Theses and Dissertations
This collection includes both ASU Theses and Dissertations, submitted by graduate students, and the Barrett, Honors College theses submitted by undergraduate students.
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- Creators: Phelan, Patrick
Description
Thermodynamic development and balance of plant study is completed for a 30 MW solar thermochemical water splitting process that generates hydrogen gas and electric power. The generalized thermodynamic model includes 23 components and 45 states. Quasi-steady state simulations are completed for design point system sizing, annual performance analysis and sensitivity analysis. Detailed consideration is given to water splitting reaction kinetics with governing equations generalized for use with any redox-active metal oxide material. Specific results for Ceria illustrate particle reduction in two solar receivers for target oxygen partial pressure of 10 Pa and particle temperature of 1773 K at a design point DNI of 900 W/m2. Sizes of the recuperator, steam generator and hydrogen separator are calculated at the design point DNI to achieve 100,000 kg of hydrogen production per day from the plant. The total system efficiency of 39.52% is comprised of 50.7% hydrogen fraction and 19.62% electrical fraction. Total plant capital costs and operating costs are estimated to equate a hydrogen production cost of $4.40 per kg for a 25-year plant life. Sensitivity analysis explores the effect of environmental parameters and design parameters on system performance and cost. Improving recuperator effectiveness from 0.7 to 0.8 is a high-value design modification resulting in a 12.1% decrease in hydrogen cost for a modest 2.0% increase in plant $2.85M. At the same time, system efficiency is relatively inelastic to recuperator effectiveness because 81% of excess heat is recovered from the system for electricity production 39 MWh/day and revenue is $0.04 per kWh. Increasing water inlet pressure up to 20 bar reduces the size and cost of super heaters but further pressure rises increasing pump at a rate that outweighs super heater cost savings.
ContributorsBudama, Vishnu Kumar (Author) / Johnson, Nathan (Thesis advisor) / Stechel, Ellen (Committee member) / Rykaczewski, Konrad (Committee member) / Phelan, Patrick (Committee member) / Wang, Robert (Committee member) / Arizona State University (Publisher)
Created2018
Description
Part of the AORA and LightWorks collaboration in utilizing exhaust heat for the AORA Tulip is the purpose to design a heat transport system that meets system requirements. The investigation included research in potential fluids, equipment, costs, and conducting an analysis to determine favorably fluids. The operating range of the system is 100℃ to 200℃ from the 270℃ exhaust heat 30 meters high. The best, affordable heat transfer fluids (HTF) for this operating temperature range are: XCELTHERM CA, XCELTHERM 600, XCELTHERM 315, Therminol 55, Paratherm NF, Water, Dynalene PG-XT, and Dynalene HC-20. These fluids consist of synthetic oils, mineral oils, propylene glycol, potassium formate/water-based, and water. The ideal operating temperature and HTF depends on the location, accessibility to these fluids, and load application for the heat transport system design. Furthermore, the cost of electricity in the area is a factor for whether the system should use a variable speed drive on the pump. Water is the ideal heat transfer fluid if the operating temperature doesn’t exceed 170℃ and can be readily maintained to avoid corrosion. It has the lowest initial cost and most favorable heat transfer characteristics. The potassium formate/water-based Dynalene HC is the next best choice if the operating temperature doesn’t exceed 210℃. It has similar heat transfer characteristics, but costs more. Lastly, if the operating temperature range exceeds 210℃, then XCELTHERM 600 (white oil) is likely the best HTF to use. It has an operating range up to 315℃, has favorable characteristics, the most affordable oil price, is food contact rated, and has one of the longest life of any fluid of its type.
ContributorsHickey, Andrew William (Author) / Phelan, Patrick (Thesis director) / Stechel, Ellen (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05