Abstract: A method is disclosed for cooling a heat transfer fluid circulating in a cooling circuit including a chiller. The method includes installing on the circuit a vacuum housing having a heat exchange conduit extending therethrough and partially filled with a coolant and an atmosphere and pre-cooling the atmosphere and coolant within the vacuum housing to a pre-cooling temperature of between 35 and 60 degrees Fahrenheit using a conventional cooling system. Thereafter the pressure in the vacuum housing is reduced to between 1 and 500 millitorr until an initial cooling temperature in the range of of ?50 to 35 degrees Fahrenheit is reached and the heat transfer fluid is then circulated through the heat exchange conduit and to the chiller and back. The pressure reduction in is obtained by selectively connecting the vacuum housing to a larger vacuum reservoir which is connected to a vacuum pump.

Abstract: A fluid chiller includes a tubular coil enclosed within a vacuum housing which is partially filled with a coolant and an atmosphere with the vacuum housing connected to a vacuum source. A valve selectively connects the vacuum source to the vacuum housing to allow selective reduction of the pressure within the vacuum housing to obtain a reduction of temperature of the coolant therein. A conventional, compressor type refrigeration system may be connected to the vacuum housing for chilling the vacuum housing and the atmosphere and coolant therein to an initial temperature, prior to applying a vacuum to the vacuum housing for further temperature reduction. A fluid, which may be a secondary coolant, flows through the tubular coil at least partially immersed in the coolant to cool the secondary coolant. The secondary coolant is used to cool a heat load.