A Comparative Study of Thermal Control Systems Using a Liquid or Gas Working Medium

Abstract

Thermal control systems (TCSs) are used to ensure an appropriate temperature environment for the internal objects. Most TCSs can be generally classified into two categories: TCS using a gas working medium (G-TCS) and TCS using a liquid working medium (L-TCS). In this work, models of G-TCS and L-TCS were constructed, and the two systems were compared in a loaded stable operation case and an unloaded starting case. The analysis of the loaded stable operation case shows that the heat consumptions of both systems are nearly the same, but the flow energy consumption of G-TCS is 21.82 times that of L-TCS, and thus its total energy consumptions are 3.49, 8.83 and 14.64 times that of L-TCS in winter, summer and spring, respectively, i.e., energy efficiencies of L-TCS are 3.81, 10.33 and 11.63 times that of G-TCS in winter, summer and spring, respectively. In terms of spatial uniformity and temporal stability of the temperature field of the object’s surface, L-TCS is far superior to G-TCS. In the unloaded starting case, each TCS has its respective advantage, but both starting performance are unsatisfactory. However, introducing a mixing fan to enhance the convection inside the envelope can greatly shorten L-TCS’s start-up duration.