Application of entransy to optimization design of parallel thermal network of thermal control system in spacecraft

For distribution optimization of the flow rate of cold fluid and heat transfer area in the parallel thermal network of the thermal control system in spacecraft, a physical and mathematical model is set up, analyzed and discussed with the entransy theory. It is found that the optimization objective of this problem and the optimization direction of the extremum entransy dissipation principle are consistent in theory. For a two-branch thermal network system, the distributions of the flow rate of the cold fluid and the heat transfer area are optimized by calculating the extremum entransy dissipation with the Newton method. The influential factors of the optimized distributions are also analyzed and discussed. The results show that the main influence factors are the heat transfer rate of the branches and the total heat transfer area. The total flow rate of the cold fluid has a threshold, beyond which further increasing its value brings very little influence on the optimization results. Moreover, the difference between the extremum entransy dissipation principle and the minimum entropy generation principle is also discussed when they are used to analyze the problem in this paper, and the extremum entransy dissipation principle is found to be more suitable. In addition, the Newton method is mathematically efficient to solve the problem, which could accomplish the optimized distribution in a very short time for a ten-branch thermal network system.