evaporator. The two-stage compression refrigeration cycle is completely cooled in the middle of the flow.

When the low-temperature evaporator of a low-pressure stage unit needs to be defrosted, the corresponding low-pressure stage unit is a defrosting cycle to realize the defrosting function, and the remaining low-pressure stage units are a refrigeration cycle to realize the refrigeration function. The connection interface of the first four-way reversing valve in the low-pressure stage unit realizing the refrigeration function and the refrigeration thermodynamic cycle process remain unchanged. The first port of the third four-way reversing valve 2-3 is connected to the fourth port, and the second port is connected to the third port. In the low-pressure stage unit that realizes the defrosting function, the first port of the first four-way reversing valve 2-1 is connected to the second port, and the third port is connected to the fourth port, so that in the low-pressure stage unit that realizes the defrosting function The low-pressure stage compressor is converted into a high-pressure stage compressor. The defrosting thermal process of the low-temperature evaporator in the defrosting low-pressure stage unit is as follows: in the low-pressure stage unit realizing the defrosting function, the low-pressure stage compressor 1-1 passes through the first four-way reversing valve 2-1 , The second one-way valve 7-2 and the third four-way reversing valve 2-3 suck medium-pressure superheated steam from the exhaust end of the low-pressure stage compressor of the low-pressure stage unit that realizes the refrigeration function, and the steam passes through the defrosting function. The low-pressure stage compressor of the low-pressure stage unit is compressed and boosted to become 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 to generate the low-temperature evaporator 6-1 In the defrosting phenomenon, 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 comes out from the liquid outlet 3-5 of the intercooler 3 The medium-pressure liquid is mixed and mixed into wet vapor, which respectively enters the medium-temperature evaporator 6-2 of all low-pressure stage units and the second throttle valve 4-2 in the low-pressure stage unit that realizes the refrigeration function, and enters the medium-temperature evaporator 6-2 The wet vapor of 2 enters the intercooler 3 through the first air inlet of the intercooler, and the high-temperature hot gas discharged from the low-pressure stage compressor is used to defrost. The secondary throttling intermediate complete cooling and two-stage compression refrigeration with a medium-temperature evaporator are completed. cycle.

Example 4

The structural schematic diagram of the full-liquid type secondary throttling intermediate complete cooling refrigeration system for high-temperature hot gas defrosting of the present invention is shown in Figure 4, including a high-pressure stage compressor unit, a condenser 5, a first throttle valve 4-1, and a second throttling valve 4-1. Three and four-way reversing valves 2-3, 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. The low-pressure stage units can be used for refrigeration cycle or defrosting cycle, and 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. The second throttle valve 4-2, the low-temperature evaporator 6-1, the medium-temperature evaporator 6-2, the first one-way valve 7-1 and the second one-way valve 7-2, the low-pressure stage compressor 1 The suction end of -1 is connected to the fourth interface 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 four-way reversing valve 2-1 1, the third interface of the first four-way reversing valve 2-1 is respectively connected to the inlet of the first one-way valve 7-1 and the outlet of the second one-way valve 7-2 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 through the low-temperature evaporator 6-1, and the second throttle valve The second interface of 4-2 is connected with the second interface of the second four-way reversing valve 2-2; the first interface of the medium temperature evaporator 6-2 is connected in parallel and connected with the intercooler 3 The first air inlet 3-1 is connected, the other end of the medium temperature evaporator 6-2 is connected to the third interface of the second four-way reversing valve 2-2, and the second four-way reversing valve 2 -2, the first port and the fourth port are connected in parallel and connected with the liquid outlet 3-5 of the intercooler 3; the outlet of the first one-way valve 7-1 is connected in parallel and connected with the first The second interface of the three-way reversing valve 2-3 is connected, and the inlets of the second one-way valve 7-2 are connected in parallel and connected with the suction end of the high-pressure stage compressor unit and the third four-way reversing valve respectively. The third interface of the valve 2-3 is connected, the first interface of the third four-way reversing valve 2-3 is connected with the second air inlet 3-2 of the intercooler 3, and the third four-way The fourth interface of the reversing valve 2-3 is connected to the air outlet 3-3 of the intercooler 3; the exhaust end of the high-pressure stage compressor unit passes through the condenser 5 and the first throttle valve 4-1 It is connected with the liquid inlet 3-4 of the intercooler 3 .

