Abstract: The performance of mobile air conditioning systems is improved with the use of a pressure sensing valve to control refrigerant flow in the system. The pressure sensing valve is connected between the condenser and the evaporator. The control valve senses the refrigerant pressure adjacent the evaporator, ie. the input, or output, or the combination of both, to control the refrigerant flow through the evaporator in a manner to improve the performance of the system. The reference pressure for the valve can be the atmosphere or a fixed or variable source. Various other operating variables can be sensed to control the variable source in a manner to interact with the sensed pressure to provide added control of system performance.

Abstract: In a hot-water supply system with a heat pump cycle, a control unit controls operation of an expansion valve based on a temperature difference between a refrigerant temperature at an outlet side of a refrigerant passage in a water heat exchanger and a water temperature at an inlet side of a water passage in the water heat exchanger. When the expansion valve is controlled in a direction increasing a valve opening degree, the control unit sets an upper limit opening degree of the expansion valve, for obtaining a refrigerant pressure corresponding to a target hot-water temperature, and controls the expansion valve in an opening degree range smaller than the upper limit opening degree.

Abstract: The motor power consumption and motor winding temperature are monitored and, responsive thereto, the flow of refrigerant to the motor is controlled so as to control the temperature of the motor. The motor power consumption in the primary control input because it anticipates cooling requirements whereas the motor temperature indicates current cooling requirements. The cooling flow may be provided in an on-off manner or there may be a constant flow portion with an on-off parallel cooling flow path.

Abstract: A two-step metering device for controlling the flow of an operating fluid to a variable capacity compressor is provided. The metering device includes a valve that defines a fluid flow path having a large orifice configured to allow a flow rate corresponding to a high operating capacity of the compressor and a small orifice configured to allow a flow rate corresponding to a reduced operating capacity of the compressor. The metering device further includes a control operable to adjust the valve to direct the operating fluid through the large orifice when the compressor is operating at the high capacity and to direct fluid through the small orifice when the compressor is operating at the reduced capacity.

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 system and process for controlling an electronic exchange valve for an transport refrigeration system evaporator in the absence of a evaporator outlet pressure transducer reading is disclosed. The process includes monitoring for the absence of reliable evaporator outlet pressure readings, monitoring the supply air temperature, and supplying the supply air temperature to a processor within a controller for use in an algorithm so as to approximate the saturation reference temperature and superheat levels to derive the necessary control signals for the EXV.

Abstract: A system and process for optimizing the power drawn on a transport refrigeration system under power limitation conditions is disclosed. The invention includes a microprocessor control which adjusts the desired superheat level for the system, thereby altering the expansion valve, thereby limiting the mass flow rate of refrigerant through the system without having a comparable drop in refrigeration capacity as would a similar actuation of the suction modulation valve.

Abstract: In order to suppress the deterioration of the efficiency of the refrigeration cycle when the theoretical supercooling degree is different from the actual supercooling degree due to an error of a sensor, upon a decision that an expansion valve opening degree remains unchanged after the lapse of a predetermined time following the starting of an air-conditioning system, a target supercooling degree is corrected and the valve opening degree is reduced from an upper limit by a predetermined value to an intermediate valve opening degree. As a result, the actual supercooling degree can leave the state of zero dryness, and can approach a target supercooling degree.

Abstract: A method of controlling an expansion valve including the steps of: measuring a primary system condition; determining an error in the primary system condition; measuring a secondary system condition; determining an error in the secondary system condition; and modulating the expansion valve based upon the larger of the first or second error.

Abstract: The expanded flow through a heat exchanger type economizer is controlled by an electronic expansion valve and is supplied to the motor of a motor compressor to cool the motor. The electronic expansion valve is controlled by a microprocessor responsive to the temperature of the motor winding sensed by a thermistor.

Abstract: In a method for controlling the superheat temperature (T.sub.u) of the refrigerant in an evaporator arrangement (1) of a refrigeration system or heat pump system (1-4), the evaporator arrangement (1), a compressor arrangement (2), a condenser and a controllable expansion valve (4) are arranged in succession in a closed circuit. The superheat temperature (T.sub.u) is controlled in dependence on a comparison between desired and actual values. The desired value (W.sub.2) of the superheat temperature (T.sub.u is varied automatically in dependence on the difference (d) from a reference value (W.sub.1) of a periodically determined function (S) of a number of sampled values of a temperature (T.sub.1 ; T.sub.2) of the refrigerant with the aim of a stable control of the superheat temperature (T.sub.u). To achieve optimum filling and to optimize the superheating in such systems, provision is made for the said function (S) to characterize the variability of a number of sampled values of the temperature (T.sub.

