Heat exchange – Flexible envelope or cover type
Patent
1992-05-26
1993-06-29
Davis, Jr., Albert W.
Heat exchange
Flexible envelope or cover type
165 96, 165905, F28F 1300
Patent
active
052225488
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. 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.
REFERENCES:
Biggers et al., R.R., Influence of Electric Fields On Heat Transfer Through hermotropic Liquid Crystals Developments In Theoretical and Applied Mechanics, vol. 14, pp. 454 et seq, 1988.
Biggers, R. R. Thermotropic Liquid Crystals: A Variable CLO Material, Materials Science Branch Naval Coastal Systems Center, pp. 1-8, Feb. 1989.
Biggers Rand R.
Fuller Robert R.
Henderson Girardeau L.
Pham Chuong N.
Rish, III Jeff W.
Connors Edward J.
Davis Jr. Albert W.
Dobyns Kenneth W.
The United States of America as represented by the Secretary of
Townsend William C.
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