Thermo King Corporation

Westinghouse Electric Corporation

Roland L Roehrich

Herman H Viegas

David H Taylor

Dale T Johnson

Jay L Hanson

A refrigeration system, which conditions the air of a conditioned space via heating and cooling cycles, includes a heat exchanger and, in a first embodiment, heat pipes. A cryogen is circulated through the heat exchanger during a cooling cycle. During a heating cycle the flow of cryogen is terminated and heat is transferred into the heat exchanger via the heat pipes. In another embodiment, the temperature of evaporation of a liquid cryogen in the heat exchanger is selected according to the desired temperature of the conditioned space, via selectable cryogen flow paths which provide different pressures and thus different evaporation temperatures. Vaporized cryogen drives a motor connected to a fan which circulates air between the conditioned space and heat exchanger. In still another embodiment, the mass flow rate of liquid cryogen is controlled as a function of the degree of superheat in evaporated cryogen exiting the heat exchanger, and as a function of a predetermined floor temperature of conditioned air discharged into the conditioned space.

Air conditioning and refrigeration systems utilizing a cryogen and heat

Air conditioning and refrigeration methods and apparatus for controlling the temperature of a conditioned space to a predetermined temperature band adjacent to a predetermined set point temperature via cooling and heating cycles utilizing a supply of pressurized cryogen. A fluid flow path for the cryogen includes a heat exchanger associated with the conditioned space. A cryogen heater is connected in the active cryogen flow path during a heating cycle, and cryogen is directed through the heater and heat exchanger via at least two successive serial passes, utilizing the elevated pressure energy of the cryogen as the motive force.

Air conditioning and refrigeration systems utilizing a cryogen

Methods and apparatus for controlling the air temperature of a conditioned space to a selected set point temperature, utilizing a supply of cryogen in liquid and vapor states. The two states are drawn from the supply and maintained in first and second separate, independent flow paths. The liquid cryogen provides a cooling mode for the conditioned space via a heat exchanger disposed in the first flow path, and the vaporized cryogen provides a cooling mode for the conditioned space via a heat exchanger disposed in the second flow path. Cryogen flowing in at least one of the flow paths is used to drive a vapor motor connected to a fan, with the fan moving air between the conditioned space and at least one of the heat exchangers. Heat is applied to the cryogen as required to hold the set point temperature, or to defrost a heat exchanger.

Air conditioning and refrigeration methods and apparatus utilizing a

A refrigeration system associated with a conditioned space to be controlled to a predetermined set point temperature via heating and cooling cycles. The refrigeration system includes a fluid flow path through which a predetermined liquid is circulated. The fluid flow path includes a slush tank and first and second heat exchangers, with cryogen from a supply vessel being expanded into liquid disposed in the slush tank. The first heat exchanger is disposed to condition the air of the conditioned space, and the second heat exchanger is in heat exchange relation with heating apparatus. The first heat exchanger and slush tank are interconnected when the conditioned space requires a cooling cycle, and the first and second heat exchangers are interconnected when the conditioned space requires a heating cycle. Cryogen of the cryogenic cooling apparatus is thus not expended to heat the conditioned space, or for defrosting purposes.

Air conditioning and refrigeration apparatus utilizing a cryogen

A refrigeration system associated with a conditioned space to be controlled to a predetermined set point temperature via heating and cooling cycles. The refrigeration system includes a fluid flow path through which a predetermined fluid is circulated. The fluid flow path includes first, second and third heat exchangers. The first heat exchanger is disposed to condition air of the conditioned space, the second heat exchanger is in heat exchange relation with cryogenic cooling apparatus, and the third heat exchanger is in heat exchange relation with heating apparatus. The first and second heat exchangers are interconnected when the conditioned space requires a cooling cycle, and the first and third heat exchangers are interconnected when the conditioned space requires a heating cycle. Cryogen of the cryogenic cooling apparatus is thus not expended to heat the conditioned space, nor used for defrosting purposes.

