Heat capacity estimation of the thermal buffer mass for temperature control of satellite electronic components in periodic operation

In the present study, the analytical method to design the thermal buffer mass (TBM) used to control the temperatures of satellite electronic components that operate periodically is investigated. In the energy equation of the system composed of component and thermal control modules, the radiation heat-discharge term, which is a biquadratic equation of temperatures, is linearized, and approximate analytical solutions that guarantee minimum errors under physically valid conditions are obtained. An equation between the dimensionless thermal capacity of TBM and radiator area is derived for arbitrary design input data from the approximate solution. These two parameters are related almost linearly in the examined range of this study. Stable periodicity of temperatures is insured when thermal balance is maintained between the net thermal energy accumulated in the system during heating period and the net thermal energy discharge to space during cooling-off period. From the thermal balance, restrictive conditions for the thermal capacity of the TBM and the area of radiators are drawn. If the thermal capacity of the TBM increases, resulting difference in temperature profiles during heating phase will be very small. However, cooling rate during the component off-duty phase will be slow down, and this will reduce the duty cycle of the compensation heater. Finally, the analytic equation for mass optimization is presented to minimize the system mass.