Abstract: A first heat exchanger, a desiccant block, and a second heat exchanger are arranged in series. In a dehumidification operation, a first operation mode in which the first heat exchanger acts as a condenser or a radiator and the second heat exchanger acts as an evaporator and a second operation mode in which the first heat exchanger acts as an evaporator and the second heat exchanger acts as a condenser or a radiator are alternately repeated.

Abstract: A first flow switching device causes part of a refrigerant discharged from an injection compressor to flow through a first bypass pipe and be supplied to an outdoor heat exchanger targeting for defrosting. A second flow switching device causes part of the refrigerant supplied to the outdoor heat exchanger targeting for defrosting to enter a second bypass pipe.

Abstract: A method for operating a refrigeration system for a container for refrigerating chilled cargo includes providing a refrigeration system including a compressor and an evaporator fan associated with an evaporator. The method also includes determining the temperature of supply air and the temperature of return air. The method further includes determining one of a requirement for heating and a requirement for cooling based on the temperature of the return air and the temperature of the supply air. The method additionally includes activating the evaporator fan when a requirement for heating is determined and increasing the speed of the evaporator fan when increased heating is determined. The method also includes activating the compressor and the evaporator fan when a requirement for cooling is determined and increasing the power supplied to the compressor and maintaining the evaporator fan at a first speed when increased cooling is determined.

Abstract: Methods and systems are provided for air conditioning, capturing combustion contaminants, desalination, and other processes using liquid desiccants.

Abstract: A refrigerant circuit is configured by connecting, by pipes, a compressor that compresses a heat-source-side refrigerant, a first refrigerant flow switching device, a heat-source-side heat exchanger, an expansion device, and one or more intermediate heat exchangers that exchange heat between a heat-source-side refrigerant and a heat medium that is different from the heat-source-side refrigerant. A controller performs control of pumps to drive the pumps at a specific pump capacity or higher to circulate the heat medium at a time when a heat recovery defrosting operation for causing the heat-source-side refrigerant that has been heated by the heat medium in the intermediate heat exchangers to flow into the heat-source-side heat exchanger for defrosting purposes.

Abstract: An order in which parts of a heat source side heat exchanger are defrosted is determined on the basis of the heat exchanger capacity of the parts of the heat source side heat exchanger, the necessary heating capacity of the parts of the heat source side heat exchanger, and the arrangement of the parts of the heat source side heat exchanger, the opening and closing of first flow switching valves, second flow switching valves, and third flow switching valves are controlled accordingly, and a defrosting operation in which a refrigerant discharged from a compressor is caused to flow through the heat source side heat exchanger is performed.

Abstract: The invention relates to a method for controlling a refrigeration system by establishing a defrost period during an initial defrost period. One or more compressors of the refrigeration system are monitored to establish if the one or more compressors are running, and a parameter representative of the one or more compressors running is monitored. The monitoring establishes at least one parameter limit value representative of whether a defrost period or a non-defrost period is to be initiated. The invention also relates to a method for controlling a refrigeration system subsequent to an electrical power interruption. The invention also relates to control units for applying one or both of the methods according to the invention, and to a refrigeration system having one or more control units controlling the refrigeration system according to one or both of the methods.

Abstract: In an air-conditioning apparatus, a heat source side heat exchanger 12, intermediate heat exchangers 15a and 15b, and use side heat exchangers 26a to 26d are separately formed and adapted to be disposed at separate locations, respectively. There are provided a defrosting operation function to melt frost attached around the heat source side heat exchanger 12, and a heating function during defrosting operation that drives a pump 21a to circulate a heat medium and supply heating energy to the use side heat exchangers 26a to 26d in need of heating to perform heating operation. The defrosting operation function can be executed by switching a four-way valve 11 to cooling side to introduce a high-temperature high-pressure refrigerant flowed out of the compressor 10 into the heat source side heat exchanger 12.

