Thermal Behavior Analysis of Wire Mini Heat Pipe

Abstract

This work presents a theoretical and experimental analysis of a copper mini heat pipe (MHP), fabricated from a sandwich formed between cylindrical wires and flat plates, which are welded by means of diffusion process. The edges formed between the wires and the plates provide the working fluid capillary pressure necessary to overcome all the pressure losses. Two different experimental set ups were developed: one for test in gravity (laboratory) and other for microgravity conditions (International Space Station—ISS). The main difference between them lies in the condenser section. In the laboratory, cooling water was used to remove heat from the mini heat pipe, while at the ISS, fins and air fan were employed. In gravity, three different working fluids were tested: water, acetone, and methanol, while, for the experiments at the ISS, just water was used. A model was developed to predict the maximum heat transfer capacity of the device. In comparison to the literature models, the main difference of the present model is the variation of contact angle to adjust the mathematical model. Therefore, the main contributions of the present work are development of wire plate mini heat pipe fabrication methodology using diffusion welding, improvement of the analytical model used to predict the maximum heat transfer capacity of the device, determination of the present technology optimum design parameters, and test data obtained under microgravity conditions.