Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Engineering Science

Program

Mechanical and Materials Engineering

Supervisor

Straatman, A

Abstract

This thesis examines the effects of various heat transfer enhancement elements on the melting and solidification times of PCM within a thermal energy storage module. Physical experiments and computational investigations were conducted to understand how mass flow rate and heat transfer element geometry affected the melting and solidification times of the PCM Octadecane. Radial, square, and plate fin elements were investigated, along with an AI generated gyroid structure. The findings revealed that minimizing the regions of thick PCM led to the quickest charge and discharge times of the module and suggest that higher heat transfer element to PCM ratios must be utilized in thermal energy storage systems to accelerate their charge and discharge times. The results presented in this study contribute to the overall understanding of designing an effective and economically friendly thermal energy storage module.

Summary for Lay Audience

Global energy demand is increasing, while the current supply of fossil fuels, a heavily relied upon energy resource, is depleting. To reduce the reliance on fossil fuels, renewable energy resources, such as solar energy, must be utilized. However, renewable resources are unreliable and have intermittent natures, and their peak generation times occur at unfavorable hours. These challenges can be overcome with the implementation of energy storage systems. These systems can store energy so it can be supplied when needed.

Thermal energy storage is a promising technology that stores energy in the form of heat. Thermal energy storage has gained popularity due to phase change materials (PCMs), which are materials that are able to store large amounts of energy in a small amount of volume, due to their latent heat capabilities. However, the limitation of using PCMs is that they have low thermal conductivity, so their ability to melt and solidify, and therefore, charge and discharge a module, is hindered.

The present research examines the effect of different finned heat transfer elements on the melting and solidification of PCMs to be used in a thermal energy storage module in residential applications. To accomplish this, physical experiments and computer simulations were conducted. Five different methods to improve the heat transfer performance were considered: two different spacings of circular finned tubes, square finned tubes, plate finned tubes, and an AI generated gyroid structures. The results of the study showed that large metal plate fin structures were a better method for improving the system performance and resulted in the quickest melting and solidification times of the PCM.

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