Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Engineering Science

Program

Mechanical and Materials Engineering

Supervisor

Straatman, Anthony G.

2nd Supervisor

Siddiqui, Kamran.

Co-Supervisor

Abstract

Latent heat thermal energy storage systems can capture and store solar thermal energy, enhancing the reliability of solar energy by facilitating a continuous and consistent energy supply. However, phase change materials used in these systems suffer from low thermal conductivities making it difficult to achieve suitable charging and discharging rates. The present research investigated this issue using computational and experimental approaches to improve the design of a thermal storage module through heat transfer enhancement. Various heat transfer enhancements including a finned honeycomb structure, and metal wool were incorporated into a thermal storage module to analyze their effect on charging and discharging rates. The findings revealed that a finned aluminum honeycomb structure was the most effective in enhancing the overall module performance as it promoted natural convection within small, localized cells which was determined to be extremely effective. The results presented in this study contribute to a deeper understanding of the optimal design for thermal storage modules.

Summary for Lay Audience

Global energy demand is on the rise, and currently, fossil fuels are the primary source of energy accounting for the majority of the world’s energy consumption. The burning of fossil fuels causes the release of greenhouse gases which trap heat in our atmosphere and cause an increase in global temperatures. In order to reduce the reliance on fossil fuels, there needs to be an increase in the use of renewable energy resources such as solar and wind energy. However, a major issue with these renewable energy sources is they are unreliable as a consistent source of energy due to their daytime-only availability and weather dependency. Thermal energy storage is a technology that can make renewable energy sources reliable by storing energy when it’s available so it can be supplied at any time when needed.

Some thermal energy storage systems store energy by changing the phase of the storage material from a solid to a liquid. These materials are called phase change materials (PCMs). Systems that make use of PCMs are beneficial as they can store large amounts of energy in a relatively small volume as they take advantage of the energy required to change the phase of the material from a solid to a liquid and vice versa. However, the main limitation of PCMs is that they have low thermal conductivities which means that they do not absorb or release heat quickly. This makes it difficult to design an efficient thermal energy storage system using phase change materials only.

The present research work focused on improving this type of thermal energy storage system by investigating ways to move heat into and out of the system faster. In order to accomplish this, computer simulations and physical experiments were conducted. Two different methods to improve the system performance were considered, which were the use of metal wool and metal extended surfaces or fins. The results of the study showed that a metal finned structure was the better method for improving the system compared to the metal wool.

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