Abstract: Frost may accumulate on a heat pump. In various implementations, a primary defrost operation and/or a secondary defrost operation may be utilized to remove at least a portion of the frost from the heat pump.

Abstract: In various implementations, frost in a vapor compression system may be controlled. A property of a fan may be determined. A determination may be made whether a frost event and/or a nonfrost event has occurred based at least partially on the determined fan property.

Abstract: Adaptable evaporator defrost logic is employed in a refrigeration system to detect a build-up of ice on the evaporator. In response to the detected build-up of ice, a defrost operation is initiated that includes decreasing the speed of the compressor. At the end of the defrost operation, the adaptable evaporator defrost logic determines whether the defrost operation was a success. If the defrost operation was a success, then normal operation is resumed. If the defrost operation was not a success, then the defrost operation is modified by turning the compressor off and extending a duration of the defrost operation.

Abstract: A method of refrigeration control through a refrigeration system of a refrigerated transport container includes performing a defrost cycle on the refrigeration system by activating a heat source; and restarting the refrigeration system after the defrost cycle has completed, wherein restarting the refrigeration system includes performing a liquid slugging avoidance process including: initiating a compressor of the refrigeration system at a speed; opening a pressure equalization valve in parallel with the compressor in response to the initiating; opening a liquid valve in series between a condenser and an evaporator after opening of the pressure equalization valve; and closing the pressure equalization valve after a period of time.

Abstract: A method of defrosting a heat exchanger while the heat exchanger continues to cool air passing through the heat exchanger. The heat exchanger includes liquid passages for carrying cold liquid between an inlet and an outlet and air passages in thermal communication with the liquid passages for cooling air passing through the air passages. The method includes introducing warmer liquid to a first selected section of the heat exchanger liquid passage while continuing to provide cold liquid to the liquid passages of the heat exchanger.

Abstract: An air conditioner includes a refrigerant circuit, a switching valve, an outdoor fan and a controller. The refrigerant circuit sequentially circulates refrigerant through a compressor, an indoor heat exchanger, a decompression mechanism and an outdoor heat exchanger during a heating operation. The switching valve is connected to the refrigerant circuit to switch a flow direction of the refrigerant discharged from the compressor. The controller executes a defrosting operation control in which the outdoor fan is deactivated and the switching valve directs refrigerant discharged from the compressor towards the outdoor heat exchanger during a defrosting operation. The controller further maintains the switching valve so refrigerant discharged from the compressor is directed towards the outdoor heat exchanger and executes a fan defrosting operation control in which the outdoor fan is rotated for a predetermined period of time after completion of the defrosting operation when a predetermined condition is satisfied.

Abstract: A refrigerated merchandiser including a case, a refrigeration system, a sensor, and a controller. The refrigeration system is operable in a defrost mode defrosting the evaporator, and a refrigeration mode discharging a refrigerated airflow into the product storage area to refrigerate the product and to maintain the product within a predetermined temperature range without freezing the product, and to receive the refrigerated airflow along a return passageway. The sensor senses one or more defrost conditions of the case. The controller controls the refrigeration system in the refrigeration mode and in the defrost mode, and includes an algorithm for calculating when to initiate the defrost mode and for calculating a duration of the defrost mode. The controller is programmed to vary the refrigeration system between the refrigeration mode and the defrost mode based on the signals indicative of the defrost conditions and the calculations by the algorithm.

Abstract: A system, configured to be disposed in a information technology equipment rack for providing ice thermal storage, includes a tank configured to hold water, a heat exchanger disposed in water in the tank and configured to convey a two-phase liquid and vapor refrigerant and to transfer heat between the water and the refrigerant, a first valve connected to a liquid and a vapor refrigerant line and configured to selectively connect the liquid refrigerant line to a first port and the vapor refrigerant line to a second port in a first mode and to connect the liquid refrigerant line to the second port and the vapor refrigerant line to the first port in a second mode, a thermostatic expansion valve connected to an inlet of the heat exchanger, and a liquid/vapor pump connected to an outlet of the heat exchanger and to the second port of the first valve.

