EP2426436A1 - Méthode pour contrôler les cycles dégivrer dans une pompe de chaleur et une pompe de chaleur - Google Patents

Méthode pour contrôler les cycles dégivrer dans une pompe de chaleur et une pompe de chaleur Download PDF

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Publication number
EP2426436A1
EP2426436A1 EP10425288A EP10425288A EP2426436A1 EP 2426436 A1 EP2426436 A1 EP 2426436A1 EP 10425288 A EP10425288 A EP 10425288A EP 10425288 A EP10425288 A EP 10425288A EP 2426436 A1 EP2426436 A1 EP 2426436A1
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EP
European Patent Office
Prior art keywords
value
heat pump
pump system
ith
threshold value
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EP10425288A
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German (de)
English (en)
Inventor
Valerio Giordano Riello
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Aermec SpA
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Aermec SpA
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Priority to EP10425288A priority Critical patent/EP2426436A1/fr
Publication of EP2426436A1 publication Critical patent/EP2426436A1/fr
Withdrawn legal-status Critical Current

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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
    • F25B47/022—Defrosting cycles hot gas defrosting
    • F25B47/025—Defrosting cycles hot gas defrosting by reversing the cycle
    • 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
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/15—Power, e.g. by voltage or current
    • 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
    • F25B30/00—Heat pumps
    • F25B30/02—Heat pumps of the compression type

