Abstract: Air conditioner, and method for controlling an operation of the same, the air conditioner including a sheath heater in the accumulator for heating the refrigerant in room heating for delaying deposition of frost on the outdoor heat exchanger. The sheath heater includes a coil formed heat generating part, and two electrodes connected to the heat generating part for supplying power. The method including the step of varying the heat generating rate of the sheath heater with an exterior temperature or a capacity of the indoor unit, thereby delaying deposition of frost on the outdoor heat exchanger.

Abstract: A method and apparatus for drying the surface of a heat exchanger in a vehicle of moisture accumulating as a result of its use as an evaporator in an air conditioning system. Air is first heated by the heater core in the air conditioning system and then directed through the heat exchanger. Because of the reduced humidity of such air, any residual moisture in the heat exchanger is evaporated and is discharged to the environment. Where the system is used in a vehicle, it prevents the discharge of moist air onto the windows and/or windshield of the vehicle and thus minimizes or eliminates fogging of the windshield.

Abstract: A refrigerator freezer having an upper refrigerator compartment and a lower below freezing freezer compartment. The upper compartment can be a convertible compartment selectively operable by the user as an above freezing refrigerator compartment or as a below freezing freezer compartment. The evaporator for supplying refrigerated air is located in the upper compartment along with an auxiliary heater and upper compartment thermostat to control the temperature in the upper compartment. A control discharges an amount of refrigerated air to the upper compartment for refrigerator operation and a larger amount of refrigerated air for freezer operation. The control also energizes the auxiliary heater under control of the upper compartment thermostat during refrigerator operation to assure above freezing temperatures in the upper compartment. A low ambient heater can be provided for the upper compartment for use of the refrigerator freezer in low ambient temperature conditions such as an unheated garage.

Abstract: Heater-evaporator has a hollow refrigerator fluid evaporator body with which is incorporated a heater. The body can enclose the heater, which is separate from the body, or the body and the heater can be part of one another. The heater can be heated by any suitable means, to include electrical resistance and/or induction. The invention can be utilized in refrigeration and temperature control, to include, for example, in laboratory test devices requiring refrigeration and temperature control.

Abstract: Adaptive defrost control and method for a household refrigerator wherein a defrost heater is prevented from being powered as long as a compressor is running. The adaptive defrost control also provides a vacation mode in which the defrost interval is set to an artificially long interval if a door of refrigerator has not been opened for some predetermined period of time.

Abstract: A concentrated cooling apparatus of a refrigerator is capable of improving the reliability of an infrared sensor by preventing moisture from being condensed onto the surface of the infrared sensor. The concentrated cooling apparatus includes a nozzle rotationally supported by a cold air guide path, the nozzle intensively jetting cold air to a high-temperature load region when a high-temperature load is placed inside a chilling chamber of the refrigerator. An infrared sensor is installed at the front of the nozzle, and the infrared sensor senses the high-temperature load region while being rotated together with the nozzle. A moisture removing device is formed at a side of the nozzle, the moisture removing device jetting cold air on the surface of the infrared sensor to remove moisture condensed on the surface of the infrared sensor.

Abstract: In an air conditioner (10) including an indoor-side chamber (21) containing an indoor heat exchanger (11) and an indoor fan (12), and an outdoor-side chamber (22) containing outdoor heat exchanger (13) and an outdoor fan (14), the indoor-side chamber (21) and the outdoor-side chamber (22) being partitioned by a partition plate (20), the partition plate (2) has a top panel (42) having a ventilation opening portion and a ventilation shutter (49) for opening/closing said ventilation opening portion (48) to freely adjust the opening degree of said ventilation opening portion (48). An indoor fan casing (34) having a heater lower-portion mounting portion (64) located above a drain pan (33) is provided between the indoor fan (12) and the partition plate (20), and an electrical heater (55) is disposed on the heater lower-portion mounting portion (64) so that the electric heater (55) is located above the drain pan (33) through the lower-portion mounting portion (64).

