Thermal control system and method

A method of varying the heat transfer properties of a two phase refrigerant to exchange thermal energy with a thermal load so as to heat or cool the load to a chosen temperature within a range, comprising the steps of:

• compressing the refrigerant to a high enthalpy level such that it is wholly in gas phase;
• dividing the compressed refrigerant into first and second parts;
• lowering the enthalpy of a first part of the compressed refrigerant;
• lowering the pressure of the first part to create a controllable expanded flow at lower temperature;
• maintaining the enthalpy of the second part of the compressed refrigerant while selectively varying the flow mass thereof;
• combining the controlled expanded flow with the selectively varied flow mass into a mixture of misted vapor whose temperature is determined by the proportions of the mixture;
• exchanging thermal energy between the combined flow and the thermal load while maintaining the thermal load at a selected temperature by controlling the pressure of the combined flow, and
• restoring the combined flow to gas phase for subsequent compression.