Abstract: An energy transfer system (12) for a household refrigeration appliance (110). The energy transfer system (12) includes a venting system (120) within the refrigeration appliance (110), and a set of conduits (130,132) for enabling the transfer of outside air into, through and out of the venting system. The system (120) moves cooling air around the storage compartment (122,124) and compressor (162). In one form of the present invention, the system may also include a thermostatically actuated valve (38) for enabling outside air into, through and out of the compartment (114) in response to a predetermined temperature.

Abstract: A refrigerator includes refrigerating and freezing compartments and a cooling cycle mechanism having only one evaporator. When either of the compartments needs to be cooled, the cooling cycle mechanism is started-up and operated to cool the refrigerating compartment, but not the freezing compartment, until refrigerant pressure in the evaporator reaches a steady state condition. Then, if the freezing compartment needs cooling, it is cooled. Thereafter, if the refrigerating compartment needs cooling, it is cooled. During periods when neither of the compartments needs cooling, the cooling cycle mechanism is shut down, and air from the refrigerating compartment is conducted through the evaporator to defrost the evaporator.

Abstract: An air conditioner having a controller configured to process multiple temperature inputs, to provide a cycle of operation to provide comfort during sleeping, to provide an automatic cycle of operation wherein a burst of cooling air is provided on demand and/or which is configured to receive and respond to remote signals having different protocols.

Abstract: The invention provides a method for shipping cargo, such as produce, in a typical enclosed cargo container van.

Abstract: A cool air discharge controller for a refrigerator and a controlling method thereof are provided.

Abstract: A refrigerator having a cool air path and a cool air discharge control blade for distributing cool air and controlling the discharge direction thereof and a method for controlling refrigerator temperature by controlling a cool air discharge direction are provided. By placing a disk-shaped cool air guiding portion in a discharge hole, cool air is rapidly and uniformly distributed via the cool air path and by low-speed rotation of the cool air discharge control blade, thus keeping the refrigerator at a predetermined temperature. Temperature sensors are installed on each side of the refrigeration compartment and the sensed averages or representative temperatures are compared with control reference temperatures, so that cool air can be discharged to high temperature areas by controlling the cool air discharge direction such that the cool air discharge control blade is rotated to provide cool air flow depending on a sensed temperature difference.

Abstract: Merchandise temperature sensors 16 for detecting merchandise temperatures simultaneously with in-housing temperature sensors 17 for detecting the in-housing air temperature of a merchandise housing are provided in the merchandise housing of a vending machine. Further, the cooling mechanism is controlled by means of the merchandise temperature sensor 16 during the peak shift or peak cut, whereas the cooling mechanism is controlled by means of in-housing temperature sensor 17 during normal operation. Thus the merchandise temperature is directly detected during the peak shift or peak cut where the temperature sharply varies so as to increase merchandise temperature control accuracy. Even when the installation of the merchandise temperature sensors is limited to some columns in view of cost reduction, the cooling mechanism is made controllable by collectively detecting the merchandise temperature in the whole column by means of the in-housing temperature sensors 17 during the normal operation.

Abstract: An electronic controller for a room air conditioner includes a memory for storing operational parameters, a thermistor for measuring ambient temperature, and a microprocessor capable of calculating the difference between the ambient temperature and the temperature set point, and capable of controlling the speed of the fan and fan motor based on the difference between the ambient temperature and the temperature set point. The controller includes an electronic system clock, an electronic control panel with a display, the ability to store in memory a start time for normal operation of the room air conditioner and a stop time for ending normal operation of the room air conditioner, and a timer mode activation device.

Abstract: An air conditioner and a method for controlling an air conditioner which can operate in at least two operation modes, such as a cooling mode and heating mode. The capacity of the air conditioner is determined based on a difference between a set temperature and the temperature detected by a room temperature sensor every time a set time has elapsed, and the amount of variation of the detected temperature over the set time. The capacity can be controlled using PID control, fuzzy control, genetic algorithm control, or the like. The set time is varied based on the operating mode. Also, the set time can be varied in accordance with the volume of air blown into the room from the air conditioner, the direction of the blown air, the performance rating of the air conditioner and/or the size of the room to be conditioned.

