Numerical study of the thermal performance of a hydrogen pulsating heat pipe

Abstract

The pulsating heat pipe (PHP) has the characteristics of high thermal conductivity, simple structure, and light weight. It can meet the industry's needs for high heat transfer efficiency, flexibility, and low cost. Many attempts have been made to simulate their complex thermal behavior, but existing models have not been validated for cryogenic PHPs. In this study, a one-dimensional numerical model based on slug flow has been developed to predict the thermal performance of cryogenic PHPs. Vapor is considered a real gas. The RKS (Redlich-Kwong-Soave) equation of state is used to determine the thermodynamic properties of vapor bubbles such as pressure and internal energy. Hydrogen is the working fluid in this study. The comparison shows the consistency between the experiment and the simulation, indicating the good predictive ability of the model. Numerical results show that the response time of the hydrogen PHP to heat load changes is less than 5 s. The temperature of the vapor bubbles in the evaporator can be higher than their saturation temperature, showing a superheated state. The proportions of sensible heat and latent heat in heat transfer are similar, and the contribution of latent heat is between 45% and 51%.