Abstract: A method of detecting electrical failure in a refrigeration system is provided. The method includes determining whether a present superheat of the refrigeration system is between a maximum superheat and a minimum superheat for the refrigeration system, the maximum superheat and the minimum superheat defining a normal operating range. The method also includes detecting an electrical property of an expansion valve assembly of the refrigeration system responsive to the superheat being outside the normal operating range. The method further includes determining whether the expansion valve assembly as experienced an electrical failure based on at least the electrical property. A signal indicating that the expansion valve has experienced an electrical failure is generated based on a determination that the expansion valve assembly has experienced the electrical failure.

Abstract: Methods and related systems for controlling superheat in a climate control system are disclosed. In an embodiment, the method includes (a) determining a superheat of a refrigerant downstream of a coil of a heat exchanger of the climate control system. In addition, the method includes (b) determining that an expansion valve upstream of the heat exchanger is fully open. Further, the method includes (c) adjusting a speed of air flowing across the coil or a speed of a compressor of the climate control system after (b) based on the determination in (a) to control the superheat of the refrigerant.

Abstract: A method of operating a refrigeration system includes initiating a compressor shutdown operation, determining a difference in a saturation temperature at a port of a compressor of the refrigeration system and an ambient temperature and comparing the difference in the saturation temperature and ambient temperature with a threshold. If the difference in the saturation temperature and ambient temperature is less than or equal to the threshold, a pump down operation is performed and if the difference in the saturation temperature and ambient temperature exceeds the threshold, a compressor shutdown operation is completed.

Abstract: An air conditioner system including a compressor, a condenser, an expander, an evaporator, and a bypass pipeline that guides the evaporated refrigerant from the evaporator to the condenser, wherein the bypass pipeline includes: a first bypass pipe configured to guide at least some of the evaporated refrigerant from the evaporator to the condenser; a second bypass pipe attached to the first bypass pipe to allow heat exchange between refrigerant in the condenser and refrigerant therein; and a third bypass pipe coupled to the second bypass pipe to guide the refrigerant from the second bypass pipe out of the condenser.

Abstract: A system and method of controlling an electronic expansion valve in a refrigeration system is provided. The system and method include providing an evaporator, a compressor, and an electronic expansion valve in a refrigeration circuit with a suction line between the evaporator and the compressor, determining a change rate at the suction line, determining a superheat value at the suction line if it is determined that the change rate is less than or equal to a change rate limit, and operating the electronic expansion valve based on the superheat value.

Abstract: A heat exchanger is provided including a first manifold, a second manifold, and a plurality of heat exchange tubes arranged in spaced parallel relationship and fluidly coupled to the first manifold and the second manifold. At least one divider plate is arranged within the first manifold such that the first manifold has a fluidly distinct first chamber and second chamber and the heat exchanger has a multi-pass flow configuration. The first chamber is configured to receive at least a partially liquid refrigerant and has a length between about 20% and about 60% a length of the first manifold.

Abstract: A computing device calculates a quality of a refrigerant flowing out of an expansion device on the basis of an inlet liquid enthalpy calculated on the basis of a temperature of the refrigerant flowing into the expansion device, and a saturated gas enthalpy and a saturated liquid enthalpy calculated on the basis of a temperature or pressure of the refrigerant flowing out of the expansion device; calculates a liquid-phase concentration and a gas-phase concentration of the refrigerant flowing out of the expansion device on the basis of the temperature and pressure of the refrigerant flowing out of the expansion device; and calculates a composition of the refrigerant circulating in a refrigeration cycle on the basis of the calculated quality, liquid-phase concentration, and gas-phase concentration.

Abstract: A system and method for a compressor includes a compressor connected to a condenser, a discharge line temperature sensor that outputs a discharge line temperature signal corresponding to a discharge line temperature of refrigerant leaving the compressor, and a control module connected to the discharge line temperature sensor. The control module determines a saturated condenser temperature, calculates a discharge superheat temperature based on the saturated condenser temperature and the discharge line temperature, and monitors a flood back condition of the compressor by comparing the discharge superheat temperature with a predetermined threshold. The control module increases a speed of the compressor or decreases an opening of an expansion valve associated with the compressor when the discharge superheat temperature is less than or equal to the predetermined threshold.

