Abstract: In a heat pump type air conditioner, a refrigerant ejection port of a compressor in a refrigerating cycle thereof is connected to a refrigerant inflow port of an outdoor heat exchanger via a bypass pipe with a shut-off valve, and temperature sensors detect the temperatures of the refrigerant inflow and runoff port sides of an outdoor heat exchanger. In a heating operation mode, when the temperature of the refrigerant inflow or runoff port side reaches a certain value or lower that requires defrosting, the shut-off valve of the bypass pipe is "opened" to start defrosting using the hot gas bypass defrosting method.

Abstract: Method and apparatus for defrosting an evaporator in a closed loop refrigeration system are provided. In one embodiment, liquid is circulated from a receiver containing refrigerant through an evaporator in a reverse direction to normal flow and then to another evaporator in the system. Hot gas from a compressor may be used to displace the liquid to the evaporator being defrosted. Alternatively, gas from the top of the receiver may be used for displacement of the liquid. Steps are taken to insure that cold gas from the evaporator that is input to the compressor does not contain liquid. Apparatus making possible flow of liquid in reverse direction through an evaporator selected for defrosting and then to another evaporator is provided, along with apparatus for controlling the flow.

Abstract: A refrigerator having an apparatus for defrosting. The refrigerator provides an apparatus for defrosting which uses a wasted heat from a compressor. The apparatus has a container placed on an upper surface of the compressor and an antifreezer solution for absorbing and storing the wasted heat from the compressor by performing a heat exchange. A pipe and a pump for circulating the fluid via a space section is provided. In the space section, the pipe is formed with a bending portion so as to transfer a heat to a surrounding air. In addition, a valve for preventing a high temperature air from flowing into a freezer compartment while a defrost operation is being carried out, and a plate for preventing a cabinet from being melted are provided.

Abstract: A fluid defrost system and method for defrosting the cooling coil of a product fixture normally cooled by circulating a cold secondary liquid coolant in a cooling loop refrigerated by a primary vapor compression system having compressor, condenser and evaporator means; the defrost system comprising a heat exchanger associated with the condenser means for warming secondary liquid coolant in a heating loop, and means for controlling the circulation of warm liquid coolant through the heat exchanger and cooling coil.

Abstract: This invention provides an air conditioner for simultaneously cooling or heating a plurality of rooms by using a single outdoor unit and at least two and more indoor units connected to the outdoor unit, the air conditioner including indoor heat exchangers installed in each room, for heat-exchanging a room air, a unit for detecting varying temperatures of conduit during the air conditioning, a control unit for controlling low temperature, high temperature, and defrosting operations for respective indoor units on the basis of the detected conduit temperature, and for coding operation states of respective indoors to input/output the coded communication signals, a communicating unit for transmitting and receiving the coded communication signals through input/output ports provided with the control unit for communicating between any indoor units.

Abstract: A new method for defrosting a dehumidifier. The new method minimizes the formation of liquid "slugs" which can occur during normal defrosting and which can damage the compressor, and also makes the operation of the dehumidifier more efficient. In the new method, defrosting takes place with the fan running to draw warm, room air over the condenser to warm the refrigerant passing through it in reverse, to thus minimize the formation of liquid "slugs". The warm air however is prevented by baffles from passing over the evaporator where it would undesirearably pick up moisture from the melting ice on the evaporator. An apparatus for carrying out the above method is also provided.

Abstract: A refrigerant reservoir (23') and heat exchanger unit (25) for a refrigerated counter (11) and method of reducing compressor load and lowering energy consumption of the refrigerated counter system is described. The refrigerant reservoir (23') and heat exchanger unit (25) comprises a reservoir having a heat exchanger section provided with a cooling coil (26) to cool liquid refrigerant from a condenser (14) as it enters into the reservoir (23'). The reservoir is secured in a cooled area of a refrigerated counter (11). The outlet (31) of the reservoir feeds an expansion valve (29) where the pressure of the liquid refrigerant is lowered to further cool the liquid refrigerant. The expansion valve (29) has an outlet (28) which is connected to the inlet (17) of the cooling coil (26) whereby the cool refrigerant liquid in a feedback path, cools refrigerant entering the reservoir.