Abstract: An HVAC system may include a building controller, two or more HVAC components and at least two Equipment Interface Modules (EIM). Each of the EIMs may include a wired and/or wireless interface for communication to the HVAC controller. Each EIM may be wired to one or more of the HVAC components of the HVAC system. In some cases, the HVAC controller may be configured to provide one or more control commands to control two or more of the HVAC components of the HVAC system via the EIMs. In some cases, the EIMs may provide control signals to the HVAC controller, and the HVAC controller may generate one or more commands in response to the received control signals.

Abstract: An air-conditioning apparatus including a check valve in a passage between a first flow switching device and a suction side of a compressor, an expansion valve midway of a liquid extension piping, and an additional unit having a first bypass and a second bypass that are branched off from a passage between an indoor unit and the liquid expansion valve, and are connected to a passage between the check valve and the suction side of the compressor. The first bypass has, midway thereof, a first bypass expansion valve capable of controlling a throughput of refrigerant and an auxiliary heat exchanger that has a heat source different from the refrigerant, the auxiliary heat exchanger functioning as an evaporator heating the refrigerant flowing in the first bypass. The second bypass has, midway thereof, a second bypass expansion valve capable of controlling a throughput of refrigerant.

Abstract: A climate control system for the interior cabin of an automotive vehicle. The climate control system includes a mode selection device configured for selecting a defrost mode. When the system is in the defrost mode, a controller receives a signal from a humidity sensor indicative of the measured humidity level in the vicinity of the window. The controller compares this measured humidity level with a threshold humidity level and, if the humidity is below the threshold humidity level, the controller stops operation of a compressor being used to dehumidify the air being provided to defrost the window, thereby minimizing possible fogging of the window and increasing the efficiency of the vehicle.

Abstract: A refrigeration machine for a domestic refrigerator includes a compressor, a condenser and an evaporator, which are connected to form a refrigerant circuit, wherein a stop valve is arranged in a refrigerant path from the condenser to the evaporator.

Abstract: A refrigeration cycle apparatus 100 includes a first compressor 101, a second compressor 102 provided in parallel with the first compressor 101, a radiator 103 for cooling a refrigerant compressed by the compressors 101 and 102, an expander 104 for recovering power while expanding the refrigerant cooled by the radiator 103, an evaporator 105 for evaporating the refrigerant expanded by the expander 104, a rotation shaft 123 connecting the first compressor 101 to the expander 104 so that the first compressor 101 uses the power recovered by the expander 104, a controller 112 for executing a control including a step of increasing a flow rate of the refrigerant gradually during a defrosting operation in which frost formed on the evaporator 105 is melted by allowing the refrigerant having a high temperature to flow through the evaporator 105.

Abstract: An air conditioner for a vehicle is provided with: a compressor that compresses a heat exchange medium; an external heat exchanger that receives the heat exchange medium and that exchanges heat with the outside of a vehicle compartment; and an evaporator that receives the heat exchange medium and exchanges heat with the inside of a vehicle compartment, and the air conditioner for a vehicle is able to perform: a defrosting cooling operation in which the heat exchange medium that has been compressed by the compressor is made to flow into the evaporator and absorb heat, and to then flow into the external heat exchanger and release heat; and a hot gas operation in which the heat exchange medium that has been compressed by the compressor is made to flow into the external heat exchanger and release heat without being made to absorb heat in the evaporator, and, by switching between performing the defrosting cooling operation and performing the hot gas operation, the air conditioner for a vehicle performs a defrostin

Abstract: A vehicle air conditioning apparatus is provided that can extend the mileage of a vehicle by reducing the power consumed by the operation of a compressor and a heater. When a required quantity of heating Q_req is acquired, the minimum power sharing ratio between quantity of heat release Q_hpof a water-refrigerant heat exchanger 22 and quantity of heat release Q_htrof a water heater 32 is calculated, which allows the power consumption W_total to be minimized, and a compressor 21 and the water heater 32 is operated based on the result of the calculation.

