WO2020100768A1 - Échangeur de chaleur et procédé de dégivrage d'échangeur de chaleur - Google Patents

Échangeur de chaleur et procédé de dégivrage d'échangeur de chaleur Download PDF

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Publication number
WO2020100768A1
WO2020100768A1 PCT/JP2019/043988 JP2019043988W WO2020100768A1 WO 2020100768 A1 WO2020100768 A1 WO 2020100768A1 JP 2019043988 W JP2019043988 W JP 2019043988W WO 2020100768 A1 WO2020100768 A1 WO 2020100768A1
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WIPO (PCT)
Prior art keywords
heat transfer
transfer tube
upstream
heat
defrost
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Application number
PCT/JP2019/043988
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English (en)
Japanese (ja)
Inventor
雅士 加藤
耕作 西田
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株式会社前川製作所
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Publication of WO2020100768A1 publication Critical patent/WO2020100768A1/fr

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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
    • 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
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D21/00—Defrosting; Preventing frosting; Removing condensed or defrost water
    • F25D21/06—Removing frost
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F1/00—Tubular elements; Assemblies of tubular elements
    • F28F1/10—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses
    • F28F1/12—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only outside the tubular element
    • F28F1/24—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only outside the tubular element and extending transversely
    • F28F1/32—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only outside the tubular element and extending transversely the means having portions engaging further tubular elements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
    • F28F13/04—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by preventing the formation of continuous films of condensate on heat-exchange surfaces, e.g. by promoting droplet formation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F17/00—Removing ice or water from heat-exchange apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
    • F28F9/26—Arrangements for connecting different sections of heat-exchange elements, e.g. of radiators

Definitions

  • the present disclosure relates to a heat exchanger and a defrosting method for the heat exchanger.
  • Fin-tube heat exchangers are used as heat exchangers such as air coolers installed in freezers and freezers.
  • the fin tube type heat exchanger radiating fins are likely to be covered with frost, and the frost layer formed between the fins blocks the air flow, so that frequent defrost operation is required. Therefore, the present inventors have proposed a defrosting method of sublimating and removing frost attached to the fins and the heat transfer tubes (Patent Document 1).
  • frost is sublimated and scattered on the air flow, so that no molten water is generated. Therefore, there is an advantage that the work of removing the melted water from the heat exchanger becomes unnecessary and defrosting can be performed while the operation of the air cooler is continued.
  • the heat transfer surface of the most upstream heat transfer tube has a high heat transfer coefficient, and the mist (liquid and solid) contained in the gas to be cooled collides with the most upstream heat transfer tube and the tips of the fins due to inertial force.
  • the phenomenon occurs in which frost is concentrated and frost grows faster. Therefore, since the cooling air flow passage is closed earlier in these portions due to the growth of the frost layer than in other portions, there is a problem that the heat exchange between the cooled air and the cooling medium flowing through the heat transfer tube is hindered.
  • One embodiment prevents frost adhering to the upstream end portions of the upstream heat transfer tubes and fins from growing and blocking the cooling gas flow path, and by performing efficient defrost operation, the defrost operation It is intended to suppress a decrease in thermal efficiency of a heat exchanger in operation due to heat applied to a heat transfer tube or fins.
  • the heat exchanger is A gas flow path through which the cooled gas flows, A plurality of heat transfer tubes provided in the gas flow path, Of the plurality of heat transfer tubes, at least one frost layer of at least one upstream heat transfer tube located in an upstream region in the flow direction of the gas to be cooled or a heat radiation member provided on the outer periphery of the upstream heat transfer tube.
  • An upstream heating unit for maintaining the temperature of the adhering surface below 0 ° C. and higher than the gas to be cooled; Equipped with.
  • the surface temperature of the heat radiating member (hereinafter, also referred to as “upstream heat radiating member”) provided on the upstream heat transfer tube or the outer circumference of the upstream heat transfer tube by the upstream heating unit.
  • upstream heat radiating member By adjusting the temperature range (upstream heating), the frost attached to the upstream heat transfer tube or the upstream heat dissipation member can be sublimated and scattered. This suppresses the growth of the frost layer on the heat transfer surface formed by the upstream heat transfer tube and the upstream heat dissipation member (hereinafter also referred to as the "upstream heat transfer surface"), and the gas around the heat transfer surface due to the frost layer. The blockage of the flow path can be suppressed.
  • the growth of the frost layer is suppressed and the transfer by the frost layer is suppressed only by making the temperature of the frost layer adhering surface on the upstream heat transfer surface slightly higher than the gas to be cooled. It is possible to suppress clogging of the gas flow path around the hot surface and save energy. Even if there is a part of the upstream heat transfer tube and the upstream heat radiating member that is not maintained in the above temperature range, it is premised that the part is maintained at a temperature not to exceed 0 ° C. This is because if there is a portion where the temperature is 0 ° C. or higher, molten water will be generated at that portion.
  • the plurality of heat transfer tubes extend in the gas flow path along a first direction orthogonal to the flow direction in the gas flow path, and a second direction orthogonal to the flow direction and the first direction.
  • a heat transfer tube row formed by the plurality of heat transfer tubes arranged along the direction is arranged so as to be lined up in the flow direction,
  • the upstream heat transfer tubes include at least one or more heat transfer tubes belonging to the heat transfer tube row on the most upstream side in the flow direction.
  • the "most upstream heat transfer tube row" is meant to include one row or a plurality of heat transfer tube rows provided on the most upstream side.
