Abstract: The present invention relates to systems and methods for controlling head pressure in a vapor compression system, e.g. in a precision air conditioning system. One embodiment of the invention provides a method for regulating working fluid flow in a vapor compression system including a compressor. The method includes: providing a controller; receiving signals at the controller representative of a monitored discharge pressure in a discharge line of the compressor; and using the controller to provide a control signal to an actuator that controls a flow control valve that, in turn, controls working fluid flow into the system, the control signal being responsive at least in part to a difference between a set point pressure and the monitored discharge pressure.

Abstract: A method for operating a vapor compression system includes the steps of providing a vapor compression system having a compressor circuit including a compressor having an inlet port and an outlet port, a circuit incorporating the compressor, a condenser, an evaporator and an expansion device for sequentially generating a cooling refrigerant for cooling a stream of air so as to provide a dehumidified cooled stream of air, and a reheat refrigerant for heating the dehumidified cooled stream of air to provide a reheated dehumidified stream of air; controlling discharge pressure from the compressor outlet so as to increase discharge pressure from the compressor outlet. Furthermore, system dehumidification performance is improved in terms of latent capacity boost, undesired sensible capacity reduction, latent efficiency enhancement, and recovery of supply air temperature to a desired level.

Abstract: The present invention discloses an apparatus and method for controlling an operation of an outdoor unit which can efficiently control the outdoor unit by mounting sensors on the outdoor unit. The apparatus for controlling the operation of the outdoor unit includes: a pressure sensor for sensing a pressure of refrigerants in an outlet of a compressor of the outdoor unit; a temperature sensor for sensing a temperature of the refrigerants in an outlet of a condenser; and a microcomputer for comparing the pressure from the pressure sensor and the temperature from the temperature sensor with optimal pressure and temperature ranges, and controlling operation conditions of at least a blast fan and the compressor in the outdoor unit to be inversely proportional to each other according to the comparison results.

Abstract: Disclosed is a method for controlling noise reduction of an air conditioner comprising the steps of: (a) stopping a compressor, when the air conditioner is stopped under the condition that the compressor and an outdoor fan are operated; and (b) stopping the outdoor fan after a designated time after a point in time when the compressor is stopped in the step (a) elapses, thus reducing the size and duration of noise generated by the flow of the refrigerant due to a difference of inner pressures in the air conditioner and allowing the noise at a designated frequency band generated by the flow of the refrigerant, which causes unpleasantness to users, to be concealed by noise generated by the operation of the outdoor fan. Accordingly, the method of the present invention increases reliability of air conditioner products.

Abstract: A heat pump having an indoor coil that operates as a condenser when the system is in a heating mode and an outdoor coil that operates as an evaporator when the system is in the heating mode. A variable speed indoor fan is used to move supply air over the indoor coil and a temperature sensor is arranged to provide ambient outdoor temperature data to a programmable computer. The computer contains a schedule for continuously adjusting the speed of the indoor fan in response to changes in the ambient temperature so as to maintain the temperature of the supply air at a constant level. In doing so, the compressor discharge pressure is also maintained within allowable limits and is held substantially constant.

Abstract: A water-cooled auxiliary condenser device 200 receives refrigerant from an external refrigeration system 210 just downstream from its air-cooled condenser 110. The refrigerant passes through a water-cooled condenser 250, and the refrigerant state is sensed by a temperature or pressure sensor 226. If the sensed state of the refrigerant rises above a first threshold, the flow of water through the water-cooled condenser 250 is increased, e.g., turned ON, using a controllable water valve 234. When the sensed state of the refrigerant drops below a second threshold, the water flow through the water-cooled condenser 250 is decreased, e.g., turned OFF. The refrigerant returns to the refrigeration system just upstream from its liquid receiver 120. In the event that air-cooled condenser 110 fails, device 200 automatically activates the water-cooled condenser 250 to maintain safe refrigeration temperatures in the appliance. When not required, device 200 remains passive and does not use any water or electric.