Abstract: According to a method of cooling gases, in particular air which is drawn in through a compressor, in a compressed air arrangement the gas flows alternately through at least one of a plurality of refrigerating driers (5, 6) equipped with heat exchangers (15, 16). The gas drawn in is cooled by means of a heat exchanger (15, 16) to below 0.degree. C. over a cooling section. Whilst the gas is being cooled, the ice produced in the refrigerating drier (5, 6) is defrosted by at least one of the refrigerating driers (5, 6) or in the further refrigerating drier(s) (5, 6) by the supply of a hot refrigerant vapour. The liquid refrigerant flowing out of the refrigerating drier (5, 6) to be defrosted is introduced into a pressure and/or connection line (17, 18) of the refrigerant circuit between the inlet of the heat exchanger (15, 16) used for cooling the gas drawn in and the condenser (59), which is arranged upstream of this (these) heat exchangers, or the tank.

Abstract: A heat pump system includes, in an operable relationship for transferring heat between an exterior atmosphere and an interior atmosphere via a fluid refrigerant: a compressor; an interior heat exchanger; an exterior heat exchanger; an accumulator; and means for heating the accumulator in order to defrost the exterior heat exchanger.

Abstract: A refrigeration module removably suitable for use in either a refrigerator or a freezer uses signals from a series of temperature sensors for refrigeration control. An automatic defrost cycle is initiated when the evaporator outlet temperature drops to a value equal to the inlet temperature and is accompanied by a constant or rising temperature in the refrigerated cabin to which the module is connected. Field service is limited to an exchange of modules, so that refrigerating gas is not lost into the environment.

Abstract: An air conditioning system usually referred to as an electric heat pump, which employs reverse cycle refrigeration apparatus to condition air inside a building for heating in the winter months, and for cooling in the summer months, utilizing one heat exchanger coil disposed in heat exchange relation to the flow of conditioned air circulating within a building, and two heat exchanger coils disposed in heat exchange relation to the flow of ambient air circulating outside a building, wherein each said heat exchanger coil comprises a separate and singular component part of a single air conditioning circuit connected to, and served by one single compressor; and wherein, each of the said outside heat exchanger coils are designed to change functions independent of the other, from that of an evaporator, to that of a condenser, for the purpose of inhibiting the accumulation of frost on, and/or removing frost from said outside heat exchanger coil when the heat pump is operating in the heating mode without reversing the

Abstract: The present invention relates to a method for alleviating a short-term "cold blow" effect in a heat pump heating system. According to a method of the invention, reversing of a system valve in response to the sensing of a defrost condition is delayed by a predetermined time. The amount of this delay time depends upon the amount of time required for a supplementary heating unit to achieve an output sufficient to offset the cooling effect resulting from there being a cold indoor coil.

Abstract: An apparatus for heating or cooling a space comprises a main flow loop including a compressor (1012), an outside heat exchanger (1014), an inside heat exchanger (1016) connected to allow working fluid to circulate therebetween, and a first valve (1026) between the outside heat exchanger (1014) and the inside heat exchanger (1016) selectively to block flow between the outside heat exchanger (1014) and the inside heat exchanger (1016). A first bypass line extends between the outlet of the outside heat (1014) and the inlet of the inside heat exchanger (1016). A thermal storage device (1018) is positioned in the first bypass line. A second bypass line extends between the inlet of the inside heat exchanger (1016) and the outlet of the inside heat exchanger (1016) and communicates with the first bypass line to bypass the inside heat exchanger (1016). A second valve (1030) is positioned in the second bypass line to block flow through the second bypass line selectively.

Abstract: An air conditioning apparatus for heating and cooling a room, which has a four-way valve to reverse the flow of a refrigerant, thereby switching the operation mode, heating or cooling, and which has a bypass line for bypassing an inside heat-exchanger, a control valve for controlling the flow ratio of the refrigerant passing through the bypass line and the inside heat-exchanger, and a refrigerant-heating element disposed in a line between the control valve and the compressor, thereby, in the defrosting mode, melting the frost formed on endothermic fins without cooling the room and without a liquid return to the suction side of the compressor.

