Automatic Thermal Switches With No Moving Parts

Quasi-thermostatic gas-gap thermal switches have been proposed. These switches would operate automatically, would contain no moving parts, would not require power supplies or controls, would not consume any materials, and would not create vibrations. The operation of a switch of this type would be based on the increase, with temperature, in the vapor pressure of a condensible fluid in a gap; the effective thermal conductance across the gap would increase with vapor pressure and thus with temperature. The design of the gap and the fluid would be chosen so that the thermal conductance across the gap would increase sharply with temperature in the desired switching temperature range.