Abstract: Food thawing apparatus is disclosed specially adapted for used in a refrigeration appliance. An enclosure having good thermal communication with surrounding environment is provided with a pair of planar electrodes defining a food thawing zone. One of the electrodes is movable to allow insertion of a frozen food load. A high frequency, relatively low wattage power supply provides uniform energy distribution throughout the food load for gentle heating (thawing). Frequencies of 27.12 MHz or 43 MHz are suggested along with a power level of 100 watts or below, preferably 35-80 watts.A low cost, semi-automatic embodiment is also disclosed employing a compartment built into a refrigerator with a removable drawer. A drawer latch simultaneously operates to lock the drawer into place and to lower the movable electrode into contact with the food load.

Abstract: Food thawing apparatus is disclosed specifically adapted for use in a refrigeration appliance. An enclosure having good thermal communication with surrounding environment is provided with a pair of planar electrodes defining a food thawing zone. One of the electrodes is movable to allow insertion of a frozen food load. A high frequency, relatively low wattage power supply provides uniform energy distribution throughout the food load for gentle heating (thawing). Frequencies of 27.12 MHz or 43 MHz are suggested along with a power level of 100 watts or below, preferably 35-80 watts.

Abstract: An automatic defrost system in which the actual defrost time of an evaporator coil, for example, is the controlling parameter for establishing a defrost cycle. The system automatically adjusts itself so that a predetermined amount of frost builds up in the frost accumulating period.

Abstract: In crystallization units such as wax crystallization units where a scraped surface double pipe heat exchanger type chiller is used, the improvement of replacing the scraped surface chiller tube with a porous tube to provide positive flow of coolant through the tube wall to prevent crystal deposition on the process side of the tube, whereby crystal degradation is eliminated and increased filter rate is obtained.

Abstract: Apparatus and method for storing material at and below a permissible upper temperature below the freezing point in a refrigeration chamber containing a heat exchanger and a thermostat to activate a refrigeration to supply coolant to the heat exchanger to maintain a set temperature. Periodically defrosting the heat exchanger by introducing heat, usually by an electric heating element in the refrigeration chamber, but prior to initiating defrosting, the thermostat is taken out of control of the refrigeration unit and the latter automatically activated to effect a drop in temperature in the chamber sufficient to prevent the stored material from exceeding it permissible upper temperature during subsequent defrosting.

Abstract: In a compressed air powered refrigeration system for aircraft containing a refrigeration turbine and associated heat exchangers for supplying cool air to the aircraft cabin, air is recirculated from the cabin by a recirculation means and combined with the turbine discharge air to simultaneously melt ice present in the turbine discharge and provide cooling to the recirculated air. The lack of ice in the turbine discharge allows the use of an ice-free regenerative heat exchanger, in heat exchange relation with the mixture of the turbine discharge air and recirculated cabin air, to condense moisture from the air entering the turbine. The use of heat from the cabin air to melt ice coupled with maximum utilization of the recirculation means supplying the recirculating cabin air enables the turbine to provide air at a temperature below freezing and results in improved cycle efficiency as well as maximum possible ventilation rate to the load.

Abstract: For use in a refrigeration system, at least two coolers are provided symmetrically on opposite sides of a rotatable thermal shield plate separating the compartment to be refrigerated from the area outside the compartment. Defrosting method comprises alternately placing two coolers inside and outside the compartment at regular intervals in such a manner that one cooler placed inside is actuated for entering the refrigeration cycle while the other placed outside is disactuated out of the refrigeration cycle for having the accumulated frost or ice removed by melting in a higher temperature atmosphere. The alternate cooling and defrosting operations for each of the coolers are continuously repeated so that the compartment to be refrigerated can always be maintained at appropriate cooling temperatures.

Abstract: A method and apparatus are disclosed for utilizing existing defrost heater conductors as a transmission medium for high frequency signals generated in response to selected control or alarm information. The signals are detected by a receiver connected to the heater conductors at a location remote from the evaporator coil and adjacent to the defrost heater power contactor. The detected signals are then routed to the various locations for selected control for alarm functions. Among such functions are providing remote readouts of temperature information from the refrigerator cooling section, providing alarm indications in the event of a malfunction within the cooling section resulting in over temperature, and energizing defrost heaters in response to accumulation of frost on the evaporator coil of the refrigeration system on a demand cycle defrost basis.

Abstract: A demand defrost control system which responds to whether a predetermined evaporator temperature is reached during a defrosting operation. If the predetermined temperature is not reached, then a relatively shorter interval before the next defrosting operation is established. If the predetermined temperature is reached, then a relatively longer interval before the next defrosting operation is established.

Abstract: A demand defrost control system which bases the interval between future defrosting operations on the time (heater ON time) required for the defrost heater to raise the evaporator temperature to a predetermined temperature during a previous defrosting operation. There is an inverse relationship between heater ON time and defrost intervals. Additionally, an override is provided which measures the time the compressor and evaporator are energized during any single operation cycle. If this time exceeds a predetermined length of time, the interval before the next defrosting operation is shortened.

