Numerical and Experimental Investigation of Wire Cloth Heat Exchanger for Latent Heat Storages

Sebastian Gamisch,Stefan J. Rupitsch,Stefan Gschwander

doi:10.3390/en14227542

Sebastian Gamisch, Stefan J. Rupitsch + Show 1 more

Open Access

https://doi.org/10.3390/en14227542

Copy DOI

Abstract

Latent thermal energy storages (LTES) offer a high storage density within a narrow temperature range. Due to the typically low thermal conductivity of the applied phase change materials (PCM), the power of the storages is limited. To increase the power, an efficient heat exchanger with a large heat transfer surface and a higher thermal conductivity is needed. In this article, planar wire cloth heat exchangers are investigated to obtain these properties. They investigated the first time for LTES. Therefore, we developed a finite element method (FEM) model of the heat exchanger and validated it against the experimental characterization of a prototype LTES. As PCM, the commercially available paraffin RT35HC is used. The performance of the wire cloth is compared to tube bundle heat exchanger by a parametric study. The tube diameter, tube distance, wire diameter and heat exchanger distance were varied. In addition, aluminum and stainless steel were investigated as materials for the heat exchanger. In total, 654 variants were simulated. Compared to tube bundle heat exchanger with equal tube arrangement, the wire cloth can increase the mean thermal power by a factor of 4.20 but can also reduce the storage capacity by a minimum factor of 0.85. A Pareto frontier analysis shows that for a free arrangement of parallel tubes, the tube bundle and wire cloth heat exchanger reach similar performance and storage capacities.

Highlights

One of the main drawbacks of phase change materials (PCM) is the low thermal conductivity limiting the heat transfer and the thermal power of latent heat storages [1]. This can be compensated by an efficient heat exchanger immersed in the PCM, which is passed by a conventional heat transfer fluid (HTF)
We evaluated the performance of the wire cloth heat exchanger in comparison to a tube bundle heat exchanger without wire cloth
We evaluated planar wire cloth heat exchanger for the application in Latent thermal energy storages (LTES) with the Paraffin RT35HC as PCM

Summary

Introduction

The main drawback is the implied temperature change of the storage material during operation leading to reduced process efficiency. Latent thermal energy storages (LTES) overcome this drawback by phase change materials (PCM) as storage material. One of the main drawbacks of PCM is the low thermal conductivity limiting the heat transfer and the thermal power of latent heat storages [1]. This can be compensated by an efficient heat exchanger immersed in the PCM, which is passed by a conventional heat transfer fluid (HTF). The heat exchanger requires a high thermal conductivity and heat transfer surface area within the PCM volume

Methods

Results

Discussion

Conclusion