Definitions

  • the present invention concerns a method for controlling the defrosting cycles in a heat pump system and a heat pump system.
  • a heat pump is a thermal machine that, through mechanical work, removes an amount of heat from an external environment (source) and sends the overall heat energy into an internal environment (receiver) so as to heat it.
  • the heat pump can also operate reversibly as a refrigerating machine, in which it subtracts heat energy from the internal environment (source) so as to cool it down.
  • frost A problem of heat pump systems in which an air heat exchanger is used in the external environment is represented by frost that, due to atmospheric water vapour, forms on the exchanger when the temperature of a surface thereof in contact with the external environment falls below 0°C. Such a layer of frost blocks the flow of air through the exchanger, compromising the heat exchange.
  • thermoelectric heat pump systems there is a transducer that periodically measures the value of a state parameter (pressure or temperature) of the coolant fluid that flows in the external exchanger or the value of the temperature of the surface of the exchanger in contact with the external environment.
  • a state parameter pressure or temperature
  • the heat pump system carries out a defrosting cycle, for example inverting the operation of the system. In this way, the external exchanger heats up (subtracting heat from the internal environment) and melts the frost formed on it.
  • a drawback of known heat pump systems consists of the fact that, above all with low values of the temperature of the external environment and of the relative humidity, the defrosting cycle is also initiated when the external exchanger is not frosted; in this way unnecessary defrosting cycles are carried out, with a consequent decrease in efficiency of the entire system.
  • Document WO 98/36277 discloses a system for controlling the defrosting cycles, based on the monitoring of the temperature of the internal heat exchanger: if the measured temperature differs from the maximum temperature TMAX reached by the internal heat exchanger, after the last defrosting cycle carried out, by a value greater than a predetermined value ⁇ T, this means that the efficiency of the heat exchanger is compromised by the formation of frost on the external heat exchanger.
  • the defrosting cycle is activated when a state parameter of the refrigerating system falls below a threshold value, irrespective of its absolute value.
  • the state parameter can be low pressure or rather the pressure in the heat exchanger that acts as an evaporator. Indeed, if the external temperature is low the low pressure is also low but, when frost has not formed, it remains constant and therefore no defrosting cycle is carried out.
  • a drawback of this method is represented by the fact that it cannot be applied to heat pumps with cooling systems having variable capacity. Heat pumps having variable capacity, compared to systems having constant capacity, offer numerous advantages including greater efficiency at partial load, better temperature control and low inrush current.
  • a system having variable capacity can be obtained for example by using compressors with variable capacity, such as compressors with variable speed or screw compressors equipped with a slide valve.
  • the state parameters When the capacity of the system varies, for example after thermostat control of the heat pump, the state parameters also vary as a consequence of the changed capacity of the system. Consequently, a variation of the state parameters does not necessarily indicate an accumulation of frost on the external exchanger.
  • a further different approach is based on the measurement of the resistance of the air flow through the external exchanger.
  • the resistance of the air flow is normally measured through a differential pressure sensor that measures the air pressure downstream and upstream of the exchanger.
  • the accumulation of frost blocks the air flow through the exchanger and determines a greater pressure difference.
  • a drawback of such a method is represented by the fact that it is often difficult to arrange the differential pressure sensors, particularly if the external exchanger is not mounted in a duct.
  • the purpose of the present invention is therefore to provide a method for controlling the defrosting cycles of a heat exchanger in a heat pump system having structural and functional characteristics such as to satisfy the aforementioned requirements and at the same time to avoid the drawbacks mentioned with reference to the prior art.
  • Such a purpose is accomplished by a method for controlling the defrosting cycles of a heat exchanger in a heat pump system in accordance with claim 1.
  • the method of the invention has an application in heat pump systems with an external heat exchanger in air under forced circulation.
  • the activation of the defrosting cycles is based on an electrical variable representative of the power absorbed by the electric motor of the fan and therefore on a parameter that is independent from the capacity of the system and that varies only in the presence of frost formation on the heat exchanger.
  • the heat pump system 100 can be an air conditioner for winter heating and for summer cooling. Alternatively, the heat pump system 100 can also be used in different applications, like in a thermal power station, in a distillation device and the like.
  • the heat pump system 100 uses a coolant fluid (for example Freon) subjected to a thermodynamic cycle (as described in detail hereafter), which flows through a fluid circuit 103 defined by suitable pipes.
