Heat Transfer Enhancement of Phase Change Materials for Thermal Energy Storage Systems
Abstract
In recent studies, the energy storage capability of phase change materials
(PCMs) in thermal energy storage systems, such as in the case of solar water
heaters has attracted many attentions; however, PCMs may not be fully effective
due to their poor heat transfer characteristics, namely thermal conductivity. This
study aims to explore the thermal performance of heat transfer materials to be
applied in conjunction with PCMs. The selected types of PCMs are paraffin waxes
with melting point temperatures of 28-72◦C.
In an effort to study both convective and conductive heat transfer enhancement the experimental analysis has been divided into two phases. In the
first analysis, silicone oil is selected as a heat transfer medium to be used with
the PCMs to establish convective heat transfer enhancement. The melting point,
latent heat and specific heat capacity were measured by a differential scanning
calorimeter (DSC). The obtained results show that silicone oil will lead to melting point depression of maximum 3◦C in the PCMs. In the second analysis, the
conductive heat transfer enhancement by addition of nanoparticles has been investigated. The selected nanoparticles for this analysis are Aluminum Oxide
(Al2O3), Cupric Oxide (CuO), Titanium Oxide (TiO2) and Multi-Walled Carbon
Nanotubes (MWCNT). The nanoparticles displayed capabilities of increasing the
specific heat capacity by up to 46.15%. The micro-structure of the nano-enhanced
PCMs was analyzed using SEM technology to observe the effectiveness of the
dispersion process of the nanoparticles into the PCM.
The obtained results from this study show thermal performance improvement of PCMs, which is expected to lead to overall efficiency improvement in
thermal energy storage systems.
Table of Contents
Introduction -- Phase change materials -- Thermal analysis methods -- Phase I: Convective heat transfer enhancement -- Phase II: Conductive heat transfer enhancement -- Scanning electron microscopy -- Conclusion -- Future work -- Appendix A. Thermodynamic properties of n-alkanes -- Appendix B. Instrument parameters
Degree
M.S. (Master of Science)