Abstract: A disclosed refrigerator installing structure that enables a refrigerator including a cylinder and a displacer to be installed in a vacuum vessel in which an object to be cooled is accommodated, the displacer being removed from the cylinder during maintenance, the cylinder being movable inside a sleeve between a position at which the cylinder thermally contacts the sleeve and another position at which the cylinder does not thermally contact the sleeve includes a discharge mechanism configured to discharge a gas inside a space formed between the sleeve and the cylinder if a pressure inside the space becomes greater than or equal to a predetermined pressure.

Abstract: A computer includes a motherboard with a signal receiving port and a switch circuit. The switch circuit includes a force sensing module and a transistor. The transistor includes a first terminal connected to the force sensing module, a second terminal connected to a power source, and a third terminal connected to the signal receiving port. When there is a pressure applied to the force sensing module, the force sensing module outputs a first driving signal to turn on the transistor and enables the computer to maintain its current power on or off state. When there is no pressure applied to the force sensing module, the force sensing module outputs a second driving signal to turn off the transistor and switches on or off the computer.

Abstract: An air conditioning system including a blower, an evaporator, an airflow chamber, and a thermal expansion valve assembly. The airflow chamber extends between the blower and the evaporator to direct airflow generated by the blower to the evaporator. The thermal expansion valve assembly includes a valve and a sensor bulb. The valve is on an input side of the evaporator. The sensor bulb is arranged on an output side of the evaporator external to the airflow chamber, and in an airflow path of ambient air.

Abstract: A refrigeration cycle apparatus achieves efficient operation by constantly recovering power in a wide operating range. The refrigeration cycle apparatus regulates a pressure of a high pressure side by changing either one or both of an opening degree of the intermediate-pressure bypass valve and an opening degree of the pre-expansion valve on the basis of a density ratio that is obtained from an inflow refrigerant density of the expander and an inflow refrigerant density of the sub-compressor in an actual operating state and a design volume ratio that has been expected at the time of design and that is obtained from a stroke volume of the sub-compressor, a stroke volume of the expander, and a ratio of a flow rate of the refrigerant flowing to the sub-compressor.

Abstract: An air conditioning apparatus includes a refrigerant circuit, an operation controlling device and a liquid refrigerant accumulation determining device. The refrigerant circuit has an accumulator. The operation controlling device performs normal operation control where each device of the heat source unit and the utilization unit are controlled in accordance with operating load of the utilization unit, and refrigerant quantity determination operation control where properness of quantity of the refrigerant in the refrigerant circuit is determined while performing the cooling operation. The liquid refrigerant accumulation determining device determines whether or not liquid refrigerant is accumulating in the accumulator. When it has been determined that liquid refrigerant is accumulating in the accumulator, liquid refrigerant accumulation control is performed to eliminate liquid refrigerant accumulation in the accumulator.

Abstract: A refrigeration system for a container for refrigerating chilled cargo includes a compressor, a condenser, and an evaporator connected in series. The system further includes a heater and sensors configured to sense the temperature of the supply air and the temperature of the return air. A controller is programmed to determine one of a requirement for heating and a requirement for cooling based on the temperature of the return air and the temperature of the supply air. The controller is programmed to activate the evaporator fan when a requirement for heating is determined and to increase the speed of the evaporator fan when increased heating is determined. The controller is also programmed to activate the compressor and the evaporator fan when a requirement for cooling is determined and to increase the power supplied to the compressor and maintain the evaporator fan at a first speed when increased cooling is determined.

Abstract: A vapour compression system comprises a compressor, a condenser, an expansion device, e.g. in the form of an expansions valve, and an evaporator arranged along a refrigerant path. A method for operating the vapour compression system comprises the steps of: obtaining a superheat value being representative for the superheat of refrigerant entering the compressor; obtaining a subcooling value being representative for the subcooling of refrigerant entering the expansion device; and operating the expansion device on the basis of the obtained superheat value and on the basis of the obtained subcooling value. The subcooling value is taken into account when operating the expansion device, because variations in the subcooling value have significant influence on the refrigerating capacity of the evaporator at a given opening degree of the expansion device, thereby resulting in a more stable operation of the system. The system may further comprise an internal heat exchanger.

