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- Creators: Phelan, Patrick
Description
Concentrated Solar Power and Thermal Energy Storage are two technologies that are currently being explored as environmentally friendly methods of energy generation. The two technologies are often combined in an overall system to increase efficiency and reliability of the energy generation system. A collaborative group of researchers from Australia and the United States formed a project to design solar concentrators that utilize Concentrated Solar Power and Thermal Energy Storage. The collaborators from Arizona State designed a Latent Heat Thermal Energy Storage system for the project. It was initially proposed that the system utilize Dowtherm A as the Heat Transfer Fluid and a tin alloy as the storage material. Two thermal reservoirs were designed as part of the system; one reservoir was designed to be maintained at 240˚ C, while the other reservoir was designed to be maintained at 210˚ C. The tin was designed to receive heat from the hot reservoir during a charging cycle and discharge heat to the cold reservoir during a discharge cycle. From simulation, it was estimated that the system would complete a charging cycle in 17.5 minutes and a discharging cycle in 6.667 minutes [1]. After the initial design was fabricated and assembled, the system proved ineffective and did not perform as expected. Leaks occurred within the system under high pressure and the reservoirs could not be heated to the desired temperatures. After adding a flange to one of the reservoirs, it was decided that the system would be run with one reservoir, with water as the Heat Transfer Fluid. The storage material was changed to paraffin wax, because it would achieve phase change at a temperature lower than the boiling point of water. Since only one reservoir was available, charging cycle tests were performed on the system to gain insight on system performance. It was found that the paraffin sample only absorbs 3.29% of the available heat present during a charging cycle. This report discusses the tests performed on the system, the analysis of the data from these tests, the issues with the system that were revealed from the analyses, and potential design changes that would increase the efficiency of the system.
ContributorsKocher, Jordan Daniel (Author) / Wang, Robert (Thesis director) / Phelan, Patrick (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Phase Change Material (PCM) plays an important role as a thermal energy storage device by utilizing its high storage density and latent heat property. One of the potential applications for PCM is in buildings by incorporating them in the envelope for energy conservation. During the summer season, the benefits are a decrease in overall energy consumption by the air conditioning unit and a time shift in peak load during the day. Experimental work was carried out by Arizona Public Service (APS) in collaboration with Phase Change Energy Solutions (PCES) Inc. with a new class of organic-based PCM. This "BioPCM" has non-flammable properties and can be safely used in buildings. The experimental setup showed maximum energy savings of about 30%, a maximum peak load shift of ~ 60 min, and maximum cost savings of about 30%. Simulation was performed to validate the experimental results. EnergyPlus was chosen as it has the capability to simulate phase change material in the building envelope. The building material properties were chosen from the ASHRAE Handbook - Fundamentals and the HVAC system used was a window-mounted heat pump. The weather file used in the simulation was customized for the year 2008 from the National Renewable Energy Laboratory (NREL) website. All EnergyPlus inputs were ensured to match closely with the experimental parameters. The simulation results yielded comparable trends with the experimental energy consumption values, however time shifts were not observed. Several other parametric studies like varying PCM thermal conductivity, temperature range, location, insulation R-value and combination of different PCMs were analyzed and results are presented. It was found that a PCM with a melting point from 23 to 27 °C led to maximum energy savings and greater peak load time shift duration, and is more suitable than other PCM temperature ranges for light weight building construction in Phoenix.
ContributorsMuruganantham, Karthik (Author) / Phelan, Patrick (Thesis advisor) / Reddy, Agami (Committee member) / Lee, Taewoo (Committee member) / Arizona State University (Publisher)
Created2010