  • the uppermost stream side heat transfer tube array in the flow direction of the gas to be cooled (hereinafter also simply referred to as “flow direction”) can be intensively heated to the temperature range.
  • flow direction the uppermost stream side heat transfer tube array in the flow direction of the gas to be cooled
  • a defrost unit for defrosting a defrost target tube among the plurality of heat transfer tubes includes a plurality of flow path regions arranged in the second direction,
  • the plurality of heat transfer tubes respectively correspond to the plurality of flow path areas and belong to two or more heat transfer tube rows adjacent to each other in the same flow path area in the flow direction.
  • Including a plurality of heat transfer tube groups formed by The defrost unit is configured to selectively defrost the heat transfer tubes of one or more heat transfer tube groups of the plurality of heat transfer tube groups as the defrosting target tubes.
  • the defrost unit is configured to selectively defrost only the heat transfer tube row on the most upstream side in the flow direction among the plurality of heat transfer tube rows as the defrosting target tube. According to the above configuration (4), by selectively defrosting only the heat transfer tube row on the most upstream side in the flow direction as the defrosting target tube, the most upstream heat transfer tube row where frost is likely to grow rapidly is given priority. It is possible to suppress the blockage of the gas flow path of the most upstream heat transfer tube array.
  • the upstream heat transfer tube is configured to be able to supply only the defrost fluid.
  • the upstream heat transfer tube only supplies the defrost fluid and does not perform the normal cooling operation.
  • the upstream heating unit is configured to heat the upstream heat transfer tube or the heat dissipation member.
  • the upstream heating unit heats the upstream heat transfer tube or the upstream heat dissipation member to a temperature at which sublimation of frost is possible, thereby sublimating the frost adhering to the upstream heat transfer surface. It can be scattered and removed.
  • upstream heating is enabled by means other than the supply of defrost fluid.
  • the upstream heating unit includes a defrost fluid supply unit capable of supplying a defrost fluid capable of maintaining the temperature of the frost attachment surface to a temperature lower than 0 ° C. and higher than the temperature of the gas to be cooled to the upstream heat transfer tube.
  • a defrost fluid supply unit capable of supplying a defrost fluid capable of maintaining the temperature of the frost attachment surface to a temperature lower than 0 ° C. and higher than the temperature of the gas to be cooled to the upstream heat transfer tube.
  • the upstream heat transfer surface can be heated by the defrost fluid supplied from the defrost fluid supply unit to the upstream heat transfer tube.
  • the upstream heating by the defrost fluid and the upstream heating by the upstream heating unit can be used together.
  • the upstream heating unit is configured to maintain the temperature difference between the frost layer adhering surface temperature of at least one of the upstream heat transfer tube or the upstream heat dissipation member and the gas to be cooled to more than 0 ° C and 10 ° C or less. It According to the configuration of (8) above, the temperature difference between the upstream frost layer adhesion surface temperature and the gas to be cooled is maintained at more than 0 ° C. and 10 ° C. or less (low temperature heating), so the amount of heat required for upstream heating is reduced. it can.
  • the heat dissipation member is a plate-shaped heat dissipation member that is provided in the gas flow path along the flow direction so that the plurality of heat transfer tubes penetrate or contact each other.
  • the heat transfer area of the heat exchanger is increased by including the plate-shaped heat dissipation member, and the heat transfer performance of the heat exchanger can be improved.
  • the plate-shaped heat dissipation member is provided along the flow direction of the gas to be cooled, it is possible to suppress the turbulence of the gas to be cooled.
  • a temperature boundary layer is formed on the surface of the plate-shaped heat dissipation member in which the turbulence of the gas to be cooled is suppressed, and the temperature gradually decreases toward the surface of the plate-shaped heat dissipation member.
  • the formation of the temperature boundary layer reduces the heat transfer coefficient of the heat transfer surface, so that the growth of the frost layer formed on the surface of the plate-shaped heat dissipation member can be suppressed.
  • the temperature boundary layer is disturbed (for example, a louver fin or the like), the heat transfer coefficient is increased and the growth of frost is promoted.
  • the heat dissipating member has a heat insulating area between the tip portion in the flow direction of the heat dissipating member and the downstream side portion for suppressing heat transfer between the tip portion in the flow direction and the downstream side portion.
  • the configuration of (10) above since the heat insulating zone is provided, the heat applied to the tip portion by the upstream heating unit is transmitted to the downstream side portion of the heat dissipation member, and the cooling operation is performed in the downstream side portion It is possible to suppress a decrease in efficiency.
  • the heat dissipation member is Of the plurality of heat transfer tube groups, it is arranged so as to straddle an upstream heat transfer tube group arranged on the upstream side in the flow direction and a downstream heat transfer tube group arranged on the downstream side in the flow direction from the upstream heat transfer tube group.
  • a heat insulating region that suppresses heat transfer between the upstream heat transfer tube group and the downstream heat transfer tube group is provided in a portion of the heat dissipation member between the upstream heat transfer tube group and the downstream heat transfer tube group. ..
  • the plate-shaped heat dissipation member is arranged so as to straddle the upstream heat transfer tube group and the downstream heat transfer tube group, so that the temperature boundary layer is continuously formed except for the tip portion in the flow direction. Can be extended. As a result, it is possible to suppress the growth of frost in the entire region except the tip portion in the flow direction. Further, since the heat insulating zone is provided between the upstream heat transfer tube group and the downstream heat transfer tube group, when performing upstream heating, or when performing defrosting on either the upstream heat transfer tube group or the downstream heat transfer tube group. The heat applied to the heat transfer tubes or the heat radiating member by the upstream heating or the defrosting operation can be prevented from being transferred to the other heat transfer tube group in the cooling operation and lowering the cooling efficiency.
