New phase change material storage concept including metal wool as heat transfer enhancement method for solar heat use in industry

Abstract

Thermal energy storage is recognized as a key technology in the energy transition the world is facing today. But the main technical barrier this technology has to achieve wider deployment the low thermal conductivity of the materials used, the so-called phase change materials (PCM). This paper presents a new concept for thermal conductivity enhancement of a PCM tank using metal wool. Metal wool is one of the least studied method to enhance PCM thermal conductivity, while it has high potential to do so at a low cost. This study shows the experimental prototype that developed for the validation of the effective conductivity of the composite formed by NaNO3 salts and metal wool. The metal wool used is produced and arranged to ensure the right porosity and packaging to increase 300% the effective thermal conductivity of the mixture. The model validated confirms the movement of the fluid during the melting standardizes the temperature of the molten material, increasing the transference. The model also validates the new composite, with wool and NaNO3 as PCM, as one of the most promising materials to be used in applications that need heat to be stored at around 280-300 °C. Such applications include use of solar energy and waste heat in industry.

The research leading to these results has received funding from CDTI in the project Innterconecta Thesto (ITC-20111050). The work partially funded by the by the Ministerio de Ciencia, Innovación y Universidades de España (RTI2018-093849-B-C31 - MCIU/AEI/FEDER, UE). This work was partially funded by the Ministerio de Ciencia, Innovación y Universidades - Agencia Estatal de Investigación (AEI) (RED2018-102431-T). Dr. Cabeza would like to thank the Catalan Government for the quality accreditation given to her research group GREiA (2017 32 SGR 1537). GREiA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. This work is partially supported by ICREA under the ICREA Academia programme.