CAPILLARY LIMIT IN HEAT PIPES

Permeability and apparent diffusivity within a heat pipe wick were measured over a wide range of moisture content. Obtained data showed a strong dependence on the saturation of working fluid. By use of the results, saturation distributions within wick were calculated for several kinds of heat pipes under various operating conditions. Also, the capillary limit was predicted by taking account of the saturation-dependent permeability and apparent diffusivity. Fairly good agreement was obtained between predicted and experimental data of saturation distribution and maximum heat transfer rate at the capillary limit.