Abstract: An air conditioner in accordance with the invention comprises a first unit including a compressor and a heat exchanger; a second unit including a heat exchanger; a refrigerant circuit connecting the compressor and the heat exchanger of the first unit, with the heat exchanger of the second unit, through which a refrigerant flows; a refrigerant pressure reduction valve disposed in the refrigerant circuit and provided in the second unit; a control unit provided in the first unit for controlling the refrigerant pressure reduction valve in the second unit.

Abstract: A liquid injection type scroll compressor is used to a refrigerating apparatus using hydrocarbon fluoride refrigerant which does not contain chlorine (HFC-125/HFC-143a/HFC-134a) as an operating fluid and an amount of an injected liquid is controlled according to a discharge temperature of the compressor. Further, ester oil and/or ether oil is used as refrigerator oil and a dryer is disposed in a refrigerating cycle. With this arrangement, a refrigerating cycle operation can be stably realized in a wide range without almost changing the arrangement of a conventional refrigerating apparatus.

Abstract: A controller operates an electronic expansion valve (EEV) to control flow of refrigerant in an evaporator coil of a refrigeration system. The controller measures a superheat of the coil over a natural fill and boil cycle of the coil to determine an average rate at which the flow of refrigerant into the coil produces a desired temperature difference across the coil. The controller then operates the valve in a manner to control the flow of refrigerant based on the average rate.

Abstract: A refrigeration system comprises a compressor, a condenser, a receiver and an evaporator, each having an inlet and an outlet, and a separator having an inlet and a first and a second outlet, connected to each other conventionally. The separator is positioned laterally of the evaporator and closer thereto than to the compressor. A controller ensures overfeed of the evaporator by regulating the feed rate of liquid refrigerant from the receiver such that the separator is feeding the evaporator with liquid refrigerant in proportion to demand and safeguarding the desired overfeed. The separator comprises a cylindrical container having two outlets and an inlet for separating the vapor and liquid components of a refrigerant. The inlet is directed tangentially into the cylindrical container.

Abstract: A refrigerator having an opening degree control means and a control method thereof which have an opening degree control means for controlling a refrigerant flow provided into each evaporator, and thus enhance an energy efficiency, in a refrigerator which independently cools or maintains the freezing and refrigerating compartments at different temperatures by including an evaporator in each of the freezing and refrigerating compartments.

Abstract: A defrost control system comprises a superheat detector for detecting the degree of superheat of refrigerant leaving an evaporator or the presence of liquid in the refrigerant, a temperature sensor for sensing the temperature of a thermal load cooled by the evaporator and an electrically operable expansion valve for controlling the flow of refrigerant through the evaporator, each connected to a control circuit. In normal operation, the control circuit controls the flow of refrigerant to keep the temperature of the thermal load constant. However, if the superheat detector detects that the superheat is too low, the control circuit overrides the normal operation and reduces the flow of refrigerant. If the control circuit determines that the time spent in override condition over a period exceeds a maximum level, defrosting of the evaporator is triggered.

Abstract: A refrigerator for rapidly cooling down and then maintaining a plurality of wine bottles of arbitrary configuration within a selected temperature range comprises a compression type refrigeration unit in association with the refrigerated compartment which receives the wine bottles. The refrigeration unit includes a controllable expansion valve and a control system in which a microcontroller is arranged with a plurality of stored cooldown models as references for bringing the wine bottles to temperature without damage to the wine. Temperature, pressure and air flow measurements are used by a computer programmed to determine the status of the thermal load as affected by the number of wine bottles and their temperatures, and to adjust variations in the load compartment temperature for both cooldown modes and a steady state mode. Given an arbitrary thermal load, the refrigerator system lowers the wine temperature in a maximized but controlled manner so that chilled wine is available in no more than 30 minutes.

Abstract: A monitoring system for a heating or cooling system includes a neural network for computing the status of one or more expansion valves within the system. The neural network is trained to learn certain characteristics of the heating or cooling system during a development mode of operation. The thus trained neural network timely computes the status of the one or more expansion valves during a run time mode of operation. Information as to the status of the one or more expansion valves is made available for real time assessment during the run time mode of operation.