Abstract: A method and apparatus for drying the surface of a heat exchanger in a vehicle of moisture accumulating as a result of its use as an evaporator in an air conditioning system. Air is first heated by the heater core in the air conditioning system and then directed through the heat exchanger. Because of the reduced humidity of such air, any residual moisture in the heat exchanger is evaporated and is discharged to the environment. Where the system is used in a vehicle, it prevents the discharge of moist air onto the windows and/or windshield of the vehicle and thus minimizes or eliminates fogging of the windshield.

Abstract: A method and apparatus for accessing low temperature refrigeration systems is provided. In one embodiment, an access tunnel is provided and a heater, an access door, a vacuum insulation panel, a thermal break, a sealing gasket that mates with a sealing surface together or in part(s) helps to prevent condensation from forming on the exterior of the freezer.

Abstract: Adaptive defrost control and method for a household refrigerator wherein a defrost heater is prevented from being powered as long as a compressor is running. The adaptive defrost control also provides a vacation mode in which the defrost interval is set to an artificially long interval if a door of refrigerator has not been opened for some predetermined period of time.

Abstract: A water removal device for refrigeration system comprises an electrode and a voltage source; the voltage source provides voltage for the electrode, which is located under the evaporator of the refrigeration system. Through the electric effect produced by the electrode, the condensed water condensed on the evaporator can be swiftly removed, a result that thoroughly takes advantage of the heat transfer function of the evaporator. In addition, there shall not be any electricity-discharging sparks between the electrode and the evaporator, thus assuring the normal operation of the refrigeration system.

Abstract: The present invention provides a compound type Kim-chi refrigerator having a heater composed of the electrically heated wire to the backside of a vertical partition wall defining vegetable chamber for maintaining the temperature of the vegetable chamber within a predetermined temperature range and removing the frost within the vegetable chamber. The compound type Kim-chi refrigerator according to the present invention comprise a heater 9 attached to the lower part of the condensed water vent formed on the vertical partition wall 6b defining the vegetable chamber 61 to remove the frost and heat the vegetable chamber 61 properly to the predetermined temperature range.

Abstract: A device for heating a first article and cooling a second article. The device may include an enclosure with a hot compartment and a cold compartment. The device also may include a Stirling cooler with a hot end and a cold end. The hot end may be positioned in communication with the hot compartment so as to heat the first article and the cold end may be positioned in communication with the cold compartment so as to cool the second article.

Abstract: In an air conditioner (10) including an indoor-side chamber (21) containing an indoor heat exchanger (11) and an indoor fan (12), and an outdoor-side chamber (22) containing outdoor heat exchanger (13) and an outdoor fan (14), the indoor-side chamber (21) and the outdoor-side chamber (22) being partitioned by a partition plate (20), the partition plate (2) has a top panel (42) having a ventilation opening portion and a ventilation shutter (49) for opening/closing said ventilation opening portion (48) to freely adjust the opening degree of said ventilation opening portion (48). An indoor fan casing (34) having a heater lower-portion mounting portion (64) located above a drain pan (33) is provided between the indoor fan (12) and the partition plate (20), and an electrical heater (55) is disposed on the heater lower-portion mounting portion (64) so that the electric heater (55) is located above the drain pan (33) through the lower-portion mounting portion (64).

Abstract: An electrical conductor and a gas-filled layer are located at or near the surface of an object being deiced. The conductor carries an AC voltage that generates an alternating electric field in the gas-filled layer. A conductive layer increases the electric field strength in the gas-filled layer between the electrical conductor and the conductive layer. The alternating electric field causes electric breakdown of gas and plasma-formation in the gas-filled layer. The plasma absorbs energy released during electric discharge through the plasma, which heats ice, causing it to melt. The alternating electric field typically has a field strength in a range of about from 1 to 100 kV/cm. The AC voltage typically has an amplitude in a range of about from 10 kV to 1300 kV, and a frequency in a range of about from 50 Hz to 1 MHz. The gas-filled layer includes a plasma-forming gas selected from, among others, air, nitrogen and argon.

