A hot liquid defrosting system and defrosting method

Abstract

The present invention relates to a hot liquid defrosting system and a defrosting method. A hot liquid defrosting system of the present invention comprises a compressor, a first reversing valve, a condenser, a liquid storage, a low-pressure circulation barrel and a second reversing valve which are sequentially connected through pipelines; the low-pressure circulation barrel is connected to a circulation pump, the circulation pump is connected to a gas-liquid mixer, the gas-liquid mixer is connected to an evaporator, the evaporator is connected to a low-pressure circulation barrel, and the air inlet port of the gas-liquid mixer is connected to the second reversing valve. Its beneficial effect is that only one gas-liquid mixer is added, and the system reversal of the refrigeration cycle and the defrosting cycle is realized by a reversing valve, so that defrosting can be realized, and a gas-liquid two-phase mixing conveyor is used to mix the hot gas with the liquid in the low-pressure circulation barrel into a medium-temperature liquid and then send it to each terminal evaporator for heat exchange and defrosting. The process does not need to be switched through complex valves, and the whole process is simple and reliable, with little impact on the system pipelines or valves, and is safe and efficient.

Description

Technical Field

[0001] The invention relates to the field of refrigeration, and in particular to a hot liquid defrosting system and a defrosting method. Background Art

[0002] At present, most cold storage refrigeration systems use a large temperature difference cooling method, and the temperature difference between the evaporation temperature and the storage temperature is 10-15℃. This operation causes the terminal evaporator to frost quickly, and frequent defrosting operations are required. Therefore, the defrosting system and corresponding methods and control logic of the terminal evaporator under low temperature conditions have always been a major difficulty in the refrigeration industry. There are three traditional defrosting methods: electric defrosting, hot water spray defrosting, and hot gas defrosting. Under the technical ideas of safety and energy saving, the hot gas defrosting method has been increasingly used for its efficient defrosting effect. In actual engineering applications, in order to make hot gas defrosting safe and efficient, there are three hot gas defrosting methods: three-pipe defrosting method and four-pipe defrosting method. However, these two methods require separate hot gas inlet pipelines, defrost return pipelines and multiple control valves. There are too many valves used, complex control, many welds, high failure rate, and difficult troubleshooting and maintenance. During hot gas defrosting, hot gas at 70-120℃ directly enters the evaporator. Due to the small specific heat capacity of gas, when the pipe diameter is determined, a very high gas flow rate is required to meet the heat required for defrosting. If the defrosting process control program is not operated properly, the high-pressure and high-speed gas will press the remaining liquid to quickly impact the pipeline or valve, causing pipeline shaking, abnormal sound, and even pipeline leakage, valve core damage, liquid explosion or liquid impact in severe cases. Furthermore, frequent hot gas defrosting in the warehouse will cause leakage at the valve body weld, and repeated thermal expansion and contraction will seriously damage the close contact between the pipeline and the fin, resulting in a series of adverse consequences such as reduced efficiency of the air cooler and large temperature fluctuations in the warehouse. Summary of the invention

[0003] The object of the present invention is to overcome the deficiencies of the prior art and to provide a hot liquid defrosting system and defrosting method with simple system piping, simple control and greatly reduced number of valves used.

[0004] The present invention provides a hot liquid defrosting system, and its technical solution is as follows:

[0005] A hot liquid defrosting system comprises a compressor, a first reversing valve, a condenser, a liquid storage device, a low-pressure circulation barrel and a second reversing valve which are sequentially connected through a pipeline; the low-pressure circulation barrel is connected to a circulation pump, the circulation pump is connected to a gas-liquid mixer, the gas-liquid mixer is connected to an evaporator, the evaporator is connected to the low-pressure circulation barrel, and the air inlet port of the gas-liquid mixer is connected to the second reversing valve.

[0006] Preferably, the first reversing valve is a four-way reversing valve.

[0007] Preferably, the second reversing valve is a three-way reversing valve.

[0008] Preferably, a relief valve and an electronic expansion valve are arranged in parallel on the pipeline between the condenser and the liquid receiver.

[0009] Preferably, a solenoid valve is provided between the liquid reservoir and the low-pressure circulation barrel.

[0010] Preferably, the evaporator is a ceiling fan.

[0011] Preferably, the evaporator is a heat exchange tube.

[0012] Preferably, the gas-liquid mixer comprises a liquid refrigerant inlet, a gas refrigerant inlet and a gas-liquid outlet.