  • a defrosting method for a heat exchanger is A gas flow path through which the gas to be cooled flows, a plurality of heat transfer tubes provided in the gas flow path, and one or more upstreams of the plurality of heat transfer tubes located in an upstream region in the flow direction of the gas to be cooled.
  • a method of defrosting a heat exchanger comprising: During operation of the heat exchanger, the temperature of the frost layer attachment surface of at least one of the upstream heat transfer tube or the heat dissipation member is constantly kept below 0 ° C. and higher than the gas to be cooled by the upstream heating unit.
  • An upstream heating step is provided.
  • “always" means that the upstream heating step is performed for 50 to 100% of the cooling operation time.
  • the upstream heating step is always performed, and the temperature of the upstream heat transfer surface is adjusted to a temperature at which sublimation defrost can be performed (upstream heating), so that the upstream heat transfer surface is Frost that adheres can be sublimated and scattered.
  • upstream heating a temperature at which sublimation defrost can be performed
  • the plurality of heat transfer tubes extend in the gas flow path along a first direction orthogonal to the flow direction of the gas to be cooled in the gas flow path, and in the flow direction and the first direction.
  • a heat transfer tube array formed by a plurality of the heat transfer tubes arranged along a second direction orthogonal to each other is arranged so as to be lined up in the flow direction,
  • the heat exchanger includes a defrost unit for defrosting a defrost target pipe among the plurality of heat transfer pipes,
  • the gas flow path includes a plurality of flow path regions arranged in the second direction,
  • the plurality of heat transfer tubes respectively correspond to the plurality of flow path areas and belong to two or more heat transfer tube rows adjacent to each other in the same flow path area in the flow direction.
  • the defrost unit is configured to selectively defrost the heat transfer tubes of one or more heat transfer tube groups of the plurality of heat transfer tube groups as the defrost target tubes, A defrosting step of defrosting each of the one or more heat transfer tube groups among the plurality of heat transfer tube groups is provided.
  • the defrost unit is configured to selectively defrost only the heat transfer tube row on the most upstream side in the flow direction among the plurality of heat transfer tube rows as the defrosting target tube
  • the defrosting step includes a step of selectively defrosting only the heat transfer tube row on the most upstream side in the flow direction as the defrosting target tube.
  • One defrost time required to defrost all the heat transfer tube groups once is set to be within a limit time at which the amount of frost adhering to at least a part of the heat transfer tubes reaches an allowable upper limit value, and from the one defrost time to the heat transfer tube group. Allocate a defrosting time interval for each. According to the above method, by setting the limit time to an upper limit value at which the flow of the gas to be cooled is not blocked on at least a part of the heat transfer surface, the block of the gas to be cooled does not occur in each heat transfer tube group, and Defrost can be carried out efficiently.
  • the defrosting step When the heat transfer tube group arranged on the upstream side in the flow direction is subjected to defrosting, the flow direction is reversed.
  • the flow direction of the gas to be cooled is reversed so that the frost separated from the adhering surface is on the downstream side. It is possible to suppress re-adhesion to the heat transfer tube, and it is possible to perform processing on the upstream side. Moreover, the frost adhering to the tip portion can be efficiently removed.
  • the gas to be cooled which has been heated by the heat applied during defrosting, once returns to the upstream side and is mixed and flows into another heat transfer tube group, so that temperature unevenness in the downstream of the heat exchanger can be suppressed.
  • the gas flow passage from being blocked by frost adhering to the upstream heat transfer surface, and to enable efficient defrost operation.
  • the influence of the applied heat on the thermal efficiency of the heat exchanger can be reduced.
  • expressions such as “identical”, “equal”, and “homogeneous” that indicate that they are in the same state are not limited to a state in which they are exactly equal to each other. It also represents the existing state.
  • the representation of a shape such as a quadrangle or a cylinder does not only represent a shape such as a quadrangle or a cylinder in a geometrically strict sense, but also an uneven portion or a chamfer within a range in which the same effect can be obtained.
  • the shape including parts and the like is also shown.
  • the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one element are not exclusive expressions excluding the existence of other elements.
  • FIG. 1 is a perspective view of a heat exchanger 10 (10A) according to one embodiment
  • FIG. 2 is a plan view showing a part of the heat exchanger 10 (10B) according to another embodiment
  • the casing 12 of the heat exchanger 10 (10A, 10B) has an open front surface that flows in from the air to be cooled a and a rear surface that flows out from the air to be cooled a. A path is formed.
  • a plurality of heat transfer tubes 16 are provided facing the cooling air flow path.
  • the fan 14 (14a, 14b, 14c) is arranged on the downstream side in the flow direction of the casing 12 in FIG. 1, it may be arranged on the upstream side in the flow direction of the casing 12 and operated as a push-type fan.
  • the heat dissipation member 40 is provided on the outer periphery of the heat transfer tube 16.
  • the heat radiating member 40 is not shown in the heat exchanger 10 (10A) shown in FIG. 1, the heat radiating member 40 may or may not be provided.
  • the heat exchanger 10 is provided with the upstream heating unit 50 (50a, 50b, 50c), and the upstream heating unit 50 controls the cooling air a of the plurality of heat transfer tubes 16.
