CN111536723A - Defrosting method and device for secondary condensation and supercooling of main path refrigerant - Google Patents
Defrosting method and device for secondary condensation and supercooling of main path refrigerant Download PDFInfo
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- CN111536723A CN111536723A CN202010458378.1A CN202010458378A CN111536723A CN 111536723 A CN111536723 A CN 111536723A CN 202010458378 A CN202010458378 A CN 202010458378A CN 111536723 A CN111536723 A CN 111536723A
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- 239000003507 refrigerant Substances 0.000 title claims abstract description 230
- 238000010257 thawing Methods 0.000 title claims abstract description 144
- 238000009833 condensation Methods 0.000 title claims abstract description 37
- 230000005494 condensation Effects 0.000 title claims abstract description 37
- 238000004781 supercooling Methods 0.000 title claims abstract description 33
- 238000000034 method Methods 0.000 title claims abstract description 32
- 239000007788 liquid Substances 0.000 claims abstract description 98
- 238000001704 evaporation Methods 0.000 claims abstract description 59
- 239000000203 mixture Substances 0.000 claims abstract description 24
- 238000005057 refrigeration Methods 0.000 claims description 63
- 230000008020 evaporation Effects 0.000 claims description 50
- 238000001816 cooling Methods 0.000 claims description 34
- 238000010521 absorption reaction Methods 0.000 claims description 15
- 230000007246 mechanism Effects 0.000 claims description 12
- 238000002844 melting Methods 0.000 claims description 7
- 230000008018 melting Effects 0.000 claims description 7
- 230000015572 biosynthetic process Effects 0.000 claims description 2
- 230000001105 regulatory effect Effects 0.000 claims 1
- 230000008569 process Effects 0.000 description 13
- 230000000694 effects Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- 238000005265 energy consumption Methods 0.000 description 3
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000004069 differentiation Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
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- 230000004048 modification Effects 0.000 description 1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B47/00—Arrangements for preventing or removing deposits or corrosion, not provided for in another subclass
- F25B47/02—Defrosting cycles
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B39/00—Evaporators; Condensers
- F25B39/02—Evaporators
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B40/00—Subcoolers, desuperheaters or superheaters
- F25B40/02—Subcoolers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B5/00—Compression machines, plants or systems, with several evaporator circuits, e.g. for varying refrigerating capacity
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2347/00—Details for preventing or removing deposits or corrosion
- F25B2347/02—Details of defrosting cycles
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Abstract
The invention discloses a defrosting method and a defrosting device for secondary condensation and supercooling of a main path refrigerant, wherein the defrosting method comprises the following steps: diverting the liquid refrigerant formed after condensation to a first cooler; the liquid refrigerant is evaporated and absorbs heat in the first cooler and is converted into a vapor-liquid mixture refrigerant or a gas refrigerant; the vapor-liquid mixture refrigerant or the gas refrigerant is conveyed to an evaporator to be defrosted, and heat is released to melt frosting on the evaporator; the defrosted refrigerant is conveyed to a second cooler, and is evaporated and absorbed in the second cooler to supercool the refrigerant in the main refrigerating pipeline; the refrigerant after evaporating and absorbing heat is conveyed back to the compressor. According to the invention, a vapor-liquid mixture refrigerant or a gas refrigerant formed after a liquid refrigerant evaporates and absorbs heat in the first cooler is used as a defrosting medium to melt frosting on the evaporator, and the defrosted refrigerant is adopted to supercool the refrigerant in the main refrigerating pipeline, so that the refrigerating capacity of the refrigerating system is effectively improved.
Description
Technical Field
The invention relates to a defrosting technology of a refrigerating system, in particular to a defrosting method and a defrosting device for secondary condensation and supercooling of a main path refrigerant.
Background
In a refrigerating system, when a refrigerating unit carries out refrigerating work with an evaporation temperature device lower than 0 ℃, a frosting phenomenon often occurs, so that the heat exchange efficiency of an evaporator is reduced, and the refrigerating efficiency of the unit is reduced.