[0013] Preferably, the condenser is a flash condenser, comprising a shell, a negative pressure fan and a heat exchange unit, wherein the negative pressure fan is arranged on the top of the shell to form a negative pressure in the shell; a plurality of heat exchange units are arranged in the shell in a stacked manner, the heat exchange unit comprising a water atomizer, a plurality of rows of coils for circulating refrigerant and fins for fixing the plurality of rows of coils, the plurality of rows of coils and the fins are fixed by a fixing frame, the refrigerant flows in from the inlet end and is discharged from the outlet end; the plurality of rows of coils of the plurality of heat exchange units are connected in series or in parallel; the water atomizer is connected to a water source to atomize water.

[0014] A hot liquid defrosting method comprises the following steps: connecting the exhaust end of a compressor to the gas refrigerant inlet of a gas-liquid mixer by controlling a first reversing valve and a second reversing valve; a circulating pump mixes the refrigerant liquid in a low-pressure circulation barrel with the high-temperature gas generated at the exhaust end of the compressor in the gas-liquid mixer to form a medium-temperature liquid, which is then sent to each terminal evaporator for heat exchange and defrosting; the low-temperature refrigerant medium after defrosting returns to the low-pressure circulation barrel, and then passes through a solenoid valve, a liquid storage device, and an electronic expansion valve in sequence to enter a condenser for heat exchange; the refrigerant then passes through the first reversing valve to enter the air inlet end of the compressor, thus forming a defrosting cycle.

[0015] The implementation of the present invention includes the following technical effects:

[0016] The hot liquid defrosting system of the present invention only adds a gas-liquid mixer, and then realizes the system reversal of the refrigeration cycle and the defrosting cycle through the reversing valve, so that defrosting can be achieved. A gas-liquid two-phase mixing conveyor is used to mix the hot gas with the low-pressure circulation barrel liquid into a medium-temperature liquid (10-30°C) and then send it to each terminal evaporator for heat exchange and defrosting. This process does not need to be switched through complex valves, and the whole process is simple, reliable, safe and efficient. Compared with the existing three-pipe defrosting method and the four-pipe defrosting method, there is no need to add control valves, the control is simple, troubleshooting and maintenance are easy, and the failure rate is low. The hot liquid defrosting method of gas-liquid mixing takes advantage of the large specific heat capacity of liquid, the temperature difference of defrosting is small, the damage caused by thermal expansion and contraction to the close contact between the pipeline and the fin is reduced, and the temperature fluctuation in the warehouse can also be reduced. The defrosting method of the present invention has little impact on the system pipeline or valve, and no liquid explosion or liquid shock will occur. The system is safe to use and has a long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the connection system of the hot liquid defrosting system in the refrigeration mode according to an embodiment of the present invention.

[0018] Figure 2 Schematic diagram of the connection system of the hot liquid defrosting system in the defrosting mode according to an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of the flash condenser structure.

[0020] In the figure: 1. compressor; 2. first reversing valve; 3. condenser; 30. shell; 31. negative pressure fan; 32. heat exchange unit; 33. water atomizer; 4. overflow valve; 5. electronic expansion valve; 6. liquid storage tank; 7. solenoid valve; 8. low-pressure circulation barrel; 9. circulation pump; 10. gas-liquid mixer; 11. evaporator; 12. second reversing valve. DETAILED DESCRIPTION

[0021] The present invention will be described in detail below in conjunction with embodiments and drawings. It should be pointed out that the described embodiments are only intended to facilitate the understanding of the present invention and do not have any limiting effect on the present invention.

[0022] See also Figure 1 and Figure 2 As shown, a hot liquid defrosting system provided in this embodiment includes a compressor 1, a first reversing valve 2, a condenser 3, a liquid reservoir 6, a low-pressure circulation barrel 8 and a second reversing valve 12 which are sequentially connected through pipelines; the low-pressure circulation barrel 8 is connected to a circulation pump 9, the circulation pump 9 is connected to a gas-liquid mixer 10, the gas-liquid mixer 10 is connected to an evaporator 11, the evaporator 11 is connected to the low-pressure circulation barrel 8, and the air inlet port of the gas-liquid mixer 10 is connected to the second reversing valve 12.

[0023] See also Figure 1As shown, in the refrigeration mode, the exhaust end of the compressor 1 is connected to the condenser 3 through the first reversing valve 2, and the condenser 3 condenses the high-temperature refrigerant into liquid. The liquid refrigerant flows into the liquid reservoir 6 through the overflow valve 4, and the liquid refrigerant in the liquid reservoir 6 flows into the low-pressure circulation barrel 8 through the solenoid valve 7. The liquid refrigerant in the low-pressure circulation barrel 8 flows through the evaporator 11 through the circulation pump 9 and the gas-liquid mixer 10. After evaporation and refrigeration, the refrigerant returns to the low-pressure circulation barrel 8. The refrigerant gas in the low-pressure circulation barrel 8 returns to the suction end of the compressor 1 after passing through the second reversing valve 12 and the first reversing valve 2, forming a refrigeration cycle. In the refrigeration mode, the connection between the gas-liquid mixer 10 and the second reversing valve 12 is not conductive, that is, the gas-liquid mixer 10 does not take in air, and only plays the role of circulating liquid refrigerant.

