Influence of gas compressibility on gas flow through bed of granular phase change material

Abstract

One-dimensional time-dependent gas flow through a bed of granular phase change material (PCM) is considered. Such process takes place in thermal energy storage (TES) based on granulated or encapsulated PCM. Using a novel numerical model, the influence of gas compressibility on considered processes is investigated. The study is carried out in a wide range of problem parameters for both known gas pressure at the open boundaries of the bed and known gas flow rate at the object inlet. It is shown that for some problem parameters the neglect of the gas compressibility can lead to large errors in the solution of the problem, and it can cause significant inaccuracies in calculating the full heating time and the full melting time of the granular PCM in TES. Moreover, the neglect of the gas compressibility cannot give guaranteed upper or lower bound for the real time of the process. So, for some problem parameters the gas compressibility must be taken into account to model the TES with granulated or encapsulated PCM more adequately and accurately.