Abstract: In a vehicular air conditioning control apparatus having a compressor and an electric cooling fan of an externally controlled type, a fan motor control for increasing fan motor load is carried out in a compressor discharge capacity region lower than in normal control in below-listed cases. (1) When a requested cooling performance is predicted to increase. (2) When a vehicle is brought into an idling state. (3) In cool down in which a requested cooling performance is predicted to increase to be equal to or larger than a set value, or when a vehicle is brought into an idling state.

Abstract: A vehicle control system capable of achieving improvement in fuel efficiency by performing optimum control over an engine in consideration of power load applied onto an engine by auxiliary machines.

Abstract: A control device for a motor fan of a vehicle, which controls the motor fan to cool a radiator for engine coolant and a condenser for air conditioner refrigerant, includes: a first command value calculation section which calculates a first command value for control of the motor fan according to refrigerant pressure; a second command value calculation section which calculates a second command value for control of the motor fan according to coolant temperature; a first target value setting section which sets the greater of the first command value and the second command value as a first target value; a second target value setting section which obtains a second target value for control of the motor fan which corresponds to a total torque which is smaller than a total torque of a torque of an alternator and a torque of a compressor corresponding to the first target value; and a control section which controls the motor fan according to the second target value.

Abstract: The present invention relates to systems and methods for controlling head pressure in a vapor compression system, e.g. in a precision air conditioning system. One embodiment of the invention provides a method for regulating working fluid flow in a vapor compression system including a compressor. The method includes: providing a controller; receiving signals at the controller representative of a monitored discharge pressure in a discharge line of the compressor; and using the controller to provide a control signal to an actuator that controls a flow control valve that, in turn, controls working fluid flow into the system, the control signal being responsive at least in part to a difference between a set point pressure and the monitored discharge pressure.

Abstract: A commercial refrigeration system including a compressor, a condenser, a valve, and an evaporator coil, all of which are in fluid communication. The refrigeration system further including a fixture adapted to be cooled by the evaporator coil, a system controller operable to control operation of the refrigeration system, and a subsystem controller in communication with the system controller. The subsystem controller being operable to monitor at least one parameter of a subsystem having at least one of the compressor, condenser, valve, and fixture, and being further operable to execute a command from the system controller to affect the operation of the subsystem.

Abstract: A refrigerating cycle is capable of performing both an operation in which the maximum cooling power is desired to be unleashed and an operation in which the most excellent performance coefficient is attained. A refrigerating cycle is configured such that a differential pressure-regulating valve forming a pressure-reducing device is arranged between a condenser and a receiver. As a result, by setting the differential pressure regulated by the differential pressure-regulating valve 3 to 0, it is possible to cause the refrigerating cycle to perform an operation in which the maximum cooling power is desired to be unleashed, whereas by setting the same to a desired value, it is possible to cause the same to perform an operation in which an excellent performance coefficient is attained.

Abstract: An air conditioner employing a flammable refrigerant, comprises a sensor (11) that is provided on an external surface of an indoor unit (1) and detects the flammable refrigerant gas, in order to prevent the accident of a fire or the like even when the flammable refrigerant leaks. Furthermore, an air conditioner is provided with a indoor unit housing a heat exchanger (3) and a fan (7) inside its casing (2) that has an inlet port (8) and an outlet port (5). The air conditioner rotates the fan (7) and flows the flammable refrigerant through the heat exchanger (3) during operation, performing heat exchange between air taken into the casing (2) through the inlet port (8) and the flammable refrigerant, and blows out the air that has undergone the heat exchange to the inside of a room through the outlet port (5).

Abstract: A cooling system controller controls the capacity of a variable capacity compressor based upon the temperature of a housing being cooled, the suction pressure of the compressor or both of these criteria. The cooling system controller is capable of controlling either single-evaporator or multiple-evaporator refrigeration systems. The multiple-evaporator systems can have evaporators of similar temperatures or of mixed temperatures. The controller also allows the use of one or more condenser fans that are operated in a lead/lag fashion to control the cooling capability of the system.