Abstract: A new method and apparatus for thawing frozen food product utilizing desuperheated gas thawing medium near its saturation point. The transfer of the latent heat of condensation from the thawing medium to the frozen food product immediately condenses the thawing medium into a condensate liquid, after which it is recycled back through the refrigeration system. Since the thawing medium quickly condenses upon giving up energy to the frozen food product, it falls away from the upper surface of the thawing deck tube interiors, being replaced by additional gaseous thawing medium near its saturation point, which in turn condenses upon giving up heat, and the process continues until the food product is completely thawed. Since the state of the thawing medium is consistent throughout the thawing deck tubes, the temperature along the length of each of the tubes is uniform.

Abstract: A non-compressible coolant fluid system for cooling product merchandisers having heat transfer means constructed and arranged for maintaining preselected product zone temperatures, comprising an integrated closed circuit system having pumping means for circulating non-compressible coolant fluid, a first coolant fluid loop between the pumping means and the heat transfer means and including means for cooling coolant fluid in said first loop, a second coolant fluid loop between the pumping means and the heat transfer means in by-pass relation with the first loop and including means for heating coolant fluid in the second loop, and means for selectively controlling coolant fluid circulation by said pumping means through the first and second loops.

Abstract: A refrigerant evaporator has a first heat exchange portion with an uninterrupted surface formed from sheets of conductive material joined together to form passages therebetween. A second heat exchange portion is connected to and adjacent the first portion. The second portion is formed from hollow, serpentine tubes with spine fins. Condensed refrigerant passes through the first portion, which accummulates frost and ice, and then through the second portion. The first portion also includes a labyrinth of passages that define an accumulator for refrigerant that has passed through the second heat exchange portion.

Abstract: A refrigerating system having a refrigerating cycle constructed by connecting an accumulator, a refrigerant compressor, a four-way valve, an outdoor unit heat exchanger, an outdoor unit expander, a receiver, an indoor unit expander and an indoor unit heat exchanger sequentially by pipes. Normally, excessive refrigerant is stored in the receiver and when it becomes necessary to raise a ratio of lower boiling point refrigerants, a flow amount of the refrigerant is decreased by restricting the outdoor unit expander during the cooling operation or by restricting the indoor unit expander during the heating operation to move the excessive refrigerant within the receiver to the accumulator. Thereby, the composition of the refrigerant circulating within the refrigerating system using non-azeotrophic refrigerant mixtures may be changed without using a complicated system structure or control method thereof and the capacity of the refrigerating cycle may be changed.

Abstract: A refrigeration system includes a compressor, a condenser, an expansion throttle, an evaporator and a control valve. All of the above elements are connected in series, in that order, in a refrigerant flow relationship. During periods in which the compressor initiates a passive defrost mode, control valve disposed within the conduit connecting the compressor and the evaporator remains open. Liquid refrigerant, by force of gravity, drains from the bottom of evaporator through the conduit to the compressor. This draining liquid refrigerant is evaporated by the hot compressor, flowing upward to the cold evaporator surfaces and condensing. The condensation releases latent heat of vaporization and heats the surface of the evaporator melting ice buildup thereon. In another embodiment, the refrigeration system further includes a bypass line connecting the compressor to the top of the evaporator.

Abstract: The invention prevents the temperature of supplied air from being decreased by a defrosting operation when a vehicle is in operation. During the heating operation, it is judged whether the vehicle is in operation. When the vehicle is in operation, it is judged whether an external heat exchanger is frosted or not relying upon the external air temperature, temperature of the external heat exchanger (coolant) and the time of heating operation. When it is judged that frost is formed, the rotational speed of the compressor is increased to increase the ability to supplying the coolant, to maintain heating ability and to prevent the drop of temperature of the supplied air. When the frost is formed after the operation of the vehicle has been finished, it is judged whether the secondary batteries are being charged or not, i.e., whether the charging circuit of the secondary batteries is connected to the external power source for charging or not.

Abstract: A method of producing a higher temperature cold and a lower temperature cold comprises the steps of generating a higher temperature cold and a lower temperature cold each including a compression of vapors of refrigerant condensation of the compressed vapors and subsequent expansion of the refrigerant with accompanying cooling, accumulating the generated colds, supplying the generated colds to corresponding consumers of higher temperature cold and lower temperature cold, and performing the generating, the accumulating and the supplying of the lower temperature cold at a second auxiliary stage during periods of reduced demand in the higher temperature cold generated at a first stage.