A refrigeration system which controls the temperature of a conditioned space to a predetermined temperature range adjacent to a selected set point temperature SP via a cooling cycle which includes evaporation a cryogen, such as CO.sub.2 or N.sub.2, in a heat exchanger. In an apparatus embodiment, a controller determines a desired evaporation vapor pressure value EPX of the cryogen as a function of the selected set point temperature SP, and then controls the evaporation pressure EP in the heat exchanger means as a function of the determined desired evaporating vapor pressure value. The controller further determines a desired superheat value SHX of the cryogen exiting the heat exchanger means as a function of the selected set point temperature SP, and controls the mass flow rate of liquid cryogen evaporating in the heat exchanger as a function of the determined desired superheat value. A method embodiment includes the steps of providing a desired evaporation vapor pressure value EPX of the cryogen as a function of the selected set point temperature SP, controlling the evaporation pressure in the heat exchanger means as a function of the desired evaporation vapor pressure value, providing a desired superheat value SHX of the cryogen exiting the heat exchanger means as a function of the selected set point temperature SP, and controlling the mass flow rate of liquid cryogen from the cryogenic cooling means to the heat exchanger means as a function of the desired superheat value.

Methods and apparatus for controlling a conditioned space to a predetermined set point temperature, utilizing a supply of cryogen. Cryogen is drawn from the supply in a flow path to provide a cooling mode via a heat exchanger disposed in the flow path. A vapor motor in the flow path, downstream from the heat exchanger, drives a fan which moves air between the conditioned space and the heat exchanger. Heat is applied to the cryogen downstream from the heat exchanger, after all cooling modes have been performed, to provide the desired fan horsepower, without interfering with a cooling cycle. A by-pass flow path selectively directs cryogen directly to the vapor motor, by-passing the heat exchanger, to provide air circulation in the conditioned space when the temperature of the conditioned space is satisfied.

Methods and apparatus for controlling the temperature of a conditioned space to a predetermined set point temperature, utilizing a supply of cryogen in liquid and vapor states. The two states are drawn from the supply in two separate flow paths. The liquid cryogen is vaporized in a heat exchanger, and the two flow paths are then combined. The combined cryogen is used to drive a vapor motor connected to a fan, with the fan moving air between the conditioned space and the heat exchanger. Heat is applied to the cryogen as required to hold the set point temperature or to defrost the heat exchanger. In a preferred embodiment, the cryogen is added to a first vessel at the pressure provided by ground support apparatus, and expanded into a second vessel as a function of system conditions, to provide the supply of cryogen in both the liquid and vapor states.

Methods and apparatus for controlling the temperature of a conditioned space, including a supply of cryogen, and a fluid flow path for the cryogen which includes a heat exchanger. A heater is disposed to heat cryogen in the flow path in response to predetermined conditions, and a cryogen pre-heater is disposed to aid the heater. In a first embodiment, the pre-heater is aided by directing warm cryogen in heat exchange relation with cryogen flowing through the pre-heater, with the warm cryogen being taken from a point downstream from the heat exchanger. In another embodiment, the heater generates heated gases as a by-product, with the pre-heater being aided by directing the heated gases in heat exchange relation with cryogen flowing through the pre-heater.

A refrigeration system associated with a conditioned space to be controlled to a predetermined set point temperature via heating and cooling cycles. The refrigeration system includes a heat exchanger, air mover apparatus disposed to circulate air between the conditioned space and the heat exchanger, cryogenic cooling apparatus which includes a combustible fuel in a cryogenic state, and heating apparatus. The cryogenic characteristic of the fuel is utilized to implement the cooling cycle, and the combustible characteristic of the fuel is utilized by the heating apparatus to implement the heating cycle. In preferred embodiments of the invention an internal combustion engine is associated with the refrigeration system, and the air mover means includes a vapor motor, with the cryogenic fuel being vaporized and then expanded in the vapor motor to drive same, and with the expanded vaporized fuel operating the internal combustion engine.

A transport refrigeration unit, and method of operating same, with the unit being associated with a vehicle having a drive engine and a cargo space to be conditioned to a predetermined set point temperature. The transport refrigeration unit includes a refrigerant compressor driven directly, or indirectly, by the vehicle engine. Sensors and control determine when the engine may be safely started and stopped under control of the transport refrigeration unit. A comparison between cargo temperature and set point temperature determines when a refrigeration cycle is required to maintain the set point temperature, and when the cargo space temperature is satisfied. The engine is started, when off, when the engine may be safely started and the cargo space requires a refrigeration cycle to maintain the set point temperature. The engine is stopped, when running, when the engine may be safely stopped and the cargo space is satisfied.

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Pittsburgh, PA, United States of America

Roland L Roehrich