Abstract: A refrigeration system (10) has a compressor (12) that forces a refrigerant to flow in a loop between an evaporator (17) and a condenser (16). The present method controls the speed of a condenser fan (16) in response to the condenser temperature. In a first control state, the speed of the fan (16) is varied in response to the condenser temperature. In a second state, the fan (16) is turned on and off by a pulse width modulated signal that has a duty cycle which varies in response to the condenser temperature. A transition occurs from the first state to the second state when the fan (16) operates at the slowest possible speed for a predetermined period while the condenser temperature is below a desired value. A transition occurs from the second state to the first state when the duty cycle is at 100% for a given period and the condenser temperature is above the desired value.

Abstract: A compact forced air-cooling condenser is provided which is overall of light weight, but can be manufactured inexpensively, and which is of high heat exchange performance. In a forced air-cooling condenser employed in a refrigerator of the type which forcibly cools the coolant condensing the coolant using a cooling fan, a condenser 1 for forced air-cooling is constituted of a construction in which a large number of heat-radiating wires 3 are attached extending across above and below a coolant pipe 2 that is bent back in bellows fashion in the same plane, and this is then as a whole bent into spiral shape.

Abstract: An air conditioner employing a flammable refrigerant, comprises a sensor (11) that is provided on an external surface of an indoor unit (1) and detects the flammable refrigerant gas, in order to prevent the accident of a fire or the like even when the flammable refrigerant leaks. Furthermore, an air conditioner is provided with a indoor unit housing a heat exchanger (3) and a fan (7) inside its casing (2) that has an inlet port (8) and an outlet port (5). The air conditioner rotates the fan (7) and flows the flammable refrigerant through the heat exchanger (3) during operation, performing heat exchange between air taken into the casing (2) through the inlet port (8) and the flammable refrigerant, and blows out the air that has undergone the heat exchange to the inside of a room through the outlet port (5).

Abstract: In apparatus and method for controlling a cooling fan associated motor at a pulse duty ratio, the cooling fan is revolved by the cooling fan associated motor to cool a radiator of a vehicular engine coolant and a condenser of a refrigerant of a vehicular air conditioner and the duty ratio for the cooling fan associated motor is controlled in such a manner that a sum of a torque required for a generator to drive the cooling fan associated motor and a torque required to drive a compressor of the air conditioner is minimized while satisfying a control demand for a coolant temperature and a refrigerant pressure so that the cooling fan associated motor is driven at the duty ratio.

Abstract: A thermal energy storage unit is provided in connection with an air conditioning or refrigeration condenser. Working fluid waste heat is stored in the thermal energy storage unit during at least a relatively hot part of the day. Heat stored in the thermal energy storage unit is then rejected to the air during a cooler period, such as night. By rejecting the stored heat directly to the atmosphere, there is no need to provide an energy-consumptive refrigeration cycle for cooling the thermal storage medium material. In this way, a refrigeration system compressor has a reduced load and/or reduced duty cycle during hot parts of the day and relatively less energy can be used during high-demand times when energy may be more expensive.

Abstract: The present invention aims at providing an air conditioner used in an electric vehicle which can exert a sufficient cooling performance without enlarging the size of a motor for driving a compressor or supplying an excessive amount of driving current to the motor.

Abstract: Disclosed is an apparatus for controlling a cooling unit, for instance, for an automatic vending machine. A condenser fan motor and an evaporator fan motor are of DC motors having high energy efficiency. The condenser fan motor is started by a gradually increasing Dc voltage, and the condenser fan motor and the evaporator fan motor are sequentially starred with a predetermined time interval.

Abstract: A mode of operation of an air-conditioning installation of a compression cycle type helicopter cabin or cockpit air-conditioning installation is characterized in that it includes a start-up sequence controlled by an inverter controlling the motor-compressor associated with a condenser equipped with a fan and during which the fan of the condenser is first powered up, after which the motor-compressor is powered up to start it at a low speed, after which the motor-compressor is operated under its normal conditions as a function of the cooling requirements of the installation. Other features concern the mode of powering the motor-compressor in accordance with various atmospheric and operating conditions.

Abstract: An apparatus and method for a heat pump operating in the heating mode controls the condenser air flow rate and the condenser exiting air temperature depending in a first embodiment on the evaporator ambient temperature, and in a second embodiment, the evaporator air temperature and alternatively the condenser air flow rate or the condenser exiting air temperature, to alleviate a cold blow condition. The apparatus and method operate by sensing the evaporator ambient temperature with a sensor positioned proximate to the evaporator, and when that temperature is below a threshold value indicating a cold blow situation, determining by circuit means a modified condenser air flow rate to achieve at the same time a slower air flow and a higher air temperature, so that the cold blow condition is terminated or at least alleviated.

