Patent ID: 7765820

Claim:
A system for controlling the temperature of a process unit adapted for thermal energy exchange comprising: a controller responsive to the temperature of the process unit and providing process commands for the system; a pressurizing circuit for a refrigerant fluid, the pressurizing circuit including a compressor and condenser in series, and the pressurizing circuit further including a bypass path from the compressor about the condenser; separate control loops from the pressurizing circuit for flowing the refrigerant fluid from the pressurizing circuit to the process unit, a first control loop being in the bypass path and including a proportioning valve for controllably adjusting the hot gas flow proportion in response to commands from the controller, a second control loop receiving the output from the condenser that comprises the differential in flow between the total output from the pressurizing circuit and that proportion flowing in the bypass path, the second control loop including an expansion valve for varying the fluid pressure and temperature of the differential in flow by expanding the refrigerant in the second control loop to a vapor containing flow, and a mixing circuit coupled to both control loops after the controller-induced variations in the flows for supplying combined output from the control loops in heat exchange relation directly to the process unit.