Thermo King Corporation

Westinghouse Electric Corporation

Peter W Freund

Lars Ivan Sjoholm

Lee J Erickson

David H Taylor

Sung L Kwon

Bradley Michael Ludwig

Stanley O Hoium

Jeffrey Bryan Gronneberg

P Robert Srichai

Jay L Hanson

Scott C Milton

Joseph Edward LaBossiere

James E Nixon

Lowell B Naley

Stan O Hoium

A refrigeration system having a cooling circuit, a heating circuit, a pressurizing receiver tank circuit, a pilot circuit and a liquid injection circuit wherein the hot gas line includes a solenoid valve that connects an outlet of a compressor to an outlet of a receiver tank, and wherein the liquid injection circuit includes a liquid injection solenoid that connects the outlet of the receiver tank to an outlet of an economizer.

Method of operating a refrigeration system in a null cycle

A refrigeration unit includes an engine, a motor capable of producing a similar power output as the engine, and a compressor driven by one of the engine and the motor. The compressor includes a suction inlet and a discharge outlet. The refrigeration unit also includes a condenser in fluid communication with the discharge outlet through which pressurized, gaseous refrigerant is condensed, an evaporator in fluid communication with the condenser to receive liquid refrigerant and return gaseous refrigerant to the suction inlet, a passageway having a first end in fluid communication with an outlet of the condenser, and a second end in fluid communication with the suction inlet, and a purge valve defining at least a portion of the passageway between the first and second ends. The purge valve is operable to selectively divert liquid refrigerant from the condenser to the suction inlet to increase the pressure in the suction inlet.

Method of controlling inlet pressure of a refrigerant compressor

Economizer combined with a heat of compression system

A method of controlling a heating cycle of a refrigeration system is provided that includes a refrigerant circuit. The refrigerant circuit includes a compressor having a suction port and an outlet having a discharge port with a hot gas compressor discharge line, a condenser for condensing the refrigerant, an evaporator for evaporating the refrigerant and an expansion valve. The method includes using refrigerant from the hot gas compressor discharge line to heat the evaporator during a heating cycle, detecting periodically a discharge superheat of the refrigerant leaving the outlet of the compressor, producing a control signal representing a difference between the detected discharge superheat and a minimum discharge superheat setpoint, adjusting the flow rate of the refrigerant to the suction port of the compressor according to the control signal so as to maintain the discharge superheat of the refrigerant at the outlet of the compressor substantially at the minimum discharge superheat setpoint.

Control method for operating a refrigeration system

A method for controlling at least one electronic expansion valve coupled to an economizer in a refrigeration system in order to dynamically control the refrigeration system operating conditions and in order to accommodate more than one set of operating conditions. The system can also be used to control the capacity of the system. More specifically, the method can include determining the required capacity of the system and adjusting the flow of refrigerant through the electronic expansion valve to adjust the actual capacity of the system toward the required capacity of the system. In another aspect of the invention, the system is operated to maintain the power of the system below a threshold value (e.g., below a max rated horsepower). This method includes determining the power required to operate the compressor based on the measurement of system parameters; comparing the power required to a threshold value; and adjusting the flow of refrigerant through the electronic expansion valve in order to keep the power required below the threshold value. In yet another aspect of the invention, the system is operated in order to prevent overheating of the compressor. More specifically, the flow of refrigerant from the heat exchanger to the compressor can be adjusted so that some amount of liquid refrigerant is provided to quench the compressor.

Refrigeration unit apparatus and method

A method for efficiently maintaining the temperature of fluid in a conditioned space at a predetermined set point temperature, the method comprising the steps of: (a) operating the temperature control system in a first operating mode; (b) sensing the temperature of the conditioned space fluid; (c) calculating the Integral Error of the temperature of the conditioned space fluid; and (d) if the Integral Error equals or exceeds a predetermined Integral Error threshold value for the first operating mode, switching the unit to a second operating mode.

