Abstract: Liquid refrigerant is injected into the motor of a motor-compressor to cool the motor. Refrigerant is also injected to control the discharge temperature of the compressor. The refrigerant for controlling the discharge temperature may be either excess refrigerant for cooling the motor or refrigerant injected into the compressor under the control of a thermal expansion valve.

Abstract: In a multiroom air conditioner and a method of driving a multiroom air conditioner containing plural outdoor side units each containing a compressor, an outdoor fan, an outdoor heat exchanger and a refrigerant path change-over valve, plural indoor side units each containing an indoor heat exchanger, and an inter-unit pipe comprising a high-pressure gas pipe, a low-pressure gas pipe and a liquid pipe through which the plural outdoor side units are connected to the indoor side units to thereby form a refrigerant cycle, and in which each individual indoor side unit independently and selectively performs a room cooling operation or a room heating operation for an individual room, when a stop signal is output to some outdoor side unit in accordance with an indoor load during a room cooling or heating operation, the refrigerant path change-over valve of the outdoor unit is switched and the outdoor fan thereof is driven so that the driving of the compressor of the outdoor side unit is stopped, but refrigerant is all

Abstract: A control system for controlling a plurality of compressors by means of fuzzy logic. Control is provided by selecting a combination of available compressors, which may include one or more fixed speed compressors and a variable speed compressor. The controller output signals are responsive to inputs monitoring either the pressures in the system's refrigerant suctions lines, the temperatures of the refrigerated spaces, or where a plurality of evaporators are connected to a set of compressors, the temperature of the coldest refrigerated case, or a combination of the desired suction pressure and temperature of the refrigerated space. The output capacity of the system is chosen based on the degree of membership of each input variable as compared to the total for all inputs.

Abstract: The device comprises two condenser/evaporator pairs, belonging to a single refrigerant circuit, which may be selectively brought into operation and disposed at appropriate points on an air circuit having a variable configuration, the first pair being brought into operation in summer so that the evaporator cools a flow of air to be returned into the passenger space, and the second pair being brought into operation in winter so that the condenser heats a flow of air to be conveyed into the passenger space.

Abstract: A heat pump and air conditioning system is provided with a thermal storage device, a variety of distribution devices for blocking or allowing flow of the system working fluid, and a controller for manipulating the distribution devices to control flow of the working fluid through the thermal storage device to allow thermal energy storage or thermal energy discharged depending upon sensed conditions. In addition, a thermal storage device is provided which is suitable for use in a heat pump and air conditioning system. The thermal storage device includes a container through which refrigerant coils pass. The container is filled with an unencapsulated phase change material having a first melt temperature and an encapsulated phase change material having a second melt temperature higher than the first melt temperature. Further disclosed is a method for conditioning a space by use of heat pump and air conditioning systems incorporating thermal storage.

Abstract: A refrigerating system includes a first compartment used solely for cold storage, and a second compartment used either for cold storage or fermentation. First and second heat exchangers are disposed for cooling the first and second compartments, respectively. An outlet of the second heat exchanger communicates with an inlet of the first heat exchanger. A refrigerant distribution mechanism is operable in either a fermentation mode or a cold storage mode. In the fermentation mode, refrigerant is directed through first and second flow passages to the first and second heat exchangers, respectively, such that more refrigerant is delivered to the first heat exchanger than to the second heat exchanger; also, a heater in the second compartment is activated. In the cold storage mode, refrigerant is directed to the second flow passage but not to the first flow passage.

Abstract: A multi-chamber heat-pump type air conditioner in which a plurality of room units (2, 3, 4) are connected to one heat source unit (1), cooling and heating can be effected selectively for each room unit (2, 3, 4), and cooling can be effected by one room unit and heating can be simultaneously effected by another, wherein the high-level pressure or low-level pressure is controlled from rising high as compared to the time of normal operation, and the reliability of the compressor (17) is improved. In which, a third pressure-detector (48) is provided for detecting a rise in pressure between a compressor (17) and a four-way changeover valve (18), and a control circuit (49) is provided for controlling such that, in the event that the pressure within the pipe is below a predetermined pressure, a sixth valve (45) and a seventh valve (46) are closed, while in the event that the pressure within the pipe exceeds the predetermined pressure, the sixth valve (45) and seventh valve (46) are opened.