Abstract: The blocked fan or obstructed airflow condition is detected by measuring the difference between outdoor air temperature and outdoor exchanger coil temperature. If a very high difference is detected, or if no decrease in the difference is achieved after termination of the defrost cycle, and if either of these conditions persists over a plurality of defrost cycles, then the blocked condition is declared. The diagnostic system can be integrated in an existing demand defrost cycle and is capable of detecting blocked conditions attributable to foreign matter such as leaves, paper and debris which cannot be cleared by defrosting.

Abstract: A self-calibrating defrost controller for use with heat pump. The outdoor heat exchanger coil of a heat pump is defrosted based upon either compressor run-time exceeding 6 hours, or the temperature difference between the coil and ambient air exceeding a value that changes depending upon outdoor coil temperature. A programmable controller mounted to a printed circuit board within a housing executes a control program to monitor temperature sensor produced temperature signals. One sensor that monitors ambient temperature is mounted to the printed circuit board that also supports the programmable controller.

Abstract: A blocked fan or obstructed airflow condition is detected by measuring the difference between outdoor air temperature and outdoor exchanger coil temperature. If a very high difference is detected, or if no decrease in the difference is achieved after termination of the defrost cycle, and if either of these conditions persists over a plurality of defrost cycles, then the blocked condition is declared. The diagnostic system can be integrated in an existing demand defrost cycle and is capable of detecting blocked conditions attributable to foreign matter such as leaves, paper and debris which cannot be cleared by defrosting.

Abstract: A refrigeration system for providing cooling to two or more compartments utilizing respective first and second evaporators. During the initial operation of a cooling cycle, the refrigerant is utilized for cooling the compartment (such as a fresh food compartment) which is to be maintained at a higher temperature as compared with another compartment (such as a freezer compartment). Cooling can thus be achieved by operating a fan in the fresh food compartment, even where the refrigeration system has not yet reached steady state after the compressor initially begins operating. After cooling has been achieved in the fresh food compartment, the refrigerant in the system has reached a state suitable for cooling of the freezer compartment, and the fan for the freezer evaporator is turned on while the fan for the fresh food compartment is turned off.

Abstract: A method of eliminating odor in a heat pump system of a vehicle includes the steps of detecting removal of the vehicle passengers and ignition key after use of the cooling mode or air conditioning of the passenger compartment heat exchanger, operating the blower, reversing the flow of refrigerant in the heat pump to place the passenger compartment heat exchanger in heating mode to remove latent moisture to eliminate odor therefrom.

Abstract: Method and apparatus to defrost evaporator coils of a refrigeration system by periodically replacing the refrigerant in the evaporator coils by hot refrigerant gas from the compression side of a compressor. The gas from the compressor is sent through an oil separator, then through a solenoid valve to a vaporizer tank. From the vaporizer tank, a portion of the hot gas is fed constantly during the defrosting cycle through a metering flow control valve to the evaporator coils. As the pressure builds up in the vaporizer tank due to the compressor supplying more gas than the amount flowing through the metering flow control valve, a pressure control senses the pressure increase and opens a vaporizer solenoid valve to allow additional hot gas to flow to the evaporator coils. In the evaporator the gas heats the evaporator coils and melts the frost on the coils and then passes to the suction line of the compressor.

Abstract: An air cooling unit having a hot gas defrost coil disposed below the air cooling coil assembly proximate the condensate pan and a hot gas defrost pipe disposed proximate the lower front edge of the air cooling coil assembly for receiving a heated refrigerant gas.

Abstract: During the heating cycle of an air conditioning system, a portion of the compressed refrigerant is conducted between outdoor and indoor heat exchangers for heating a dwelling, and another portion of the compressed refrigerant is conducted to an auxiliary condenser. Heat from the auxiliary condenser is directed against the outdoor heat exchanger to defrost the latter.

Abstract: A passive defrost system uses a heat-exchanger/storage defrost module containing a thermal storage material such as a phase change material to capture and store low grade, waste heat contained in the liquid refrigerant line of a refrigeration system. The waste heat is stored during normal operation. Upon shut down of the refrigeration system, the stored heat in the defrost module is released by an automatic device for defrosting the evaporator. The preferred embodiment of this passive defrost system includes the defrost module and some device to transfer heat from the defrost module to the evaporator, preferably in the configuration of a gravity heat pipe. Since waste heat is taken out of the liquid refrigerant line, the efficiency of the refrigeration system is improved, and no additional energy is needed for the defrost operation.

