Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Cho, Heejin

Committee Member

Knizley, Alta

Committee Member

Mago, Pedro J.

Committee Member

Bhushan, Shanti

Date of Degree

5-3-2019

Original embargo terms

Worldwide

Document Type

Dissertation - Open Access

Major

Mechanical Engineering

Degree Name

Doctor of Philosophy

College

James Worth Bagley College of Engineering

Department

Department of Mechanical Engineering

Abstract

In this dissertation, an increased thermal capacitance (ITC) and thermal storage management (TSM) system was simulated to reduce building energy consumption, specifically energy related to heating, cooling and domestic hot water. An increased thermal capacitance allows phase shift and amplitude reduction of heat flow fluctuations associated with the building’s internal temperature response due to weather. An adaptive allocation and control of the added capacitance through TSM significantly improves the benefits of the extra capacitance. This dissertation was conducted in three parts: (1) a first-order analysis of the ITC/TSM applied to a micro-building; (2) a transient simulation of the ITC/TSM with PCM implementation for tank volume control; and (3) a parameter study on the ITC/TSM system with added complexities such as the inclusion of DHW and a multiple story residential building. The first-order analysis was used for transient simulation comparison, as simple models are much more suitable for real time implementation in actual control systems. A first order study on a small residential building is also used to establish the merit of the ITC/TSM concept before integrating into a more complex analysis. This study determined that the ITC/TSM could potentially provide savings but required a very large thermal mass. The ITC/TSM system was then coupled with phase change materials (PCMs), which enable thermal energy storage volume reduction. The transient energy modeling software, TRNSYS, is used to simulate the building’s thermal response and energy consumption, as well as the ITC/TSM system and controls. Four temperature-controlled operating regimes are used for the ITC/TSM operations: building shell circulation, heat exchanger circulation, solar panel circulation, and storage. After this, 125 simulations were conducted to design and optimize the ITC/TSM. The three parameters of interest were: tank volume size, solar panel size, and mass flowrate. Domestic hot water usage was also included as another energy savings opportunity. Results for the parameter study showed that savings are optimized when the solar panel and the hot water tank are size together. If they are not sized simultaneously, the temperature of the large thermal capacitance is not adequately controlled. For all simulations conducted in the parameter study, the building energy usage was reduced significantly.

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