Abstract: A heat exchanger subsystem for an environmental control system comprises a heat exchanger array having a plurality of heat exchanger elements that operate in parallel to an inlet cooling airflow to the heat exchanger array such that each load heat exchanger is connected to a separate load with each heat transfer loop operating in substantially independent fashion without load interaction effects. In addition, continuous ice and water removal is provided allowing continuous subfreezing operation improving cooling performance along with anti-ice provisions which recover rejected heat for improved energy efficiency. The heat exchanger elements may include air-to-air heat exchanger cores, liquid-to-air heat exchanger cores, and hot bars internal or external to the heat exchanger cores.

Abstract: To prevent ice build up around the door of a walk in freezer a heater is provided under the threshold of the door to heat a column of air between the inner surface of the door and the flexible thermal barrier inside the freezer. The heater is operated continuously regardless of whether the door is open or closed to maintain the surfaces around the door, and the thermal barrier, at above freezing temperatures.

Abstract: An ultra-low temperature refrigeration system (10) comprising a housing (12) and a door (14) which together define an interior storage compartment (16). The system (10) uses multiple layers (20,22) of varying insulative materials to insulate the housing (12), including conventional foam (20) and vacuum insulation panels (22), to balance cost, size, and capacity considerations. The vacuum insulation panels (22) are provided with beveled edges (26) or otherwise positively interfacing edges so as to overlap adjacent panels and present a more reliably insulative seam. The system (10) further includes a self-defrosting pressure equalization port (30) for automatically equalizing interior and exterior pressures.

Abstract: A sectional roll-up door has two generally planar panels having confronting longitudinally extending edges, a hinge between the panels at the edges, a seal extending longitudinally along one of the edges and operatively engageable with the other of the edges, and an element for heating the seal. Each panel comprises a pair of parallel and spaced skins, edge strips bridging the skins and forming the edges, and a mass of insulation between the skins. The heater is provided at the edges.

Abstract: Methods and devices for retaining a heating element, such as warm refrigerant tubing, within a refrigerator cabinet. Semispherical raised dimples are formed upon a retaining panel in a rolled triple flange. The dimples are intermittently positioned along the retaining panel and maintain the warm refrigerant tubing in intimate surface contact with the exterior surface panel of the refrigerator. The raised dimples preclude significant intimate surface contact between the retaining panel and the tubing and permit insulating foam to be disposed between the two so that heat transfer is minimized. A dimpled flange arrangement is also used to retain tubing within a mullion. A sheet metal insert is also described that is formed having two retaining panels with raised dimples thereupon that maintain the tubing in intimate surface contact with the exterior surface panel that forms the facing for the mullion.

Abstract: An engine charge air cooler system including a charge air compressing system, a refrigerant cycling system, and a charge air cooling apparatus for transferring heat from the compressed charge air of the charge air compressing system to the refrigerant fluid of the refrigerant cycling system. The charge air cooling apparatus comprises a housing with a charge air passage for charge air moving through the housing. A plurality of fins are positioned in the charge air passage. A fluid tube is provided in the housing and passes through each of the fins in a plurality of locations. Preferably, the refrigerant compressor of the system is adapted to also compress a separate flow of refrigerant fluid for an air conditioning system of the vehicle in addition to the refrigerant fluid of the system of the invention. A heating element may be provided in the interior of the housing, and may be selectively heatable for preventing accumulated moisture from freezing in the interior of the housing in sub-freezing temperatures.