Abstract: A refrigerator is provided that includes a chilled interior and a cooling circuit for a coolant, the cooling circuit being provided with an evaporator, a compressor, and a condenser. The refrigerator further includes a controller as well as a fan for cooling the condenser and the compressor. The controller controls the fan to operate during an idle phase of the compressor.

Abstract: An air conditioner and a method for controlling the same for securing reliability and increasing efficiency are provided. The air conditioner and the method of controlling the same detect freezing occurring in the heat exchanger of the outdoor unit, determine a time of the defrosting operation according to a freezing degree such that the defrosting operation is performed, thereby preventing cooling/heating operation efficiency and capability due to a frequent defrosting operation from being deteriorated. The air conditioner and the method of controlling the same according to the present invention provide comfort of a predetermined level to the user to solve deterioration of convenience, and remove freezing due to a defrosting operation to thereby improve efficiency during cooling/heating operations.

Abstract: A freezer that uses liquid cryogen as a refrigerant includes an inner vessel defining a storage chamber and an outer jacket generally surrounding the inner vessel so that an insulation space is defined there between. A heat exchanger is positioned in a top portion of the storage chamber and has an inlet in communication with a supply of the liquid cryogen refrigerant so that the liquid cryogen refrigerant selectively flows through the heat exchanger to cool the storage chamber while being vaporized. A purge line is in communication with the outlet of the heat exchanger and includes a purge outlet positioned over the exterior of the heat exchanger. A purge valve is positioned within the purge line so that the vaporized liquid cryogen from the heat exchanger is selectively directed to the exterior of the heat exchanger to reduce ice formation on the heat exchanger.

Abstract: The defrost timer is typically provided to remove frost on an evaporator in a refrigerator. The defrost timer includes a circuit board, a first terminal, a second terminal, a third terminal, a fourth terminal, a switching unit, a first AC line, a second AC line, a third AC line and a fourth AC line. The first AC line is provided on the circuit board and connects the first terminal and the switching unit. The second AC line is provided on the circuit board and connects the second terminal and the switching unit. The third AC line is provided on the circuit board and connects the third terminal and the switching unit. The fourth AC line is provided on the circuit board and connects the fourth terminal and the switching unit. Distance between the third AC line and the fourth AC line is at least 5 mm.

Abstract: A method for defrost control of a refrigerator having a refrigeration and defrost system that includes a compressor, an evaporator, an evaporator fan and a heater. The refrigerator also has a control system to control the operation of the refrigerator. The method includes stopping the compressor operation; starting a defrost process; starting the heater; maintaining a start state over a preset period of time; closing off the heater; and starting the compressor. After starting the compressor and before the evaporator fan is started to perform the refrigeration operation, the evaporator fan is operated at least once briefly and intermittently.

Abstract: A refrigerator according to the present invention includes a compressor compressing a coolant, a condenser condensing the coolant compressed in the compressor, an expander through which the coolant condensed in the condenser passes, an evaporator evaporating the coolant expanded in the expander and cooling an inside of the refrigerator, a defroster defrosting the evaporator, a coolant adjusting valve adjusting the coolant flowing from the condenser to the evaporator, and a controller driving the compressor and turning on the defroster after closing the coolant adjusting valve. The refrigerator may minimize power consumed for defrosting and the defrosting time.

Abstract: A refrigerator and a control method of the same are disclosed. A refrigerator includes a plurality of evaporators and a refrigerant path conversion device connected with the plurality of the evaporates, the refrigerant path conversion device controlling a path of refrigerant to perform defrosting operations for predetermined evaporators and cooling operations for the other evaporators.