Abstract: A cooling unit for refrigeration systems having a substantially vertically disposed air cooling element, utilizing either a volatile or a non-volatile refrigerant, upon which element frost accumulates during the course of the refrigeration process. The element includes heaters to periodically warm the element to a temperature above 32.degree. F. to thaw the frost. These heaters have their heating capacity adjusted so that more heat is applied at the bottom portion of the frost-collecting air cooling element and less heat is supplied to the upper portion.

Abstract: An elevator shaft in a multi-story cold storage warehouse is modified to substantially isolate the atmosphere in the shaft from that in the warehouse and also from the ambient. Small amounts of heat are then added to the shaft and also means to cause positive circulation of the shaft atmosphere to prevent build up of frost and ice on the shaft interior, the elevator car, the cables and other parts within the shaft.

Abstract: A control system for monitoring frost accumulation on the coil of a heat pump. An operational parameter of the heat pump compressor responsive to frost accumulation, such as compressor current, is compared to a reference level developed during a non-frost condition of the coil to initiate and terminate coil defrosting in response to a predetermined variation between the operational and reference parameter levels.

Abstract: The embodiment of the invention disclosed herein is directed to a new and improved method and apparatus for preventing condensation from forming about refrigerator and freezer doors. Warm air produced by the compressor of a refrigerator or freezer unit is channeled either directly or indirectly therefrom to flow vertically along the peripheral sealed edges of the freezer door to prevent condensation from developing therealong. The heated air from the compressor is directed through a vent or outlet port formed in a kick plate or through outlets formed in the housing at a location near the bottom vertical edges of the door. This will provide vertical columns of warm air to flow therealong and prevent condensation.

Abstract: A refrigerating device has a housing including at least one storage compartment. A cooling apparatus including an evaporator, a compressor and a condenser is accommodated in the base of the housing, the evaporator being surrounded by a casing of a thermally conductive material in good thermal contact with the evaporator. The casing separates a passage for circulating a stream of air to be cooled from an additional passage through which an additional stream of air is intermittently passed, after being conducted past or through the condenser or compressor of the cooling apparatus and being heated thereby, the heated additional stream of air defrosting the evaporator. The intermittent passage of the stream of hot air is controlled by deviating flap valves which may be insulated, the position of the flap valves being controlled in dependence on operating parameters of the cooling apparatus.

Abstract: A food receptacle for a refrigerator freezer compartment for fast-thawing and fast freezing food by the use of a concavo-convex heat energy reflective damper pivotally mounted in an air passage of the receptacle which communicates with an opening in the refrigerated air duct of the compartment. A high energy radiating lamp is located on the pivotal axis of the damper such that a manual control pivots the damper to a first evaporator defrost position closing the passage with the damper operative to direct heat energy from the lamp via reflective surfaces in the duct to the refrigerator cooling coil. The damper upon being pivoted to a second position, opens the passage and cooperates with the duct reflective surfaces to circulate below freezing air through the receptacle to fast freeze food therein. The damper, upon being pivoted to a third position, closes the passage and reflects heat energy from the lamp into the receptacle to fast-thaw food therein.

Abstract: A defrost control system for the defrosting evaporators of a refrigeration system which utilizes a first timer which runs continuously and attempts to initiate evaporator defrost at predetermined times and a second timer which accumulates compressor operating time and prevents defrost initiation by the first timer at those preselected times until a predetermined period of operation of the refrigerating system has occurred.

Abstract: Recuperative heat exchangers are disposed in the supply and exhaust ducts of a ventilating system. To reduce frost build-up at the exit end of the exhaust-duct heat exchanger, the heat exchanger is disposed so that the exhaust air flows through it alternately from one end to the other, and vice-versa, when the temperature is below freezing. The reversal of flow of the exhaust air is accompanied by a reversal of the flow of heat exchange medium so that the efficiency of heat exchange is not adversely affected. Several systems of heat exchange are disclosed.

Abstract: A cooling arrangement, particularly for a no-frost refrigerator, including a heat-insulated housing, containing air; heating means located in said heat-insulating housing for heating a portion of said air; cooling means located in said heat-insulating housing for cooling a portion of said air; and air guiding means for mixing at least a portion of the heated air with a portion of the cooled air.

Abstract: A heat pump having an auxiliary outdoor coil equipped with heating means preventing the surface temperature during the heating cycle from falling below 32.degree. C. The heating means comprises an electrical resistance heater in thermal contact with the fins of the outdoor coil such that heat is transferred to the fins by conduction. The system incorporates means to permit functioning immediately upon return to the heating cycle from a cooling cycle even though the pressure in the receiver of the system initially exceeds that in the indoor coil. Additionally, the system incorporates means for protecting the compressor from liquid floodback when changeover occurs from heating to cooling.