Abstract: An improved electrically controlled thermotropic liquid-crystal heat valve to control the flow of heat between two bodies of different temperatures by interposing therebetween a fluid layer of liquid-crystal material having a nematic temperature range that includes the temperature of both bodies. This type of heat valve has particular application to any free-swimming divers' diving garments, to provide some thermal protection against the cold ambient water. The heat valve uses stable liquid-crystal materials encapsulated in a sealed environment, with the valves' electrodes being shielded and not in direct electrical contact with the liquid-crystal material. This arrangement essentially completely eliminates the electrochemical effects which can otherwise degrade the liquid-crystal materials, so that the liquid crystal may function for a very long time.

Abstract: A liquid-crystal heat valve is constructed to be controlled with multiple ectrode pairs. So constructed, it is controllable by alternating electric potentials in different phases applied to corresponding electrode pairs, thus increasing the maximum heat-transfer rate of the heat valve by increasing its duty cycle.