  • the temperature of that part is maintained so as not to exceed 0 ° C. This is because if there is a portion where the temperature is 0 ° C. or higher, frost-melting water is generated at that portion.
  • the upstream heating unit 50 constantly adjusts the surface temperature of the upstream heat transfer pipe 16 (16a) or the upstream heat dissipation member 40 (40a) within the above temperature range in which sublimation defrosting is possible. ..
  • the frost adhering to the upstream heat transfer surface formed by the upstream heat transfer tube 16 (16a) and the upstream heat dissipation member 40 (40a) can be sublimated and scattered, so that the frost on the upstream heat transfer surface. It is possible to suppress the growth of the layer and to prevent the air passage around the heat transfer surface from being blocked by the frost layer.
  • the growth of the frost layer on the upstream heat transfer surface is suppressed only by making the temperature of the frost layer adhering surface slightly higher than that of the air to be cooled a (light heating). It is possible to prevent the gas passage around the heat transfer surface from being blocked by the frost layer.
  • the plurality of heat transfer tubes 16 configuring the heat exchanger 10 (10A) shown in FIG. 1 are in the cooling air flow path in a direction orthogonal to the flow direction of the cooled air a (arrow b direction. And a direction (arrow c direction; hereinafter also referred to as "second direction") extending along the "first direction") and orthogonal to the flow direction of the cooled air a and the first direction.
  • a plurality of heat transfer tube rows formed by the plurality of heat transfer tubes 16 arranged in parallel are arranged so as to be aligned in the flow direction.
  • the upstream heat transfer tubes 16 (16a) include at least one or more heat transfer tubes belonging to the most upstream heat transfer tube row in the flow direction.
  • the upstream heating unit 50 selectively adjusts at least one or more heat transfer tubes belonging to the row of heat transfer tubes on the most upstream side in the flow direction to the above temperature range.
  • Frost attached to the heat transfer surface formed in the side heat transfer tube row can be sublimated and scattered intensively. As a result, it is possible to suppress the growth of the frost layer in the uppermost stream side heat transfer tube array where frost is likely to grow rapidly and to prevent the cooling air flow passages around the heat transfer surface from being blocked.
  • the heat exchanger 10 includes a defrost unit 18 for defrosting the tubes to be defrosted among the plurality of heat transfer tubes 16.
  • the cooling air flow passage includes a plurality of flow passage regions Fa, Fb, and Fc arranged in the second direction, and the plurality of heat transfer tubes 16 correspond to the plurality of flow passage regions Fa to Fc, respectively.
  • the plurality of heat transfer tube groups are not shown in the flow path regions Fb and Fc, but the flow path regions Fb and Fc also include a plurality of heat transfer tube groups like the flow path region Fa.
  • the defrost unit 18 is configured to selectively defrost the heat transfer tubes 16 of one or more heat transfer tube groups among the plurality of heat transfer tube groups as defrosting target tubes.
  • the fan 14 (14a, 14b, 14c) is provided in each flow passage region Fa, Fb, and Fc, and selects the flow of the cooled air a for each flow passage region. Can be formed as desired.
  • the plurality of heat transfer tube groups Ta, Tb, Tc are sequentially arranged from the upstream side in the flow direction, and the upstream heat transfer tube 16 (16a) constitutes the heat transfer tube group Ta provided on the upstream side. Is a part of the heat transfer tubes arranged on the upstream side.
  • one or more heat transfer tube groups are selected from the plurality of heat transfer tube groups as defrosting target tubes, and defrosting is performed from the selected heat transfer tube group.
  • defrosting is performed from the selected heat transfer tube group.
  • defrosting is performed simultaneously on both the upstream side and the downstream side, so that the frost layer separated from the upstream side adhering surface is on the downstream side. Redeposition on the side heat transfer surface can be suppressed.
  • the defrost operation can be made more efficient by reducing the defrost frequency in the heat transfer tube group on the downstream side in the flow direction in which the frost layer grows slowly.
  • the closing time of the air flow path on the heat transfer surface is obtained for each heat transfer tube group, and at least one defrost operation is performed per closing time of each heat transfer tube group.
  • the refrigerator 20 supplies the refrigerant to the heat transfer tube 16 during the cooling operation to cool the cooled air a.
  • the defrost unit 18 supplies the defrost fluid to the heat transfer tube group to be defrosted during defrosting.
  • the refrigerant circulating in the refrigerant circuit 22 is sucked into the compressor 24 in a gaseous state, pressurized by the compressor 24, cooled by the condenser 26, and liquefied.
  • the refrigerant liquid liquefied by the condenser 26 is once stored in the receiver 28, and then depressurized via the expansion valve 30.
  • the refrigerant decompressed by the expansion valve 30 is non-returned except for the heat transfer tube group Ta (Ta, Tb, and Tc) of the upstream side heat transfer tube 16 (16a) of the heat exchanger 10 which is the defrost target. It is supplied to the heat transfer tubes 16 of the heat transfer tube groups Tb and Tc through the valve 32 and cools the cooled air a to a predetermined cooling temperature. The refrigerant that has been used to cool the cooled air a is returned to the refrigerant circuit 22.
  • the refrigerant (gas phase portion) under high pressure in the receiver 28 is stored in the buffer tank 45 as the defrost fluid, and is supplied to the heat transfer tube group that is the target of defrost through the defrost flow passage 34.
  • the refrigerant under high pressure is stored in the buffer tank 45 after adjusting the temperature, pressure, and other conditions.