Abstract: An evaporator having defrosting capabilities for space-saving and hard-to-reach installations and for connecting to a condensing unit with a condensing coil and a compressor. The evaporator includes a center tube, a middle tube, and an outer tube. The center tube has a refrigerant inlet for supplying a refrigerant before being evaporated, and conducting the refrigerant in a first direction opposite to the refrigerant inlet of the center tube. The middle tube concentrically receives the center tube and defines a first passage therebetween for conducting a hot injected gas for performing a mild, but positive, defrost of the evaporator as the evaporator continues to operate.

Abstract: A water removal enhancement device applicable to an evaporator of a refrigeration system includes a pulse power supply, an electrode mounted under the evaporator, and metallic needles formed on the bottom of the evaporator. The needles of the evaporator and the electrode are electrically connected to the power of the pulse power supply, so that negative (or positive) electricity is charged to the evaporator and the needles, while the positive (or negative) power of the pulse power supply is charged to the electrode. The condensed water formed on the evaporator and falling to the needles is therefore easily attracted by the electrode via electric discharge effect on tip points and easily drop from the evaporator to the electrode and drain away.

Abstract: A de-icing system operable to facilitate the removal of ice from the door (18) and closure surface (22) of a low temperature refrigeration or ultra-low freezer device (10) and to thereby ensure proper operation of the device (10) and protect its contents. The de-icing system employs manually activated heaters (32) and a timing circuit (38) to thaw the ice. Because the de-icing system focuses heat only on specific, ice-sensitive areas, the temperature of the freezer's interior compartment (14) remains constant so that the contents need not be removed during the de-icing process. In use, an operator activates the de-icing system a few minutes prior to opening the freezer door (18). When the door (18) is opened, the melted or loosened ice can be removed with a soft cloth. If the operator forgets that the heaters have been activated, the timing circuit (38) automatically terminates the de-icing process and stops the heaters (32) before the freezer's interior storage temperature has been affected.

Abstract: A device for defrosting the finned cooling assembly of a refrigeration system having an ellipsoid transparent polymer material housing a light source. The light source is positioned substantially in correspondence with one of the focal points of the ellipsoid. A sensor for the light beam radiated by the light source and reflected by an inner surface of the ellipsoid recognize variations in the luminous intensity of the beam caused by the formation of frost along the path of the light beam. A plurality of finned cooling assemblies are activated by the signal emitted by the sensor.

Abstract: A water removing mechanism for the evaporator in a refrigeration system in which an electrode element is disposed beneath the evaporator and a pulse voltage source is provided to connect the evaporator and the electrode element to generate an electric field with high voltage and low current between the evaporator and the electrode element, causing water condensed on the surface of the fins of evaporator to bear negative charge and the electrode element to bear positive charge and thereby allowing the water on the evaporator to be driven by the electric field to leave the evaporator at an accelerated speed.

Abstract: In a refrigerating device for a vehicle (1) major components for performing a refrigerating cycle, i.e., an evaporator (19), an evaporator fan (25), a condenser (15) and a condenser fan (23), except for the condenser, are preliminarily attached to an evaporator housing (29) to form an integral refrigerating unit (9). Thus, the refrigerating device may be mounted easily to a refrigeration container (3) easily and quickly only by fitting the refrigerating unit (9) having the evaporator housing as a frame into an opening portion (27) of the refrigeration container (3). Further, because the evaporator (19) and the evaporator fan (25) are not protruded from an inner wall of the refrigeration container, the capacity of the refrigeration container is never reduced.

Abstract: A method and apparatus of an externally mounted radiant reflector defrost heater, is a curved reflector combined by means of electrical insulators to a discrete heating means to form an apparatus to reduce ice buildup on a heat pump system's exterior unit heat exchangers through a non-reverse cycle defrost, via an apparatus which can be installed into a newly manufactured heat pump or by the retrofit of said apparatus onto an existing heat pump system, on site at location, said apparatus operating a non-reverse cycle defrost; independent of and uninterrupted by the said heat pump system's reversing valve defrost cycle.