Abstract: A heat exhaust system for installation in the space behind the refrigerator of a recreational vehicle for disposal of heat that builds up behind an RV refrigerator from the operation thereof. The system operates automatically to turn on a fan to dissipate the heat at a predefined high temperature, and operates automatically at a predefined low temperature to turn off the fan thereof.

Abstract: A method for preventing an evaporator of an air conditioner from freezing comprises the steps of (1) detecting an outdoor temperature, (2) determining whether or not the outdoor temperature is 20.degree. C., (3) determining whether or not the outdoor temperature is in a first temperature range, (4) determining whether or not the outdoor temperature is in a second temperature range, (5) varying an R.P.M. of the motor assembly based on the outdoor temperature detected in steps (3) and (4), (6) detecting a surface temperature of a condenser and determining whether or not the surface temperature of the condenser is in a third temperature range, (7) repeating steps (1) through (6) if the surface temperature of the condenser is higher than the third temperature range, and (8) rotating the motor assembly at a low speed if the surface temperature of the condensor is lower than the third temperature range.

Abstract: A compressor discharge pressure control system employed on a container refrigeration unit utilizes a pressure transducer located in the high pressure side of the system and a data processor to control and limit the compressor discharge pressure to a maximum value when the normal condenser pressure controls are inactive. The pressure control system operates the suction modulation valve in a manner that significantly reduces compressor cycling and increases refrigeration system capacity during pull-down periods. The pressure control system also operates during water-cooled operation of a refrigeration system having a water-cooled condenser thereby eliminating the need to provide a water pressure switch in the refrigeration system.

Abstract: A method of controlling fans in a rooftop air conditioning unit. The method comprises the steps of: determining a measure of compressor operating capacity; calculating an indoor fan speed as a function of that capacity; maintaining a fixed relationship between the indoor fan speed and an outdoor fan speed; and controlling the indoor fan in accordance with the calculated indoor fan speed.

Abstract: An engine cooling system and method and apparatus for controlling hydraulic fluid flow between a plurality of hydraulic components in a hydraulic system is shown. The system and method utilized at least one hydraulic sensor for actuating a hydraulic valve which controls the fluid delivery to the hydraulic components. At least one of the hydraulic sensors includes a thermosensitive material which causes the sensor to deliver hydraulic pressure to an actuator on the valve when the material is heated in response to an increase in temperature of, for example, a coolant associated with the engine.

Abstract: An Integrated controller for a commercial vehicle air conditioning system according to the present invention includes a central control unit in communication with a high-pressure switch or sensor, a low-pressure switch or sensor, and an evaporator thermostat. The central control unit includes outputs that control the air conditioning system compressor and fan according to the conditions detected by the high pressure switcher sensor, the low pressure switch or sensor, and the evaporator thermostat.

Abstract: A heat pump type air conditioner having a refrigeration circuit including a variable speed compressor, a four-way valve, an indoor heat exchanger, an expansion device and an outdoor heat exchanger, and capable of operating in a cooling mode to cool a room and a heating mode to heat the room. The compressor speed is set in accordance with air conditioning load, such as the temperature difference between a setting room temperature and the actual room air temperature and the operation mode. An outdoor fan blows air through the outdoor heat exchanger which selectably rotates at a high speed or a low speed. The rotational speed of the outdoor fan is selected based on the operation mode, a cooling mode reference compressor rotational speed value, a heating mode reference compressor rotational speed value and the set compressor rotational speed. The cooling mode reference compressor rotational speed value is smaller than the heating mode reference compressor rotational speed value.