  • the control unit 48 controls the opening degree of the pressure adjusting valve 36 so that the detection value of the pressure sensor 47 becomes a predetermined value, controls the operation of the heating unit 46, and controls the defrosting refrigerant gas flowing in the defrosting flow path 34. , When it is sent to the heat transfer tube group that is the target of defrosting, the frost adhesion surface temperature is adjusted to a temperature lower than 0 ° C.
  • the adjusted defrosting refrigerant gas is sent to the heat transfer tube group that has been defrosted.
  • the refrigerant gas provided for defrosting is condensed and liquefied inside the heat transfer tube, then expanded and decompressed through the capillary tube 38, and joins the low pressure refrigerant line 22a. After that, the vaporized gas is returned to the refrigerant circuit 22 through another heat transfer tube group.
  • a pressure reducing valve such as a solenoid valve or an expansion valve may be used as a pressure reducing mechanism instead of the capillary tube 38.
  • the upstream heating unit 50 (50a) has a temperature of the heat transfer surface where frost adheres to the upstream heat transfer pipe 16 (16a) at a temperature of less than 0 ° C. and less than 0 ° C. It includes a defrost fluid supply unit 44 capable of supplying a defrost fluid that can be maintained at a temperature higher than the temperature of the cooling air a.
  • the defrost fluid supply unit 44 includes a buffer tank 45 and a heating unit 46.
  • the defrost fluid supply unit 44 supplies the defrost fluid capable of maintaining the temperature of the frost adhering surface at ⁇ 2 ° C. to ⁇ 5 ° C., for example.
  • the defrost fluid supply unit 44 supplies the defrost fluid capable of maintaining the temperature of the frost adhering surface below 0 ° C. and higher than the temperature of the cooled air “a” to the heat transfer tube group that is the object of defrost. This enables sublimation defrost to sublime and remove the frost attached to the frost layer attachment surface. Further, by supplying the defrost fluid, which is adjusted to allow sublimation of frost, to the upstream heat transfer pipe 16 (16a), upstream heating becomes possible. Due to the structure, frost formation that cannot be handled by upstream heating can be dealt with by defrosting operation.
  • the defrost fluid is a refrigerant under high pressure that is stored in the receiver 28 and is supplied through the defrost flow passage 34.
  • this refrigerant By using this refrigerant as the defrost fluid, it is not necessary to obtain the defrost heat source from another heat source. ..
  • the defrost unit 18 sets only the upstream heat transfer tube 16 (16a), which is the most upstream heat transfer tube row in the flow direction among the plurality of heat transfer tube rows, as the defrosting target tube. It is configured to selectively defrost. According to this embodiment, by selectively defrosting only the upstream heat transfer pipe 16 (16a) as the defrosting target pipe, the upstream heat transfer pipe 16 (16a) in which the frost layer is likely to grow rapidly can be preferentially defrosted. . As a result, it is possible to suppress the growth of frost on the upstream heat transfer tube 16 (16a) where the growth of frost is remarkable. In this case, by maintaining the defrost fluid in a state where sublimation of frost can be performed by the upstream heating unit 50 (50a), the upstream heating can also be performed by the defrost operation.
  • a defrost flow passage 35 that supplies the defrost fluid from the buffer tank 45 to only the upstream heat transfer pipe 16 (16a) that is the most upstream heat transfer pipe array is provided. Only the defrost operation is performed for the heat transfer tube row of the upstream heat transfer tube 16 (16a), and the normal cooling operation is not performed in this embodiment.
  • the defrost fluid in a state of temperature, pressure, etc., which allows constant sublimation defrost, to the heat transfer tube row of the upstream heat transfer tube 16 (16a), upstream heating becomes possible.
  • the temperature of the frost layer adhering surface of the upstream heat transfer tube 16 (16a), which is the most upstream heat transfer tube row, is lower than the temperature of the frost layer adhering surface of the downstream heat transfer tube group during defrosting.
  • the temperature of the defrost fluid is controlled by the pressure control valve 37 provided in the defrost flow path 35 to adjust the temperature of the frost layer adhering surface. This makes it possible to efficiently suppress the growth of the frost layer.
  • the defrost fluid that has been defrosted in the upstream heat transfer pipe 16 (16a) is expanded and decompressed through the capillary tube 38, and joins the low pressure refrigerant line 22a. Unlike the other heat transfer tube group, the upstream heat transfer tube 16 (16a) is not provided with the branch line 23 into which the refrigerant flows from the refrigerant circuit 22.
  • the upstream heating section 50 (50b, 50c) is configured to heat the upstream heat transfer tube 16 (16a) or the upstream heat dissipation member 40 (40a).
  • the upstream heating section 50 (50b, 50c) heats the upstream heat transfer surface formed by the upstream heat transfer tube 16 (16a) or the upstream heat dissipation member 40 (40a) to a temperature at which sublimation defrost is possible.
  • the frost layer F attached to the upstream heat transfer surface can be sublimated and removed.
  • upstream heating can be performed by means other than the defrost operation.
  • the upstream heating section 50 (50b) shown in FIG. 4 includes a high frequency current induction section 52.
  • the high-frequency current induction section 52 is connected to the upstream heat transfer tube 16 (16a) via a conductor wire 54.
  • the cooling medium r cooled by the refrigerator 20 flows inside the heat transfer tube 16 (16a).
  • the surface temperature of the upstream heat-transfer tube 16 (16a) can be set to a temperature at which sublimation defrosting is possible.