The existing defrosting modes mainly comprise refrigerant defrosting and non-refrigerant defrosting. The refrigerant defrosting mainly comprises superheated gas defrosting, liquid defrosting and gas-liquid mixed defrosting. The existing method for obtaining the defrosting refrigerant by compressing and then depressurizing increases energy consumption. The defrosting is carried out by mixing liquid refrigerant or vapor and liquid for defrosting, although the same problem as that of superheated gas defrosting does not exist, the specific enthalpy of defrosting is small, the required flow is large, the defrosting efficiency is low, the time required for single defrosting is long, and the defrosting time interval is short. The defrosting medium for liquid defrosting is mainly a high-pressure liquid refrigerant formed by condensing gas through a condenser; the vapor-liquid mixed defrosting refrigerant is directly throttled by the liquid refrigerant, and is not subjected to heating treatment, and has equal enthalpy with the high-pressure liquid refrigerant of the liquid defrosting only for reducing the temperature and the pressure of defrosting.
Further, in a common defrosting process, when a defrosting medium passes through an evaporator, heat is released to defrost, and the defrosting medium is often led into the evaporator to perform evaporation refrigeration. For example, in a continuous defrosting system, the defrosted refrigerant is sent to an evaporator (non-defrosted evaporator) that is cooling to absorb heat by evaporation; in the discontinuous defrosting system, the liquid can be stored temporarily, and the evaporator can be randomly selected to realize evaporation, and can be the evaporator which just completes the defrosting process. The defrosted refrigerant enters a refrigerating evaporator to cool a cooling object, and the evaporating temperature is required to be lower than the temperature of a cooled object, so that the refrigerating capacity of the defrosted refrigerant is not fully utilized, and the refrigerating capacity is small.
Disclosure of Invention
The invention aims to overcome the existing problems and provides a defrosting method for secondary condensation and supercooling a main path refrigerant, which takes a vapor-liquid mixture refrigerant or a gas refrigerant formed after a liquid refrigerant is evaporated and absorbs heat in a first cooler as a defrosting medium to melt frosting on an evaporator, so that the defrosting method has the advantages of easy control, higher defrosting efficiency and the like and can effectively improve the refrigerating capacity of a refrigerating system; and the refrigerant in the main refrigerating pipeline is supercooled by the defrosted refrigerant, so that the heat absorption capacity of the refrigerant in the main refrigerating pipeline is improved, the refrigerating capacity of the system is increased, and the defrosting mode is continuous defrosting.
It is another object of the present invention to provide a defrosting apparatus that secondarily condenses and supercools a main path refrigerant.
The purpose of the invention is realized by the following technical scheme:
a defrosting method for secondary condensation and subcooling of a main path refrigerant comprising the steps of:
the liquid refrigerant formed after the condenser is condensed is shunted to the first cooler through a shunting pipeline; the liquid refrigerant is evaporated and absorbs heat in the first cooler and is converted into a vapor-liquid mixture refrigerant or a gas refrigerant; delivering a vapor-liquid mixture refrigerant or a gas refrigerant to an evaporator to be defrosted through a defrosting pipeline, wherein the vapor-liquid mixture refrigerant or the gas refrigerant is used as a defrosting medium to release heat to melt frosting on the evaporator; the defrosted refrigerant is conveyed to a second cooler, the defrosted refrigerant is evaporated in the second cooler to absorb heat, and the refrigerant in the main refrigerating pipeline is supercooled, wherein the evaporation temperature in the second cooler is higher than that of an evaporator which is refrigerating; and conveying the gas refrigerant which finishes the supercooling work back to the compressor for circulating work.
The working principle of the defrosting method for performing secondary condensation and supercooling on the main path refrigerant is as follows:
when the refrigeration system works, the compressor compresses low-temperature and low-pressure gas refrigerant into high-temperature and high-pressure gas refrigerant through compression work, the high-temperature and high-pressure gas refrigerant is converted into liquid refrigerant after being condensed by the condenser, and then the liquid refrigerant is conveyed to the refrigeration evaporator through the refrigeration main pipeline. In the process, the liquid refrigerant formed after condensation of the condenser is shunted to the first cooler through the shunt pipeline, and in the first cooler, the liquid refrigerant is converted into a vapor-liquid mixture refrigerant or a gas refrigerant after evaporation and heat absorption.
