Low cost, eco-friendly, modified fly ash-based shape-stabilized phase change material with enhanced thermal storage capacity and heat transfer efficiency for thermal energy storage

Abstract

Owing to the high thermal capacity and nearly constant temperature during phase change, phase change material has been considered one of the most promising solar thermal energy storage materials. However, the development of high-performance shape-stabilized phase change material (SSPCM) based on a low-cost and eco-friendly supporting material remains a big challenge. Herein, a systematic experimental framework is proposed and used to respond to the challenge. By applying this framework, acid-modified fly ash (AMFA) was firstly used as the supporting material for lauric acid (LA) to prevent its leakage, while carbon nanotubes (CNTs) were utilized to improve its thermal conductivity. Specifically, the LA/AMFA/CNTs composites were synthesized via a facile and low-cost direct impregnation method. Subsequently, the as-prepared composites were systematically investigated by various characterization techniques. The results of leakage tests exhibited that the acid treatment could improve the PCM loading of fly ash and the relevant mechanism of acid-modified fly ash was identified. With the introduction of CNTs, the heat transfer efficiency of LA/AMFA/CNTs had been enhanced substantially. More importantly, compared with conventional supporting materials, the used fly ash in this work revealed much better environmental sustainability which we believe is of vital importance for the large-scale application of SSPCMs. Therefore, the study results not only facilitate the development of the desirable SSPCM based on cheap and eco-friendly supporting material and promote its practical application, but also serve to improve the comprehensive utilization level of fly ash solid waste. • Acid modification of fly ash was carried out to improve the latent heat of the SSPCM. • Mechanism of the latent heat enhancement was in-depth analyzed. • Heat transfer enhancement mechanism of the SSPCM was provided. • Sustainable assessment of the prepared SSPCM was performed.