Fabrication and Thermal Properties of Capric Acid/Calcinated Iron Tailings/Carbon Nanotubes Composite as Form-Stable Phase Change Materials for Thermal Energy Storage

Peng Liu,Zhikai Zhang,Jun Rao,Liang Bian,Jianping Shi,Xiaobin Gu

doi:10.3390/min9110648

Abstract

In this study, a novel form-stable phase change material (FSPCM) consisting of calcination iron tailings (CIT), capric acid (CA), and carbon nanotubes (CNT) was prepared using a simple direct melt impregnation method, and a series of tests have been carried out to investigate its properties. The leakage tests showed that CA can be retained in CIT with a mass fraction of about 20 wt.% without liquid leakage during the phase change process. Moreover, the morphology, chemical structure, and thermal properties of the fabricated composite samples were investigated. Scanning electron microscope (SEM) micrographs confirmed that CIT had a certain porous structure to confine CA in composites. According to the Fourier transformation infrared spectroscope (FTIR) results, the CA/CIT/CNT FSPCM had good chemical compatibility. The melting temperature and latent heat of CA/CIT/CNT by differential scanning calorimeter (DSC) were determined as 29.70 °C and 22.69 J/g, respectively, in which the mass fraction of CIT and CNT was about 80 wt.% and 5 wt.%, respectively. The thermal gravity analysis (TGA) revealed that the CA/CIT/CNT FSPCM showed excellent thermal stability above its working temperature. Furthermore, the melting and freezing time of CA/CIT/CNT FSPCM doped with 5 wt.% CNT reduced by 42.86% and 54.55% than those of pure CA, and it showed better heat transfer efficiency. Therefore, based on the above analyses, the prepared CA/CIT/CNT FSPCM is not only a promising candidate material for the application of thermal energy storage in buildings, but it also provides a new approach for recycling utilization of iron tailings.

Highlights

In recent years, the environmental issue and the energy crisis are driving people to develop renewable energy
This study aims to fabricate an form-stable phase change material (FSPCM) with an appropriate phase change temperature, good thermal conductivity, and high heat latent, which could be used in the intelligent temperature control of buildings
calcination iron tailings (CIT) was used as the supporting material to prevent the liquid leakage of capric acid (CA) and

Summary

Introduction

The environmental issue and the energy crisis are driving people to develop renewable energy. The sharp unbalance contradiction of energy supply and demand makes it urgent to develop energy storage technology to store the renewable energy [1,2]. Thermal energy storage (TES) as an efficient and clean method can improve energy utilization efficiency and ease the contradiction between energy supply and demand [2]. In the TES technologies, the latent heat storage using phase change materials (PCMs) was considered to be one of the promising solutions due to their many advantages such as high energy storage density, nearly constant temperature during thermal energy storage, etc. According to the phase change process, PCMs can be divided into solid-liquid, solid-solid, solid-gas, and liquid-gas categories [19]

Objectives

Results

Conclusion