Abstract: A cooling device having a refrigeration chamber (1) and a freezer chamber (3), a refrigeration plant having an evaporator (15) and condenser (18), a compressor (16) and air flow passageways (5, 8, 11) for conducting air flow across the evaporator and through the refrigerator and freezer. Capillaries of different size (19, 20) control the flow of refrigerant from the condenser to the evaporator to control the temperature of the evaporator. A pressure device (36) produces the air flow through the passageways to the refrigerator and freezer. Motorized valves (30, 31) are operated by temperature sensors within the refrigerator and freezer to control the flow of air therethrough. A variable temperature compartment (4) may be provided and connected to the airflow passages, with a flow control valve (32) for maintaining a temperature therein set by the user.

Abstract: The invention relates to methods of defrosting an evaporator coil of a transport refrigeration unit which includes microprocessor based electrical control. The electrical control maintains the temperature of a conditioned space at a predetermined set point temperature via hot gas heating and cooling cycles. The evaporator coil is defrosted to remove frost and ice by closing a damper to the served space and initiating a heating cycle. At the termination of defrost, a cooling cycle is initiated, but the damper is maintained in a closed position for a predetermined period of time to remove heat built up during the defrost process. The invention also detects damper malfunctions, including failure to close prior to defrost, and failure to open after defrost. The invention also evaluates manual and timed requests for a defrost operation, overriding the requests in response to predetermined conditions.

Abstract: A transport refrigeration system of the type which holds a set point temperature by way of heating and cooling cycles. A compressor discharge temperature control circuit is provided which senses the temperature of the hot compressor discharge gas and controls a flow of liquid refrigerant directly into the compressor suction line responsive to the sensed temperature. The receiver of the system is provided with hot gaseous refrigerant to thereby force liquid refrigerant therefrom which supplies the discharge temperature control circuit in all modes of operation.

Abstract: A adjustable defrost cycle for a heat pump system which ensures that the outdoor coil is maintained free of frost by adjusting a defrost initiation reference level for the initiation of the next subsequent defrost cycle depending upon the time period of the previous defrost cycle.

Abstract: A compartmentalized transport refrigeration system which holds selected set point temperatures in at least first and second served spaces via heating and cooling cycles. The system includes a refrigerant circuit having high and low pressure sides, including a compressor, a condenser, a receiver, at least first and second evaporator sections respectively associated with the first and second served spaces, an accumulator, and a mode selector valve having heating and cooling positions. Control provides a heat signal when the need for a heating cycle in one of the served spaces is detected. The receiver is connected to the low pressure side of the refrigerant circuit for a predetermined period of time in response to the heat signal. At the end of the period of time the mode selector valve is operated from the cooling position to the heating position, and the connection between the receiver and low pressure side is terminated.

Abstract: A method of operating a transport refrigeration system having a refrigerant compressor driven by an internal combustion engine. Microprocessor based electrical control maintains the temperature of a conditioned space at a desired set point via heating, cooling and null cycles, with the engine being started and stopped, as required. During the engine starting process, a suction line modulation valve, if used, is closed, engine pre-heat time is selected, including using engine temperature to access a look-up table, and current draw is checked during pre-heat. Excessive current terminates pre-heat. Control diagnostics checks the voltage level on both sides of a refrigerant high pressure switch, before initiating engine cranking. Prior to stopping the engine, a control option initiates a heating cycle for a short time when null is being entered from a cooling cycle, to warm the evaporator and prevent premature starting of the engine.

Abstract: A method for controlling a refrigerant path apparatus including a pressurized gas refrigerant path for a flow of a pressurized gas refrigerant which has not been substantially cooled to be liquefied, a pressurized liquid refrigerant path for a flow of a pressurized liquid refrigerant which is generated from the pressurized gas refrigerant by being cooled to be liquefied, a first heat exchanger means which is fluidly connected to the pressurized gas refrigerant path to supply the pressurized gas refrigerant into the first heat exchanger so that a heat exchange is carried out between the pressurized gas refrigerant in the first heat exchanger and the outside of the first heat exchanger, comprises the steps of allowing a flow of the refrigerant from the pressurized gas refrigerant path to the pressurized liquid refrigerant path when a supply of the pressurized gas refrigerant from the pressurized gas refrigerant path into the first heat exchanger means is prevented, and preventing the flow of the refrigerant fro