Abstract: A device for rapidly defrosting a refrigerator compartment, such as a freezer compartment or the like, said compartment comprising a plurality of adjacent walls, in correspondence with at least one of said walls there being arranged a hairpin coil evaporator for a static refrigerator, or a part of an evaporator of forced-air type, within a refrigeration circuit comprising a motor-compressor unit, said device comprising heating means arranged in correspondence with at least one of said walls and/or with the evaporator, said heating means being electrically powered via an electrical supply circuit associated with the refrigerator; the heating means are at least one resistance element of PTF (polymer thin/thick film) type.

Abstract: A condensate handling assembly comprises a collection container for receiving and retaining condensate, a heating container for receiving condensate from the collection container, and a heating device for raising the temperature of condensate in the heating container to pressurize condensate in the heating container. A transfer conduit interconnects the collection container and the heating container, and a one-way valve is disposed in the transfer conduit for permitting flow of condensate from the collection container to the heating container. A level sensor senses the level of condensate in the collection container and activates the heating device upon the condensate in the collection container reaching a selected level.

Abstract: A frost control system for preventing the accumulation of frost on components of a freezer door assembly is disclosed. The system comprises a movable door disposed between a cold space and a warm space, and a header assembly. The header assembly comprises an air mover and an air inlet adapted for drawing air from the cold space to an inlet of the air mover. A conduit is provided for conducting air from an outlet of the air mover to a region of the warm space proximate to the door, and a thermostatically-controlled heater is disposed within the conduit. The conduit includes a heated air exhaust vent. Also provided is control circuitry for managing the operation of the heater and air mover.

Abstract: A condensate handling assembly comprises a collection container for receiving and retaining condensate, a heating container for receiving condensate from the collection container, and a heating device for raising the temperature of condensate in the heating container to pressurize condensate in the heating container. A transfer conduit interconnects the collection container and the heating container, and a one-way valve is disposed in the transfer conduit for permitting flow of condensate from the collection container to the heating container. A level sensor senses the level of condensate in the collection container and activates the heating device upon the condensate in the collection container reaching a selected level.

Abstract: A refrigeration unit with a thermal break member and an anti-sweat heating mechanism in the form of a heater wire suitable for high humidity environments is provided. The thermal break member includes a main body portion and a conduit portion connected to the main body portion. The conduit portion defines a channel disposed near the access opening of the refrigerated compartment and configured to receive therein the heater wire. The thermal break member includes a closure member and a flexible hinge portion. The flexible hinge portion has a first end connected to the main body portion and a second end connected to the closure member. A typical value for the durometer of the flexible hinge portion is 70 Shore A, and a typical value for the durometer of the main body portion and the closure member is 80 Shore D.

Abstract: A cover for a freezing counter includes two reciprocably pivotable oblong profile elements, and a heat emitting element and a drain along one of the profile elements.

Abstract: An anti-frost device for refrigerators includes a heating mechanism capable of preventing any frost from being formed at the outlet portion of a cool air distribution duct, thus allowing cool air to effectively circulate in the cabinet of a refrigerator. The heating mechanism may be a pipe passing over the outlet portion of the distribution duct and allowing a high temperature refrigerant from a refrigeration cycle to pass through. Alternatively, the heating means may be an electric heating wire wound around the outlet portion of the distribution duct.

Abstract: A system is provided for reducing power consumption of door and frame heaters of refrigerating devices while maintaining protection against condensation. One or more condensation sensors are attached to the door and are monitored by control circuitry which controls power applied to the door or frame heater. Condensation on the sensor will increase the conductivity of the sensor, which is detected by the control circuitry. When condensation occurs, power is applied to the heater until the condensation is eliminated. The invention includes two different condensation sensor configurations.

