Numerical Modeling of Thermal Storage Performance of Encapsulated PCM Particles in an Unstructured Packed Bed

Jeroen Mol,Amirhoushang Mahmoudi,Mina Shahi

doi:10.3390/en13236413

Abstract

In this work, a numerical model to study phase transition in unstructured packed beds of phase change particles for latent heat thermal energy storage is presented and implemented into the open-source CFDEM® coupling program. The governing equations for both fluid and solid particles are discussed. The presented model is validated using experimental data. The validated model is used to study the effect of bed structure (e.g., using multiple sizes of particles and mixing of multiple configurations of particles) on the charging and discharging of PCM bed. It is found that using smaller particles leads to faster charging and discharging of the bed. A decrease of 26% was achieved by changing half the bed into particles with half the diameter. Furthermore, it is observed that placing small particles downstream has more effect on increased charging speed than placing them upstream when charging the bed fully. A decrease of 20% in charging time and a decrease of 13% in discharging time were observed in the configurations that were tested.

Highlights

The share of renewable energy in total primary energy supply is on the rise with the need to move away from the dependency on fossil fuels and to reduce CO2 emissions
The outcome of this study provides detailed information that can be used by the designer to further optimize the phase change material (PCM) storage tank
To find the effect of particle size on Thermal Energy Storage (TES), Configurations I–IV are compared for a charging cycle

Summary

Introduction

The share of renewable energy in total primary energy supply is on the rise with the need to move away from the dependency on fossil fuels and to reduce CO2 emissions. The major problem of solar energy is the gap between peak power production and the peak power demand To bridge this gap, there is an urgent need for introduction of heat storage systems. When LHS is used, the storage medium undergoes phase change in the temperature range in which the storage system operates The advantage of this is that, for similar storage capacity, LHS offers a higher thermal energy storage density compared to SHS. Another advantage is that during phase change the temperature is constant, thereby allowing a constant temperature difference between heat transfer fluid (HTF) and energy storage material

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Conclusion