Abstract: A transport refrigeration system of the type which holds a set point by operating in heating and cooling cycles. The system includes a compressor, a condenser and an evaporator each having inlet and outlet ports. A three-way valve receives compressed gas discharged from the compressor and directs it selectively to first and second outlets. First outlet of the three-way valve directs hot compressor gas to the condenser for operation of the system in a conventional cooling cycle. A hot gas conduit is provided which connects the second outlet of the three-way valve directly to the inlet of the evaporator. A branch line extends from the hot gas line to the line interconnecting the condenser and the evaporator, upstream of the receiver. Another refrigerant line extends from the outlet of the condenser to establish fluid communication with the line interconnecting the outlet of the evaporator with the compressor suction port.

Abstract: A method of defrost for an outdoor side heat exchanger in a heat pump having a refrigeration circuit in which a compressor, an indoor side heat exchanger, an expansion device and the outdoor side heat exchanger are connected together so that a heat collected in the outdoor side heat exchanger is radiated from the indoor side heat exchanger and that defrosting for the outdoor side heat exchanger is started when the outdoor heat exchanger is frosted, and a temperature sensor is provided to detect a temperature of the indoor side heat exchanger, wherein the defrosting is started when the temperature detected by the temperature sensor is not higher than a first predetermined level with a downward gradient, which is calculated on the basis of the temperature, of the same temperature becoming as sharp as, or sharper than, a predetermined gradient, and the first temperature level is increased after the temperature becomes as high as a second predetermined level wherein the second level.gtoreq.the first level.

Abstract: An air conditioner comprising a compressor, a four-way directional control valve, an outdoor heat exchanger, and a plurality of indoor heat exchangers, which are arranged to enable the cooling/heating combined operation. The air conditioner further comprises a first connecting pipe bypassed from a piping line, which is adapted to feed a compressed coolant from the compressor toward the outdoor heat exchanger, for line communication with at least one indoor unit, and a second connecting pipe bypassed from a piping line, which is adapted to feed the compressed refrigerant from the compressor toward at least one indoor heat exchanger, for line communication with the outdoor heat exchanger.

Abstract: A heat pump is provided with a reversible fan motor in its outdoor coil and, after a delay period following initiation of the defrost cycle, the fan is caused to operate in a reverse direction to thereby cause the surrounding air to flow through the outdoor coil in a direction opposite to that in which it flows during the heating mode operation. During this time, the fan is operated at a relative slow speed to thereby prevent the convective flow of heat upwardly, while at the same time causing little, if any, flow of ambient air downwardly into the coil.

Abstract: A method and apparatus to refrigerate air in a compartment wherein liquid CO2 is delivered through a first primary heat exchanger such that sufficient heat is absorbed to evaporate the liquid carbon dioxide to form pressurized vapor. The pressurized vapor is heated in a gas fired heater to prevent solidification of the pressurized carbon dioxide when it is depressurized to provide isentropic expansion of the vapor through pneumatically driven fan motors into a secondary heat exchanger. Orifices in inlets to the fan motors and solenoid valves in flow lines to the fan motors keep the vapor pressurized while the heater supplies sufficient heat to prevent solidification when the CO2 vapor expands through the motors. CO2 vapor is routed from the second heat exchanger to chill surface in a dehumidifer to condense moisture from a stream of air before it flows to the heat exchangers.

Abstract: A refrigeration system including a compressor, condenser, capillary tube and evaporator includes a hot gas bypass defrosting capability provided by a bypass means around the capillary tube. Defrosting is achieved by the use of hot, uncondensed refrigerant, without requiring a reversal of the flow of refrigerant through the system. An exemplary bypass means includes a solenoid valve and associated tubing to form an alternate, low restriction path for the refrigerant to bypass the capillary tube. When the solenoid valve is closed, refrigerant is forced through the capillary tube for normal refrigeration. However, when the solenoid valve is open, condensation of refrigerant in the condenser is inhibited, and hot refrigerant gas is delivered directly to the evaporator for defrosting. The solenoid valve is controlled in response to the total accumulated running time of the compressor for improved control of the defrosting cycles.