  • the heating effect of the frost layer F can be improved and the high frequency current E can be increased. Energy can be saved by concentrating on the surface of the upstream heat transfer tube 16 (16a).
  • the heating target is the upstream heat dissipation member 40 (40a) instead of the upstream heat transfer tube 16 (16a), and the frost layer F attached to the upstream heat dissipation member 40 (40a) is removed by sublimation defrosting. Good.
  • a conductive material layer 58 that is heated by flowing an electric current from the current-carrying portion 56 is formed on the surface of the upstream side heat dissipation member 40 (40a).
  • An electric insulation layer 60 is formed inside the layer 58.
  • the upstream heating section 50 (50b) is configured to include an energization section 56 for passing an electric current through the conductive material layer 58 through the conductive wire 54.
  • an electric current is passed from the energizing portion 56 to the conductive material layer 58 to heat the conductive material layer 58, and the frost layer F attached to the surface of the conductive material layer 58 is heated to a temperature of less than 0 ° C.
  • the frost layer F is sublimated and removed.
  • the electrically insulating layer 60 is provided inside the conductive material layer 58, the electric current can be concentrated on the conductive material layer 58 to flow the current.
  • the object to be heated is the upstream heat dissipation member 40 (40a), but the upstream heat transfer pipe 16 (16a) may be used instead.
  • the upstream heating unit 50 sets the temperature difference between the frost layer attachment surface temperature of at least one of the upstream heat transfer tube 16 (16a) and the upstream heat dissipation member 40 (40a) and the cooled air a to 0 ° C. It is configured to maintain above 10 ° C and above. This slight heating can reduce the amount of heat required as a defrost heat source during defrosting due to sublimation.
  • a plate-shaped heat dissipation member 40 is provided along the flow direction (direction of arrow a) in the cooling air flow path so that the plurality of heat transfer tubes 16 penetrate or contact each other. .. Since the heat transfer area is increased by providing the plate-shaped heat dissipation member 40, the heat transfer performance of the heat exchanger 10 can be improved. Further, since the plate-shaped heat dissipation member 40 is provided along the flow direction of the cooled air a, it is possible to suppress the disturbance of the cooled air a. As shown in FIG.
  • FIG. 6A schematically shows the temperature distribution of the temperature boundary layer Bt.
  • a plurality of plate-shaped heat dissipation members 40 are arranged in parallel with each other at intervals along the flow direction.
  • the plate-shaped heat dissipation member 40 is arranged along the flow direction of the cooled air a, it is possible to suppress the disturbance of the cooled air a, and a plurality of them are arranged in parallel, so that the heat transfer area is increased. The heat transfer performance can be improved.
  • the temperature boundary layer Bt is formed on the surface of the plate-shaped heat dissipation member 40. This can suppress the growth of the frost layer.
  • the plate-shaped heat dissipation member 40 can suppress the disturbance of the cooled air a to the maximum by forming the plate-shaped heat dissipation member 40. It may be a heat dissipation member.
  • the arrangement of the plurality of heat transfer tubes 16 suppresses the growth of the frost layer without forming the turbulent flow of the cooled air a, and suppresses the concentration of frost formation due to the attachment of mist due to inertia. From the viewpoint, it is preferable to use the lattice arrangement rather than the staggered arrangement with respect to the flow of the cooled air a. In addition, from the viewpoint of promoting heat transfer, it is desirable to arrange in a staggered manner, and it may be appropriately selected in relation to the conditions such as the heat exchange amount and the defrost cycle time.
  • the tip end portion 40 (40b) and the downstream side are provided between the tip end portion 40 (40b) in the flow direction of the upstream heat dissipation member 40 (40a) and the downstream side portion. It has the heat insulation area
  • 6A and 6B show an embodiment in which the heat dissipation member 40 is provided on the upstream side of the upstream heat transfer tube 16 (16a).
  • the heat insulating area 62 (62a) is formed by a gap s formed to have a length such that the temperature boundary layer Bt can be maintained without interruption in the flow direction of the cooled air a. Since the air existing in the gap s has a heat insulating property, the heat insulating region can be formed by forming the gap s. Further, since the gap s is formed to have a length that allows the temperature boundary layer Bt to be maintained without interruption in the flow direction of the cooled air a, frost formation is promoted at the end of the heat dissipation member 40 formed by the gap s. It will not be done. In the embodiment shown in FIG.
  • the heat insulating zone 62 (62b) constitutes a heat insulating zone made of a material having a low thermal conductivity.
  • the surface of this adiabatic region is formed so as not to disturb the cooled air a, and does not form a step with the other tip portion 40 (40b).
  • the heat insulating area 62 may be provided between the heat transfer tube groups.
  • the heat dissipation member 40 flows from the upstream heat transfer tube group Ta and the upstream heat transfer tube group Ta arranged on the upstream side in the flow direction of the plurality of heat transfer tube groups. It is arranged so as to straddle the downstream heat transfer tube group Tb arranged on the downstream side in the direction. Then, in a portion of the heat dissipation member 40 between the upstream heat transfer tube group Ta and the downstream heat transfer tube group Tb, a heat insulating region that suppresses heat transfer between the upstream heat transfer tube group Ta and the downstream heat transfer tube group Tb. 62 (62a, 62b).
  • the temperature boundary layer Bt can be continuously extended except for the tip portion 40 (40b) in the flow direction. As a result, it is possible to suppress the growth of frost in the entire region except the flow direction tip portion 40 (40b). Further, since the heat insulating zone 62 (62a, 62b) is provided between the upstream heat transfer tube group Ta and the downstream heat transfer tube group Tb, when performing upstream heating, or when the upstream heat transfer tube group Ta or the downstream heat transfer tube is used.