Abstract: A method and apparatus for removing vapor inside a liquid pump at the start up operation of the pump. In addition, a method and apparatus for removing liquid inside a compressor at the start up operation of the compressor. The pump and compressor each include a sensor attached to them that determines the physical state (i.e., liquid or vapor) of a material inside the pump or compressor. If vapor is detected inside the pump, a thermoelectric module connected to the pump is powered to condense the vapor into a liquid. Likewise, if liquid is detected inside the compressor a heater connected to the compressor is powered to evaporate the liquid into a vapor. After the state of the material inside the pump or compressor is changed, the pump or compressor is powered up for operation in a cooling system.

Abstract: A system and method of operating a vehicle air conditioning system having an engine driven, fixed capacity refrigerant compressor and a compressor clutch is disclosed. The method may comprises setting a preliminary evaporator air temperature target; charging a cold storage apparatus in the vehicle air conditioning system; determining if the cold storage apparatus has reached a predetermined threshold; if the cold storage apparatus has reached a predetermined threshold, determining a new evaporator air temperature target by: determining a maximum allowable dewpoint evaporator air temperature for maintaining a passenger compartment humidity below a predetermined value; determining a maximum allowable mode evaporator air temperature based on a mode to which the vehicle air conditioning system is set; and setting the evaporator air temperature target to the lower of the dewpoint evaporator air temperature and the mode evaporator air temperature.

Abstract: An electrically controlled expansion valve package (10) comprises an expansion valve (30), sensors (32, 33, 36) and control electronics (35) all included in a monolithic package that greatly simplifies installation, while also enabling performance enhancements. The expansion valve is controlled by control electronics that, among other things, determines from pressure and temperature sensors the type or nature of the refrigerant being used in the refrigeration system for adapting control of the expansion valve to the refrigerant.

Abstract: A refrigeration device includes a compression mechanism, a radiator, a first expansion mechanism (15), a liquid receiver (16), a second expansion mechanism, an evaporator, a temperature detector, a first pressure storing unit (23a), and a second pressure determining unit, a pressure detector, and a control unit (23c). The first pressure storing unit stores an upper limit and lower limit of an intermediate pressure. The second pressure determining unit determines an upper limit and lower limit of a high pressure based on the upper limit and lower limit of the intermediate pressure and on a temperature in a vicinity of an exit of the radiator. The control unit controls the first expansion mechanism and the second expansion mechanism so that a pressure detected by the pressure detector will be equal to or less than the upper limit and equal to or greater than the lower limit of the high pressure.

Abstract: A control method regulates an electronic expansion valve of a chiller to maintain the refrigerant leaving a DX evaporator at a desired or target superheat that is minimally above saturation. The expansion valve is controlled to convey a desired mass flow rate, wherein valve adjustments are based on the actual mass flow rate times a ratio of a desired saturation pressure to the suction pressure of the chiller. The suction temperature helps determine the desired saturation pressure. A temperature-related variable is asymmetrically filtered to provide the expansion valve with appropriate responsiveness depending on whether the chiller is operating in a superheated range, a saturation range, or in a desired range between the two.

Abstract: Refrigeration circuit (2) for circulating a refrigerant in a predetermined flow direction, having in flow direction a heat rejecting heat exchanger (4), an evaporator throttle valve (8), an evaporator (10), a compressor (22), an internal heat exchanger (16) placed with its “cool side” between the evaporator (10) and the compressor (22), an inlet temperature sensor (24) located between the evaporator (10) and the internal heat exchanger (16) and an outlet temperature sensor (26) located between the internal heat exchanger (16) and the compressor (22), and a control (28) for controlling the evaporator throttle valve (8) based on the inlet and outlet temperature sensor measurement, wherein the control is adapted for controlling the evaporator throttle valve (8) based on an inlet temperature setpoint at the inlet temperature sensor (24); and shifting the inlet temperature setpoint based on the outlet temperature sensor measurement (26).

Abstract: Methods, systems, and apparatus for linearizing control of a commercial refrigeration system. In an embodiment of the invention, a controller is configured to receive a non-linear sensed suction pressure and convert the suction pressure to a linear temperature equivalent. The linear temperature equivalent is used by the controller to achieve efficient system operation over an entire range of operating temperatures.

