Date of Award

12-2021

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical and Civil Engineering

First Advisor

Hamidreza Najafi

Second Advisor

Troy Nguyen

Third Advisor

Gerald Micklow

Fourth Advisor

Ju Zhang

Abstract

In the United States, buildings account for a large share of the annual energy consumption, nearly 40%. Fossil fuels including coal, oil, and natural gas account for the main source of electric power generation and constitute the largest portion of the building energy consumption. Such a high level of fossil fuel consumption is a multifaceted challenge as demand for energy grows, and natural resources become scarce and expensive, while the climatic effects of massive energy use will be clearly felt by all. As a necessary component for occupants’ thermal comfort, cooling and air conditioning systems are among the largest energy end-users in buildings. Additionally, most air conditioning systems rely on using refrigerants that are harmful to the environment with considerable potential for ozone depletion and global warming. Hence, the design and development of clean and energy-efficient building cooling and heating systems are critical for a sustainable future. One of the alternatives proposed is thermoelectric technology. The thermoelectric (TE) modules do not require refrigerant which can be a considered as a solution that alleviates the environmental concerns. When supplied by DC electricity, TE modules produce a temperature gradient through the Peltier effect which in turn can be used for cooling or heating purposes. Because of the attractive characteristics that TE technology offers (controllability, lack of refrigerant and large moving parts, and quiet operation) TE-based radiant systems are becoming an emerging viable technology for building cooling/heating applications. TE-based radiant cooling technologies have recently been developed and tested through integrated and non-integrated systems in the building envelope. In the present dissertation, the feasibility of the TE-based radiant ceiling panel is investigated through analytical, numerical, and experimental studies. Initially, a numerical model of a ceiling panel with integrated TE modules was developed in COMSOL Multiphysics and the optimum number of TE modules was evaluated. An analytical model was then developed through energy balance equations and simulated in MATLAB to calculate the transient temperature variation in a hypothetical test chamber that uses a TE based radiant ceiling panel. The model is used to find the optimum input current required for the system to maintain an acceptable level of coefficient of performance (COP> 1.5). In the next step a numerical model of the full-scale test chamber was built in COMSOL and the impact of the radiant ceiling surface area and its temperature on the thermal comfort inside the chamber was thoroughly explored. The test chamber was then built and a series of experiments were conducted to validate the results that were generated through the model. The results from this study demonstrated that the TE-based radiant ceiling system has a high potential to be employed as an alternative to conventional cooling systems.

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