Abstract: System and process are disclosed for reacting to conditions that may arise in a plurality of discrete chiller units all individually controlled by dedicated control units. The system and process react to temperature conditions of the coolant when it enters and when it leaves the chiller units. The system normally supervises the manner in which the chillers are allowed to individually increase or decrease chilling capacity. The system furthermore overrides this supervisory control of the individual chiller units when the coolant entering the chiller units drops below a threshold value. The chilling capacity of all running chiller units is decreased when this latter condition occurs.

Abstract: System and process are disclosed for the monitoring of certain parameters for the purpose of exercising supervisory control over a number of discrete chiller units each having their individual dedicated controls. The supervisory control is accomplished by imposing limits on the amount of compression that can be demanded by the individual dedicated control units. These limits are selectively changed when certain parameters pertaining to the collective chilling capacity of all of the active chiller units exceed or fall below acceptable levels.

Abstract: An improved refrigeration system is disclosed for chilling a circulating water supply, particularly a supply intended for cooling industrial equipment. The system includes a water container having at least one coiled water tube disposed in the container and positioned in heat-transfer relation with respect to at least one coiled refrigerant-conducting passage external to the water tube(s). A pump circulates water through the water tube(s) in a direction opposite the flow of refrigerant through the adjacent refrigerant-conducting passage(s). The refrigerant circulating system includes two circuits, the first of which connects the outlet of the condenser-compressor to the inlet of the coiled refrigerant-conducting passage(s), and the second of which includes a subcooling condenser tube disposed within the body of water in the container and interposed between the condenser/compressor and the inlet of the refrigerant-conducting passage(s).

Abstract: Disclosed is a multi-airconditioner including a plurality of outdoor units and at least one indoor units in which refrigerant conduits connecting the outdoor units and the at least one indoor units are united in the form of two or three conduits. In the case of the multi-airconditioner for effecting either room-cooling or room-heating, each of the outdoor units and each of the indoor units have a liquefied refrigerant conduit and a gasified refrigerant conduit, which are connected with a single common liquefied refrigerant conduit and a single common gasified refrigerant conduit, respectively.

Abstract: A method and apparatus for controlling the capacity of a multi-stage cooling system is disclosed. The system of the invention utilizes a plurality of commonly piped compressors being a variable speed compressor, means for establishing a single predetermined cooling state "cut-in" pressure and a single predetermined cooling state "cut-out" pressure, a plurality of condenser fans and a microprocessor based control means for controlling the operation of the system.

Abstract: A method and apparatus for sequentially operating a refrigeration system with multiple evaporators is provided in which only one evaporator is operated at a time and is run until a set of fuzzy logic rules determines that one of the other evaporators should be operated or that the operation of the evaporators should be terminated.

Abstract: A system for compressing gas that changes ambient atmosphere conditions which uses a hermetic compressor, a condenser to receive compressed gas from the compressor and condense it, a liquid receiver to store the condensed gas, an expansion valve to vaporize the condensed gas and an evaporator which interacts with the ambient atmosphere. Isolating devices are used to isolate the compressor from the other parts of the system. A power invertor which changes the direct current to alternating current used with the isolating devices enable the use of a hermetic compressor in a direct current environment. Also included are cooling devices that use the cool internal vapor and the cool water formed on the outside of the evaporator to cool the compressor and its components.

Abstract: A refrigeration system for refrigerators having two or more compartments maintained at different temperatures comprises separate cycles for each compartment, each cycle in turn comprising separate evaporator means, heat exchanger means and compressor. To provide for cycle separation, the condenser may be split into separate units, connected by phase separators where appropriate. The system is particularly designed for use in connection with mixed, nonazeotropic refrigerants.

Abstract: An apparatus and a method for heating and cooling with a refrigerant wherein the refrigerant is compressed by a compressor, and circulated to and from the compressor through a condenser, an expansion valve and an evaporator, in this order. A first fluid is heated with the heat generated in the condenser, and a second fluid is cooled with the cooling effect or cold generated in the evaporator. When heat is low and a temperature of the first fluid is decreased, the flow passages of the refrigerant are changed from entering into the evaporator to entering into a second heat-exchanger wherein the refrigerant is heated, and the heated refrigerant is entered into the compressor and circulated. When the cooling effect or cold is low and a temperature of the second fluid is increased, the flow passages of the refrigerant are changed from entering into the condenser to entering into a first heat exchanger wherein the refrigerant is cooled, and the cooled refrigerant is entered into the evaporator and circulated.

