MS, University of Cincinnati, 2021, Engineering and Applied Science: Mechanical Engineering

In effort to both save operating expenses and be environmentally friendly, thermal energy storage provides a means for companies to handle daytime HVAC requirements while using off-peak (nighttime) electrical power. This paper sets out to compare three of the most common techniques used for thermal energy storage, by comparing both the analytical modeling of their energy storage and actual experimental data for their energy storage, using the same exact test apparatus for each of the techniques. The results of this experiment show that using normal HVAC temperatures, sensible water chilled to its maximum value after only about two hours, while PCM would take nearly six hours to achieve “linkage,” or solidified material merging between the helix coils. Ice building, done with -7° coolant, took 4.5 hours to achieve linkage. Initial heat transfer was proportional to the difference between initial tank temperature and the coolant temperature, and went asymptotically towards zero for sensible as the temperature of the tank and coolant reach equilibrium. For ice, the heat transfer rate was always more than twice that of PCM during latent storage, which is attributed to the difference between coolant temperatures and freezing points for the respective materials. Sensible water cooldown would require 232.8% of the tank volume to store the same energy relative to the environment compared to ice building, and 126.3% of the tank volume compared to phase change material. This is to be weighed with the benefit of using existing HVAC condensing units to chill the water, and the fact that water itself is inexpensive. The high latent heat of freezing for water meant it held more energy than both the water sensible cooldown and PCM freezing, but with the downside of requiring medium temperature condenser units in order to be efficient (instead of the high temperature units used in typical HVAC). After 4.5 hours, PCM would surpass the energy stored in the same volume as water sensi (open full item for complete abstract)

Committee: Michael Kazmierczak Ph.D. (Committee Chair); Ahmed Elgafy Ph.D. (Committee Member); Sang Young Son Ph.D. (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 1984, Graduate School

Committee: Not Provided (Other) Subjects: Agriculture

Doctor of Philosophy (PhD), Ohio University, 2007, Chemistry (Arts and Sciences)

Despite extraordinary advances in heart transplantation during the last decade, little work has been completed in effective long-term organ preservation storage during the time between donor and recipient. Based on U.S. transplantation data, approximately 3,000 are on the waiting list for possible heart transplants and less than half of these people will receive transplants. The shortage of quality transplant organs is a major problem, especially for recipients waiting for hearts. In addition, cardiovascular disease is the number one killer of people, obviously, leaving the heart from those deaths unfeasible for transplantation. The goal of this research was to develop and optimize a solution for long-term heart preservation suitable for transplantation. There are many factors that affect the tissue after removal. Cold preservation causes ischemia, which puts the tissue under extreme biochemical stress. A lack of O2 in the stored tissues causes a change from aerobic to anaerobic metabolism, which triggers ischemic injury. The negative affects caused by cold storage must be remedied by the storage solution. Supporting the L-arginine/NO/ONOO- pathway and maintaining a proper NO/ONOO- ratio is essential for keeping endothelial functional. The solution has to maintain the L-arginine/NO/ONOO- pathway during storage time and during transplantation. This research elucidated the L-arginine/NO/ONOO- pathway during heart preservation and how the pathway changes with standard cold storage solutions (University of Wisconsin solution, Celsior solution, and Hepes buffer). The factors which can affect the L-arginine/NO/ONOO- pathway were examined (gender, eNOS co-factors and activators, and NO pre-cursors). The cardio-protective effects of adding L-arginine, NADH, sepiapterin, sildenafil, and BH4 were developed and evaluated utilizing nanomedical sensors for the detection and quantification of NO and ONOO-. Western blot analyses were utilized to give insight into the changes of eN (open full item for complete abstract)

Committee: Tadeusz Malinski (Advisor) Subjects: Chemistry, Analytical