Accession Number : ADD015872

Title :   Electrically Controlled Liquid-Crystal Heat Valve.

Descriptive Note : Patent, Filed 26 May 92, patented 29 Jun 93,

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s) : Biggers, Rand R ; Rish, Jeff W , III ; Henderson, Girardeau L ; Pham, Chuong N ; Fuller, Robert R

Report Date : 29 Jun 1993

Pagination or Media Count : 16

Abstract : An improved electrically controlled thermotropic liquid-crystal heat valve to control the flow of heat between two bodies of different temperatures by interposing there between 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. The valve is electrically controlled between the respective two different modes of its open and closed conditions, the open mode occurring when a low frequency AC field is applied to one of the liquid crystal materials; and the closed mode occurring when a high frequency field is applied to effect reorientation of the molecules of the liquid crystal materials in a direction perpendicular to the applied AC field, precluding establishment of convective flow cells, thereby retarding the transfer of heat.

Descriptors :   *HEAT, *LIQUID CRYSTALS, *VALVES, *PATENTS, *ELECTRIC FIELDS, BODIES, CELLS, CONTROL, CRYSTALS, DIVING, ELECTRODES, ENVIRONMENTS, FLOW, FLUIDS, HIGH FREQUENCY, LAYERS, LOW FREQUENCY, MOLECULES, PROTECTION, SWIMMING, TEMPERATURE, TIME, WATER, HEAT TRANSFER, CONVECTION(HEAT TRANSFER), COMPOSITE MATERIALS

Subject Categories : Crystallography
      Electricity and Magnetism
      Thermodynamics
      Pumps, Filters, Pipes, Tubing, Fittings & Vlvs

Distribution Statement : APPROVED FOR PUBLIC RELEASE