[0024] See also Figure 2 As shown, in the defrost mode, the exhaust end of the compressor 1 is connected to the gas-liquid mixer 10 through the first reversing valve 2 and the second reversing valve 12, and the circulating pump 9 mixes the refrigerant liquid and the high-temperature gas generated at the exhaust end of the compressor 1 into a medium-temperature liquid (10-30°C) in the gas-liquid mixer 10 and then sends them to each terminal evaporator 11 for heat exchange and defrosting. The low-temperature refrigerant medium after defrosting returns to the low-pressure circulation barrel 8, and then passes through the solenoid valve 7, the liquid storage tank 6, and the electronic expansion valve 5 in sequence to enter the condenser 3 for heat exchange, and then enters the air inlet end of the compressor 1 through the first reversing valve 2, forming a defrost cycle.

[0025] Specifically, the first reversing valve 2 is a four-way reversing valve, which realizes reversing when the refrigeration cycle is switched to the defrost cycle. The second reversing valve 12 is a three-way reversing valve, which realizes reversing when the refrigeration cycle is switched to the defrost cycle. An overflow valve 4 and an electronic expansion valve 5 are arranged in parallel on the pipeline between the condenser 3 and the liquid reservoir 6. The function of the overflow valve 4 is to introduce the refrigerant liquid condensed by the condenser 3 into the liquid reservoir 6 under set pressure conditions. In the refrigeration cycle mode, the electronic expansion valve 5 can be opened or closed, but in the defrost cycle mode, the electronic expansion valve 5 is opened to ensure the defrost cycle. The overflow valve 4 can only flow in one direction and has a pressure regulating function, which can keep the pressure in the system within an appropriate range at all times, ensuring efficient operation of the system. The electronic expansion valve 5 has a throttling and pressure reduction function. A solenoid valve 7 is arranged between the liquid reservoir 6 and the low-pressure circulation barrel 8 to control the flow between the liquid reservoir 6 and the low-pressure circulation barrel 8. The evaporator 11 is a ceiling fan or a heat exchange exhaust pipe. See Figure 2 As shown, the gas-liquid mixer 10 includes a liquid refrigerant inlet, a gas refrigerant inlet and a gas-liquid outlet. The high-pressure gas and the low-temperature liquid quickly complete gas-liquid mixing under the action of pressure to obtain a gas-liquid mixture of corresponding temperature, which can improve the gas-liquid production efficiency, simplify the production device, save space, greatly reduce investment, and save operating costs and maintenance costs.

[0026] The hot liquid defrosting system of the present invention only adds a gas-liquid mixer 10, and then realizes the system reversal of the refrigeration cycle and the defrosting cycle through the reversing valve, so that defrosting can be realized. The gas-liquid two-phase mixing conveyor is used to mix the hot gas with the liquid in the low-pressure circulation barrel 8 into a medium-temperature liquid (10-30°C) and then send it to each terminal evaporator 11 for heat exchange and defrosting. This process does not need to be switched through complex valves. The whole process is simple, reliable, safe and efficient. Compared with the existing three-pipe defrosting method and the four-pipe defrosting method, there is no need to add too many control valves, the control is simple, troubleshooting and maintenance are easy, and the failure rate is low. The hot liquid defrosting method of gas-liquid mixing takes advantage of the large specific heat capacity of liquid, the temperature difference of defrosting is small, the damage caused by thermal expansion and contraction to the close contact between the pipeline and the fin is reduced, and the temperature fluctuation in the warehouse can also be reduced. The defrosting method of the present invention has little impact on the system pipeline or valve, and no liquid explosion or liquid shock phenomenon will occur. The system is safe to use and has a long service life.