Temperature control system and method for efficiently obtaining and

A transport refrigeration system for heating and cooling a conditioned space is provided that includes an improved, combined heat exchanger and economizer for increasing the efficiency of the refrigeration cycle. The system includes a refrigerant compressor driven by an internal combustion engine that includes suction and discharge ports, and an intermediate pressure port; a refrigeration circuit including a heating coil and evaporator assembly thermally connected to the conditioned space, and a mode valve for selectively routing the refrigerant through either the heating coil or the evaporator assembly via a condenser to heat or cool the conditioned space, respectively. The combined heat exchanger and economizer includes a tube connected to the intermediate suction port of the compressor, a shell for conducting refrigerant to the evaporator assembly depending upon the position of the mode valve, and a jacket for circulating engine coolant. During the heating mode of the system, a volume of refrigerant is maintained in the shell of the combined heat exchanger and economizer to act as a thermal buffer for heat transferred between engine coolant circulating through the jacket, and refrigerant flowing through the tube of the device.

Refrigeration system and method utilizing combined economizer and engine

A refrigeration unit of the type having an economizer cycle driven by a prime mover cooled by a liquid coolant. Electrical control configures refrigerant flow paths of the unit to provide heating and cooling cycles, as required to control the temperature of a conditioned space to a predetermined set point temperature. Heat from the liquid coolant is used to enhance the heating cycle. A heating cycle is initiated immediately, when required, when the temperature of the liquid coolant is above a predetermined temperature. A heating cycle is delayed by a special refrigeration cycle which increases the load on the prime mover, when the temperature of the liquid coolant is not above the predetermined temperature. In a preferred embodiment of the invention, the special refrigeration cycle provides simultaneous heating and cooling cycles, which include evaporating liquid refrigerant in an evaporator associated with the conditioned space, as in a cooling cycle, while condensing hot gas refrigerant from the compressor in a condenser associated with the conditioned space, as in a heating cycle.

Methods and apparatus for operating a refrigeration unit

A refrigeration system of the type having an economizer cycle is provided with a null cycle, in addition to heating and cooling cycles, without shutting a compressor prime mover down, to preserve air flow in a conditioned space. First, second and third controllable valves respectively: (1) select main and auxiliary condensers, (2) open and close a liquid line, and (3) open and close a line which provides a warm liquid to an economizer heat exchanger. The valves are controlled in at least one predetermined open/close pattern during a null cycle, and preferably in a plurality of selectable predetermined open/close patterns, to provide a null cycle at any instant which substantially matches the net heat gain or loss taking place in the conditioned space. Thus, the temperature of the served space will be more apt to remain in a null temperature range close to set point, providing smoother and more accurate control over the temperature of the conditioned space for longer shelf life of perishables stored therein. The system achieves the latter by controlling cooling circulation in the compressor oil cooler.

Methods and apparatus for operating a refrigeration system characterized

A refrigeration system of the type having an economizer cycle is provided with a null cycle, in addition to heating and cooling cycles, without shutting a compressor prime mover down, to preserve air flow in a conditioned space. First, second and third controllable valves respectively: (1) select main and auxiliary condensers, (2) open and close a liquid line, and (3) open and close a line which provides a warm liquid to an economizer heat exchanger. The valves are controlled in at least one predetermined open/close pattern during a null cycle, and preferably in a plurality of selectable predetermined open/close patterns, to provide a null cycle at any instant which substantially matches the net heat gain or loss taking place in the conditioned space. Thus, the temperature of the served space will be more apt to remain in a null temperature range close to set point, providing smoother and more accurate control over the temperature of the conditioned space for longer shelf life of perishables stored therein. The system achieves the latter by controlling a bypass value according to the load of the compressor.

Methods and apparatus for operating a refrigeration system

A refrigeration system of the type having an economizer cycle is provided with a null cycle, in addition to heating and cooling cycles, without shutting a compressor prime mover down, to preserve air flow in a conditioned space. First, second and third controllable valves respectively: (1) select main and auxiliary condensers, (2) open and close a liquid line, and (3) open and close a line which provides a warm liquid to an economizer heat exchanger. The valves are controlled in at least one predetermined open/close pattern during a null cycle, and preferably in a plurality of selectable predetermined open/close patterns, to provide a null cycle at any instant which substantially matches the net heat gain or loss taking place in the conditioned space. Thus, the temperature of the served space will be more apt to remain in a null temperature range close to set point, providing smoother and more accurate control over the temperature of the conditioned space for longer shelf life of perishables stored therein.

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Bloomington, MN, United States of America

Peter W Freund