A cooling system for an indwelling heat exchange catheter includes a heat exchange bath that is configured to receive a conduit that carries saline to and from the catheter. A heating/cooling fluid is in the bath and exchanges heat with the saline. The heating/cooling fluid flows through a heat exchanger that includes a refrigerant and two variable speed DC compressor for removing heat from the refrigerant. A gear pump circulates the working fluid to and from the catheter and is removably engaged with a pump support platform.

A flow rate of a heat transfer medium is computed without a flow meter. In a control apparatus (30), a storing portion (36) stores an aerodynamic characteristic map indicating a line causing a rotating stall and lines showing a sonic velocity in a refrigerant sucked in by a compressor (12) on a map displaying a variable reflecting a suction volume of the compressor (12) and a variable reflecting a head of the compressor (12); a estimation portion of chilled water flow rate (30b) computes the variable , derives the variable according to the variable from the map, computes a heat amount exchanged between the refrigerant and the chilled water in an evaporator (24) based on the suction volume of the compressor (12) according to the computed variable , and computes the flow rate of the chilled water based on the heat amount.

A packaged, pumped liquid, evaporative-condensing recirculating ammonia refrigeration system with charges of 10 lbs or less of refrigerant per ton of refrigeration capacity. The compressor and related components are situated inside the plenum of a standard evaporative condenser unit, and the evaporator is close coupled to the evaporative condenser. Single or dual phase cyclonic separators may also be housed in the plenum of the evaporative condenser.