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

Abstract

International audienceA 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

Design, Manufacturing, and Characterization of Copper Capillary Structures for Loop Heat Pipes

“…The modelled LHP is expected to cool an electronic component dissipating a heat flux up to 10 W/cm². Siedel et al (2015) developed a model to predict the thermal and hydrodynamic behaviors of a flat-disk shaped LHP. The objective of his model is to find evaporator designs enabling to reduce the heat leaks from the heating plate to the reservoir, while shortening the thermal path between the heating plate and the evaporating interface.…”

“…The objective of his model is to find evaporator designs enabling to reduce the heat leaks from the heating plate to the reservoir, while shortening the thermal path between the heating plate and the evaporating interface. The model of Siedel et al (2015) considers a monolayer nickel wick saturated with liquid. In the present study, it is modified to consider the influence of a double layer wick with different characteristics at the bottom part (in contact with the heated wall) and at the top part (in contact with the reservoir) ( Fig.…”

“…The model of Siedel et al (2015) is a nodal network based on a combination of energy balance equations for each component of the LHP. To precisely describe the heat and mass transfer inside evaporator casing / porous wick assembly, two analytical models were developed and coupled with the nodal model.…”

A numerical comparative study of the effect of working fluids and wick properties on the performance of capillary pumped loop with a flat evaporator

“…The vapor flow is considered to be incompressible and isothermal [4,5,27,28,30]. The momentum balance is applied to determine the vapor pressure at the vapor line inlet.…”

One-dimensional steady-state mathematical model of a novel loop heat pipe with liquid line capillary wick

“…More detailed descriptions of the mathematical model of LHPs can be found in Bai et al (2009Bai et al ( , 2010Bai et al ( , 2011 and Ramasamy et al (2018). For the LHP with flat evaporator, it can mainly be divided into two types according to the position of CC and evaporator: integrate type (CC is above evaporator capillary wick) and connection type (CC is at the end of evaporator, connecting liquid line and evaporator) (Siedel et al, 2013(Siedel et al, , 2015Zhu and Yu, 2016).…”