Abstract: A refrigerated display case comprising a housing having a front display window, a top, a rear wall, and a base, all defining an enclosed space for display of food products, the base having a chamber containing a refrigeration coil and air propelling fans for propelling cooled air, an air inlet duct from the enclosed space to the chamber and an outlet duct from the chamber to the enclosed space oriented upwardly inside the chamber for propelling circulated air up to the top and down across the front display window inner surface to the air inlet duct for recirculation, the top having a contour outlet from the space to the exterior of the housing, oriented toward the front display window for flow of a portion of circulated cool air down across the front display window outer surface to cool it and evaporate moisture to prevent sweating.

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: A heat pump provides improved operating comfort, less noise and vibration by exhausting air upwardly with the use of a fan which is exterior of the heat pump housing. In one embodiment the fan is mounted on the roof and in another embodiment the exhaust fan is positioned in the attic.

Abstract: A method of cooling a vending machine in which the products are stored behind a closable opening at the front side of the vending machine, said opening being opened for a direct removal of the product at the activation of the vending machine, said method implying that a flow of cold air (36, 37, and 42) is directed substantially between the products adjacent the delivery area and the opening. The vending machine comprises a plurality of drums (3) rotatably journalled about a vertical axis, as well as a front window adapted to be opened for a direct access to at least one removal opening (8). The flow of air in question is provided by means of a vertical outlet slot (22) directed substantially tangentially towards the front side of the drums (3) and a horizontal downward outlet slot (26).

Abstract: An energy transfer system for a household refrigeration appliance. The energy transfer system includes a compartment for enclosing a condenser which is associated with the refrigeration appliance, and a set of conduits for enabling the transfer of outside air into, through and out of the compartment. The system also includes a movable barrier for selectively controlling the transfer of air through the compartment. In one form of the present invention, the system also includes a thermostatically actuated fan for forcing outside air into, through and out of the compartment in response to a predetermined temperature.

Abstract: An automatic mechanism for opening the outlet of an air conditioner enables the outlet to be open to an extent creating a selected velocity of discharge air. The movement of the door is monitored and is terminated when the door reaches a position for establishing the selected velocity or when the door fails to reach that position within a predetermined position. A support member is provided on which are mounted a door-moving motor and air-directing vanes. The support member includes guides for guiding vertical movement of the door.

Abstract: A method of utilizing an economizer to reduce the energy usage of a mechanical refrigeration system. The method comprises the steps of: economizing if both cooling demand and the prerequisites to economize are present; measuring economizer capacity; determining if the measured economizer capacity is sufficient to meet the needs of a zone being conditioned; continuing to economize as long as there is both a cooling demand and the prerequisites to economize; and initiating the use of the mechanical cooling system only if the economizer capacity has been determined to be insufficient to meet the needs of the zone being conditioned.

Abstract: In combination with a tractor and refrigeration trailer, a cooling system for cooling the air within the tractor with cooled air as conducted from the refrigeration trailer to reduce fuel consumption, pollutants, or the like, of the tractor. A method for conducting air from a refrigeration trailer to a tractor coupled thereto and a method for retrofitting a cooling system to a combination tractor and refrigeration trailer for cooling the air within the tractor with the cooling system.

Abstract: Outside air temperature detected by an outside air temperature sensor (13) is given to an outside air temperature memory (14), a comparator (15) and a fan volume control section (16), respectively. The fan volume control section (16) drives an outside fan motor (18) at a revolution speed determined by outside air temperature and revolution speed of a compressor. The outside air temperature memory (14) is activated in response to an operation start command to store the outside air temperature detected at the operation start therein. Further, a timer (17) is activated in response to the same operation start command, and a time-up signal (e.g., after 18 min has elapsed) is outputted from the timer to activate the comparator (15). The comparator (15) compares the outside air temperature detected at the operation start with that detected in response to the timer-up signal to check whether air short circuit occurs or not.

