CONSIDERATION OF FREQUENCY-CHARACTERISTICS OF HEAT-TRANSFER USING PHYSICAL MODELS OF HEAT PIPES

This paper deals with the frequency response characteristics of dynamic heat transfer models of a heat pipe, which has been proposed in a previous paper. Transfer functions of the models are derived and calculated frequency response characteristics are represented by a Bode diagram. The relationships among the model and the effect of the model parameters on the frequency response characteristics are considered. For a typical heat pipe, where conditions of the cooling section have been each water circulation, natural convection and forced convection of air, frequency response characteristics are experimentally obtained by accommodation analysis using M sequence signal. Results obtained are compared with those predicted by each model, and it is found that for natural air cooling of small Bi, experimental values are approximated fairly well by the lumped model. For water cooling of larger Bi the lumped model is not appropriate, but a model that takes the radial thermal resistance, into account, snch as the stairs model, is recommended.