Abstract: A high-pressure side discharge port of a two-stage compressor (12A) and a condenser (14A) are connected, condenser (14A) and a PMV (15A) are connected, a refrigerating side exit of PMV (15A) is connected to a medium pressure side suction port of two-stage compressor (12A) via an R capillary tube (16A) and an F evaporator (18A), connected to an F evaporator (26A) via an F capillary tube (24A), F evaporator (26A) is connected to a low-pressure side suction port of two stage compressor (12A) via a low-pressure suction pipe (28A), PMV (15A) can switch a simultaneous cooling mode and a freezing mode, and in the simultaneous cooling mode, a refrigerant flow rate toward R evaporator (18A) is adjusted by PMV (15A), and thereby a temperature difference control is performed so as to make a difference between an entrance temperature and an exit temperature of R evaporator (18A) equal to a preset temperature difference (for example, 4° C.).

Abstract: A system for detecting a mis-connected state between communication lines for a multi-type air conditioner and a method thereof. The system comprises an indoor unit pipe temperature detection unit for detecting a temperature of an indoor unit pipe, and a microprocessor for controlling an opening of an electronic expansion valve based on a temperature detected by the indoor unit pipe temperature detection unit, comparing a temperature response characteristic of the indoor unit pipe with a preset temperature response characteristic of a normal indoor unit pipe based on an opening of the electronic expansion valve, and thereby judging whether the communication lines are mis-connected to one another or not. An indoor unit from which the mis-connection has been generated is fast detected, and error information is displayed. Accordingly, the mis-connected state between the communication lines is restored, thereby preventing a damage of the system due to the mis-connection.

Abstract: Disclosed herein is a method of controlling a linear expansion valve of a cooling cycle apparatus. The method comprises a first step of calculating a target opening level value according to suction overheat level of compressors to control a linear expansion valve based on the calculated target opening level value, and a second step of calculating a new target opening level value according to the suction overheat level of the compressors and discharge temperature of the compressors to control the linear expansion valve based on the calculated new target opening level value. Consequently, the discharge temperature of the compressors is prevented from being excessively increased, and therefore, the compressors are prevented from being overheated and damaged, and reliability of the cooling cycle apparatus is improved.

Abstract: The present invention relates to a monitoring system for connection to an air conditioning system. The monitoring system includes a primary monitor for sensing the suction temperature and suction pressure of the air conditioning system along with the air conditioning unit temperature. In addition, the monitoring system includes a remote sensing device that is placed in the structure to monitor and transmit return air temperature and relative humidity to the primary monitor. The collected data is then used to calculate the superheat condition of the air conditioning system which is related to its efficiency.

Abstract: A method and apparatus for refrigeration system control includes a control system operable to meet cooling demand and control suction pressure for a plurality of refrigeration circuits each including a variable valve and an expansion valve. The controller controls the variable valve independently of the expansion valves to meet cooling demand by determining a change in a measured parameter and controlling at least one of the variable valves based upon the change to an approximately fully open position.

Abstract: A method and apparatus for detecting surge in a refrigeration system that includes a centrifugal compressor having an impeller and a compressor entrance, an evaporator that receives a fluid refrigerant, a suction line that flows the refrigerant from the evaporator to the compressor entrance. The evaporator includes a heat-exchange coil supplied with a liquid through a supply line entering the evaporator. The liquid is disposed in a heat-exchange relationship with the refrigerant within the evaporator. The method and apparatus automatically and periodically performing the steps of measuring a fluid temperature of the liquid proximate the supply line entering the evaporator; measuring a refrigerant temperature of the refrigerant proximate the compressor entrance; and using the fluid temperature and the refrigerant temperature to detect surge in the refrigeration system.

Abstract: A controller for an expansion valve of a refrigeration system for cooling a medium is configured to include, in the generation of a control signal, a measure of the evaporation temperature (T0) of the refrigerant in an evaporator and a measure of a property of the cooled medium, preferably without influence from a measure of the superheat temperature (SH) of the refrigerant. The controller comprises a PI-element for integrating and for producing a control signal for the expansion valve for controlling the flow of refrigerant into the evaporator, the PI-element being arranged in an inner control loop, a reference for which is produced by an outer control loop. The controller allows for fast response to disturbances and/or fast response of the medium temperature when the operating conditions of the refrigeration system are changed and/or fast response during start-up of the refrigeration system and maintains stable operation conditions with low, but positive superheating and a stable evaporation pressure.

