Complete analytical model of a loop heat pipe with a flat evaporator

Abstract

A steady-state analytical model has been developed to determine the thermohydraulic behaviour of a loop heat pipe with a flat evaporator. Its main originality lies in the combination of energy balance equations for each component of the system with 2D analytical solutions for the temperature field in the evaporator. Based on Fourier series expansion, heat transfer in the wick as well as in the evaporator casing are accurately modelled, enabling a thorough consideration of the parasitic heat fluxes. The model is based on the thermal contact resistance between the wick and the casing, the thermal conductivity of the wick and the accommodation coefficient. This analytical method offers a simple solution that can be implemented in LHP design analysis without the need of large computational resources. A sensitivity analysis has been carried out to evaluate the influence of several parameters on the LHP behaviour. The results show that the main parameters of the model are independent. Therefore, they could be experimentally determined using an appropriate test bench with only few temperature measurements. The model has been validated with a set of experimental data from the literature. A good agreement is found between the theoretical and the experimental results.