Abstract: The present invention relates to an operational control method and apparatus for an air conditioner in which a rotary speed of an outdoor fan motor is controlled according to a rotary speed of an indoor fan motor, to thereby perform cooling or heating operations thereof. The apparatus includes a zero voltage detector for detecting a zero potential of a commercial alternating current voltage, a controller for controlling an overall operation by being synchronized with the zero potential of the commercial alternating current voltage detected by the zero voltage detector, an indoor fan motor driver for driving an indoor fan motor according to control of the controller, an indoor fan speed detector for detecting a rotary speed of the indoor fan motor driven by the indoor fan motor driver, an outdoor fan motor driver for driving an outdoor fan motor according to control of the controller, and an outdoor fan speed detector for detecting a rotary speed of the outdoor fan motor driven by the outdoor fan motor driver.

Abstract: Apparatus for providing integrated control of a space cooling system is disclosed. The apparatus receives inputs from a plurality of temperature sensors, including a temperature sensor for measuring evaporator superheat, space temperature and compressor discharge temperature. The control apparatus incrementally adjusts the position of the cooling system expansion valve to regulate evaporator superheat and compressor discharge temperature and cycles the outdoor condenser fan on and off to raise condenser pressure in response to a low condenser pressure condition. In one embodiment, the cooling system includes a plurality of evaporators and a corresponding plurality of controllers electrically interconnected in a series loop for controlling the expansion valves and defrost heaters associated with the respective evaporators.

Abstract: An air conditioning apparatus by which the air conditioning apparatus is controlled with optimal respondency and stability so as to enjoy indoor-space comfortability. The air conditioning apparatus for use with cycle dry, includes: an outdoor heat exchanger; a fan unit for blowing air to the outdoor heat exchanger; an adjusting portion, connected to the outdoor heat exchanger, for adjusting flow rate of refrigerant; a first indoor heat exchanger and a second heat exchanger connected to the adjusting means; a compressor which is connected both to the indoor heat exchanger and the outdoor heat exchanger, and which is controllable by an inverter unit; a detecting portion for detecting temperature and humidity indoors; and a cross control system for determining rotation frequencies of the fan unit and the inverter unit by comparing data obtained from the detecting portion with predetermined values of temperature and humidity indoors.

Abstract: Disclosed is a method for reducing the temperature of the air passing over the condenser surface of an air conditioner unit, thereby reducing the power requirements of the unit. The method is carried out by applying water to the condenser surface to achieve coverage of substantially the entire outside surface and the entire inside surface of the condenser with water while the unit is operating. The amount of water applied should be sufficient to wet substantially the entire inside and outside surface of the condenser. The water can be applied from a tubing having a plurality of passages opening through its sidewall at generally linearly spaced apart positions. An adjustable valve means can be positioned near the inlet end of the tubing to regulate water flow through the tubing. An electrically actuated on-off valve can be operatively connected to the tubing between the adjustable valve and the passages so that water will flow only when the compressor is operating.

Abstract: A fluid cooler having contiguous air cooled and evaporative portions and having a heat exchanger common to both portions. The heat exchanger employs a series of straight tubes which traverse both the air-cooled and the evaporative portions. Separate fans are provided for the air-cooled and for the evaporative portions. The segments of the straight tube laying within the air-cooled portion are finned. The segments of straight tubes laying within the evaporative portion are partially finned and extend further downwards as a sub-cooling section of the evaporative coil portion, thereby providing means for cooling the fluid to a temperature lower than ambient dry-bulb temperature.

Abstract: A refrigerating cycle machine characterized by comprising hardware or software means for raising the speed of rotation of the compressor or stopping the fan for producing an air current through the condenser when the operation of the machine is turned off and stopping the operation of the machine when a predetermined time has elapsed. This increases the suction and discharge pressure difference to such an extent that generates a sufficiently high pressure difference between both sides of the valve body to move the valve body toward the closing position surpassing the sticking force when the machine stops.

Abstract: An air conditioner employs a refrigerating cycle involving a compressor 1, an outdoor heat exchanger 5, an indoor heat exchanger 9, an expansion valve 7, and a non-azeotropic coolant mixture composed of high and low boiling coolants sealed in the refrigerating cycle. The outdoor heat exchanger 5 is provided with a first blower 15 and a second blower 17. A speed controller 18 drives and controls the first, and second blowers 15 and 17. The speed controller 18 achieves a first mode to decrease an air quantity to part of the outdoor heat exchanger located on the upstream side of a flow of the coolant smaller than an air quantity to part of the outdoor heat exchanger located on the downstream side of the flow of the coolant, and a second mode to increase the air quantity to the upstream side of the outdoor heat exchanger greater than the air quantity to the downstream side of the outdoor heat exchanger.