Abstract: An apparatus for heating a space using waste heat from a biologically heated product, the apparatus including a storage tank for storing a quantity of the milk and a heat exchanger in thermal communication with the product carrying a thermally conductive fluid. The fluid absorbs heat from the milk and cools the milk as it flows through the heat exchanger. A first condenser in fluid communication with the heat exchanger and carries fluid heated by the milk therein. A fan forces air over the first condenser, heating the air and cooling the fluid in the first condenser. The fan forces the heated air into the space to be heated.A method for recovering waste heat from a biologically heated product is also disclosed.

Abstract: A method and control system for operating a chiller system having a lead compressor and a lag compressor in which the load on the compressors is balanced by limiting the % KW demand on the lag compressor from exceeding the 90 KW of the lead compressor while forcing the lag compressor to supply chilled water at a temperature lower than the lead compressor chilled water.

Abstract: An improved gas pumping recirculating refrigeration system is disclosed. A controlled pressure flash tank provides flash gas for forcing liquid refrigerant from a dump tank. A controlled pressure receiver receives liquid from the dump tank and recirculates it to an evaporator. The flash gas pressure in the flash tank is controlled by a pressure regulator valve connected between the controlled pressure flash tank and the controlled pressure receiver. The pressure regulator valve may set so that the flash gas in the flash tank is at the pressure needed to force liquid from the dump tank. Thereby, optimum refrigeration efficiency is achieved with very little energy waste.

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 compartmentalized transport refrigeration system having first, second and third compartments respectively served by a host refrigeration unit and first and second remote refrigeration units. The method includes the steps of providing a first signal when either of the first and second remote refrigeration units is in a cooling cycle, cycling the host refrigeration unit between cooling and heating cycles to hold a selected set point temperature of a fresh load in the first compartment, in the absence of the first signal, and providing a predetermined null period between the heating and cooling cycles of the host unit when the first signal is present. In a preferred embodiment a prime mover for a refrigerant compressor is operable at a selected one of high and low speeds, with the method including the step of preventing high speed operation when any remote refrigeration unit is in a heating cycle.

Abstract: A refrigeration system which may be operated to control superheat at an inlet to a compressor (12) to produce a controlled superheat or to control a temperature of a fluid cooled by at least one evaporator (68) to provide the cooled fluid at a set temperature by controlling an opening of at least one expansion valve (62) in accordance with the invention includes a temperature control (206) which is activable to control the at least one expansion valve to cool the fluid to a set temperature in response to an enabling signal; a superheat control (208) which is activable to control the at least one expansion valve to control the superheat at the inlet of the compressor in response to an enabling signal; and a controller (204) responsive to the at least one logic operational state of the refrigeration system, for generating one of the enabling signals to activate one of the temperature control or the superheat control to control the at least one expansion valve to control superheat or provide cooled fluid at the

Abstract: A refrigeration circuit is provided in which economizer control is provided together with variable capacity control. Constant cooling is achieved by controlling an economizer cycle responsive to the suction pressure of the compressor. Additionally, compressor discharge temperature is controlled by controlling the portion of liquid refrigerant supplied to the interstage line.

Abstract: This invention provides a multi-staged refrigeration system which includes a method for optimizing the energy used by measuring the energy used by the compressors and increasing the intermediate pressure if the energy decreases when increasing the pressure and decreasing the pressure if the energy increases when increasing the pressure.

Abstract: An economizer is connected to a fluid line connecting the booster compressor and high stage compressor of a refrigeration system at a point downstream of the bypass for unloading the booster compressor. The economizer flow controls the discharge temperature of the second stage and, in addition, coacts with the bypassing of the booster compressor such that all of the flow supplied to the high stage is at system suction pressure when the bypass is fully open. When the booster compressor is fully unloaded and the unloading valve is fully open, the booster compressor is shut off and bypass flow for unloading reverses direction to permit flow from the condenser to the second stage past the shut off booster compressor.

Abstract: A vapor control system (10) utilizes a variable speed compressor (11) driven by a motor (12) or the like. A condenser (13) is provided downstream of the compressor (11). Multiple evaporators (14, 15, etc.) are arranged in parallel with stepper motor controlled thermal expansion valves (16, 17, etc.) located upstream thereof. Refrigerant exit temperatures (T.sub.r1, T.sub.r2, etc.) are sensed at the exits of the evaporators (14, 15, etc.) and source exit temperatures (T.sub.S1, T.sub.S2, etc.), are also sensed. A function generator (18) calculates refrigerant dewpoint temperature (T.sub.dew) is subtracted from each of the refrigerant exit temperatures (T.sub.r1, T.sub.r2, etc.) to determine a minimum superheat temperature which is used to calculate an error signal for providing a speed signal (N.sub.c). The loads on the evaporators (14, 15, etc.) are individually controlled with the thermal expansion valves (16, 17, etc.) whose positions are responsive to signals (X.sub.C1, X.sub.C2, etc.