Further, after the refrigerant is condensed by the condenser (namely, the refrigerant serving as a defrosting medium is subjected to primary condensation), the part of the refrigerant enters the first cooler to be evaporated and absorb heat, and is supercooled in the main refrigerating pipeline or is cooled in a specific environment, so that the first evaporation and heat absorption of the refrigerant serving as the defrosting medium are realized, and a first refrigerating effect is generated.
The vapor-liquid mixture refrigerant is conveyed to an evaporator to be defrosted through a defrosting pipeline, and the mixture refrigerant is used as a defrosting medium for releasing heat to melt frosting on the evaporator. In the defrosting process, the refrigerant serving as a defrosting medium is subjected to secondary condensation (equivalently, the heat absorption capacity is improved for the second time), then, the defrosted refrigerant is conveyed into the second cooler through the defrosting liquid outlet pipeline for secondary evaporation, the refrigerant in the refrigeration main pipeline is supercooled, the secondary refrigeration effect is generated, the output of two refrigeration amounts is realized, and finally, the refrigerant which is subjected to supercooling operation is conveyed back to the compressor.
Further, in the second cooler, the refrigerant after defrosting supercools the refrigerant of the main refrigeration pipeline, which is equivalent to a high-pressure liquid refrigerant for transferring cold energy to the main refrigeration pipeline, and then the refrigerant of the main refrigeration pipeline is evaporated in the evaporator (non-defrosting evaporator) which is refrigerating. Since the temperature of the liquid refrigerant in the main cooling line is higher than the temperature of the object to be cooled (the object to be cooled) of the refrigeration system and the evaporation temperature of the refrigerant must be lower than the temperature of the object to be cooled, in the present invention, the liquid refrigerant in the main cooling line is used as the object to be cooled of the defrosted refrigerant, and the evaporation temperature for supercooling the liquid refrigerant in the main cooling line can be higher than the evaporation temperature of the evaporator that is cooling (i.e., the former evaporation pressure is higher than the latter evaporation pressure). According to the refrigeration and evaporation law, the lower the evaporation temperature is, the smaller the refrigeration capacity of the refrigeration system is, the lower the operation efficiency is, and the larger the energy consumption is; therefore, in the invention, the defrosted refrigerant is conveyed to the second cooler (with higher evaporation temperature) to supercool the refrigerant of the main refrigerating pipeline, so that the refrigerating capacity obtained is larger than that obtained by conveying the defrosted refrigerant to the refrigerating evaporator (with lower evaporation temperature) for evaporation, the defrosted refrigerant is more fully utilized, and more refrigerating capacity is obtained.
In a preferred embodiment of the present invention, in the first cooler, the liquid refrigerant is evaporated to absorb heat, and the liquid refrigerant in the main refrigeration pipeline is subcooled or used for cooling a preset refrigeration environment. Specifically, when the liquid refrigerant in the refrigeration main pipe is supercooled, that is, the specific enthalpy of the liquid refrigerant to be sent to the refrigeration evaporator is made lower (lower temperature), to improve the heat absorption (refrigeration) capacity. When the refrigerant serving as the defrosting medium is evaporated for the first time to absorb heat for cooling the set refrigeration environment, the energy use efficiency can be improved.
In a preferred embodiment of the present invention, before defrosting, the number of times of evaporating the refrigerant as the defrosting medium is several times, that is, not limited to one time, and may be several times, and the specific number of times may be flexibly selected according to the actual application.
In a preferred embodiment of the present invention, at least one of the evaporators is refrigerating during defrosting operation.
In a preferred embodiment of the present invention, the enthalpy of the vapor-liquid mixture refrigerant is greater than the enthalpy of the gas compressed by the compressor and discharged after the gas is completely condensed, and is less than or equal to the enthalpy of the refrigerant as a defrosting medium after the refrigerant is evaporated for cooling.
In a preferred embodiment of the present invention, the evaporation temperature of the refrigerant is higher than the frost melting temperature of the evaporator to be defrosted and lower than the condensation temperature of the refrigeration system.
Preferably, when the frosting component is ice, the melting temperature is 0 ℃.