Abstract: An energy transfer system for a household refrigeration appliance. The energy transfer system includes a venting system within the refrigeration appliance, and a set of conduits for enabling the transfer of outside air into, through and out of the venting system. The system moves cooling air around the storage compartment and compressor. In one form of the present invention, the system may also include a thermostatically actuated valve for enabling outside air into, through and out of the compartment in response to a predetermined temperature.

Abstract: A canister for specimen holders, includes a receptacle (1) having an upper opening (50) and a rod (3) for supporting the receptacle. A cover (5), supported on a support (8) mounted on the rod (3), is displaceable between a first position, over the opening (50) and a second position freeing the opening. The support (8) is mounted by hooking (10, 11) on the rod (3). A manually releasable lock (18) releasably locks the cover (5) in its first position. The cover (5) is pivotally mounted on the support (8) about a pivot (14) whose axis is parallel to the rod (3).

Abstract: A method and apparatus for providing preconditioned air to a parked aircraft is disclosed. The apparatus includes a booster unit (10) adapted for association with an existing preconditioned air unit (12). The booster unit (10) includes an auxiliary compressor (112), an auxiliary evaporator (109) and an auxiliary condenser (100 and 100A). These auxiliary elements are interconnected by suitable conduit (114, 115, and 118) and an expansion valve (116). The booster unit (10) is associated with the preconditioned air unit (12) whereby the condenser fan(s) (82 and 84) of that unit is utilized to cool the condenser(s) (100 and 100A) of the booster unit (10).

Abstract: A vehicle has a cabin and an air conditioning system for cabin air, the system including a ventilator and a compressor. With a view to energy consumption and the time taken for reducing the cabin air temperature to an acceptable value when the vehicle has been left stationary in full sun, the air conditioning system is used for reducing cabin air temperature in three successive stages. These stages are controlled in response to the internal temperature T.sub.i and the external temperature T.sub.e, as follows:(a) when T.sub.i is much greater than T.sub.e, for example due to heating by the sun, the air in the cabin is renewed by direct admission of external air to the cabin at a high flow rate;(b) when T.sub.i is close to T.sub.

Abstract: A dual compartment single evaporator refrigerator and temperature control apparatus that effectively controls two compartment temperatures by making the evaporator fan control independent of the compressor cycle. The compressor cycle is initiated by the fresh food compartment temperature, runs for a predetermined minimum time, and is terminated by the freezer temperature. The evaporator fan runs with the compressor and is terminated by the freezer control temperature. A small portion of the evaporator air circulation flows through the fresh food compartment and compartment temperatures are balanced according to the freezer temperature settings during the post-compressor cycle fan control. The temperature control set points to operate the compressor and fan are based on algorithms that compensate the control for the combination of freezer and fresh food temperature settings.

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 refrigerated cargo bay such as a cargo bay of a refrigerated cargo transport in combination with a plurality of generally rectangular product support platforms. The product support platforms each have a generally rectangular upper panel and a plurality of spacers depending from the upper panel for spacing the upper panel from the floor of the cargo bay. The spacers are arranged in spaced apart locations and define passageways for air beneath the upper panel and above the floor between all of the four sides of the platform to permit the flow of air into any one of the sides between the upper panel and the floor and out all three of the other sides of the platform. The platforms are arranged in a side-by-side relationship on the floor of the cargo bay with adjacent sides of the platforms generally in engagement with one another such that air is permitted to flow under the upper panels between all platforms in substantially all directions parallel to the floor.

