Results of studies of heat-transfer characteristics of miniaturized heat pipes with the diameter 2.4 and 6 mm and length from 50 to 250 mm are presented. Pipe shell material is copper. It is shown that decrease of the vapor space dimensions in heat pipes leads to deterioration of their heat-transfer properties (increase of thermal resistance, reduction of transferred heat fluxes, and increase of the temperature difference between the evaporator and the condenser). The thermal resistance value depends on the diameter of miniaturized heat pipes. Physical processes occurring in miniaturized heat pipes are analyzed; heat-transfer coefficients in evaporation and condensation zones are obtained. Dependences of transferred heat loads on the diameter of the vapor space and the total length of miniaturized heat pipes are given. Dependences of the temperature drop between evaporation and condensation zones on the transferred heat flux are presented. Possibilities for increase of heat-transfer characteristics of such heat pipes by application of optimal-structure capillary structures, possessing a high capillary pressure and a high liquid permeability, are analyzed.
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