A defrosting device for secondary condensation and supercooling of a main refrigerant is integrated in a refrigerating system and comprises a secondary condensation mechanism and a main pipeline supercooling mechanism; the secondary condensation mechanism comprises a first cooler for evaporating and absorbing heat of liquid refrigerants condensed by the condenser, a shunt pipeline for conveying the liquid refrigerants in the main refrigeration pipeline to the first cooler, and a defrosting pipeline for conveying vapor-liquid mixture refrigerants or gas refrigerants formed by evaporation and heat absorption to the evaporator to be defrosted; the head end of the shunting pipeline is connected to a refrigeration main pipeline for conveying liquid refrigerant in a bypassing way, and the tail end of the shunting pipeline is connected to the inlet of the first cooler; the head end of the defrosting pipeline is connected to the outlet of the first cooler, and the tail end of the defrosting pipeline is connected to the inlet of the evaporator to be defrosted;
the main pipe supercooling mechanism comprises a second cooler for supercooling the refrigerant of the refrigeration main pipe and a defrosting liquid outlet pipe for conveying the defrosted refrigerant to the second cooler, wherein the head end of the defrosting liquid outlet pipe is connected to the outlet of the evaporator to be defrosted, and the tail end of the defrosting liquid outlet pipe is connected to the inlet of the second cooler.
In a preferred aspect of the present invention, the first cooler includes a first expansion valve and a first evaporative heat exchanger, and the first expansion valve is disposed on the diversion conduit.
Preferably, the first evaporation heat exchanger is arranged outside a main refrigeration pipeline for conveying liquid refrigerant and used for supercooling the refrigerant in the main refrigeration pipeline and improving the refrigeration capacity of the refrigerant.
In a preferred embodiment of the present invention, the defrosting pipe is provided with a defrosting pressure controller for adjusting the pressure of the defrosting medium in the pipe and a temperature sensor for detecting the temperature of the defrosting medium in the pipe.
In a preferred embodiment of the present invention, the inlet of the second cooler is connected to a head end of a circuit pipe, and a tail end of the head end of the circuit pipe is connected to the inlet of the compressor.
Preferably, a loop pressure controller for adjusting the pressure of the gas refrigerant in the pipeline is arranged on the loop pipeline, and the loop pressure controller is used for controlling the evaporation temperature in the second cooler, so that the evaporation pressure of the defrosted refrigerant is the same as the defrosting condensation pressure.
In a preferred aspect of the present invention, the second cooler includes a supercooling evaporator provided outside the main refrigeration pipe. The specific structure of the supercooling evaporator can refer to the structure of the evaporator in the prior art.
Compared with the prior art, the invention has the following beneficial effects:
1. the defrosting method provided by the invention takes the gas-liquid mixture refrigerant or the gas refrigerant formed after the liquid refrigerant is evaporated and absorbs heat in the first cooler as a defrosting medium to melt frosting on the evaporator, and has the advantages of easiness in control, higher defrosting efficiency and the like.
2. After being condensed by the condenser, the refrigerant serving as a defrosting medium is subjected to primary condensation, and the refrigerating capacity is obtained. And part of the liquid refrigerant is shunted into the first cooler, and the liquid refrigerant is evaporated for the first time to absorb heat, so that the first refrigeration is completed. In the defrosting process, the refrigerant serving as a defrosting medium is subjected to secondary condensation (equivalently, the heat absorption capacity is improved for the second time), then, the defrosted refrigerant is subjected to secondary evaporation in the second cooler, the refrigerant in the main refrigerating pipeline is supercooled, a secondary refrigerating effect is generated, the output of twice refrigerating capacity is realized, and the refrigerating capacity of the refrigerating system is effectively improved.
3. Compared with the traditional superheated gas defrosting mode (the gas taking pipe orifice is arranged on a main refrigerating pipe between the oil separator and the condenser), the refrigerant liquid taking pipe orifice can be arranged on a high-pressure liquid pipe between the condenser and the evaporator and is closer to a cooled environment, the length of the pipe is effectively shortened, and the using amount of the pipe is reduced.