Abstract: A control arrangement for cooling of an apparatus comprising a compressor, a condenser, and at least one branch with an expansion valve and an evaporator in series, contains a controller, a superheat temperature measuring device, and an ambient temperature sensor. The controller controls the expansion valve for maintaining the superheat temperature substantially at the desired value. The flow of coolant to the evaporator is controlled by the signal from the temperature sensor for maintaining the ambient temperature constant. The controller operates continuously and in two operating modes in which the first mode the superheat temperature is controlled to the maximum admissible state of fill of liquid coolant in the evaporator and is switchable to a second mode in which the state of fill of liquid coolant is controlled by the expansion valve.

Abstract: In the heating operation mode, the condensed temperature is calculated by the value of the discharged pressure sensor disposed at the discharge side of the compressor. Based on a difference between the condense temperature and a value of the outlet temperature sensor for detecting the refrigerant having passed through the heating indoor heat exchanger, the supercooling degree is calculated. Then, an opening degree of the expansion valve for heating is controlled so that the calculated supercooling degree is set to a target supercooling degree. Thus, since the condensed temperature is calculated by employing a high responsive pressure sensor, an error in the calculation of the condensed temperature can be reduced, thereby reducing an error in the calculation of the supercooling degree.

Abstract: The invention relates to a vapor compression refrigeration system for cooling air, particularly for use in automobiles, having a closed circuit for refrigerant fluid incorporating an expansion device in the form of an orifice tube supplying expanded refrigerant fluid to an evaporator for cooling the air, wherein the system comprises electrical heating means such as a resistive wire winding or film resistor to supply heat to the refrigerant fluid within the orifice tube, and control means for controlling the heating means so as to achieve desired mass flow rates of the expanded fluid in the evaporator. The control means may operate in response to signals from a pressure sensor downstream of the evaporator and from further sensors sensing the temperature and speed of the air to be cooled as it enters the evaporator.

Abstract: An air conditioner comprises a first unit including a compressor and a heat exchanger, a second unit including a heat exchanger, a refrigerant circuit connecting the compressor and the heat exchanger of the first unit, with the heat exchanger of the second unit, through which a refrigerant flows, a refrigerant pressure reduction valve disposed in the refrigerant circuit and provided in the second unit, a control unit provided in the first unit for controlling the refrigerant pressure reduction valve in the second unit.

Abstract: A liquid injection type scroll compressor is used to a refrigerating apparatus using hydrocarbon fluoride refrigerant which does not contain chlorine (HFC-125/HFC-143a/HFC-134a) as an operating fluid and an amount of an injected liquid is controlled according to a discharge temperature of the compressor. Further, ester oil is used as refrigerator oil and a dryer is disposed in a refrigerating cycle. With this arrangement, a refrigerating cycle operation can be stably realized in a wide range without almost changing the arrangement of a conventional refrigerating apparatus.

Abstract: Compressor discharge temperature, ambient outdoor air temperature and thermal load are used as control parameters for controlling the expansion valve setting and the indoor fan speed. In a variable capacity system the thermal load parameter also controls the compressor capacity. Thermal load is measured by an integrating procedure that increments or decrements an accumulated demand counter value used as an indication of thermal load on the system. The counter value is incremented and decremented based on the room temperature and thermostat setpoint. These same parameters are also used in the overcharge/undercharge diagnostic system.

Abstract: An air conditioner using a non-azeotropic mixture refrigerant formed of a high boiling-point refrigerant and a low boiling-point refrigerant is provided with a first temperature sensor for detecting a temperature at an inlet of an outdoor heat exchanger when the outdoor heat exchanger serves as an evaporator in heating cycle, a second temperature sensor for detecting an outside air temperature, and a controller for controlling an opening degree of an expansion valve on the basis of a temperature difference between the outside air temperature and the inlet temperature of said evaporator. For example, the opening degree of the expansion valve is controlled so that the temperature difference between the outside air temperature and the inlet temperature is equal to a predetermined value.

Abstract: An indoor heat exchange unit and method of making same characterized by an arcuate coil shape heat exchange unit made by bending a single tubing row, planar heat exchange unit to fit within a limited space with an open inlet at one end and blocked at the other end so as to force air to flow past the coil and transfer heat through the fins and tubes of the coil in the process. Also disclosed are preferred embodiments in which an air circulation fan circulates air and where a thermostat controls the flow of heat exchange fluid through the coil as the air is passed through the arcuate coil to obtain a predetermined temperature, or the like, in the air.

