Thermal Energy Storage Using a Hybrid Composite Based on Technical-Grade Paraffin-AP25 Wax as a Phase Change Material

Abstract

Thermal energy storage (TES) has a strong ability to store energy and has attracted interest for thermal applications such as hot water storage. TES is the key to overcoming the mismatch between energy supply and demand by using phase change materials (PCMs). However, a common organic PCM characteristic is low thermal conductivity. This causes a slow thermal response for paraffin-AP25, which is not suitable for many applications. Hence, a search is underway for modifications to enhance its thermal properties. Thus, the current investigation introduces a novel PCM system based on the use of waste material as an economic and efficient system. In the current investigation, nanoparticles were added to a PCM; specifically, a technical-grade paraffin-AP25 wax (AP25 wax)/hybrid composite was synthesized via ultrasonic dispersion. The focus of this investigation is to assess the behavior of a PCM for energy storage via charging (melting process) and discharging (solidification process). Nanoparticles of magnetite were prepared via a simple, cost-efficient route, co-precipitation, augmented with aluminum and silicon derived from waste streams from a hydrothermal facility and mixed with paraffin-AP25 wax to form a hybrid composite PCM. Transmission electron microscopy and scanning electron microscopy (augmented with dispersive X-ray analysis, EDX) micrographs, in addition to X-ray diffraction (XRD), show the prepared composite. Different mass fractions of the composite, ranging from 1 to 10 weight %, were embedded in a paraffin-AP25 phase change material. The latent heat storage capacity of the PCM was enhanced by 8% when paraffin-AP25 was applied. Finally, the overall system efficiency was evaluated, and the yield increased by 64% for the 8% hybrid composite.

Keywords

• thermal energy storage (TES)
• phase change materials (PCM)
• composite
• water heating