Abstract: Vapor compression refrigeration device using a non-azeotropic working fluid mixture with separation of liquid mixture and vapor mixture. The separation can occur at high pressure during condensation to expand the temperature glide, at low pressure during condensation, or both during evaporation and condensation. When there is separation during condensation the number of stages in the evaporator and in the condenser must be equal.

Abstract: A vapor compression type refrigerator system which utilizes a liquid pump and an eductor to reduce compressor power conmsumption and thereby achieve exceptionally high coefficient performance values. The system is useful for air conditioning or for refrigeration in residential and commerical type buildings and is convertible to heat pump operation.

Abstract: A method and apparatus for controlling the capacity of a multi-stage cooling system is disclosed. The system of the invention utilizes a plurality of commonly piped compressors having common suction load wherein at least one compressor being a variable speed compressor, means for establishing a single predetermined cooling stage "cut-in" pressure and a single predetermined cooling stage "cut-out" pressure, a plurality of condenser fans and a microprocessor based control means for controlling the operation of the system.

Abstract: An economizer is connected to a fluid line connecting the first and second stages of a compressor at a point downstream of the bypass for unloading the first stage. The economizer flow controls the discharge temperature of the second stage and, in addition, coacts with the bypassing of the first stage such that all of the flow supplied to the second stage is at system suction pressure when the bypass is fully open.

Abstract: A refrigerating cycle including a cold-accumulation material to be cooled comprises main evaporator for generating cold air to cool a refrigerator compartment, a cold-accumulation evaporator to cool the cold-accumulation material, a flowpath switching device, such as a three-way electromagnetic valve, to change the refrigerant flowpath between a first refrigerant flowpath to the main evaporator and a second refrigerant flowpath to the cold-accumulation evaporator respectively, and a refrigerant supply device, such as a compressor, a condenser, and a capillary tube connected in series, to supply refrigerant to the main evaporator and the cold-accumulation evaporator through the flowpath switching device. The outlet of the cold-accumulation evaporator is connected to the inlet of the evaporator to let the refrigerant which has not completely evaporated in the cold-accumulation evaporator flow into the main evaporator.

Abstract: A compartmentalized transport refrigeration system including a refrigeration system having a compressor and first and second selectable refrigeration circuits normally associated with cooling and heating modes, respectively, a trailer having at least first and second compartments, a host evaporator, a condenser in the first refrigeration circuit, and at least one remote evaporator, with the evaporators each being associated with a trailer compartment. The second refrigeration circuit is selected when a remote evaporator requires heating, and when another evaporator requires cooling while a remote evaporator requires heating, refrigerant is returned to the compressor via the first refrigeration circuit and the evaporator requiring cooling, entering the first refrigeration circuit at a point which by-passes the normal condenser function, to cause the evaporator requiring heating to function as a condenser for the evaporator requiring cooling.

Abstract: An outdoor unit includes at least two variable-capacity compressors. Each of a plurality of indoor units includes a detector for detecting an air conditioning load of the indoor heat exchanger to output respective required capacity data. A distribution unit couples the outdoor unit in parallel with the indoor units so as to constitute each refrigerant cycle, and has a plurality of refrigerant flow controllers. A first controller supplies a control command based on the respective required capacity data to the refrigerant flow controllers, and outputs total sum data of the respective required capacity data. A second controllers supplies a single operation command with a predetermined capacity by one of the two compressors or a parallel operation command with predetermined capacities by both the two compressors to the outdoor unit whether the total sum data is smaller or larger than a predetermined value.

Abstract: An air conditioner dehumidifier comprising coil portions cooled for example by chilled water or refrigerant. Under part load conditions, restriction of coolant flow below peak load flow, or its total elimination, is limited to some only of the coil portions, while the remainder may receive as much or more coolant flow as at peak load conditions. The relatively unrestricted coolant flow through this remainder can be greater than that under peak load conditions due to more pump output being available to supply the reduced active size of the coil.

Abstract: In a refrigeration system having a compressor driven by a variable speed motor, the refrigerant flow volume through the expansion device is controlled by way of a solenoid driven piston which alternately opens and closes the orifice, with the duty cycle of the solenoid being controlled such that the time period in which the orifice is open is proportional to the speed of the motor. A bypass channel is provided in parallel around the orifice such that a minimal flow is provided to thereby share the load with the modulating orifice and act to dampen the movement of the solenoid piston.