Abstract: A hot gas defrost type refrigeration system in which refrigerant used to defrost is returned to the system's refrigerant circuit after being collected and reduced in pressure, as by expansion valve means, to a pressure below the pressure in the system's return suction header, then heated as by means involving heat exchange with the system's high pressure refrigerant, the refrigerant used to defrost thus being in a superheated gaseous state and returned to the system's return suction header in such state without risk of introduction of liquid refrigerant to the system's compressor(s).

Abstract: A refrigeration system having a modulation valve which controls refrigerant flow to a compressor according to a control algorithm. The need for a compressor throttling valve is eliminated by a load control circuit which operates the modulation valve to perform the function of the throttling valve when load reduction is required. An overload condition of a compressor prime mover overrides the control algorithm and selects a predetermined load control position of the modulation valve. A timer ensures that a predetermined recovery time is provided, before switching back to the control algorithm. The timer also selects the load control position of the modulation valve upon start-up. A heating or defrost mode automatically selects the load control position of the modulation valve for the duration of the mode, as does an ambient air temperature sensor when the ambient exceeds a predetermined value.

Abstract: A method of defrosting a refrigerating circuit for use in cooling a vehicular chamber comprises two steps. In a first step a frost formed at an outer surface of an evaporator of a cooling unit is defrosted by directly leading discharged gas to the evaporator. In a second step a frost formed at elements of the cooling unit except the evaporator is defrosted by making air in the vehicular chamber pass through the heated evaporator. In this manner, the cooling down characteristic in the vehicular chamber is improved and compressor durability is preserved.

Abstract: The invention relates to a method and a device for compression of gases, in particular of air, within a compressed air piping system. The air drawn in for the compressor is cooled below 0.degree. C. within a freeze-dehumidifer in a cooling channel. The supply of undercooled refrigerant into the freeze-dehumidifier is interrupted during the defrosting of the freeze-dehumidifier situated within the cooling channel for the air drawn in towards the compressor. The condensate appearing in the form of ice on the freeze-dehumidifer is separated thereby. The defrosting operation is terminated after a pressure of the refrigerant corresponding to a positive temperature of the freeze-dehumidifier is exceeded, or after a presettable period has elapsed. The pressure of the refrigerant is monitored in the suction pipe and if appropriate in the delivery or pressure pipe of the refrigerant compressor.

Abstract: An air conditioning apparatus includes two different refrigerating circuits in one central unit for supplying a conditioned air into a defined space through an air duct. Each refrigerating circuit has an air exhausting damper for exhausting internal air from the defined space, and an external air intake damper for taking the external air into the defined space through the central unit. One of the refrigerating circuits forcibly carries out the heating operation, and the external air intake damper thereof is maintained in a closed state while the other refrigerating circuit carries out the defrosting operation to prevent temperature of the conditioned air fed from the central unit into the defined space from decreasing below a desirable level.

Abstract: A transport refrigeration system which includes a compressor, a condenser, a receiver, an evaporator, an accumulator, and a control valve which selectively initiates heating and cooling cycles. The heating capacity of a heating cycle is enhanced by connecting the outlet of the receiver to the inlet of the accumulator just prior to each heating cycle, while maintaining the control valve in a cooling position for a predetermined time delay. This forces any liquid refrigerant trapped in the condenser to flow into the receiver, while lower pressure in the accumulator causes liquid refrigerant in the receiver to flow into the accumulator, to provide additional liquid refrigerant in the accumulator at the start of the heating cycle, which is initiated at the end of the predetermined time delay.

Abstract: A transport refrigeration system, and method of operating same, in which a maximum operating pressure expansion valve and a secondary condenser are used to enhance hot gas heating cycles initiated to hold a predetermined temperature set point, and hot gas defrost cycles. The secondary condenser is disposed in an evaporator section of the refrigeration system, with hot discharge gas from a compressor being directed to the secondary condenser during heating and defrost cycles. A sufficient supply of refrigerant for heating and defrost cycles is ensured by injecting refrigerant from a receiver and condenser into an active heat cycle refrigerant circuit, when the active refrigerant is insufficient to build the pressure on the low pressure side of the refrigeration system to a value sufficient to close the maximum operating pressure expansion valve and the compressor suction pressure is less than the receiver/condenser pressure.