Abstract: A method and apparatus for detecting surge in a refrigeration system that includes a centrifugal compressor having an impeller and a compressor entrance, an evaporator that receives a fluid refrigerant, a suction line that flows the refrigerant from the evaporator to the compressor entrance. The evaporator includes a heat-exchange coil supplied with a liquid through a supply line entering the evaporator. The liquid is disposed in a heat-exchange relationship with the refrigerant within the evaporator. The method and apparatus automatically and periodically performing the steps of measuring a fluid temperature of the liquid proximate the supply line entering the evaporator; measuring a refrigerant temperature of the refrigerant proximate the compressor entrance; and using the fluid temperature and the refrigerant temperature to detect surge in the refrigeration system.

Abstract: An air conditioning unit including an expansion device (4) of the refrigerating fluid loop controlled to set the internal heat exchanger efficiency &eegr;, represented by the equation: &eegr;=TccTsc/TsrTsct, wherein: TccTsc and Tsr are respectively temperatures at the compressor input (1), and at the evaporator output (5) and at the fluid cooler output (2), at a reference value such that the fluid leaves the evaporator in a completely gaseous state and without overheating.

Abstract: Disclosed herein is a system and method for controlling the degree of superheat of an air conditioner. The air conditioner includes a compressor controlled in a pulse width modulation manner according to duty control signals, a condenser, an electronic expansion valve and an evaporator so as to form a refrigeration cycle. An entrance temperature sensor situated at the entrance of the evaporator and an exit temperature sensor situated at the exit of the evaporator are connected to a control unit. The control unit calculates the degree of superheat of the evaporator using the difference between mean entrance and exit temperatures of the evaporator sensed by the entrance temperature sensor and the exit temperature sensor for a period of time corresponding to a duty cycle period of the compressor, and regulates the opening of the electronic expansion valve according to the calculated degree of superheat.

Abstract: A diagnostic system and method for a cooling system includes producing a control signal for adjusting a valve position of a regulator valve as a demand for cooling, as well as providing an ambient temperature measurement, coil inlet temperature measurement, and coil exit temperature measurement. The valve position and at least one of the ambient temperature measurement, coil inlet temperature measurement, and coil exit temperature measurement are monitored and compared with at least one predetermined fault value indicative of a fault condition to diagnose the system. An alert module responsive to the diagnostic module issues an alert signal when at least one of the ambient temperature measurement, coil inlet temperature measurement, and coil exit temperature measurement bears a predetermined relationship to the fault value. When monitoring and comparing, an error value percentage indicative of a percentage of sampled error within an accepted offset range for a defined period of time is determined.

Abstract: In a vehicle air-conditioning system, an evaporator is disposed in an air-conditioning case to form a bypass passage through which air bypasses the evaporator, and an opening degree of the bypass passage is adjusted by a bypass door. When a vehicle engine operates, the system performs a cold-storing mode where cold quantity stored in condensed water on the evaporator is increased. On the other hand, when operation of the vehicle engine is stopped, the system performs a cold-releasing mode where air passing through the evaporator is cooled by cold released from frozen condensed water. During the cold-storing mode and the cold-releasing mode, temperature of air blown into a passenger compartment can be adjusted by adjusting the opening degree of the bypass passage. Thus, in the vehicle air-conditioning system, cold-storing quantity in the evaporator can be improved while power-saving effect of the vehicle engine is improved.

Abstract: In a vapor compression refrigerator with closed loop feedback control of evaporator superheat, a superheat stabilizer consisting of a cavity connected between the evaporator outlet and the suction line inlet, the cavity combining the functions of liquid separation and vapor superheating in order to stabilize superheat by preventing liquid from reaching the outlet vapor temperature sensor and also by achieving preset superheat downstream of the evaporator.