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 realize the refrigeration function. The first port of the third four-way reversing valve 2-3 is connected to the second port, the third port is connected to the fourth port, and the first port of the first four-way reversing valve 2-1 is connected to the fourth port. The ports are connected, the second port is connected with the third port, the first port of the second four-way reversing valve 2-2 is connected with the second port, and the third port is connected with the fourth port. The thermal process of the secondary throttling intermediate complete cooling two-stage compression refrigeration cycle with a medium-temperature evaporator is as follows: the low-pressure stage compressor 1-1 passes through the first four-way reversing valve 2-1 from the low-temperature evaporator 6-1 Inhale low-pressure steam, the working medium is compressed and boosted by the low-pressure stage compressor 1-1 to become medium-pressure superheated steam, and then passes through the first four-way reversing valve 2-1, the first one-way valve 7- 1. The third four-way reversing valve 2-3 and the second air inlet 3-2 of the intercooler 3 are discharged into the intercooler 3 for cooling; the high-pressure stage compressor in the high-pressure stage compression group 1-2 Inhale medium-pressure saturated steam from the air outlet 3-3 of the intercooler 3 through the third four-way reversing valve 2-3, and the steam is compressed and boosted by the high-pressure stage compressor 1-2 to become high pressure The superheated steam is discharged into the condenser 5 and condensed into a high-pressure liquid, and the high-pressure liquid is throttled and depressurized by the first throttle valve 4-1 to become a medium-pressure wet steam that passes through the liquid inlet of the intercooler 3 Ports 3-4 enter 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 second air inlet 3-2 of the intercooler 3 . The medium-pressure saturated liquid working medium coming out of the liquid outlet 3-5 of the intercooler 3 is divided into two parts, and a part of the medium-pressure saturated liquid working medium enters the medium-temperature evaporator through the second four-way reversing valve 2-2 6-2 Evaporation, absorbing the heat in the medium-temperature cold storage to produce medium-temperature refrigeration phenomenon, the medium-pressure saturated steam from the medium-temperature evaporator 6-2 passes through the first air inlet 3-1 of the intercooler 3 to the intercooler 3; the other part of the medium-pressure saturated liquid working fluid coming out of the liquid outlet 3-5 of the intercooler 3 passes through the second four-way reversing valve 2-2 and the second throttle valve 4-2 throttling and decompression into low-pressure wet 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 Return to the suction end of the low-pressure stage compressor 1-1 through the first four-way reversing valve 2-1 to complete a two-stage compression refrigeration cycle with secondary throttling and intermediate complete cooling with a medium temperature evaporator.

When the low-temperature evaporator in a low-pressure unit needs to be defrosted, the corresponding low-pressure unit realizes the defrosting function, and the remaining low-pressure units realize the cooling function. The connection interface and thermodynamic cycle of the first four-way reversing valve and the second four-way reversing valve in the low-pressure stage unit realizing the refrigeration function remain unchanged. The first port of the third four-way reversing valve 2-3 is connected to the fourth port, and the second port is connected to the third port. In the defrosting low-pressure stage unit, the first port of the first four-way reversing valve 2-1 is connected to the second port, the third port is connected to the fourth port, and the second four-way reversing valve 2-2 is One interface is connected to the fourth interface, and the second interface is connected to the third interface, so that the low-pressure compressor in the low-pressure unit realizing the defrosting function is converted into a high-pressure compressor. 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 in the defrosting low-pressure stage unit passes through the first four-way reversing valve 2-1, the second one-way The valve 7-2 and the third four-way reversing valve 2-3 suck medium-pressure superheated steam from the exhaust end of the low-pressure compressor 1-1 of the low-pressure unit that realizes the refrigeration function, and the steam passes through the low-pressure compressor 1 -1 after being compressed and boosted, it becomes high-pressure superheated vapor, which is discharged into the low-temperature evaporator 6-1 to condense, 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 wet steam enters the low-pressure stage unit that realizes the defrosting function through the second four-way reversing valve 2-2 The medium-temperature evaporator 6-2 evaporates, and then, together with the working fluid discharged from the medium-temperature evaporator in the low-pressure stage unit that realizes the refrigeration function, enters the intercooler 3 through the first air inlet 3-1 of the intercooler, and completes the adoption of The high-temperature hot gas discharged from the low-pressure stage compressor is defrosted, and there is a secondary throttle with a medium-temperature evaporator, and the middle is fully cooled. Two-stage compression refrigeration cycle.