[0027] As an example, see Figure 3 As shown, the condenser 3 is a flash condenser, including a shell 30, a negative pressure fan 31 and a heat exchange unit 32. The negative pressure fan 31 is arranged on the top of the shell 30 to form a negative pressure in the shell 30; multiple heat exchange units 32 are arranged in the shell 30 in a stacked manner, and the heat exchange unit 32 includes a water atomizer 33, multiple rows of coils for circulating refrigerant, and fins for fixing the multiple rows of coils. The multiple rows of coils and the fins are fixed by a fixing frame, and the refrigerant flows in from the inlet end and is discharged from the outlet end; the multiple rows of coils of multiple heat exchange units 32 are connected in series or in parallel; the water atomizer 33 is connected to a water source to atomize water. The atomized water permeates the inner cavity of the shell 30. Under the action of negative pressure, the liquid micro-groups and the refrigerant in the multiple rows of coils complete radiation heat exchange and are then drawn out of the shell 30 by the negative pressure fan 31. During cooling, the water micro-clusters in the cavity absorb the radiant heat of the refrigerant circulating in the multiple rows of coils and gradually decompose from large micro-clusters into small micro-clusters to take away the heat, condensing and liquefying the refrigerant. The water micro-clusters are dynamically and continuously decomposed into small water micro-clusters to take away the heat. The water vapor after heat exchange is not circulated or recycled, but is directly discharged into the atmosphere. Since the heat is mainly converted into internal energy during the decomposition of the water micro-clusters, the temperature of the discharged water vapor is not high and will not produce a heat island effect. The stacking of multiple heat exchange units 32 is convenient for installation and maintenance. When a heat exchange unit 32 is broken, the broken repair unit can be disassembled for repair or replacement. Compared with the existing air-cooled heat exchanger, the flash condenser performs heat exchange in the shell 30, and almost no air is introduced. When the outside temperature and humidity are high, the heat exchange effect will not be affected by the temperature and humidity of the outside natural wind. During defrosting, the condenser plays a role in heating.

[0028] The present embodiment also provides a hot liquid defrosting method, comprising the following steps: connecting the exhaust end of the compressor 1 to the gas refrigerant inlet of the gas-liquid mixer 10 by controlling the first reversing valve 2 and the second reversing valve 12; the circulating pump 9 mixes the refrigerant liquid in the low-pressure circulation barrel 8 with the high-temperature gas generated at the exhaust end of the compressor 1 in the gas-liquid mixer 10 to form a medium-temperature liquid, and then sends it to each terminal evaporator 11 for heat exchange and defrosting. The low-temperature refrigerant medium after defrosting returns to the low-pressure circulation barrel 8, and then passes through the solenoid valve 7, the liquid storage tank 6, and the electronic expansion valve 5 in sequence to enter the condenser 3 for heat exchange, and the refrigerant then passes through the first reversing valve 2 to enter the air inlet end of the compressor 1, forming a defrosting cycle.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A hot liquid defrosting system, comprising a compressor, a first reversing valve, a condenser, a liquid storage, a low-pressure circulation barrel and a second reversing valve connected in sequence through a pipeline; characterized in that: The low-pressure circulation barrel is connected to a circulation pump, the circulation pump is connected to a gas-liquid mixer, the gas-liquid mixer is connected to an evaporator, the evaporator is connected to a low-pressure circulation barrel, and an air inlet port of the gas-liquid mixer is connected to a second reversing valve; the first reversing valve is a four-way reversing valve, and the second reversing valve is a three-way reversing valve; The compressor exhaust end is connected to the gas refrigerant inlet of the gas-liquid mixer by controlling the first reversing valve and the second reversing valve; the circulating pump mixes the refrigerant liquid in the low-pressure circulation barrel with the high-temperature gas generated at the compressor exhaust end into a medium-temperature liquid in the gas-liquid mixer, and then sends it to each terminal evaporator for heat exchange and defrosting. The low-temperature refrigerant medium after defrosting returns to the low-pressure circulation barrel, and then passes through the solenoid valve, liquid receiver, and electronic expansion valve in sequence to enter the condenser for heat exchange. The refrigerant then passes through the first reversing valve into the compressor intake end, forming a defrost cycle.

2. A hot liquid defrosting system according to claim 1, characterized in that: A relief valve and an electronic expansion valve are arranged in parallel on the pipeline between the condenser and the liquid storage device.

3. A hot liquid defrosting system according to claim 1, characterized in that: A solenoid valve is arranged between the liquid storage tank and the low-pressure circulation barrel.

4. A hot liquid defrosting system according to claim 1, characterized in that: The evaporator is a ceiling fan.

5. A hot liquid defrosting system according to claim 1, characterized in that: The evaporator is a heat exchange tube.

6. A hot liquid defrosting system according to claim 1, characterized in that: The gas-liquid mixer comprises a liquid refrigerant inlet, a gas refrigerant inlet and a gas-liquid outlet.

7. A hot liquid defrosting system according to any one of claims 1 to 6, characterized in that: The condenser is a flash condenser, comprising a shell, a negative pressure fan and a heat exchange unit. The negative pressure fan is arranged on the top of the shell to form a negative pressure in the shell. Multiple heat exchange units are arranged in the shell in a stacked manner. The heat exchange unit comprises a water atomizer, multiple rows of coils for circulating refrigerant and fins for fixing the multiple rows of coils. The multiple rows of coils and the fins are fixed by a fixing frame. The refrigerant flows in from the inlet end and is discharged from the outlet end. The multiple rows of coils of the multiple heat exchange units are connected in series or in parallel. The water atomizer is connected to a water source to atomize water.

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