  • a coolant fluid for example Freon
  • thermodynamic cycle as described in detail hereafter
  • the heat pump system 100 comprises an external heat exchanger in air 130 in contact with an external environment, hereafter indicated for the sake of brevity by external exchanger 130.
  • the external exchanger 130 can operate as a source or else as a thermal receiver, in the winter and summer respectively.
  • the heat exchange takes place in air; in particular, the external exchanger 130 comprises a plurality of pipes, advantageously finned, crossed by the coolant fluid and licked on the outside by air.
  • the circulation of the air through the external exchanger 130 is forced through a fan 135 associated with the external exchanger 130.
  • the fan 135 comprises an impeller 136 and an electric motor 137 coupled with the impeller 136 to set the impeller 136 itself in rotation.
  • the heat pump system 100 also comprises an internal heat exchanger 140, hereafter for the sake of brevity indicated as internal exchanger 140, in contact with an internal environment acting as thermal receiver and source in the winter and summer, respectively.
  • a fan 145 can be foreseen to force the circulation of the air in the internal environment, through the internal exchanger 140, from an intake channel 151 to a delivery channel 153.
  • the present invention nevertheless also lends itself to use with internal heat exchangers of different types, for example with heat exchange in water, in the floor, and the like.
  • the heat pump system 100 can consist of a single body or else two separate units can be foreseen arranged, respectively, in the external environment and in the internal environment.
  • the heat pump system 100 comprises a compression unit 150 arranged between the external exchanger 130 and the internal exchanger 140.
  • the heat pump system 100 comprises a four-way valve 154 arranged between the compression unit 150 and the external exchanger 130 to allow the winter-summer inversion of the circuit 103.
  • the four-way valve 154 has a port 154a connected to the outlet of the compression unit 150, a port 154b connected to the internal exchanger 140, a port 154c connected to the inlet of the compression unit 150 and a port 154d connected to the external exchanger 130.
  • valve 154 places the port 154a in communication with the port 154b and the port 154c in communication with the port 154d.
  • valve 154 places the port 154a in communication with the port 154d and the port 154c in communication with the port 154b.
  • Two expansion valves 155, 156, or alternatively small calibrated ports or sections of capillary tubes, can be foreseen for the winter and summer circuit, respectively, of the coolant fluid.
  • the rotation of the impeller 136 produces an air flow that must pass through the external exchanger 130 overcoming the flow resistance produced by the external exchanger 130 itself.
  • the power absorbed by the electric motor 137 that actuates the impeller 136 depends, for a given supply voltage V of the electric motor 137, mainly upon the flow resistance produced by the external exchanger 130.
  • the formation of frost on the external exchanger 130 blocks the air flow through the exchanger 130 itself and causes an increase in the flow resistance. In this condition, as can be seen from figure 3 , there is an increase in the power absorbed by the electric motor 137.
  • A represents the flow rate-head characteristic curve of a fan actuated by electric motor and B 1 represents the resistant curve of a heat exchanger in a condition in the absence of frost.
  • Curve A meets with curve B1 on the point OP1 that represents the operating point with heat exchanger in a condition without frost and to which corresponds a power P1 absorbed by the electric motor.
  • the resistant curve of the heat exchanger is represented by B2.
  • Curve A meets with curve B2 in the point OP2 that represents the working point with frosted heat exchanger and to which corresponds a power P2 absorbed by the electric motor greater than the power P1 absorbed by it without frost on the heat exchanger.
  • a parameter capable of providing a reliable indication of formation of frost on the external exchanger 130 is thus represented by an electric variable representative of the power P absorbed by the electric motor 137 itself.
  • the heat pump system 100 thus comprises measurement means 160 connected to the electric motor 137 to measure the value of an electric variable representative of the power P absorbed by the electric motor 137 itself.
  • the electric variable corresponds to the current absorbed by the electric motor 137.
  • the measurement means 160 comprise a current transducer suitable for measuring the intensity of the electric current I absorbed by the electric motor 137.
  • Such an embodiment can only be used if the supply voltage V of the heat pump system 100, and in particular of the fan 135, is constant and therefore does not influence the absorbed current I.
  • the electric variable corresponds to the power P absorbed by the electric motor 137.
  • the measurement means 160 comprise a wattmeter suitable for measuring the power P absorbed by the electric motor 137.
  • this second embodiment has the advantage of being able to be used in any power supply condition of the heat pump system 100, although with greater overall cost of the measurement system.
