Effect of the time-dependent volumetric heat flux on heat transfer performance inside a heat sink based on the phase change materials

Abstract

The issue of thermal control plays an important role in the development of technical systems of computing and radio equipment. Temperature conditions are an important factor in the performance and durability of devices. New models of heat sink containing materials with phase transitions “solid body–liquid” are appeared. In the present paper, the numerical study of natural convection melting/solidification of phase change material inside a finned heat sink with a local heater having time-dependent volumetric heat flux has been carried out. An unsteady conjugate phase change problem has been solved taking into account natural convection in the melt, in the presence of a heat-dissipating copper profile. The energy equation has been formulated using a special smoothing function of temperature. The equations of hydrodynamics have been formulated using non-primitive variables, namely the stream function and vorticity. The system of transient differential equations of natural convection, taking into account the melting process and the heat-generating and heat-conducting element, has been solved using the finite-difference method. Analysis has been performed for different values of the volumetric heat generation within the heater and the periodic volumetric heat generation frequency. Obtained results have shown that a rise of the volumetric heat generation frequency leads to an increase in the amplitude of the average temperature within the heater that can have a negative effect on the system operation.