Comparison of direct and reverse cycle of the thermal control system for the non-hermetic spacecrafts

This paper covers the problem of mathematical modeling of two-phase closed thermal control systems, working on the direct and reverse cycles. Such systems are characterized by high productivity due to the magnitude of the latent heat of the vaporization (evaporation) of the working fluid, and are promising due to the current trends of increasing size and available power of spacecrafts. Mathematical modeling of such systems will allow getting their characteristics by numerical methods when changing the governing parameters, evaluate the effectiveness of various structural configurations and perform their optimization. This paper analyzes the main difficulties in the calculation and modeling of two-phase thermal control systems. The calculated scheme and mode of operation of such systems as a part of the non-hermetic spacecrafts are introduced. The technique of constructing a system of equations and calculation algorithm to obtain the characteristics of such systems are presented. The equations for calculate the flow with heat transfer are used as basic equations. The system of equations is separated into heat and hydro-gas dynamics parts. We consider the specification of the equations for the hierarchical levels of the system. In constructing the calculation algorithm used equations are divided into two types: component (describing the processes in a single element of temperature control system), and topological (linking all the elements in a closed system). System of equations of the mathematical model in lumped parameters is used. The results of the calculation of two-phase thermal control systems, working on the direct and reverse cycles and compare their effectiveness are introduced. The parameters that affect the performance of the two systems (in the framework of a mathematical model) are temperature of devices and capacity. The results of calculation have led to the conclusions about the advantages and disadvantages of the use of thermal control systems, working on the direct and reverse cycles, as part of the spacecraft.