Abstract: An air conditioner having a compressor, an outdoor fan, and two indoor heat exchangers which are connected by an electric expansion valve. During a dehumidifying operation, the opening of the electric expansion valve is decreased, thereby decompressing the refrigerant flowing from the first indoor heat exchange into the second indoor exchanger. The first and second heat exchangers thereby function as a reheater and an evaporator, respectively. The second indoor heat exchanger cools and dehumidifies the indoor air, and the first indoor heat exchanger heats the indoor air again. The indoor air, first cooled, then dehumidified, and finally re-heated, is supplied into the room. During the dehumidifying operation, a deviation (T) of the indoor temperature (Ta) from a preset indoor temperature (Ts), and a change (.DELTA.T) in the deviation (T) are detected, and the deviation (H) of the indoor humidity (Ha) from a preset indoor humidity (Hs), and a change (.DELTA.H) are also detected.

Abstract: A reversible vapour compression refrigeration plant serves as an air conditioner for cooling or as a heat pump for heating. A main stream of inlet air is divided into separate main and bypass streams of air and proportion of flow between the two streams is varied in an inverse ratio so that as flow through the bypass duct increases, flow through the main duct decreases and vice versa. When the plant is used for heating, the main stream is heated by a supply heat exchanger acting as a condenser and when the plant is used as an air conditioner, the supply heat exchanger acts as an evaporator. Also, as an additional alternative, as a desired air space temperature is approached, preferably heat rejected by a condenser in the heating mode, or heat gathered by the evaporator in the cooling mode, is gradually reduced by reducing refrigerant flow therethrough by modulating compressor suction. Full fresh air or full re-circulating air modes, or a combination of mixed and re-circulating air can be used.

Abstract: A refrigeration control system is disclosed for operating a refrigeration system in a very efficient manner by controlling the refrigerant pressure in the refrigerant line between the liquid receiver and the evaporator at a pressure which is just above that at which bubbles ("flashgas") occur. An electronic sight glass is used to detect such flashgas bubbles in that liquid refrigerant line thereby indicating that more cooling capacity is required to properly operate the refrigeration system. The system controller can efficiently control various refrigeration components such that the electrical power drawn by the compressor motor is at an optimal or near-optimal rate of consumption at any given cooling requirement within the refrigeration system's cooling capacity. Some of the devices that can be controlled by the system controller include condenser fans, pressure control valves, reciprocating compressors, and screw compressors.

Abstract: An electric expansion valve is arranged between a first indoor heat exchanger and a second indoor heat exchanger. At a time of cooling operation, the electric expansion valve is fully opened to connect both the indoor heat exchangers to each other. At a time of dehumidifying operation the electric expansion valve is narrowed to apply a pressure reducing action across these indoor heat exchangers so that the first indoor heat exchanger acts as a reheater and the second indoor heat exchanger as an evaporator. The indoor air is cooled and dehumidified by the second heat exchanger and then reheated by the first indoor heat exchanger and blown into the room. At a time of dehumidifying operation, the temperature of the air blown into the room varies by controlling the speed of an outdoor fan.

Abstract: A mass flow control apparatus and method for use in combination with a heat transfer system having a compressor, condenser, expansion valve, evaporator and working fluid in a s fluid circuit. The mass flow is controlled using a quality sensor for the working fluid exiting the evaporator, and a high side pressure sensor. A control circuit is provided that monitors the quality sensor and the high side pressure sensor, and controls operation of the compressor, condenser fan and valve in response thereto. A flow reduction mode is used to reduce high side pressure at the valve inlet without excessive compressor cycling by changing the quality sensor setpoint when the high side pressure exceeds the condenser fan turn-on pressure but is less than the compressor disengage pressure.