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 defroster for refrigerators, capable of defrosting both a prefrosting panel and an evaporator using a defrosting heater, is disclosed. In an embodiment, a heat conduction panel integrally extends from the defrosting heater and terminates at a position approximate to one end of the prefrosting panel, thus allowing heat of the defrosting heater to be transferred to the prefrosting panel through thermal conduction. The heat conduction panel has an enough width to be connected to the total length of the defrosting heater and is uniformly spaced apart from the end of the prefrosting panel. In another embodiment, the prefrosting panel extends to an enough length to be directly connected to the defrosting heater, thus being selectively defrosted with heat transferred from the defrosting heater through thermal conduction.

Abstract: A condensate evaporator apparatus in accordance with the present invention generally includes a dissipator pan for collecting condensate formed on evaporator coils of a refrigeration unit, a heating element for hastening evaporation of the condensate, a frame for housing the dissipator pan, the frame including means for permanently mounting the frame within the refrigeration unit, and structure for enabling the dissipator to be quickly and easily removed from the frame in order to facilitate maintenance, cleaning or replacement thereof. In addition, a magnetized float and guide stem may be included for detecting a level of condensate and for activating the heating element when the condensate has accumulated to a selected level.

Abstract: The invention relates to a bottle cooler where bottles, cans and similar containers, preferably containing beverages, are offered for sale in cooled condition comprising a cooling machine (3, 5, 7) for cooling air which is supplied to the bottles (14), etc. The bottle cooler is built up on a standing pipe (1), which below is assigned a blower/fan means (2) in order to drive cooled air up through the pipe (1), which above is provided with at least one opening (1"), through which the cooled air flows out from the pipe (1) which, in the upper portion thereof, is surrounded by an air flowing-down and bottle accommodating chamber, and, at a certain distance below the lower edge of the hood (17), a bottle supporting shelf (13) is disposed, from where the bottles (14) are available for the purchasing public, and which is surrounded by a lateral supporting wall or the like (15) for the bottles, said wall (15) being formed with holes.

Abstract: A method and apparatus for eliminating the accumulation of moisture condensation on air conditioning supply grills of concentric diffusers which involves the positioning of heat transfer tape around the perimeter of an air conditioning supply grill, a humidistat positioned within the return air duct of the air conditioning system, and a relay located in the electrical component compartment of the air conditioning system which is connected to the humidistat so that when the humidistat senses high levels of moisture in the return air, the relay will allow current to flow through the heat transfer tape for warming of the air conditioning supply grill and prevention of moisture condensation accumulation thereon. Applications may include, but are not limited to, use in commercial air conditioning systems having concentric diffusers.

Abstract: An upright split door, ultra low temperature freezer which includes a single chamber cooled by a cold wall refrigeration system and accessible by separate upper and lower doors. The refrigeration system maintains the chamber at a substantially constant, ultra low temperature, such as within the range of about -50.degree. C. to -90.degree. C. Short term items may be stored in and accessed from an upper portion of the chamber by the upper door without causing the very cold air in the freezer chamber from spilling out the lower portion of the chamber. Long term items may be stored in the lower portion of the chamber and accessed by the lower door. A horizontal mullion is mounted to the freezer side walls and extends between the two doors to provide a seal for respective lower and upper edges of the two doors. A self-regulating heater strip is disposed within the mullion between upper and lower resilient sealing bulbs extending horizontally to prevent condensation build up in the mullion area.

Abstract: A sealed, closed end heat pipe efficiently warms the drain for an evaporator so that condensation may flow unobstructed away from the evaporator in the refrigeration circuit. An evaporator end of the heat pipe is exposed to ambient air and a condenser end is located close to the drain inlet adjacent the evaporator. Thus, no external power source is required as fluid within the evaporator end is heated to vapor phase and circulates toward the condenser end, and cooled fluid from the condenser end returns to the evaporator end.