Abstract: An alternating type heat pump has first to third rows of outdoor unit coils adapted to selectively perform the functions of an evaporator and a condenser in accordance with the outdoor conditions and the load variations, thereby improving the performance of the heat pump, and is capable of allowing the first to third rows of outdoor unit coils to be operated as a condenser in an alternating manner under the conditions where frost on the outdoor unit coils may be formed especially in winter seasons, thereby basically preventing the conditions on which the frost is formed.

Abstract: A method of defrosting an energy recovery ventilator unit. The method comprises activating a defrost process of an enthalpy-exchange zone of the energy recovery ventilator unit when an air-flow blockage in the enthalpy-exchange zone coincides with a frost threshold in the ambient environment surrounding the energy recovery ventilator unit. The method also comprises terminating the defrost process, including terminating the defrost process when an operating condition in the vicinity of the enthalpy-exchange zone substantially returns to a pre-frosting operating condition.

Abstract: A defroster is provided in a refrigerator, in which a damper mounted to an inlet to a circulating duct controls air to flow in a reverse direction toward an evaporator to maximize a defrosting efficiency by using not only radiant heat but also convective heat. The defroster includes the evaporator, a heater that defrosts the evaporator by radiation, and a flow controller that controls air circulated by a fan to flow in a reverse direction toward the evaporator in defrosting.

Abstract: An air conditioner may include a plurality of indoor units and a plurality of outdoor units connected to the plurality of indoor units. Each of the plurality of outdoor units may include a plurality of outdoor heat exchangers. Each of the outdoor heat exchangers may include a plurality of heat exchanger parts. When a defrosting operation condition is satisfied during a heating operation, indicating that a defrosting operation should be performed the plurality of heat exchanger parts of the plurality of outdoor heat exchangers may successively perform the defrosting operation.

Abstract: A high performance refrigerator or freezer includes a cabinet with a refrigerated interior, a first evaporator cover separating a first evaporator compartment within the cabinet from the refrigerated interior, and a refrigeration fluid circuit having a first evaporator located within the first evaporator compartment, a second evaporator, and a three-way valve enabling selective communication of refrigerant to one or both of the evaporators. The second evaporator includes an air diffuser that receives chilled air from the first evaporator compartment and delivers the chilled air into the refrigerated interior. During normal operation, the three-way valve only directs refrigerant into the first evaporator such that the first evaporator cools the cabinet and the chilled air from the first evaporator passively defrosts the second evaporator by sublimation.

Abstract: A high performance refrigerator includes a cabinet with a refrigerated interior and a refrigeration fluid circuit having first and second evaporators located within the cabinet and separated from the refrigerated interior by an insulating cover. The refrigerator also includes a first damper controlling flow from the refrigerated interior into the first evaporator, a second damper controlling flow from the first evaporator to the second evaporator, and a third damper controlling flow from the second evaporator to the refrigerated interior. The first evaporator operates with refrigerant at a lower temperature than the second evaporator such that substantially all frost formed on the first and second evaporators is collected on a first evaporator coil in the first evaporator. Thus, the first evaporator acts as a sacrificial evaporator that undergoes defrost more frequently than the second evaporator.

Abstract: A high performance refrigerator includes a cabinet with a refrigerated interior, a refrigeration fluid circuit having an evaporator located within an insulated evaporator compartment outside the cabinet, and at least one damper that opens to permit air circulation from the refrigerated interior through the evaporator compartment. The refrigerator also includes a eutectic member configured to melt at an operating temperature of the refrigerator. The evaporator cools the refrigerated interior to a temperature below the operating temperature so that the eutectic member melts to cool the refrigerated interior or the evaporator compartment during a defrost cycle. The insulated evaporator cover limits heat transfer into the refrigerated interior during the defrost cycle to avoid temperature spikes in the refrigerated interior.