  • a plurality of heat transfer tube groups may be arranged in the flow direction of the cooled air a.
  • two or more heat transfer tube groups may be arranged in the flow direction of the cooled air a, or further, the upstreammost heat transfer tube 16 (16a) on the most upstream side is set as another heat transfer tube group, and Thus, the upstream heat transfer pipe 16 (16a) on the most upstream side may be preferentially defrosted.
  • a plurality of heat transfer tube groups may be arranged so as to be vertically stacked.
  • a plurality of heat transfer tube groups Ta, Tb and Tc may be formed in an arc shape so as to surround the fan 14 with the fan 14 as the center.
  • the plurality of heat transfer tube groups Ta, Tb, and Tc are arranged in this order from the upstream side of the cooled air a.
  • the embodiment shown in FIG. 8B is an example in which the heat transfer tube group is divided into a plurality of flow path areas Fa, Fb, and Fc, and each flow path area is configured by a plurality of heat transfer tube groups Ta, Tb, and Tc.
  • the upstream heating unit 50 first causes the upstream heat transfer pipe 16 (16a) or the upstream heat dissipation member 40 (40a).
  • At least one of the frost layer adhering surface temperatures of 0) is constantly maintained below 0 ° C. and higher than the air to be cooled a (upstream heating step S10).
  • the frost layer adhered to the upstream heat transfer tube 16 (16a) or the upstream heat dissipation member 40 (40a) can be sublimated and removed. Therefore, by adjusting to the above temperature condition, it is possible to suppress the growth of the frost layer and always secure the cooling air flow path on the heat transfer surface.
  • the upstream heating step S10 as shown in FIG. 3, a case where a defrost fluid capable of upstream heating is flowed into the heat transfer tube to heat the upstream heat transfer tube 16 (16a), and FIG. 5, FIG. 6A and FIG. As shown in FIG. 6B, there is a case where the upstream heat radiating member 40 (40a) is heated by energization or the like, and a case where these are used together as in FIGS. 4, 7A and 7B.
  • the energization heating is performed by passing an electric current from the energization section 56 to the conductive material layer 58 of the upstream heat dissipation member 40 (40a) to heat the conductive material layer 58, and remove the frost layer F attached to the surface of the conductive material layer 58.
  • the frost layer F is sublimated and removed by raising the temperature to below 0 ° C.
  • the plurality of heat transfer tubes 16 extend along the width direction (the arrow b direction in FIG. 1, the first direction) orthogonal to the flow direction of the cooled air a in the cooling air flow path, and A plurality of heat transfer tube rows formed by a plurality of heat transfer tubes 16 arranged in the up-down direction (the arrow c direction in FIG. 1, the second direction) orthogonal to the flow direction and the width direction are arranged in the flow direction.
  • the heat exchanger 10 includes a defrost unit 18 for defrosting the defrost target pipe among the plurality of heat transfer pipes 16, and the cooling air flow passage has a plurality of flow passages arranged in the vertical direction.
  • the plurality of heat transfer tubes 16 are formed by a plurality of heat transfer tubes that respectively correspond to the plurality of flow path areas Fa to Fc and belong to two or more heat transfer tube rows that are adjacent to each other in the same flow path area in the flow direction.
  • the plurality of heat transfer tube groups Ta, Tb, Tc, ... Are included in the defrost unit 18, and the heat transfer tubes 16 of one or more heat transfer tube groups among the plurality of heat transfer tube groups are selectively defrosted as defrosting target tubes. Is configured to do. In the heat exchanger 10 having such a configuration, defrosting is performed for each one or more heat transfer tube groups among the plurality of heat transfer tube groups (defrosting step S12).
  • the defrosting step S12 at the time of defrosting, by appropriately selecting the order of defrosting according to the difference in frost growth of each heat transfer tube group Ta, Tb, Tc, ... It is possible to perform efficient defrosting while preventing the blockage of the flow path, and it is possible to suppress the re-adhesion of the frost separated from the adhesion surface to the heat transfer surface on the downstream side in the flow direction. By using the defrosting operation and the upstream heating together, it is possible to effectively prevent the gas passage around the heat transfer surface from being blocked.
  • the defrost unit 18 is configured to selectively defrost only the upstream heat transfer tube 16 (16a), which is the heat transfer tube row on the most upstream side in the flow direction among the plurality of heat transfer tube rows, as the defrosting target tube. To be done. Then, in the defrosting step S12, the upstream heat transfer tube 16 (16a) in the flow direction is selectively defrosted as the defrosting target tube (step S12a). According to this embodiment, in the defrosting step S12, by selectively defrosting the upstream heat transfer pipe 16 (16a) as the defrosting target pipe, the upstream heat transfer pipe 16 (16a) can be preferentially defrosted, and the upstream heat transfer pipe 16 (16a) can be defrosted. The growth of frost on the heat transfer tube 16 (16a) can be suppressed.
  • the defrost execution time interval of each heat transfer tube group is set from this one defrost time.
  • the limit time is set to the upper limit value at which the flow of the cooled air a does not block the gaps between the plurality of heat radiating members 40, so that the cooling air between the heat radiating members 40 in each heat transfer tube group. The defrosting can be performed efficiently without blocking the flow path.