Abstract: A heat pump cycle system which can switches cooling operation and heating operation for a compartment includes a first inside heat exchanger and a second inside heat exchanger disposed in an air conditioning case. The first inside heat exchanger is disposed in the air conditioning case at a downstream air side of the second inside heat exchanger, while being arranged in line in a flow direction of refrigerant. The first inside heat exchanger is upstream from the second inside heat exchanger in the flow direction of refrigerant during the heating operation. In the heat pump cycle system, an expansion valve is controlled so that coefficient of performance in each operation becomes approximately maximum. Thus, during the heating operation of the heat pump cycle system, a lower limit temperature of air blown from the inside heat exchangers can be increased so that temperature of air blown into the compartment is increased, while the coefficient of performance is improved.

Abstract: An arrangement is provided for insuring that excessive demand is not placed on a refrigeration unit that supplies pressurized subcooled refrigerant to different channels having independent needs for use of refrigeration capacity. A separate reference channel receives a portion of the refrigerant and expands the refrigerant fully to a gas phase to establish a minimum level reference temperature. In the operative channels the refrigerant flows into individual evaporators/heat exchangers at rates set by external command signals, the refrigerant being in heat exchange relation with thermal transfer fluid in the evaporator/heat exchanger. Evaporation of refrigerant in each channel thus brings the thermal transfer fluid for that channel to the target temperature. By comparing the post evaporation temperature in each channel to the reference temperature, and reducing the refrigerant flow rate whenever the difference is below a threshold, individual channels are not overtaxed and the system remains stable.

Abstract: The invention concerns a method of monitoring, setting and regulating the filling level of a refrigerant evaporator using a throttle valve and a measuring apparatus mounted in the intake line, the measuring signal determined being freed from interfering portions and a useful measured value thus being generated. By using the useful measured value of a flowmeter, the fluctuations in the flow of refrigerant in the intake line are examined with respect to random short-time fluctuations from which a degree of fluctuation is derived. The degree of fluctuation is a measure of the value of the random short-time fluctuations which is simultaneously used for regulation purposes and is compared with a specified value in order to evaluate the quality of the evaporator filling.

Abstract: An air conditioner includes a housing including a front panel and a rear panel. A heat exchanger is disposed within the housing and includes a front portion disposed adjacent the front panel, and a rear portion disposed adjacent the rear panel. A lower drain tray is positioned beneath the front portion of the heat exchanger for collecting and draining away condensed water falling therefrom. An upper drain tray is positioned beneath the rear portion of the heat exchanger for collecting and draining away condensed water falling therefrom. The upper drain tray is of integrally molded construction with the rear panel, whereby no gaps are present therebetween.

Abstract: An air conditioner increases a flow rate of a refrigerant to be sucked to a compressor so that a superheat of the refrigerant is reduced when a coil temperature of a driving motor for a compressor is more than a predetermined temperature.

Abstract: A refrigerant circulation system of the present invention includes a compressor, a condenser, a evaporator, a throttle device and a control unit. The control unit controls a composition of a refrigerant circulating in the refrigerant circulation system based on a temperature and pressure of the refrigerant of an inlet and outlet portion of the compressor, condenser, evaporator and throttle device. The control unit controls to open and close the throttle device to change the composition of the refrigerant circulating in the refrigerant circulation system.

Abstract: A control-information detecting apparatus for a refrigeration air-conditioner using a non-azeotrope refrigerant is equipped with a temperature detector and a pressure detector at the refrigerating cycle of the air-conditioner, which cycle is formed by connecting a compressor, a condenser, a decompressing device, and an evaporator, to detect the temperature and the pressure of the refrigerant circulating the cycle for obtaining the circulation composition of the refrigerant with the composition computing unit thereof. The usual optimum operation of the cycle is thereby enabled even if the circulation composition of the refrigerant has changed.

Abstract: Disclosed is a refrigeration or air conditioning system comprising a refrigeration cycle that uses a refrigerant mixture of at least two kinds of refrigerants consisting of 45 to 55 weight percent of R32 and 55 to 45 weight percent of R125, and that includes at least a compressor, a condenser, a throttling device, and an evaporator. In some cases the temperature and pressure in a line leading from the inlet of the evaporator to the suction port of the compressor is controlled below a specific temperature and pressure point corresponding to the critical decomposition point of a clathrate that contains water as a host solution and the refrigerant mixture as guest molecules, and within a prescribed control range bounded by a formation limit line of the clathrate and a saturated liquid pressure line representing the pressure versus temperature relationship of saturated liquid of the refrigerant mixture (a first control mode), and a dryer for moisture removal is provided in the refrigeration cycle.