Abstract: In one exemplar embodiment, method and apparatus for controlling capacity of a multiple-stage cooling system is disclosed which utilizes means for establishing a single predetermined cooling stage "cut-in" pressure and a single predetermined cooling stage "cut-out" pressure, means for determining that the "cut-in" or "cut-out" pressures have been reached in the system, a delay means for introducing a selected minimum time delay after determining that the refrigerant fluid pressure has either reached the established "cut-in" or "cut-out" pressures, and control means for controlling the turning on or off of the next cooling stage after the time delay has elapsed.

Abstract: A liquid/gas bypass line bypasses an expansion device of a refrigeration apparatus. An inlet of the bypass line is connected slightly above the bottom of a condenser so that it can pass either liquid refrigerant or vaporous refrigerant, depending on the level of liquid refrigerant in the condenser. The other end of the bypass line is connected to discharge into the evaporator, bypassing the expansion device. The bypass line functions as a conventional hot gas bypass during low load conditions when the level of liquid refrigerant is below the line's inlet. When the level rises above the inlet, often occurring when the condenser coolant temperature is low and the compressor is fully loaded, the bypass line returns excess accumulated liquid refrigerant to the evaporator. Maintaining the proper levels of liquid refrigerant in both the condenser and the evaporator not only provides the most effective use of their heat transfer surfaces, but also promotes the proper return of oil to the compressor.

Abstract: A control system for controlling a closed-loop refrigeration system having multiple parallel commonly piped compressors is disclosed. Various combinations of compressors define the compressor capacity stages of the system. The disclosed control system responds to a system parameter, such as the suction line pressure or the temperature of an area to be cooled by an evaporator of the refrigeration system, to control the selection of the minimum system compressor capacity necessary to maintain the temperature of the area to be cooled to the lowest temperature. Control of the compressor capacity is effected by the sensed system parameter by generating an operating range defined from an upper to a lower operating limit. Operations above or below this range determines whether an increase or decrease, respectively, in compressor capacity needs to be made.

Abstract: There is disclosed a refrigeration system employing multi-stage compressors, several unique modes of operation thereof, a sub-cooler/economizer for sub-cooling the condensed refrigerant prior to vaporization in the evaporator, as well as an improved expansion valve arrangement for controlling second stage discharge temperature, another valve arrangement for controlling economizer liquid discharge temperature, an interstage intercooler for use in a hot water system, a satellite compressor arrangement for ultra-low temperature applications, and an improved liquid-suction heat exchange arrangement.

Abstract: A compartmentalized transport refrigeration system, and method of operating same, in which a host refrigeration unit controls the temperature of the air in a front compartment of a trailer, and a remote evaporator unit controls the temperature of the air in a rear compartment. In order to increase the heating and cooling capacity of the remote evaporator, the host unit is prevented from going into a heating mode in response to predetermined conditions, and more, or all in certain instances, of the discharge gas from the host compressor is made available for the remote evaporator.

Abstract: A refrigeration system is disclosed having greatly improved efficiency. The system includes a pre-cooler heat exchanger for sub-cooling the refrigerant hot gas from the compressor before entering the condenser to render the entire evaporator more effective for refrigeration purposes. The heat exchanger for pre-cooling the hot gas has one passage through which the hot gas flows and another passage, in heat exchange relation therewith, which is connected to receive a small flow of liquid refrigerant bled off from the main stream of the liquid refrigerant which refrigerant passes through an expansion valve or capillary tube to vaporize so that the refrigerant hot gas is sub-cooled by the latent heat of vaporization of the vaporizing refrigerant. This heat exchanger is located between the compressor and the condenser. The flow of the vaporized refrigerant used for cooling in the heat exchanger is connected to the return flow of vaporized refrigerant flowing from the evaporator to the compressor.

Abstract: A compartmentalized transport refrigeration system, and method of operating same, in which a host refrigeration unit controls the temperature of the air in a front compartment of a trailer, and a remote evaporator unit controls the temperature of the air in a rear compartment. In order to increase the heating capacity of the remote evaporator, the host's hot gas line is selectively controlled to enable all of the hot gas from the compressor to be directed to the remote evaporator when the host unit is in null. The host unit can only heat when the remote unit is in null. In order to increase the cooling capacity of the remote unit, the host's liquid line in selectively controlled to enable the liquid from the receiver to be all directed to the remote evaporator unit when the host unit is in null.