Wherein, the low-temperature compressor and the high-temperature compressor may be 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 evaporator is 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, the second four-way reversing valve and the third four-way reversing valve are prior art. In the system, electromagnetic valves, Hand valve, three-way reversing valve 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. the operation method of double-stage compressive refrigerating system completely cooling among a kind of second throttle, which is characterized in that each Medium temperature evaporator and cryogenic vaporizer are set in low-pressure stage unit, and the medium temperature evaporator freezes for realizing medium temperature, described low Warm evaporator includes the following steps for realizing cryogenic refrigeration or defrosting, the operation method：It realizes and makes when all low-pressure stage units When cold function, middle pressure saturated liquid working medium is flashed to middle pressure saturated vapor by the medium temperature evaporator, realizes medium temperature refrigeration；It is described Low pressure liquid working medium is flashed to low-pressure steam by cryogenic vaporizer, realizes cryogenic refrigeration；When there is cryogenic vaporizer to need defrosting, By valve transfer, realizes that the low-pressure stage compressor of defrosting function is converted into high pressure stage compressor operation, realize defrosting function Low-pressure stage compressor in low-pressure stage unit absorb pressed through in the low-pressure stage compressor for realizing refrigerating function heat steam or Middle pressure saturated vapor from intercooler, is sent into the cryogenic vaporizer to be defrosted after compression, this is low for condensation heating Warm evaporator realizes defrosting, realizes that the cryogenic vaporizer in the low-pressure stage unit of refrigerating function still realizes refrigerating function； It waits after defrosting, realizes that the low-pressure stage unit of defrosting function by valve transfer, realizes refrigerating function.

2. completely cooling system among a kind of second throttle using Defrost for realizing operation method described in claim 1 Cooling system, which is characterized in that including high pressure stage compressor group, condenser, first throttle valve, intercooler and multigroup low-pressure stage Unit；Each low-pressure stage unit include low-pressure stage compressor, the first four-way reversing valve, second throttle, cryogenic vaporizer, Medium temperature evaporator, the first check valve and the second check valve, the suction end of the low-pressure stage compressor commutate with first four-way 4th interface of valve connects, and the exhaust end of the low-pressure stage compressor is connect with the second interface of first four-way reversing valve, The third interface of first four-way reversing valve respectively with the import of first check valve and the outlet of second check valve Connection, the first interface of first four-way reversing valve are connect by the cryogenic vaporizer and the first of the second throttle Mouth connection, in multigroup low-pressure stage unit, the second interface of the second throttle and the second of the medium temperature evaporator Interface is connected in parallel and is connect with the liquid outlet of the intercooler, and the first interface of the medium temperature evaporator is connected in parallel on one Rise and connect with the first air inlet of the intercooler, the outlet of first check valve be connected in parallel after with it is described in Between cooler the connection of the second air inlet, the inlet parallel of second check valve compresses with the hiigh pressure stage together and respectively The gas outlet of the suction end of unit and the intercooler connects；The exhaust end of the high pressure stage compressor group is through the condensation Device, first throttle valve are connect with the inlet of the intercooler.

3. refrigeration system completely cooling among second throttle according to claim 2, which is characterized in that the hiigh pressure stage Compressor set includes one or more high pressure stage compressor, when using more high pressure stage compressors, every hiigh pressure stage pressure Suction end of the air-breathing interface parallel connection of contracting machine as the high pressure stage compressor group, the exhaust of every high pressure stage compressor connect The mouth exhaust end in parallel as the high pressure stage compressor group.

4. refrigeration system completely cooling among second throttle according to claim 2, which is characterized in that the low-pressure stage The quantity at least three of unit.

