US 6,446,446 B1 · Efficient cooling system and method

Abstract

A system and method for controlling the temperature of thermal loads which might be controlled by refrigeration at any temperature within a wide range from −40° C. to +120° C. employs a refrigeration loop with pressure and temperature sensitive shunt paths to provide stabilized refrigerant flow so that a thermal expansion valve can operate stably only with liquid refrigerant inputs. For efficiency, thermal energy is interchanged between refrigerant returning from thermal energy exchange with a thermal load such as a cluster tool used in semiconductor fabrication and counterflow pressurized liquid refrigerant that is to be expanded for heat exchange. If the input in a suction line to the compressor is too high in temperature, a portion of pressurized refrigerant for the thermal expansion valve that is being subcooled prior to feeding to the valve is diverted into counterflow relationship with the subcooling exchange. This diversion both lowers the temperature of the pressurized refrigerant, thereby eliminating the possibility of partial vaporization, and lowers the input temperature to the compressor, preventing overheating. The proportion of flow is sufficiently small not to interfere with the main function of controllably cooling the thermal load. Concurrently, if the pressure input to the compressor drops too low, hot gas from the compressor output is shunted back to the input through a hot gas valve in a second shunt path.

Claims12

Dependent claims

The method of cooling a thermal load to a selected temperature with a compressor/condenser system using a pressurized refrigerant when the selected temperature for the thermal load may extend to about 120° C. comprising the steps of:

pressurizing, with the compressor, gaseous refrigerant returned from the thermal load that is being cooled to a maximum gas pressure of 300-400 psi;
cooling the pressurized refrigerant to a liquid state;
subcooling the liquefied refrigerant by exchanging thermal energy between liquefied refrigerant to be used for cooling and expanded gas refrigerant returned for recycling by compression;
modulating the flow of the subcooled liquid refrigerant to provide a controlled proportion of flow for regulating the temperature of the thermal load;
cooling the thermal load by evaporative heat exchange with the controlled proportion of subcooled refrigerant;
returning the expanded refrigerant for compression via the subcooling thermal energy exchange;
diverting a part of the liquefied pressurized refrigerant flow when input temperature of the flow to be compressed is above a selected range;
and
combining the diverted flow with the returned gas refrigerant used in subcooling to lower the liquid refrigerant temperature before modulation and expansion.

6 more elements

A refrigeration system for cooling a thermal load to a selected temperature over a range of −40° C. to 120° C. without destabilization, comprising:

a compressor providing a pressurized gaseous refrigerant on an output line and having a suction line for receiving gaseous refrigerant that is returned after cooling the thermal load;
a condenser coupled to receive gaseous refrigerant from the compressor output line and including, on an output line to provide pressurized liquid refrigerant for cooling the load;
a subcooler with a refrigerant input and output for receiving the condenser output line and having a suction line input and output for transferring thermal energy between the liquid refrigerant and the returned refrigerant in the suction line;
an evaporator/heat exchanger in thermal energy exchange relation to the thermal load and coupled to receive pressurized liquid refrigerant from the subcooler and return expanded gaseous refrigerant to the suction line after thermal energy interchange with the thermal load;
an expansion control valve in the refrigerant line between the subcooler and the evaporator/heat exchanger, for controlling refrigerant flow to maintain the thermal load at the selected temperature;
a desuperheater expansion valve coupling the condenser output to the suction line input at the subcooler;
and
a hot gas bypass valve coupled to shunt a portion of the compressor output to the suction line to the compressor downstream of the subcooler in response to compressor input pressure below a selected level.

5 more elements

Dependencies are inferred from the claim text.

Efficient cooling system and method

Life of this patent

Efficient cooling system and method

Life of this patent

Abstract

Claims12