Abstract: In a multizone air conditioning system, a controlled leakage of refrigerant is provided from the high pressure side of the system to an inactive fan coil circuit to raise the pressure therein, such that when that circuit is later brought into an active state, the flow rate of refrigerant suddenly entering the circuit, and the resultant noise, is reduced. In one embodiment the controlled leakage is provided by an orifice formed between the high and low pressure sides of a valve, while in another it is provided by capillary tubes interconnected between active and inactive fan coil circuits.

Abstract: A refrigeration system includes a heat rejection loop and a heat absorbtion loop interconnected by a phase separation device. Refrigerant is circulated in the heat rejection loop by a positive displacement pump thereby permitting the pressure of refrigerant in the condensor to fluctuate as the ambient temperature fluctuates. This increases the capacity of the system and reduces the work performed by the compressors. A bypass line is provided between the phase separation device and the condensor to allow the compressors to be switched off completely when the ambient temperature is below the evaporator temperature. The output of the compressors is also used as a heat source to defrost the evaporators as required.

Abstract: The present invention provides a system and method for peak shaving for a conventional air conditioning system. Heat energy is removed from an energy storage medium during periods of low power consumption and then the storage medium is used to absorb heat energy from the refrigerant during periods of peak energy consumption.

Abstract: The invention relates to a refrigeration circuit which includes a second expansion means and a flow self-operated regulating valve, which controls the quantity of refrigerant to an intermediate suction port of compressor depending on a difference of pressure at the side of inlet from at the side of outlet of the expansion capillary.

Abstract: A refrigeration/cooling system including a compressor (12, 14, 16, 18) having an inlet (54) and an outlet (20), a countercurrent condenser (24) connected to the compressor outlet (20) and an countercurrent evaporator (30) connected to the compressor inlet (54). A heat exchanger (36) interconnects the condensor (24) and the evaporator (30). A first throttling valve (34) is interposed between the heat exchanger (36) and the evaporator (30) and a second throttling valve (64) is located in the system downstream of the condenser (24) and upstream of the evaporator (30) for providing an at least partially expanded refrigerant to the heat exchanger (36). A refrigerant return (50) interconnects the heat exchanger (36) and a portion of the compressor (16) for returning the partially expanded refrigerant to the compressor.

Abstract: A refrigeration system is disclosed having greatly improved efficiency. The system includes a pre-cooler heat exchanger for sub-cooling the liquid refrigerant from the condenser to render the entire evaporator more effective for refrigeration purposes. The heat exchanger for pre-cooling the liquid refrigerant has one passage through which the hot liquid refrigerant flows and another passage, in heat exchange relation therewith, which is connected to receive a small flow of liquid refrigerant bled off from the main stream of the liquid refrigerant which refrigerant passes through an expansion valve or capillary tube to vaporize so that the liquid refrigerant is sub-cooled by the latent heat of vaporization of the vaporizing refrigerant. This heat exchanger is located between the condenser and the receiver or between the condenser and the evaporator in systems not having a receiver.

Abstract: A control system for a compression type refrigeration unit with an air-cooled condenser exposed to outside ambient conditions. In cooler weather the head pressure is maintained by backflooding the condenser which limits the condensing surface. This also subcools the liquid in the condenser. A bypass line from a point between the outlet of the condenser and the receiver inlet connects with the liquid supply line leaving the receiver and directs this subcooled liquid to the expansion valve. A solenoid valve in the bypass line is controlled by a liquid level sensor or subcooling sensor in the line leaving the condenser. This increases the capacity of the evaporator as less evaporation is required to remove the sensible heat-down to the evaporating temperature. In warmer weather, the system automatically reverts to a conventional condensing mode.

Abstract: A refrigeration system for food display cases is disclosed, having a heat reclamation coil, to which hot gas discharged by the system's compressors may be diverted in accordance with the conventional practice, to provide heat energy usable for heating and/or controlling the moisture content of the interior store area. An improvement in such heat reclamation systems is disclosed, in that the output of the heat reclaim coil is continuously sensed to determine whether it is in an all-liquid condition, or alternatively, a mixture of liquid and gas. If the former, valving is automatically operated to bypass the liquid output from the heat reclaim coil around the system's condenser to the liquid line downstream from the condenser, so that the heat reclaim coil functions as the system's condenser in these circumstances. If the output from the heat reclaim coil is a gas-liquid mixture, it is returned to the input side of the system's condenser to reduce the energy required for normal condenser operation.