4. Adopt the refrigerant after the defrosting to carry out the subcooling to the refrigerant in the main refrigeration pipeline, be equivalent to transmit cold volume for the high-pressure liquid refrigerant of main refrigeration pipeline, the refrigerant by the main refrigeration pipeline evaporates in the refrigerated evaporimeter again, because of the liquid refrigerant's of main refrigeration pipeline temperature is higher than the cooling thing, the event carries out the evaporating temperature that the subcooling was carried out to the refrigerant of main refrigeration pipeline and is higher than the evaporating temperature who adopts refrigerated evaporimeter, has improved the heat absorption capacity of the refrigerant in the main refrigeration pipeline, has increased the refrigerating output.
Drawings
FIG. 1 is a pressure-enthalpy diagram of one embodiment of the present invention, wherein the numbers indicate the location of the refrigerant, 1 indicates the compressor inlet, 2 indicates the condenser inlet, 3 indicates the expansion valve inlet, 4 indicates the inlet of the evaporator for cooling, 5 indicates the first cooler inlet, 6 indicates the inlet of the evaporator to be defrosted, 7 indicates the second cooler inlet, 8 indicates the outlet of the defrosted refrigerant in the second cooler, and 9 indicates the inlet of the main line refrigerant of the first cooler; wherein, the circulation path of the refrigerant as the defrosting medium is as follows: 8-2-9-5-6-7, the circulation path of the refrigerant for normal refrigeration is as follows: 1-2-3-4.
Figure 2 is a pressure enthalpy diagram for another embodiment.
When neglecting the pipe pressure loss, the pressures at points 5, 6, 7 and 8 should be the same, but for clarity of the entire flow of defrosting refrigerant, the pressures at 5, 6, 7 and 8 are treated with slight differentiation in fig. 1 and 2.
Fig. 3 is a schematic configuration diagram of an embodiment of a defrosting method of secondary condensation and supercooling of a main path refrigerant in the present invention applied to a refrigeration system, wherein a dotted line indicates a defrosting pipe.
Detailed Description
In order to make those skilled in the art understand the technical solutions of the present invention well, the following description of the present invention is provided with reference to the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.
Example 1
Referring to fig. 3, the defrosting device for secondary condensation and supercooling the main refrigerant in the present embodiment is integrated in a refrigeration system, and includes a secondary condensation mechanism and a main pipe supercooling mechanism; the secondary condensation mechanism comprises a first cooler 3 for evaporating and absorbing heat of liquid refrigerant condensed by a condenser 2, a branch pipeline 1 for conveying the liquid refrigerant in a refrigeration main pipeline 4 to the first cooler 3, and a defrosting pipeline 6 for conveying a vapor-liquid mixture refrigerant or a gas refrigerant formed by evaporation and heat absorption to an evaporator 5(a) to be defrosted; the head end of the diversion pipeline 1 is connected to a refrigeration main pipeline 4 for conveying liquid refrigerant in a bypassing way, and the tail end of the diversion pipeline is connected to the inlet of the first cooler 3; the defrosting duct 6 is connected at the head end to the outlet of the first cooler 3 and at the tail end to the inlet of the evaporator 5(a) to be defrosted.
The main pipe supercooling mechanism comprises a second cooler 8 for supercooling the refrigerant of the refrigeration main pipe 4 and a defrosting liquid outlet pipe 7 for conveying the defrosted refrigerant to the second cooler 8, wherein the head end of the defrosting liquid outlet pipe 7 is connected to an outlet of the evaporator 5(a) to be defrosted, and the tail end of the defrosting liquid outlet pipe 7 is connected to an inlet of the second cooler 8.
Referring to fig. 3, the first cooler 3 includes a first expansion valve provided on the divided flow pipe 1 and a first evaporative heat exchanger.
Further, the first evaporation heat exchanger is arranged on the outer side of the main refrigeration pipeline 4 used for conveying liquid refrigerant and used for supercooling the refrigerant in the main refrigeration pipeline 4 and improving the refrigeration capacity of the refrigerant.
Referring to fig. 3, the defrosting duct 6 is provided with a defrosting pressure controller 12 for adjusting the pressure of the defrosting medium in the duct and a temperature sensor 11 for detecting the temperature of the defrosting medium in the duct.