Abstract: Programmable system and process are disclosed for adapting a generally written HVAC control program to a number of different HVAC systems. The system and process include a separate interface to the control program and a separate interface to the control elements of each particular HVAC system. Configuration data for the particular HVAC system defines the relationship between software variables of the control program and the control elements of the particular HVAC system. The configuration data is utilized when information is to be transferred between the interfaces.

Abstract: An air conditioner includes a comprising temperature regulator for regulating air temperature in a room, a circulating mechanism for circulating the temperature regulated air, a first room temperature detector for detecting room temperature in a set location in the room, a second room temperature detector for detecting room temperature in a location lower than the first room temperature detector, and a controllor for controlling the temperature regulator in accordance with outputs from the first and second room temperature detectors so as to efficiently equalize indoor temperatures and reduce energy consumption.

Abstract: The control system employs multiple, distributed architechure, processors in the indoor unit, the outdoor unit and optionally the thermostat unit. The overall system control functions are distributed across the processors, which communicate with one another over a communications link, employing a messaging system which allows sensor values to be obtained locally and transmitted to the other processors. The processors communicate to automatically refresh or update information during times when it will not degrade performance of critical functions.

Abstract: A system including a control circuit and a sensing circuit controls an expansion valve in a refrigeration system using pulse width modulation. The control circuit includes a ramp generator, a pulse width modulator, and a power switch. In response to input from the sensing circuit, the control circuit produces a control signal which cyclically opens and closes the valve. The average flow rate through the valve is varied in accordance with a condition of the refrigeration system which is detected by the sensing circuit.

Abstract: An improved control system for air conditioners. The control system detects temperatures at various points in the air-conditioner, and determines the model numbers of an indoor and an outdoor sections of the air-conditioner from these temperature data and a set of given status data associated with the air-conditioner. The control system may periodically set optimum control parameters in accordance with the model numbers and current status data of the air-conditioner and, in response to the refrigerant temperature at the outlet of compressor of its heat exchanger, may control the flow rate of the refrigerant passing through a variable expansion valve, thereby providing optimum refrigerating capacity at all times.

Abstract: The microprocessor-based HVAC control system detects sensor faults by comparing thermistor readings with predetermined extreme values, indicative of sensor fault. The system automatically selects the appropriate combination of automatic/preset modes of operating key system components such as the expansion valve, the demand defrost system and the indoor fan speed control system. With a view towards minimizing any negative impact on system performance and reliability in the event of sensor malfunction.

Abstract: Pulse width modulation is used to control the flow rate through a solenoid expansion valve in a refrigeration system. A first temperature sensor is disposed on the suction line, and a second temperature sensor is disposed in a compartment to be cooled. A controller is included for controlling the duty cycle of the pulse width modulated solenoid valve. The controller receives inputs from the two temperature sensors as a basis for controlling the duty cycle. The first temperature sensor can be located either inside or outside of the compartment. Preferred exterior locations include: immediately outside of the compartment, at the inlet of the compressor, at the inlet of the heat exchanger between the suction line and the liquid line, and at the outlet of the heat exchanger.

Abstract: Pulse width modulation is used to control the flow rate through a solenoid expansion valve in a refrigeration system. A first temperature sensor is located near the evaporator inlet, and a second temperature sensor is disposed in a compartment to be cooled. A controller is included for controlling the duty cycle of the pulse width modulated solenoid valve. The controller receives inputs from the two temperature sensors and controls the valve duty cycle based on the difference of the two temperatures. The second temperature sensor is preferably located on the back wall of the compartment and can be adjacent to the compartment air inlet, adjacent to the compartment air outlet, or between the air inlet and air outlet.

Abstract: An air conditioning system in which a single heat source unit (A) comprising a compressor (1), a four-way valve (2), a heat source unit side heat exchanger (3) and an accumulator (4) is connected to a plurality of indoor units (B, C, D) through a first and a second connection pipes (6, 7). Each indoor unit (B, C, D) comprises a suction air temperature detecting device (50) for detecting a suction air temperature of the indoor unit, an opening degree setting device for setting a minimum valve opening degree of the first flow rate controller 9 in accordance with the difference between the target temperature and the suction air temperature and a first valve opening degree control device (52) for controlling the valve opening degree of the first flow rate controller 9 at a predetermined rate to the minimum valve opening degree.