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 detected demand for cooling associated with that evaporator is satisfied, or until a predetermined time period has elapsed which corresponds to the normal run time for that evaporator. If the run time expires prior to the demand for cooling being satisfied, and if demand for cooling by another one of the evaporators is present, then operation of the first evaporator is terminated and the other evaporator is operated. Efficiency enhancements are provided such as prematurely initiating operation of a second evaporator at the conclusion of operation of a first evaporator if it appears that a demand for cooling by the second evaporator will occur within a short period of time following termination of operation of the first evaporator.

Abstract: The noise emission from the centrifuge refrigeration system, and in particular, from the condenser fan therein, are minimized by monitoring the time duration during which the refrigeration compressor is asserted and, in accordance with the time duration of compressor assertion, controlling the speed of rotation of the condenser fan.

Abstract: An environmental control system disclosed includes a refrigeration loop including a variable speed compressor having an inlet and an outlet, a condenser having an inlet connected with the compressor outlet and an outlet, and an evaporator having an inlet connected with the condenser outlet and an outlet connected with the compressor inlet. The system also includes a variable speed evaporator fan and evaporator fan control for controlling the speed of the evaporator fan and a monitor for monitoring the superheat condition of the refrigerant at the compressor inlet wherein the evaporator fan control controls the speed of the evaporator fan as a function on the value of the superheat condition. A variable speed condenser fan is controlled by a condenser fan speed control that functions in part on the value of the superheat condition.

Abstract: A control for a refrigerator having a freezer compartment, a fresh food compartment, and a refrigeration system having an evaporator disposed within the freezer compartment, a condenser, and a compressor for compressing the refrigerant in the system. The refrigerator includes a variable speed motor to drive the compressor, a variable speed condenser fan for moving air over the condenser, and a variable speed evaporator fan for circulating air over the evaporator and to the freezer compartment and fresh food compartment. Means are provided for responding to the temperature within the fresh food compartment for varying the speed of the evaporator fan such that the temperature of the fresh food compartment is controlled. Means are provided for responding to the temperature within the freezer compartment for varying the speed of the compressor motor and the condenser fan such that the temperature of the freezer compartment is controlled.

Abstract: An environmental control system disclosed includes a refrigeration loop including a variable speed compressor having an inlet and an outlet, a condenser, an evaporator and variable speed evaporator fan for moving air across the evaporator, a compressor speed control, a superheat monitor for monitoring the condition at the inlet of the compressor and a primary superheat control responsive to the superheat monitor for establishing the speed of the evaporator fan to maintain a predetermined superheat condition.

Abstract: An electronic expansion valve is provided between first and second indoor heat exchangers. At the time of cooling operation, the electronic expansion valve is fully opened with the result that the first and second indoor heat exchangers are communicated with each other. At the time of dehumidifying operation, the opening of the electronic expansion valve is decreased to apply the effect of pressure reduction between the indoor heat exchangers, so that the first indoor heat exchanger functions as a reheater and the second indoor heat exchanger functions as an evaporator. The air in the room is cooled and dehumidified by the second indoor heat exchanger and then discharged into the room after being reheated by the first indoor heat exchanger. At the time of the dehumidifying operation, controlling the speed of the outdoor fan permits the temperature of the air discharged into the room to be varied.

Abstract: A cooling apparatus includes a bypass provided to a path extending from a compressor to an expansion valve via a condenser, and a unit for controlling a ratio of a flow rate of a refrigerant of the path via the condenser to that of the bypass path, or a unit for varying an air volume of a fan of an outdoor unit for blowing the condenser so as to vary a capacity of the condenser. The degree of superheat of the refrigerant is measured at an exit of the evaporator, and an expansion valve is controlled in accordance with the measured degree of superheat.

Abstract: A system for controlling the operation of an HVAC system which includes a direct expansion coil, a condenser, a pre-cool coil, and a control system. The control system includes a controller and sensors. The controller receives signals indicative of air flow through the direct expansion coil from the sensors, compares the received signal to a stored air flow rate, and disables the compressor if the stored air flow rate is equal to or greater than the stored value. The controller is also adapted to vary air flow into an occupied space for small changes in the cooling load. In addition, the controller can artificially load the compressor during periods of small cooling load by restricting flow of a cooling agent between the cooling tower and the condenser, or by directing warm water from the condenser through the pre-coil coil.