Abstract: A refrigeration system is disposed within a refrigerator having a freezer compartment and a refrigeration compartment. The refrigeration system includes an evaporator having an inlet and an outlet. A damper is positioned so as to direct air flow into the freezer compartment or the refrigeration compartment and correspondingly block air flow to the other. A compressor is coupled to the evaporator via a conduit and a control valve is coupled to the inlet of the evaporator to control flow of refrigerant. A condenser is coupled to the control valve by a liquid line. A first temperature sensor is positioned so as to detect refrigerant temperature within the evaporator and a second temperature sensor is positioned so as to detect refrigerant temperature at the outlet of the evaporator. A first controller is coupled to the control valve and to the first and second temperature sensors to receive temperature signals therefrom.

Abstract: A Refrigerant Sensor is provided that provides within a common assembly pressure, temperature and superheat measurements and calculations with respect to a refrigerant material. The Refrigerant Sensor includes a pressure transducer for measuring the pressure of the refrigerant material and a temperature transducer for measuring the temperature of the refrigerant material. The pressure and temperature measurements are used by a microprocessor to calculate the superheat value of the refrigerant material. The microprocessor is within the common assembly. The Refrigerant Sensor can send and receive information from the network and also calibrate the pressure and temperature measurements.

Abstract: The flow of refrigerant is controlled by a strategy that strives to seek and maintain a fluctuating superheat condition. The control system causes optimal use of the evaporator coil by ensuring that the refrigerant in the coil is in the liquid state. A temperature sensor at the evaporator coil exit senses refrigerant temperature and the control system regulates refrigerant flow so that the liquid dry out point (transition between liquid state and superheat state) occurs in the vicinity of this sensor. Thus a single sensor may be used to effect closed loop control.

Abstract: An automotive air conditioning system comprises a heat pump type refrigerant circuit charged with a first refrigerant and includes first and second internal heat exchangers disposed within an air conditioning duct and an external heat exchanger located outside the duct. A plurality of electromagnetic valves are selectively operated so that in one operational state the external heat exchanger performs as an evaporator and the second internal heat exchanger performs as a condenser, and such that in another operational state the external heat exchanger and the first internal heat exchanger perform as evaporators and the second internal heat exchanger performs as a condenser. A first pressure equalizing type expansion valve mechanism associated with the external heat exchanger has a P-T characteristic curve wherein a static superheat curve intersects with a saturated first refrigerant vapor curve when the temperature of the first refrigerant immediately upstream of the external heat exchanger is in a low range.

Abstract: A control system for generating a pulse width modulated control signal for an electrically operated refrigerant valve. The controller receives inputs from evaporator inlet and outlet temperature sensors (T.sub.in, T.sub.out) and "fuzzy" logic to compute the discrete value of pulse width change needed, based upon the difference .DELTA.T=T.sub.out -T.sub.in and the time rate of change of .DELTA.T.

Abstract: A method of controlling a refrigeration case of a refrigeration system including the steps of locating an expansion valve of a refrigeration case, moving the expansion valve of the refrigeration case out of a predetermined position, sampling temperature readings from an evaporator coil of a refrigeration case, calculating an adaptive proportional-integral-differential (PID) of the temperature of the evaporator coil for the refrigeration case, and moving the expansion valve to a second position closer to the predetermined position based on the calculated proportional-integral-differential until the temperature of the evaporator coil for the refrigeration case is within a predetermined temperature range.

Abstract: The flow of refrigerant is controlled by a strategy that strives to seek and maintain a fluctuating superheat condition. The control system causes optimal use of the evaporator coil by ensuring that the refrigerant in the coil is in the liquid state. A temperature sensor at the evaporator coil exit senses refrigerant temperature and the control system regulates refrigerant flow so that the liquid dry out point (transition between liquid state and superheat state) occurs in the vicinity of this sensor. Thus a single sensor may be used to effect closed loop control.