Numerical study and parametric analysis of thermo-hydraulic behavior in a flat loop heat pipe at system scale

Abstract

Using loop heat pipes (LHPs) for thermal management of aerospace and ground electronic devices has become an efficient and attractive method in recent years. A 3-D CFD numerical model was proposed for calculating the thermo-hydraulic behavior in a LHP with a square evaporator and the accuracy was verified by experimental results. The evaporation and condensation were addressed by volume of fluid method and a momentum source term derived from flow resistance analysis was incorporated into wick as the capillary force. The simulation results aligned with experimental trends, and errors of heating surface temperature and system thermal resistance were small. Due to structural constraint and gravity effect, two eddies were formed in compensation chamber, causing uneven distribution of temperature on heating surface. Parametric analysis indicated that higher porosity deteriorated the heat transfer from heating surface to wick and enlarged heating surface temperature and system thermal resistance. Higher wick and shell thermal conductivities ensured more heat conduction to the vapor-liquid interface and enhanced the evaporation intensity. However, the higher the thermal conductivity, the lower the improvement that could be obtained. Additionally, lower heat sink temperature and higher condenser heat transfer coefficient both intensified the LHP working performance by elevating the condensation efficiency.

Keywords

• Loop heat pipe
• Two-phase flow simulation
• Thermo-hydraulic behavior
• Volume of fluid method
• Parametric analysis