Abstract: Temperature controller apparatus for generating a control signal for supply to a control device which controls the temperature inside a chamber. The apparatus includes a plurality of input devices each receiving an indication of the temperature at a respective location in the chamber. Each of the received temperature indications is processed so as to form the control signal. In the event that any of the input devices fails to receive the respective temperature indication, output signals from such input devices are not utilized in forming the control signal. If all of the input devices fail to receive the respective temperature indications, the control signal is obtained from either previous control signals or previously stored control data.

Abstract: A microprocessor based control system for controlling frost accumulation on the outdoor evaporator coil of a heat pumping system during normal heat mode operations. A demand defrost concept is implemented to increase efficiency and maximize time intervals between defrost cycles by initiating the defrost cycle only when an optimal maximum amount of frost has accumulated on the coil. The control system also facilitates monitoring of the rate of frost accumulation to make the outdoor coil conditions less favorable to frost buildup.

Abstract: Refrigerant is metered through the expansion valve based on compressor discharge temperature and ambient air temperature measurements. The microprocessor-based control system selects the appropriate stepper motor valve setting to achieve optimal performance. The temperature measurements used in the control system are decoupled from fluctuations due to shifting of the refrigerant dry out point. This allows the system to be operated at much lower superheat temperatures than heretofore attained, yielding improved performance and longer component life.

Abstract: A refrigerating circuit of an air conditioning apparatus has a refrigerating circuit which is formed with a compressor, an expansion valve, a first heat-exchanger and a second heat-exchanger. The amount of the refrigerant in the refrigerating circuit is controlled by the expansion valve which is controlled by a control unit. The control unit is provided with detector means including various sensors for detecting the ambient temperature, saturation temperature of the refrigerant in the refrigerating cycle, temperature of the discharged refrigerant fed from the compressor, etc. Detection of refrigerant leakage from the refrigerating circuit is accurately performed by the detector means. Control means responsive to the detector means controls the operation of the compressor. The compressor is stopped when the ambient temperature is within a pre-determined level and the discharged temperature exceeds a given level if the opening of the expansion valve is full. Malfunction of the compressor is thus prevented.

Abstract: A method is described for the performance optimization of refrigeration devices fed with refrigerant, in particular of air refrigeration devices in which a setting value is formed for an electrically or electronically operatable expansion valve in dependence on different temperature measurements continually ensures the ideal filling of the vaporizer. The invention includes a method of optimising the performance of a fan air refrigerator and of determining the ideal timepoint for defrosting is described, with the time for defrosting being determined by a comparative monitoring of a temperature difference, on the one hand, and a time related monitoring of the refrigerant throughflow, on the other hand. In addition the cold room temperature is regulated by the supply air sensor by switching on and switching off the compressor.

Abstract: A multichamber air conditioner which is provided with a unit for obtaining the characteristics which are approximately conformable to the reverse characteristics of the desired control dynamic characteristics, an integrator, a unit for receiving the detected room temperature as the input of the above described reverse characteristics unit, comparing the output of the above described reverse characteristic unit with the set value, inputting the compared results to the above decided integrator, controlling the opening of the expansion valve by the output of the integrator, outputting the integration gains of the above described integrator in accordance with the open air temperatures, the total sum of the number of driver stands, the performance, and the variation in the compressor suction pressure.

Abstract: A temperature control apparatus for a machine tool includes four temperature sensors for detecting a reference temperature, outlet temperature of heat transfer fluid at an outlet of a heat exchanger, and temperatures of the heat transfer fluid at both inlet and an outlet of a machine tool element having a heat generating source. The four temperature sensors are arranged to constitute a differential temperature detecting means that activates control means to control temperature of the heat transfer fluid from the heat exchanger so as to minimize both deviations of heat transfer fluid temperature and steady-state deviations of machine tool body temperature.

Abstract: A condenser (2), an electronic expansion valve (5), an evaporator (6), and a motorized suction throttle valve (8) are connected in series with a compressor. When a capacity is increased, the electronic expansion valve (5) is controlled to be in a throttling direction and the motorized suction throttle valve (8) is controlled to be in an unthrottling direction in association with the control of the electronic expansion valve (5), and when a capacity is decreased, the electronic expansion valve (5) is controlled to be in an unthrottling direction and the motorized suction throttle valve (8) is controlled to be in a throttling direction in association with the control of the electronic expansion valve (5). While a capacity control of a compressor by a throttle control is been carried out, such associated control is made between the electronic expansion valve (5) and the motorized suction throttle valve (8), realizing a fine temperature control in a refrigerating machine without hunting.