With reference to fig. 3, the inlet of the second cooler 8 is connected to the head end of a circuit pipe 9, the head end of the circuit pipe 9 being connected at the inlet of a compressor 10.
Further, a loop pressure controller 13 for adjusting the pressure of the gas refrigerant in the loop pipe 9 is provided, and the loop pressure controller 13 is used for controlling the evaporation temperature in the second cooler 8 so that the evaporation pressure of the defrosted refrigerant is the same as the defrosting condensation pressure.
Referring to fig. 3, the second cooler 8 comprises a subcooling evaporator which is disposed outside the main refrigeration conduit 4. The specific structure of the supercooling evaporator can refer to the structure of the evaporator in the prior art.
Referring to fig. 1 and 3, the defrosting method of secondary condensation and supercooling of the main path refrigerant in the present embodiment includes the steps of:
part of liquid refrigerant (mostly used for normal refrigeration work and a small part for defrosting of an evaporator) formed after condensation of the condenser 2 is shunted to the first cooler 3 through a shunt pipe 1; the liquid refrigerant evaporates in the first cooler 3 absorbing heat, subcooling the liquid refrigerant in the main refrigeration line 4 so that the liquid refrigerant to be delivered to the refrigerated evaporator 5(b) has a lower specific enthalpy (lower temperature) to increase the heat absorption (refrigeration) capacity; and converted to a vapor-liquid mixture refrigerant as in process 9-6. Delivering a vapor-liquid mixture refrigerant to an evaporator 5(a) to be defrosted through a defrosting pipeline 6, wherein the vapor-liquid mixture refrigerant is used as a defrosting medium to release heat to melt frost on the evaporator, as in the process 6-7; the defrosted refrigerant is conveyed to a second cooler 8 through a defrosted liquid outlet pipeline 7; the defrosted refrigerant evaporates and absorbs heat in the second cooler 8 to supercool the refrigerant in the main refrigerating pipeline 4, as in process 7-8, and the evaporation temperature in the second cooler 8 is higher than that of the evaporator 5(b) which is refrigerating; the gaseous refrigerant having completed the subcooling operation is sent back to the compressor 10 through the return conduit 9 for cycle operation, as in process 8-2.
Before defrosting, the evaporation frequency of the refrigerant as a defrosting medium is several times, namely, the refrigerant is not limited to one time, and can be multiple times, and the specific frequency can be flexibly selected according to practical application.
Referring to fig. 3, in the defrosting operation, at least one evaporator is refrigerating; in this embodiment, two evaporators which are switched to operate in turn are provided, but of course, the number of the evaporators can be three, four or more.
Specifically, in the present embodiment, the evaporation temperature of the refrigerant is higher than the melting temperature of frost formation of the evaporator 5(a) to be defrosted and lower than the condensation temperature of the refrigeration system. Wherein, when the frosting component is ice, the melting temperature is 0 ℃.
Referring to fig. 3, the defrosting duct 6 is connected to the output end of the first cooler 3 at the head end and extends to the evaporator 5(a) to be defrosted at the tail end.
Further, the defrosting pipe 6 is provided with a temperature sensor 11 for detecting the temperature of the refrigerant in the pipe and a defrosting pressure controller 12 for adjusting the pressure of the defrosting medium in the pipe.
Referring to fig. 3, the defrost-outlet duct 7 is connected at its head end to the outlet of the evaporator and at its tail end to the inlet of the second cooler 8.
With reference to fig. 3, the loop conduit 9 is connected at its head end to the outlet of the second cooler 8 and at its tail end to the inlet of the compressor 10.
Further, a loop pressure controller 13 for adjusting the pressure of the gas refrigerant in the loop pipe 9 is provided, and the loop pressure controller 13 is used for controlling the evaporation temperature in the second cooler 8 so that the evaporation pressure of the defrosted refrigerant is the same as the defrosting condensation pressure.
Referring to fig. 3, the first cooler 3 includes a first cold expansion valve and a first supercooling evaporator connected to the rear of the condenser 2 through the diverging pipe 1, and the first supercooling expansion valve is disposed on the diverging pipe 1.
Reference is made to the prior art for details of the construction of the cooler.