  • the defrosting time interval of each of the plurality of heat transfer tube groups is set to the downstream side in the flow direction because the growth of frost tends to be slower in the heat transfer tube group on the downstream side in the flow direction of the cooled air a.
  • the arranged heat transfer tube group is set longer. According to this embodiment, by setting the defrost execution time interval to be longer in the heat transfer tube group on the downstream side in the flow direction of the cooled air a, it is possible to reduce the frequency of defrost operation, and thus the heat exchanger during the defrost operation. It can suppress that the cooling efficiency of 10 falls.
  • a defrosting fluid capable of maintaining the frost attachment surface temperature below 0 ° C. and higher than the temperature of the gas to be cooled is transferred to the heat transfer tubes 16 of the heat transfer tube group which is the defrosting target.
  • the frost adhered to the heat transfer tube 16 is sublimated by the retained heat of the defrost fluid (sublimation defrost step S12b).
  • the defrost fluid is, for example, a refrigerant under high pressure that is stored in the receiver 28 and supplied through the defrost flow passage 34 in the refrigerator 20 shown in FIG. According to this embodiment, by supplying the defrost fluid capable of maintaining the frost adhesion surface temperature below 0 ° C. and higher than the temperature of the gas to be cooled to the heat transfer tube 16 for defrosting, the frost adhesion surface adheres to the adhesion surface. Sublimation defrost that sublimates and removes frost is possible.
  • the temperature difference between the air to be cooled a and the defrost fluid is set to be smaller as the heat transfer tube group is arranged on the downstream side in the flow direction of the air to be cooled a.
  • Step S12c when the heat transfer tube group to be defrosted is arranged on the upstream side in the flow direction of the cooled air a, the fan 14 is reversely rotated to reverse the flow direction (reverse flow).
  • Step S12c when the heat transfer tube group arranged on the upstream side in the flow direction is defrosted, the flow direction of the cooled air a is reversed so that the frost separated from the adhering surface causes the frost on the downstream side to flow. It is possible to suppress re-adhesion to the surface and to perform processing on the upstream side. Moreover, the frost adhering to the tip portion can be efficiently removed.
  • the gas to be cooled which has been heated by the heat applied during defrosting, once returns to the upstream side and is mixed and flows into another heat transfer tube group, so that temperature unevenness on the downstream side of the heat exchanger 10 can be suppressed.

Abstract

Selon un mode de réalisation, la présente invention concerne un échangeur de chaleur comprenant : un circuit d'écoulement de gaz apte à être traversé par un gaz à refroidir ; une pluralité de tuyaux de transfert de chaleur disposés à l'intérieur du circuit d'écoulement de gaz ; et une partie de chauffage côté amont destinée à maintenir la température d'une surface de formation de couche de givre d'au moins un tuyau de transfert de chaleur côté amont, parmi ladite pluralité de tuyaux de transfert de chaleur, situé dans une région côté amont dans la direction d'écoulement du gaz à refroidir, et/ou la température d'une surface de formation de couche de givre d'un élément de dissipation de la chaleur agencé au niveau de la circonférence externe dudit tuyau de transfert de chaleur côté amont, à une valeur inférieure à 0 °C mais supérieure à la température du gaz à refroidir.
PCT/JP2019/043988 2018-11-13 2019-11-08 Échangeur de chaleur et procédé de dégivrage d'échangeur de chaleur WO2020100768A1 (fr)

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JP2018213342A JP7208770B2 (ja) 2018-11-13 2018-11-13 熱交換器及び熱交換器のデフロスト方法
JP2018-213342 2018-11-13

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS50145056U (fr) * 1974-05-17 1975-12-01
JPS5731769A (en) * 1980-07-31 1982-02-20 Tokyo Shibaura Electric Co Heat pump type air conditioner
JPS5727371B2 (fr) * 1976-07-30 1982-06-10
JPS604056Y2 (ja) * 1976-03-22 1985-02-04 ダイキン工業株式会社 冷蔵庫用冷凍回路
US5771699A (en) * 1996-10-02 1998-06-30 Ponder; Henderson F. Three coil electric heat pump
JP2002286332A (ja) * 2001-03-27 2002-10-03 Kubota Corp 蒸気圧縮式ヒートポンプ
JP2013160483A (ja) * 2012-02-08 2013-08-19 Daikin Industries Ltd 空気調和装置
WO2017175411A1 (fr) * 2016-04-07 2017-10-12 株式会社前川製作所 Procédé de dégivrage par sublimation, dispositif de dégivrage par sublimation, et dispositif de refroidissement

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS50145056U (fr) * 1974-05-17 1975-12-01
JPS604056Y2 (ja) * 1976-03-22 1985-02-04 ダイキン工業株式会社 冷蔵庫用冷凍回路
JPS5727371B2 (fr) * 1976-07-30 1982-06-10
JPS5731769A (en) * 1980-07-31 1982-02-20 Tokyo Shibaura Electric Co Heat pump type air conditioner
US5771699A (en) * 1996-10-02 1998-06-30 Ponder; Henderson F. Three coil electric heat pump
JP2002286332A (ja) * 2001-03-27 2002-10-03 Kubota Corp 蒸気圧縮式ヒートポンプ
JP2013160483A (ja) * 2012-02-08 2013-08-19 Daikin Industries Ltd 空気調和装置
WO2017175411A1 (fr) * 2016-04-07 2017-10-12 株式会社前川製作所 Procédé de dégivrage par sublimation, dispositif de dégivrage par sublimation, et dispositif de refroidissement

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