Abstract: A refrigerator includes a freezing compartment and refrigerating compartment. Dew prevention heaters are provided for the respective compartments. The dew prevention heater for the freezing compartment cannot be activated if the freezer temperature is above 0.degree. C., but it can be activated if that temperature is below 0.degree. C. as follows: if the compressor is on, then the heater is always on; and if the compressor is off, then the heater will cycle on and off at a frequency dependent upon the magnitude of the temperature outside of the refrigerator. The activation of the dew prevention heater for the refrigerating compartment is independent of the temperature of the refrigerating compartment. Rather, that heater is "off" if the compressor is "off", and if the compressor is "on", the heater will cycle on and off at a frequency dependent upon the temperature outside of the refrigerator.

Abstract: A through-the-door ice and cold water dispenser for domestic refrigeration units provides a housing positioned within a recess formed in the door insulation. The dispenser provides an actuation cradle formed with a smoothly curved concave surface in combination with a switch operating system which requires low forces for operation so that the dispenser can be actuated by fragile containers, such as styrofoam cups. An insulated damper door is closed when the dispenser is not operating to prevent heat transfer into the freezer compartment where the ice is produced and stored. A heater positioned against the damper door operates to release the damper door should it become frozen in the closed position. All of the controls for the dispenser are located in the upper portion of the housing and are accessible with a minimum amount of disassembly when service or maintenance is required. A spill tray is located in the bottom of the dispenser recess to contain and retain spilled water and melted ice water.

Abstract: A refrigerator has freezing and cooling compartments, and a cooling device disposed in a space between those compartments. The cooling device includes a refrigerant-conducting pipe arrangement. Attached to that pipe arrangement is a deodorizer comprised of an odor adsorbing element and a heater for heating the odor adsorbing element. The deodorizer is suspended from pipe sections of the pipe arrangement so as to extend transversely relative to a direction of air flow through the cooling device. The cooling device includes a defrosting heater actuated simultaneously with the deodorizer heater so that both heaters perform a defrosting function.

Abstract: A refrigeration apparatus is provided having a refrigeration system including means to enable automatic defrosting of the evaporator that is located in the compartment where food products are maintained at a temperature that is below the freezing point of water. The system includes a defrosting evaporator located exteriorly of the freezer compartment and connected in series flow relationship with the freezer evaporator whereby refrigerant first flows through the defrost evaporator and then through the freezer evaporator. The system includes means for applying heat to the defrost evaporator at periodic intervals of time to elevate the temperature of the refrigerant flowing through the freezer evaporator to a level above the freezing point of water. In one embodiment, this heat is obtained from an electrical resistance heating element disposed in heat-transferring relationship to the defrost evaporator.

Abstract: A frost control system is described for inhibiting and removing frost from the door of a storage locker. Relatively cool air is received by an inlet to the frost control system at an inlet placed above the door. The air is drawn into the system by a blower which forces the air through the ducts of the system. The air passes through strip heaters within the vertical ducts of the defrost system positioned on either side of the door. The warm air is discharged horizontally across the bottom portion of the door and simultaneously rises creating a blanket of relatively warm air in comparison to the ambient area. Discharge apertures are included in the ends of the vertical ducts which blow a portion of the warmed air to the base of the door to enhance coverage of the door by the warmed air.

Abstract: A refrigeration system, which conditions the air of a conditioned space via heating and cooling cycles, includes a heat exchanger and, in a first embodiment, heat pipes. A cryogen is circulated through the heat exchanger during a cooling cycle. During a heating cycle the flow of cryogen is terminated and heat is transferred into the heat exchanger via the heat pipes. In another embodiment, the temperature of evaporation of a liquid cryogen in the heat exchanger is selected according to the desired temperature of the conditioned space, via selectable cryogen flow paths which provide different pressures and thus different evaporation temperatures. Vaporized cryogen drives a motor connected to a fan which circulates air between the conditioned space and heat exchanger.

Abstract: A method and apparatus to refrigerate air in a compartment wherein liquid CO.sub.2 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 CO.sub.2 vapor expands through the motors. CO.sub.2 vapor is routed from the second heat exchanger to chill surfaces in a dehumidifier to condense moisture from a stream of air before it flows to the heat exchangers.