Referring to fig. 1 and 3, the defrosting apparatus for secondary condensing and supercooling the main path refrigerant in the present embodiment operates on the principle that:
when the refrigeration system works, the compressor 10 compresses low-temperature and low-pressure gas refrigerant into high-temperature and high-pressure gas refrigerant through compression work, the high-temperature and high-pressure gas refrigerant is converted into liquid refrigerant after being condensed by the condenser 2, and then the liquid refrigerant is conveyed to the refrigeration evaporator through the refrigeration main pipeline 4. In the process, the liquid refrigerant formed after condensation of the condenser 2 is branched to the first cooler 3 through the branch pipeline 1, and in the first cooler 3, the liquid refrigerant is converted into a vapor-liquid mixture refrigerant after evaporation and heat absorption.
Further, after the refrigerant is condensed by the condenser 2 (equivalent to the refrigerant serving as the defrosting medium is subjected to primary condensation), the part of the refrigerant enters the first cooler 3 to be evaporated and absorb heat, and is supercooled in the main refrigerating pipeline 4 or is cooled in a specific environment, so that the first evaporation and heat absorption of the refrigerant serving as the defrosting medium are realized, and a first refrigeration effect is generated.
The vapor-liquid mixture refrigerant is conveyed to the evaporator 5(a) to be defrosted through the defrosting pipeline 6, and the mixture refrigerant is used as a defrosting medium for releasing heat to melt frost on the evaporator. In the defrosting process, the refrigerant serving as a defrosting medium is subjected to secondary condensation (equivalently, the heat absorption capacity is improved for the second time), then the defrosted refrigerant is subjected to secondary evaporation in the second cooler 8, the refrigerant in the main refrigerating pipeline 4 is subcooled to generate a secondary refrigerating effect, the output of twice refrigerating capacity is realized, and finally the gas refrigerant after the subcooling operation is conveyed back to the compressor 10, so that the refrigerating capacity of the refrigerating system is effectively improved.
Further, in the second cooler 8, the refrigerant after defrosting supercools the refrigerant of the main cooling pipe 4, which corresponds to a high-pressure liquid refrigerant that transfers cooling energy to the main cooling pipe 4, and is evaporated in the evaporator 5(b) that is cooling (non-defrosting evaporator) by the refrigerant of the main cooling pipe 4. Since the temperature of the liquid refrigerant in the main cooling pipe 4 is higher than the temperature of the cooling object (cooling target) of the refrigeration system and the evaporation temperature of the refrigerant must be lower than the temperature of the cooling target, in the present invention, the liquid refrigerant in the main cooling pipe 4 is used as the cooling object of the defrosted refrigerant, and the evaporation temperature for supercooling the liquid refrigerant in the main cooling pipe 4 may be higher than the evaporation temperature of the evaporator 5(b) that is cooling (i.e., the former evaporation pressure is higher than the latter evaporation pressure). According to the refrigeration and evaporation law, the lower the evaporation temperature is, the smaller the refrigeration capacity of the refrigeration system is, the lower the operation efficiency is, and the larger the energy consumption is; therefore, in the present invention, the defrosted refrigerant is delivered to the second cooler 8 (with a higher evaporation temperature) to subcool the refrigerant in the main cooling pipe 4, so as to obtain a cooling capacity greater than that of the defrosted refrigerant delivered to the evaporator 5(b) that is refrigerating (with a lower evaporation temperature), thereby more fully utilizing the defrosted refrigerant and obtaining a larger cooling capacity.
Example 2
Referring to fig. 2, unlike embodiment 1, the liquid refrigerant evaporates and absorbs heat in the first cooler 3, and after being supercooled, the liquid refrigerant in the main refrigeration pipeline 4 is converted into a gas refrigerant, as in processes 9 to 6. Gaseous refrigerant is delivered to the evaporator 5(a) to be defrosted through the defrosting conduit 6, which acts as a defrosting medium, exothermically melting frost build-up on the evaporator, as in process 6-7.
Example 3
Unlike embodiment 1, when the refrigerant serving as the defrosting medium in this embodiment is first evaporated to absorb heat for cooling the set cooling environment, the energy use efficiency can be improved.
The present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents and are included in the scope of the present invention.