  • the heat pump system 100 also comprises processing means 165 suitable for receiving as input the value I measured by the measurement means 160 and processing this measured value I and a threshold value Ith of the electric variable measured to generate as output a control signal S to control the actuation of the electric motor 137 and the inversion of the operating cycle of the heat pump system 100.
  • the processing means 165 can be suitable for comparing the measured value I with the threshold value Ith and generating as output the control signal S for the actuation of the electric motor 137 and the inversion of the cycle of the system 100 when the measured value I reaches or exceeds a threshold value Ith.
  • the processing means 165 are suitable for processing the measured value I, the threshold value Ith and a minimum value Imin of the electric variable measured to generate as output a control signal S.
  • the processing means 165 have an input in signal communication with the measurement means 160 to receive as input the measured value I and an output in signal communication with the electric motor 137 and the four-way valve 154 to generate as output a control signal S to control the actuation of the electric motor 137 and the inversion of the operating cycle of the heat pump system 100.
  • control signal S it is meant the set of control signals necessary to control the actuation of the electric motor 137 and the inversion of the operating cycle of the heat pump system 100.
  • the processing means 165 are suitable for processing the measured value I, the minimum value Imin and the threshold value Ith and generating a control signal S to stop the electric motor 137 and control the four-way valve 154.
  • the processing means 165 are configured to calculate the difference DI between the measured value I and the minimum value Imin, compare the calculated difference DI with the threshold value Ith, and generate as output the control signal S when the calculated difference DI is greater than the threshold value Ith.
  • storage means 170 are provided to store the minimum value Imin and the threshold value Ith. Such storage means 170 can be incorporated in the processing means 165 or may be outside.
  • the processing means 165 are also connected to the compression unit 150 to control the operation of the heat pump system 100 through suitable control signals and to carry out a defrosting cycle of the external exchanger 130.
  • the coolant fluid in vapour phase at the outlet of the external exchanger 130 which operates as an evaporator, is compressed in the unit 150.
  • the internal exchanger 140 operates as a condenser, in which the coolant fluid cools down until it condenses into liquid state supplying heat to the internal environment.
  • the coolant fluid thus expands with partial vaporisation in the valve 155, so as to adjust the flow rate of the coolant fluid itself so that it is completely vaporised in the external exchanger 130 through the effect of the heat subtracted from the external environment.
  • the external exchanger 130 operates as a condenser; the coolant fluid partially expands in the valve 156 and the internal exchanger 140 operates as an evaporator, so as to subtract heat from the internal environment.
  • a defrosting cycle (as described in detail hereafter) is carried out to melt the layer of frost deposited on an outer surface of the external exchanger 130.
  • the operation of the system 100 is inverted, so that the external exchanger 130 (operating as a condenser) heats up melting such frost.
  • the operation of the heat pump system 100 is interrupted and the melting of the frost is obtained through electrical heating, with a flow of air or water at a suitable temperature, or else with injection of hot gas coming from the outlet of the compression unit 150.
  • a method for controlling the defrosting cycles of the heat pump system 100 starts, at the system activation time t0, in block 205, where the heat pump system 100 is activated.
  • the method comprises a step of carrying out a first defrosting cycle.
  • the value of the pressure LowP of the coolant fluid flowing in the external exchanger 130 is detected.
  • the method verifies whether a first defrosting cycle has been carried out from time t0 in which the heat pump system 100 was activated.
  • the method proceeds to block 225 where the conditions for activating a first defrosting cycle are verified. It should be noted that, in the case in which at the moment of verification a first defrosting cycle has not been activated, it is not possible to know whether the heat exchanger has no frost. Therefore in accordance with an embodiment, the conditions for activating a first defrosting cycle are different from those used to activate the defrosting cycles after the first.
  • the method provides verifying whether the value of the pressure LowP is below a pressure threshold LowPth, specific of the first defrosting cycle and, optionally, whether the time t since the activation time t0 of the heat pump system 100 has exceeded a minimum first defrosting time threshold tfmin, for example 10 minutes.
  • the method proceeds to block 220 where, at the measurement time tm, the value I of an electric variable representative of the power P absorbed by the electric motor 137 of the fan 135 is acquired.
  • the method provides, in block 230, a step of stabilization of the measurement of the electric variable. In particular, it is verified whether the time between the system activation time t0 and the measurement time tm in which the measurement of the electric variable value took place is below a threshold value tmth. In the positive case the method goes back to block 220 where a further value I of the electric variable is measured.