5. completely cooling refrigeration system, feature among a kind of second throttle for realizing operation method described in claim 1 It is, including high pressure stage compressor group, condenser, first throttle valve, intercooler and multigroup low-pressure stage unit；It is each described Low-pressure stage unit includes low-pressure stage compressor, the first four-way reversing valve, the second four-way reversing valve, second throttle, low-temperature evaporation Device, medium temperature evaporator, the first check valve and the second check valve, the suction end of the low-pressure stage compressor are changed with first four-way It is connected to the 4th interface of valve, the exhaust end of the low-pressure stage compressor and the second interface of first four-way reversing valve connect It connects, the third interface of first four-way reversing valve goes out with the import of first check valve and second check valve respectively Mouth connection, first interface of the first interface through the cryogenic vaporizer Yu the second throttle of first four-way reversing valve Connection, the second interface of the second throttle are connect with the second interface of second four-way reversing valve, the medium temperature evaporation The second interface of device is connect with the third interface of second four-way reversing valve, in multigroup low-pressure stage unit, in described The first interface of warm evaporator is connected in parallel and is connect with the first air inlet of the intercooler, and second four-way changes It is connected in parallel with the 4th interface to the first interface of valve and is connect with the liquid outlet of the intercooler；Described first is unidirectional The outlet of valve is connected in parallel and is connect with the second air inlet of the intercooler, the inlet parallel of second check valve It is connect together and respectively with the gas outlet of the suction end of the high pressure stage compressor group and the intercooler；The high pressure The exhaust end of grade compressor set is connect through the condenser, first throttle valve with the inlet of the intercooler.

6. completely cooling refrigeration system, feature among a kind of second throttle for realizing operation method described in claim 1 It is, including high pressure stage compressor group, condenser, first throttle valve, intercooler, third four-way reversing valve and multiple low pressure Grade unit；Each low-pressure stage unit include low-pressure stage compressor, the first four-way reversing valve, second throttle, cryogenic vaporizer, in Warm evaporator, the first check valve and the second check valve, the suction end of the low-pressure stage compressor and first four-way reversing valve The connection of the 4th interface, the exhaust end of the low-pressure stage compressor connect with the second interface of first four-way reversing valve, institute The third interface for stating the first four-way reversing valve connects with the import of first check valve and the outlet of second check valve respectively It connects, the first interface of first four-way reversing valve connects through the first interface of the cryogenic vaporizer and the second throttle It connects；In multigroup low-pressure stage unit, the first interface of the medium temperature evaporator be connected in parallel and with the intercooler The first air inlet connection, the second interface of the second throttle and the second interface of the medium temperature evaporator are connected in parallel And connect with the liquid outlet of the intercooler, the outlet of first check valve be connected in parallel and with the third four-way The second interface of reversal valve connects, the inlet parallel of second check valve together and respectively with the high pressure stage compressor group Suction end and connect with the third interface of the third four-way reversing valve, the first interface of the third four-way reversing valve with it is described Second air inlet of intercooler connects, the outlet of the 4th interface and the intercooler of the third four-way reversing valve Mouth connection；The exhaust end of the high pressure stage compressor group through the condenser, first throttle valve and the intercooler into Liquid mouth connects.

7. completely cooling refrigeration system, feature among a kind of second throttle for realizing operation method described in claim 1 It is, including high pressure stage compressor group, condenser, first throttle valve, third four-way reversing valve, intercooler and multiple low pressure Grade unit；Each low-pressure stage unit includes low-pressure stage compressor, the first four-way reversing valve, the second four-way reversing valve, second Throttle valve, cryogenic vaporizer, medium temperature evaporator, the first check valve and the second check valve, the suction end of the low-pressure stage compressor It is connect with the 4th interface of first four-way reversing valve, the exhaust end of the low-pressure stage compressor commutates with first four-way The second interface of valve connects, the third interface of first four-way reversing valve respectively with the import of first check valve and described The outlet of second check valve connects, and the first interface of first four-way reversing valve is saved through the cryogenic vaporizer and described second The connection of valve first interface is flowed, the second interface of the second throttle is connect with the second interface of second four-way reversing valve； The first interface of the medium temperature evaporator is connected in parallel and is connect with the first air inlet of the intercooler, the medium temperature The other end of evaporator is connect with the third interface of second four-way reversing valve, the first interface of second four-way reversing valve And the 4th interface be connected in parallel and connect with the liquid outlet of the intercooler；The outlet of first check valve is connected in parallel on Connect together and with the second interface of the third four-way reversing valve, the inlet parallel of second check valve together and respectively It is connect with the third interface of the high pressure stage compressor group suction end and the third four-way reversing valve, the third four-way commutation The first interface of valve is connect with the second air inlet of the intercooler, the 4th interface of the third four-way reversing valve with it is described The gas outlet of intercooler connects；The exhaust end of the high pressure stage compressor group is through the condenser, first throttle valve and institute State the inlet connection of intercooler.