Abstract: A refrigeration system is disclosed which utilizes an expansion engine in the condensate line of the condenser. The liquid leaving the condenser drives the expansion engine when it passes therethrough. The expansion engine, in turn, drives a compressor which compresses gas from the reservoir to the condenser. The discharge of the liquid refrigerant from the condenser is controlled by a micro-controller circuit. The micro-controller circuit increases the flow when the temperature difference between the liquid refrigerant and the ambient air flowing across the condenser is below a predetermined value and decreases the flow when the temperature difference is above a predetermined value. A liquid pump is used to elevate the pressure of the liquid refrigerant leaving the receiver.

Abstract: An air conditioning system for multiple rooms, comprising:an outdoor unit including a variable delivery compressor, a four way reversing valve and an outdoor heat exchange unit;two main connecting pipes composed of a high pressure main pipe and a low pressure main pipe to connect between outdoors and indoors;a distribution controller which is connected to the main connecting pipes to divide them into a high pressure pipe, a low pressure pipe and a medium pressure pipe therein;a plurality of indoor units which include indoor heat exchangers, respectively, which are one end connected to the medium pressure pipe through electronic expansion valves, respectively, and which are the other end selectively connected to either one of the high pressure pipe and the low pressure pipe, respectively;detecting means for detecting either one of refrigerant temperatures and refrigerant pressures; andcontrol means for carrying out a predetermimed control based on such detection.

Abstract: This invention provides a refrigeration system which includes in a closed loop connection a compressor for compressing a refrigerant into a condenser for condensing the compressed refrigerant into a liquid refrigerant, a control valve for controlling the discharge of the liquid refrigerant from the condenser into a reservoir, a sensor for measuring the temperature of the liquid refrigerant near the control valve, a fan for circulating air through the condenser, a sensor for measuring the ambient temperature of the airflow through the condenser and an electronic control system to control various functions of the refrigeration system, including the flow of the liquid refrigerant through the condenser as function of the temperature difference between the ambient temperature and the temperature of the liquid refrigerant. During operation, a minimal flooding of the condenser is always maintained, i.e.

Abstract: In a thermostatic expansion valve having a thermo bulb, a valve opening degree is defined by the force difference between a first force at one side surface of a diaphragm and a second force at the other side surface thereof. The former force is the sum of the pressure of a refrigerant, sensed at the downstream side of a valve seat and applied on one side surface by an auxiliary pressure applying capillary tube, and the biasing force, applied on one side surface by a valve body spring. The latter force is the sum of the pressure of an actuator vapor, contained in a thermal bulb and applied on the other side surface of the diaphragm, and the pressure of the refrigerant, sensed at the upstream side of the valve seat in a refrigerant pathway of a valve housing and applied on the other side surface by way of a force transmitting member.

Abstract: An indoor heat exchange unit and method of making same characterized by an arcuate coil shape heat exchange unit made by bending a planar heat exchange unit to fit within a limited space with an open inlet at one end and blocked at the other end so as to force air to flow past the coil and transfer heat through the fins and tubes of the coil in the process. Also disclosed are preferred embodiments in which an air circulation fan circulates air and where a thermostat controls the flow of heat exchange fluid through the coil as the air is passed through the arcuate coil to obtain a predetermined temperature, or the like, in the air.

Abstract: A method and system for conditioning the cargo containing space of a vehicle are disclosed wherein refrigerated or heated air is introduced into a supply duct and circulated through the cargo to a return duct. The return duct or ducts are preferably formed by movable reefer pallets or racks, controlled openings in the pallets regulating flow into the return duct to develop a uniform pressure differential between the cargo space and the return duct and achieve more uniform cooling. Heat barrier spacers are arranged on vertical walls to minimize heat passage to the cargo. A method and system are also disclosed for supplying refrigerated gas through a supply duct and returning it through a return duct, a control unit being normally responsive to a master temperature sensor arranged in an inlet, a sub-master temperature sensor being arranged for sensing freezing or chilling conditions and overriding the master temperature sensor.