  • the method proceeds to block 235 where the step of updating the minimum value Imin begins, in which the measured value I is compared with a stored minimum value Imin.
  • the stored minimum value Imin of the measured electric variable is pre-set and able to be adjusted by the user according to the type of heat pump system 100.
  • the minimum value Imin corresponds to a condition without frost on the external exchanger 130.
  • the measured value I is below the stored minimum value Imin, the measured value I is assigned to the stored minimum value Imin (block 240) and the method proceeds to block 245 of verifying the conditions for the activation of a defrosting cycle, otherwise the stored minimum value Imin remains unchanged and the method proceeds directly to block 245 of verifying the conditions for the activation of a defrosting cycle.
  • the measured value I, the minimum value Imin and the threshold value to activate a defrosting cycle are processed.
  • the difference DI between the measured value I and the stored minimum value Imin is greater than the threshold value Ith and, optionally, whether the time td since the activation of the previous defrosting cycle is greater than a defrosting time threshold tdth.
  • the threshold value Ith is a function of the minimum value Imin, in the example equal to 8% of the minimum value Imin.
  • the threshold value Ith can be a pre-set value able to be adjusted by the user.
  • the defrosting time threshold tdth can for example be equal to 15 minutes so as to avoid the activation of the defrosting cycles a short time from one another.
  • the method proceeds to block 250 where a defrosting cycle is activated. In the negative case, the method goes back to block 220 where a new value I of the electric variable representative of the power P absorbed by the electric motor 137 is measured.
  • the present invention allows a defrosting cycle to be activated only when the frost has actually accumulated on the heat exchanger. In this way, the activation of needless defrosting cycles is avoided with a consequent saving of electrical energy.
  • the present invention can also be applied to heat pump systems having variable capacity with a heat exchanger also not installed in ducts.
  • defrosting cycle can still be activated for safety should specific safety conditions be present.
  • a verification of the conditions for safety defrosting can be carried out at block 245 where it is verified whether the value of the pressure LowP is below a safety pressure threshold Ps and, optionally, whether the time since the activation of the previous defrosting cycle is greater than the defrosting time threshold tdth.
  • the defrosting cycle begins, at a defrosting activation time tda, in block 255 and, at the temperature measurement time tmt, the temperature of the external heat exchanger 130 is acquired.
  • the temperature Te is detected at the coolant fluid delivery duct of the external heat exchanger 130. It should be considered that, during defrosting, the heat pump system 100 switches from the heating mode to the cooling mode. Consequently, during the defrosting cycle, the flow of coolant fluid circulates in the opposite direction with respect to the normal operating condition. Therefore, during the defrosting cycle, the delivery duct is referred to the cooling mode.
  • the temperature Te can be detected on the surface of the fins of the pipes of the external exchanger 130.
  • block 260 it is verified whether the time since the activation time of the defrosting cycle tda at the measurement time tmt of the temperature Te is greater than a minimum defrosting time threshold tdmin. In the negative case, the method goes back to block 255 where a new temperature value Te of the external heat exchanger 130 is acquired. In the affirmative case, the method proceeds to block 265 where it is verified whether there are the conditions to stop the defrosting cycle.
  • the fan 135 is normally not active. Therefore, it is advantageous to use the temperature or pressure of the external exchanger 130 as parameters for stopping the defrosting cycle.
  • the method then provides to verify whether the temperature Te of the external exchanger 130 is greater than a temperature threshold Tend, set for example at 40°C and/or whether the time since the activation of the defrosting cycle tda at the time of detection of the temperature tmt has reached a maximum time threshold tdmax, for example equal to 10 minutes.
  • a temperature threshold Tend set for example at 40°C and/or whether the time since the activation of the defrosting cycle tda at the time of detection of the temperature tmt has reached a maximum time threshold tdmax, for example equal to 10 minutes.
  • the defrosting is stopped (block 270), the minimum value Imin is set at the predefined value (block 275) and the method continues at block 215.
  • the method goes back to block 255 with the measurement of a new temperature value Te.
  • the method and heat pump system according to the present invention allows the drawbacks mentioned with reference to the prior art to be overcome.
  • the present invention allows a defrosting cycle to be activated only when the frost has actually accumulated on the heat exchanger. In this way, the activation of needless defrosting cycles is avoided with a consequent saving of electrical energy.
  • the present invention can also be applied to heat pump systems having variable capacity with a heat exchanger also not installed in ducts.
EP10425288A 2010-09-07 2010-09-07 Méthode pour contrôler les cycles dégivrer dans une pompe de chaleur et une pompe de chaleur Withdrawn EP2426436A1 (fr)

