Numerical Simulation on the Effects of Component Layout Orientation on the Performance of a Neon-Charged Cryogenic Loop Heat Pipe

Abstract

As a typically highly efficient two-phase heat transfer under cryogenic temperature range, the operation performances of cryogenic loop heat pipes (CLHPs) might be affected by the relative location of different components. A transient mathematical model is established in present work. The model validation is demonstrated by comparing the simulation results with an auxiliary loop type neon-charged CLHP (Ne-CLHP) experiment data, and a good agreement is achieved. The effect of gravity caused by different layout orientations on the Ne-CLHP operation performances are then investigated numerically. There are three operation modes, namely normal LHP mode (n-LHP), gravity-assisted LHP mode (g-LHP), and gravity thermosyphon mode (GTP), according to different layout orientations and heat loads. Under the gravity resistance condition with a positive layout inclination angle, the Ne-CLHP is operated in n-LHP. The operating temperature increases with the positive layout inclination angle, and the heat transport capacity decreases. Under the gravity assistance condition with a negative layout inclination angle, all three operation modes may occur according mainly to the primary heat load. Only the two LHP modes are simulated in the present study, which located in the range between the transition heat load from GTP to g-LHP and the heat transport capacity. The lager negative layout incline angle, the higher transition heat load and the heat transport capacity, while lower operating temperature. In addition, the gravity-independence of cross-sectional two-phase distribution in the transport lines is discussed in the frame of dominant force analysis. The modeling effort will contribute to the technology research and development, as well as the operation control of CLHPs for space and ground applications.