Abstract: An automatic control for an air conditioner having a compressor motor and a fan motor and a method for its operation are provided. While the control operates both motors to cool an enclosed space, a temperature indicative of the air temperature in the space is sensed and compared with a first preselected temperature value. When the sensed temperature is no longer greater than the preselected temperature, operation of the compressor motor is terminated. Thereafter the fan motor is operated for a first preselected time period. During the first time period, a currently sensed temperature indicative of the air temperature in the space is compared with a second preselected temperature value. When the sensed temperature is no longer less than the second preselected temperature during the first time period, operation of the compressor motor is resumed and the process described above with respect to cooling the space is repeated.

Abstract: Disclosed is a process for supplying cold to at least one refrigerated enclosure particularly an open enclosure for the display and sale of fresh products in a supermarket, characterized in that:a) in the sales point are disposed said open enclosures provided in manner known per se with cold air dispensing and recovery nozzles, passing through the interior of the enclosures, the air streams sweeping the products displayed and the air heating up by taking calories exchanged from the products;b) there is positioned in a zone offset with respect to said enclosures and chosen for its convenient access, an air cooling plant principally comprising an evaporator of refrigerant liquid-gas and a ventilator, this plant is furthermore supplied with refrigerant by a refrigerating unit;c) the cold air coming from the evaporator of said plant is entrained by forced circulation through appropriate pipes towards said enclosures, the cold air coming from the air cooling plant being delivered to cold air dispensing nozzles ser

Abstract: A central air conditioning unit with a blower and feed duct is provided with a filter unit between the blower and the air outlet into the space applied with the conditioned air. The filter unit has both a sorption filter and a suspended filter and is constructed and arranged to form a sound barrier, i.e. a sound-damping or sound-blocking system.

Abstract: A temporary air conditioning condensing fan is mounted in a rigid housing which may be easily and rapidly mounted at the air exhaust side of an air conditioning unit to provide a temporary flow of cooling air to the condenser, in the event the existing condensing fan fails. A portion of the housing forms a shroud around the temporary condensing fan and directs the flow of air over the condenser. A head pressure adjusting valve adapts the temporary condensing fan to differently sized air conditioning units and maintains an efficient head pressure on the condenser of the existing air conditioning unit.

Abstract: A refrigerated container for receiving, storing, and transporting materials without necessity of personnel contacting the materials after deposit in the container. The container is particularly adapted for use with medical wastes which may contain infectious materials. The container comprises a lower portion and a lid portion. The container lower portion includes an open-topped inner box for holding waste materials, and an open-topped insulated outer box surrounding and spaced apart from the inner box forming an annular space therebetween. The lid is releasably attached to the outer box and has doors for access into the inner box of the container. A refrigeration unit and air circulation fan are attached to the lid, and are in communication with the annular space for cooling the inner box by circularing refrigerated air through the annular space.

Abstract: A method of operating a refrigeration unit to improve the uniformity of temperature distribution in a conditioned space, with the refrigeration unit including a refrigerant compressor and an evaporator fan driven at a selectable one of high and low operating speeds by a prime mover arrangement. The method includes the step of periodically operating the compressor and evaporator fan at the higher of the two operating speeds, notwithstanding a set point temperature control algorithm calling for operation of the compressor at the lower of the two speeds. When the refrigeration unit is operating in a continuous mode, the value of a constant entered into an operating program by the user determines the minimum number of minutes of each hour the prime mover should be forced to operate in the higher speed mode.

Abstract: A temperature control method for a refrigerator which is capable of promptly restoring temperatures inside a freezing compartment and a refrigerating compartment by controlling a rotation speed of a fan of an operation control system of the refrigerator via a rotation speed-variable control unit to allow cooling air to flow into the freezing compartment and the refrigerating compartment in inverse proportion to each other in response to the temperatures inside the freezing compartment and the refrigerating compartment.

Abstract: A method of refrigerator control for operating a refrigerator which may experience an abnormal temperature condition due to operation in low ambient temperatures includes a temperature sensor for sensing the temperature of a portion of a refrigerator compartment in order to detect an abnormally low temperature in another portion of the compartment. If the compartment temperature at the end of a predetermined length of time since cooling was last supplied to the compartment is below a predetermined value, then an abnormal condition is assumed to exist and corrective action is taken to eliminate the abnormal condition. A preferred form of corrective action is to prevent compressor re-energization until the compartment temperature reaches a second predetermined value.

