Date of Award
Doctor of Philosophy (PhD)
For long-term presence on the lunar surface, a reliable and efficient power source is required. A novel thermodynamic bottoming cycle which utilizes ammonia and water—the Kalina Cycle—is evaluated for use on the lunar surface. Terrestrial utilization of the Kalina Cycle shows higher efficiencies at lower temperatures and more compact packaging when compared to some other solar-powered systems. The research question is, "Can an ammonia-water thermodynamic cycle have benefits over other proposed power generation schemes on the lunar surface?" To analyze this question, an analysis of alternatives is performed which evaluates the Kalina Cycle against previously analyzed lunar power systems. Eight steps based on the Simple Multi-attribute Rating Technique (SMART) are taken leveraging requirements development of standard space systems engineering processes. The results of this analysis have six top level functional requirements with associate performance requirements. In addition to the functional, performance, and human factor requirements, ten operational scenario variants give the bounding scenarios for which system architectures can be compared. Using the requirements, candidate ammonia-waterer thermodynamic architectures for the task of providing power for a growing lunar base are developed and analyzed. The candidate architectures thermodynamic size and efficiencies are modeled using Engineering Equation Solver (EES) and Microsoft Excel. The data developed from the thermodynamic analysis provide the economic analysis data to use for comparison. The candidate system’s mass at launch, component expenses, life cycle costs, reliability, and monetary impacts of power production expansion are compared. The study determined that a Kalina cycle can provide some economic benefit in select situations and scenarios. A Kalina cycle system has lower estimated launch costs than a photovoltaic system for medium size bases at the lunar equator, but not at the lunar pole. Compared to a Brayton cycle, a Kalina cycle requires a smaller thermal heat sink due to higher system thermodynamic efficiencies across a variety of operating temperatures. A smaller heat sink equals lower launch and equipment costs. A nuclear-powered thermodynamic system has lower costs for medium and large size power demands. The benefit that a Kalina-cycle system has over a nuclear-powered system is heat source life and safety. A nuclear-powered system only lasts 12-15 years before needing a new nuclear core. If a base has a lifespan which lasts decades, the estimated launch costs mount for nuclear systems. In summary, an ammonia-water thermodynamic power scores higher than competing systems in select scenarios at the lunar equator, not the lunar pole.
Harris, Jeremy David, "Ammonia/Water Thermodynamic Cycle For Lunar Power Applications" (2021). Theses and Dissertations. 4075.