Abstract: A high performance refrigerator includes a cabinet with a unitary refrigerated interior and a refrigeration fluid circuit having first and second evaporators located within the cabinet and separated from the refrigerated interior by respective first and second evaporator covers. The refrigerator also includes a first damper controlling flow between the first evaporator and the refrigerated interior, and a second damper controlling flow between the second evaporator and the refrigerated interior. A controller directs the refrigerator to operate a three-way valve in the refrigeration fluid circuit so as to direct refrigerant to only one of the evaporators when the other requires defrosting. Both evaporators may be used to remove heat from the unitary refrigerated interior during an initial cooling or immediately after the cabinet is opened.

Abstract: A high performance refrigerator includes a cabinet with a refrigerated interior, an insulating cover separating a portion of the cabinet from the refrigerated interior, and a refrigeration fluid circuit having an evaporator located within the portion of the cabinet separated by the insulating cover from the refrigerated interior. The refrigerator also includes a controller that commands the refrigerator to perform a defrosting cycle when the evaporator coil requires defrosting. This defrosting cycle includes closing dampers in the insulating cover during the defrosting of the evaporator coil, thereby keeping the refrigerated interior thermally isolated from the evaporator during the defrost cycle. The controller is also operable to stop operation of a defrost heater when the evaporator reaches a first target temperature above the freezing point of water, and to re-open the dampers when the evaporator reaches a second target temperature above the freezing point of water.

Abstract: An pulse electro thermal defrost evaporator system has multiple refrigerant tubes formed from an electrically conductive metal and connected in parallel for refrigerant flow. These tubes are, however, connected electrically in series. A controller is capable of detecting ice accumulation and connecting the tubes to a source of electrical power for deicing when it is necessary to deice the tubes. Embodiments having a manifold having multiple conductive sections insulated from each other are disclosed for coupling tubes electrically in series. Alternative embodiments with a single, long, wide-bore, tube are disclosed, as are embodiments having an evaporating pan coupled in series or parallel with the tubes, and embodiments with thermal cutoff and electrical safety interlocks.

Abstract: There is disclosed an air conditioner including a compressor to compress refrigerant, an indoor heat exchanger to cool or heat a room, using the refrigerant, an outdoor heat exchanger to heat-exchange the refrigerant with outdoor air, the outdoor heat exchanger comprising a front heat exchange member and a rear heat exchange member, and a defrosting module to adjust an opening degree of a passage of the refrigerant drawn into the front heat exchange member and the rear heat exchange member, wherein the defrosting module includes a first expansion valve to adjust an opening of a passage of the refrigerant introduced into the front heat exchange member and a defrosting unit to adjust an opening degree of a passage of the refrigerant between the front heat exchange member and the rear heat exchange member.

Abstract: A heat exchanger for exchanging heat between gasses such as air and a liquid or gaseous coolant has narrow spacing between exchanger surfaces for high efficiency. To avoid undue obstruction of gas flow due to ice buildup on the exchanger surfaces, the heat exchanger is equipped with sensors to monitor the gas flow and an actuator that widens the spacing between exchanger surfaces such that gas flow remains unimpeded. Embodiments provide for defrosting of the exchanger surfaces when an limit on spacing of exchanger surfaces is reached, and for relaxing the spacing to the original narrow spacing when defrosting is completed.

Abstract: An air conditioning system is provided. The air conditioning system allows coolant to selectively flow through a series of bypass pipes and valves connecting an outlet of a compressor and an outlet of an expansion member. The series of bypass pipes and valves allow a defrosting function to be performed without performing a reverse cycle.

Abstract: A system and a method are provided for monitoring a condition and selectively executing a certification defrost algorithm for a heating, ventilation, and air conditioning (HVAC) system in response to the status of the monitored condition. A system and a method are provided for selectively operating a certification defrost algorithm in parallel to a field defrost algorithm. A system and a method are also provided for causing a controller to execute a first algorithm and for causing the controller to selectively execute a second algorithm while also executing the first algorithm where each of the first algorithm and the second algorithm are configured to selectively cause the HVAC system to operate in a defrost mode.