Abstract: A portable air conditioning apparatus includes a refrigerating circuit comprising a variable capacity compressor and a condenser cooled by water fed from a water tank and a flow of air generated by a fan device, an inverter for outputting a variable driving frequency to the compressor, and a control section for controlling the frequency of the inverter in response to an air conditioning load in a defined space. The control section has a frequency control function by which the driving frequency of the inverter is forcibly decreased irrespective of the air conditioning load to reduce the consumption of water at the condenser when an amount of water is detected to be below a prescribed value in the water tank.

Abstract: A method of operating a transport refrigeration system having a compressor driven by a prime mover at a selected one of high and low speeds, an evaporator, and an evaporator blower driven by the prime mover. Refrigeration control provides an error value which controls the temperature of a load space to a predetermined set point via heating and cooling modes. The method includes the steps of driving the compressor at high speed during pull down, and injecting hot gas into the evaporator when the error is reduced to a predetermined value. The prime mover is maintained at high speed, to keep evaporator air flow at a high rate, continuing a relatively rapid temperature pull-down across the entire load space. The speed of the prime mover is reduced to low speed when the error is further reduced to a second value, which also initiates suction line modulation while maintaining hot gas injection.

Abstract: A subatmospheric pressure swing filter is integrated with a vapor cycle refrigeration system so as to provide both air filtration and air conditioning.

Abstract: A method of automatically checking components and associated wiring of electrical control associated with a microprocessor controlled transport refrigeration system. The transport refrigeration system has a prime mover which drives a refrigerant compressor and an alternator. The control includes a battery and a current shunt which measures battery current. During the automatic checking procedure, the prime mover is off, to provide a zero alternator output. Upper and lower battery current draw limits are provided for each component to be checked. Each of the components to be checked is energized and de-energized, with the microprocessor individually and successively connecting each component to, and disconnecting it from, the battery. The microprocessor compares the battery current draw of each component, when energized, with the associated battery current draw limits. An alarm is provided when a battery current draw is outside the associated draw limits, with the alarm identifying the associated component.

Abstract: A method of controlling a multiplicity of condenser fans in a refrigeration system comprising the steps of: calculating a first difference in state between a high pressure side and a low pressure side of the refrigeration system; determining an optimum state for the refrigeration system; determining a second difference in state between the first difference and the optimum difference; and controlling the multiplicity of condenser fans if the second difference exceeds a predetermined value.

Abstract: A method of operating a transport refrigeration unit having electrical control which includes a display, including the steps of detecting the occurrence of predetermined events in the transport refrigeration unit, and classifying at least certain of them into first, second and third categories of fault conditions, and into a fourth category related to maintenance associated events. When a first category fault occurs, the unit is shut down, a visual alarm is flashed, and the nature of the fault is immediately identified. When a second category fault occurs, a visual alarm is steadily energized, and the nature of the fault if immediately identified. When third category faults and fourth category events occur, they are stored and periodically displayed, with the display respectively identifying the nature of the fault and the type of maintenance event.

Abstract: A method of operating a transport refrigeration unit with microprocessor based control. The microprocessor automatically selects an operative control algorithm, according to system configuration, with each algorithm having one or more operating conditions. Return air and discharge air temperature sensors provide inputs to the microprocessor. First, second and third sets of look-up tables are accessed by the microprocessor to determine which conditions are in the selected algorithm, and the high and low trip points of each condition. The first set of tables is accessed when the return air sensor is functional, the second set is accessed when the discharge air sensor is functional and the discharge air sensor is not, and the third set is accessed when both the return air and the discharge air sensors are not functional and the conditioned load is frozen. Failure of both sensors when the load is fresh shuts the unit down.