Claims (10)
1. A defrosting method for secondary condensation and subcooling of a main path refrigerant, comprising the steps of:
the liquid refrigerant formed after the condenser is condensed is shunted to the first cooler through a shunting pipeline; the liquid refrigerant is evaporated and absorbs heat in the first cooler and is converted into a vapor-liquid mixture refrigerant or a gas refrigerant; delivering a vapor-liquid mixture refrigerant or a gas refrigerant to an evaporator to be defrosted through a defrosting pipeline, wherein the vapor-liquid mixture refrigerant or the gas refrigerant is used as a defrosting medium to release heat to melt frosting on the evaporator; the defrosted refrigerant is conveyed to a second cooler, the defrosted refrigerant is evaporated in the second cooler to absorb heat, and the refrigerant in the main refrigerating pipeline is supercooled, wherein the evaporation temperature in the second cooler is higher than that of an evaporator which is refrigerating; and conveying the gas refrigerant which finishes the supercooling work back to the compressor for circulating work.
2. The defrosting method of secondary condensation and sub-cooling of a main path refrigerant according to claim 1, wherein in the first cooler, the liquid refrigerant is subjected to evaporation heat absorption, the liquid refrigerant in the main cooling pipe is sub-cooled, or a set cooling environment is cooled.
3. A defrosting method of secondary condensing and sub-cooling a main path refrigerant according to claim 1, wherein the number of times of evaporation of the refrigerant as a defrosting medium is at least one before defrosting.
4. A defrosting method according to claim 3 wherein the secondary condensing subcooling is carried out on the main circuit refrigerant and wherein at least one evaporator is refrigerating during defrosting operation.
5. The defrosting method of secondary condensation and sub-cooling of a main path refrigerant according to claim 4, wherein the evaporating temperature of the defrosting refrigerant in the first cooler is higher than the melting temperature of frost formation of the evaporator to be defrosted and lower than the condensing temperature of the refrigeration system.
6. An apparatus for applying the defrosting method of secondary condensation and supercooling of main refrigerant according to any one of claims 1 to 5, integrated in a refrigeration system, comprising a secondary condensation mechanism and a main pipe supercooling mechanism; the secondary condensation mechanism comprises a first cooler for evaporating and absorbing heat of liquid refrigerants condensed by the condenser, a shunt pipeline for conveying the liquid refrigerants in the main refrigeration pipeline to the first cooler, and a defrosting pipeline for conveying vapor-liquid mixture refrigerants or gas refrigerants formed by evaporation and heat absorption to the evaporator to be defrosted; the head end of the shunting pipeline is connected to a refrigeration main pipeline for conveying liquid refrigerant in a bypassing way, and the tail end of the shunting pipeline is connected to the inlet of the first cooler; the head end of the defrosting pipeline is connected to the outlet of the first cooler, and the tail end of the defrosting pipeline is connected to the inlet of the evaporator to be defrosted;
the main pipe supercooling mechanism comprises a second cooler for supercooling the refrigerant of the refrigeration main pipe and a defrosting liquid outlet pipe for conveying the defrosted refrigerant to the second cooler, wherein the head end of the defrosting liquid outlet pipe is connected to the outlet of the evaporator to be defrosted, and the tail end of the defrosting liquid outlet pipe is connected to the inlet of the second cooler.
7. The frost melting apparatus for secondary condensation and subcooling of a main circuit refrigerant of claim 6, wherein the first cooler includes a first expansion valve and a first evaporative heat exchanger, the first expansion valve being disposed on the bypass line.
8. The defrosting apparatus of claim 6 wherein the defrosting conduit is provided with a defrosting pressure controller for adjusting the pressure of the defrosting medium in the conduit and a temperature sensor for detecting the temperature of the defrosting medium in the conduit.
9. The defrosting apparatus of claim 6 wherein the inlet of the secondary cooler is connected to the head of a loop pipe, the tail end of the head of the loop pipe being connected to the inlet of the compressor.
10. The defrosting device of claim 9 wherein the loop conduit is provided with a loop pressure controller for regulating the pressure of the gaseous refrigerant in the conduit, the loop pressure controller being adapted to control the evaporation temperature in the secondary cooler.
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Cited By (1)
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