Abstract: Provided is a refrigerator, which includes a main body, a door, an evaporator, a defrosting heater, a defrosting sensor, and a control part. The main body includes a food storage space and an evaporation compartment. The door selectively closes the food storage space. The evaporator is disposed in the evaporation compartment. The defrosting heater is disposed at a side of the evaporator to remove frost from an outer surface of the evaporation compartment or the evaporator. The defrosting sensor is disposed at a side of the evaporation compartment or the evaporator to sense a frost formation amount. The control part receives a sensed value transmitted from the defrosting sensor, and controls an operation of the defrosting heater according to the sensed value. A sensing period of the defrosting sensor is varied according to a frost formation amount sensed by the defrosting sensor.

Abstract: An intelligent defrosting control for an air conditioner is disclosed, which comprises the following steps: setting a standard air pressure value; placing a high-pressure sensor on the exhaust pipe of the compressor of the air conditioner to measure the air pressure; When the air pressure measured by the high-pressure sensor is lower than the standard air pressure value, said air conditioner begins to come into the defrosting mode; otherwise, said air conditioner working in previous mode.

Abstract: In a controller for a refrigerating system including refrigerating machines and showcases, a showcase that is about to execute a defrost operation is detected on the basis of a defrost operation indicating information. When the controller receives a notification indicating start of the defrost operation from the showcase concerned or on the basis of a comparison result between a pre-stored defrost-operation start time and the present time, at least one of the refrigerating machines is instructed to reduce the output power thereof. When the showcase finishes the defrost operation, the at least one of the refrigerating machines is instructed to increase the output power thereof so that the output power of the refrigerating machine is set to stationary output power.

Abstract: The refrigerator of the present invention comprises: a refrigeration cycle composed of a compressor, a condenser and an expansion unit; an evaporator for evaporating a refrigerant which passes through the expansion unit; a heating unit for providing the heat for defrosting the evaporator; and a frost sensor unit which is provided at one side of the evaporator for sensing the amount of frost on the evaporator, and is characterized in that an operation of the frost sensor unit is started on the basis of whether operation conditions of the frost sensor unit are recognized and the heating unit selectively generates the heat according to the sensed result of the frost sensor unit. According to one embodiment of the present invention, the amount of frost on the evaporator is easily determined by the operation of the frost sensor unit and the evaporator is effectively defrosted according to the amount of frost determined thereby.

Abstract: A refrigeration cycle that is formed by connecting a compressor, a condenser, expansion means, and an evaporator and that performs cooling operation; an evaporator heating device that heats the evaporator; a drain pan that receives drain-water from the evaporator and drains the drain-water; a drain-pan heating device that heats the drain pan; frost detecting means including a light-emitting element that emits light to the evaporator and a light-receiving element that receives reflected light from the evaporator and outputs a voltage according to the reflected light; and a control device that controls on-off operation of the evaporator heating device and the drain-pan heating device. The control device determines a frosting condition on the evaporator from an output of the frost detecting means and individually controls the evaporator heating device and the drain-pan heating device in accordance with the determination result.

Abstract: The present invention provides an energy efficient air conditioner that can provide a continuous supply of air at dew point that is several degrees Celsius below zero, without requiring a defrost cycle. The air conditioner in accordance to present invention comprises a plurality of cooling coils with interconnecting refrigerant piping, refrigeration circuit consisting of compressor and condenser coils, control circuit and one or more electric motor driven centrifugal fan. The present invention uses two cooling systems. The first cooling system having single coil cools the air to a temperature just above zero deg. C., say four deg. C. so that the second stage gets a steady supply of cold air. The second stage has two coils, each being half the size of the first stage coil, thus taking half the air from it so that all the air from stage 1 passes through stage 2. In operation, only one coil of the second stage is active arid chills the air going through it to say minus 14 Deg. C.