Abstract: A method of logging the operating time of a plurality of predetermined timeable functions of a transport refrigeration unit which includes the step of providing a plurality of hourmeters, at least certain of which are programmable. One of the plurality of timetable functions is selected for each programmable h ourmeter. Each hourmeter includes a first memory, with the operating time of the associated selected timeable function being stored in the first memory. The times stored in the first memories of the hourmeters are individually transferred to a second memory which is common to all of the hourmeters in response to a predetermined event. In a preferred embodiment, the second memory has a plurality of memory banks, one of which is an active storage location for all hourmeters, until the occurrence of a predetermined event, at which time another of the memory banks becomes the active storage location for all hourmeters.

Abstract: A portable air conditioning apparatus includes a refrigerating circuit comprising a variable capacity compressor and a condenser cooled by water fed from a water tank and a flow of air generated by a fan device, an inverter for outputing a variable driving frequency to the compressor, and a control section for controlling the frequency of the inverter in response to an air conditioning load in a defined space. The control section has a frequency control function by which the driving frequency of the inverter is forcibly decreased irrespective of the air conditioning load to reduce the consumption of water at the condenser when an amount of water is detected to be below a prescribed value in the water tank.

Abstract: A system for cooling the interior of a building which monitors the temperature differential between indoor and outdoor air, and provides outside ventilation and cooling when there is a demand for cooling and the indoor air temperature exceeds the outdoor air temperature by a predetermined degree. The system includes an air conditioner for supplementing the cooling effect provided by the outdoor air in a controlled manner.

Abstract: The refrigeration plant disclosed herein includes an evaporator, a compressor connected to the outlet of the evaporator, a condenser connected to the outlet of the compressor, a controllable expansion valve connected to the outlet of the condenser and having its outlet connected to the evaporator and condenser pressure controls for providing at the least possible condenser pressure, the degree of opening of the expansion valve to obtain an optimum ratio between the condenser pressure and the evaporator evaporator performance. That is, the degree of opening of the expansion valve lies in a range giving the least possible condenser pressure.

Abstract: An air conditioner mounted on a vertical wall and an method, with the air conditioner including air intake ports and air exhaust ports provided on each side of and air conditioner body which contains heat exchangers, fans and motors. The air is drawn in from the sides of the air conditioner where it is heat-exchanged and then discharged from sides thereof.

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.

Abstract: The present invention utilizes the combination of a vehicle having a passenger compartment, a heating and cooling air-conditioning system, and an air vent opening for providing conditioned air to the passenger compartment. Within the storage compartment of the vehicle, a food container is placed which has an air conduit connected thereto. The air conduit is also connected to the air vent opening on the dash of the vehicle so that conditioned air is directed to the internal food compartment of the food container. A fan may be provided within the conduit for facilitating the movement of air from the air-conditioning vent of the vehicle into the food compartment of the container. A modified form of the invention utilizes collapsible container walls and collapsible shelves within the container.

Abstract: In a method for cooling rooms, the energy exchange between warm room air and cold air takes place through inherent convection of the air by means of a drop shaft arranged in the room, which has cooling surfaces in its upper part, at which the in-coming warm room air cools, and flows downwards owing to the specific weight difference. The cooled air leaves the drop shaft at the lower end in a laminar flow and then spreads in the room in an unbroken cool layer. The air leaving the drop shaft can also be deflected into a hollow floor. It is possible to use a fan to add to the cooled air current moved by gravity disturbing air, which then occasions turbulence.

Abstract: A method of controlling a refrigeration system by determining an average air temperature by sensing and averaging evaporator return and discharge air temperatures, and developing an average error by using the average air temperature and a selected set point temperature. The average air temperature is then used to calculate a proportional error and an integral error, and the discharge air temperature is used to calculate a floor error. The proportional error, integral error and floor error are weighted by predetermined gain factors and then summed to provide an error signal which is used to modulate the capacity of the refrigeration system, with the control mode depending upon the location of the error signal relative to set point.

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.