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EP10425288A EP2426436A1 (fr) 2010-09-07 2010-09-07 Méthode pour contrôler les cycles dégivrer dans une pompe de chaleur et une pompe de chaleur

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EP10425288A EP2426436A1 (fr) 2010-09-07 2010-09-07 Méthode pour contrôler les cycles dégivrer dans une pompe de chaleur et une pompe de chaleur

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2851635A4 (fr) * 2012-05-16 2015-12-30 Panasonic Ip Man Co Ltd Procédé de commande de système de chauffage et système de chauffage
CN106705379A (zh) * 2017-01-10 2017-05-24 美的集团武汉制冷设备有限公司 化霜控制方法、化霜控制系统和空调器
WO2023105574A1 (fr) * 2021-12-06 2023-06-15 株式会社日立製作所 Système de gestion d'entrepôt frigorifique, dispositif de traitement de détermination de dégivrage, et procédé de gestion d'entrepôt frigorifique

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3110850A1 (de) * 1981-03-20 1982-09-30 Küppersbusch AG, 4650 Gelsenkirchen Steuereinrichtung fuer die automatische abtauung eines verdampfers
US4400949A (en) * 1981-03-03 1983-08-30 Mitsubishi Denki Kabushiki Kaisha Frost detector for refrigerating apparatus
FR2595806A1 (fr) * 1986-03-12 1987-09-18 Total Energie Dev Procede et dispositif pour la detection de givre sur un echangeur de chaleur
JPH0849956A (ja) * 1994-08-04 1996-02-20 Fuji Electric Co Ltd 冷蔵ショーケースの除霜制御装置
WO1998036277A2 (fr) 1997-02-18 1998-08-20 Dade Behring Inc. Stabilisation de reactifs particulaires
EP0893663A1 (fr) 1997-07-22 1999-01-27 RIELLO CONDIZIONATORI S.p.A. Procédé de commande pour des cycles de dégivrage dans un système de pompe à chaleur
JPH11287538A (ja) * 1998-03-31 1999-10-19 Sanyo Electric Co Ltd 空気調和機
US6263686B1 (en) * 2000-07-10 2001-07-24 Carrier Corporation Defrost control method and apparatus
JP2003269772A (ja) * 2002-03-13 2003-09-25 Sanyo Electric Co Ltd 冷凍装置、空気調和装置及びそれらの制御方法
US20050172648A1 (en) * 2004-02-11 2005-08-11 Julio Concha Defrost mode for HVAC heat pump systems

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4400949A (en) * 1981-03-03 1983-08-30 Mitsubishi Denki Kabushiki Kaisha Frost detector for refrigerating apparatus
DE3110850A1 (de) * 1981-03-20 1982-09-30 Küppersbusch AG, 4650 Gelsenkirchen Steuereinrichtung fuer die automatische abtauung eines verdampfers
FR2595806A1 (fr) * 1986-03-12 1987-09-18 Total Energie Dev Procede et dispositif pour la detection de givre sur un echangeur de chaleur
JPH0849956A (ja) * 1994-08-04 1996-02-20 Fuji Electric Co Ltd 冷蔵ショーケースの除霜制御装置
WO1998036277A2 (fr) 1997-02-18 1998-08-20 Dade Behring Inc. Stabilisation de reactifs particulaires
EP0893663A1 (fr) 1997-07-22 1999-01-27 RIELLO CONDIZIONATORI S.p.A. Procédé de commande pour des cycles de dégivrage dans un système de pompe à chaleur
JPH11287538A (ja) * 1998-03-31 1999-10-19 Sanyo Electric Co Ltd 空気調和機
US6263686B1 (en) * 2000-07-10 2001-07-24 Carrier Corporation Defrost control method and apparatus
JP2003269772A (ja) * 2002-03-13 2003-09-25 Sanyo Electric Co Ltd 冷凍装置、空気調和装置及びそれらの制御方法
US20050172648A1 (en) * 2004-02-11 2005-08-11 Julio Concha Defrost mode for HVAC heat pump systems

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2851635A4 (fr) * 2012-05-16 2015-12-30 Panasonic Ip Man Co Ltd Procédé de commande de système de chauffage et système de chauffage
CN106705379A (zh) * 2017-01-10 2017-05-24 美的集团武汉制冷设备有限公司 化霜控制方法、化霜控制系统和空调器
WO2023105574A1 (fr) * 2021-12-06 2023-06-15 株式会社日立製作所 Système de gestion d'entrepôt frigorifique, dispositif de traitement de détermination de dégivrage, et procédé de gestion d'entrepôt frigorifique

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