Browsing by Author "AlZahrani, Abdullah"

Now showing 1 - 2 of 2

Development and analysis of a solar-based integrated system with a CO2 Rankine power cycle
(2013-10-01) AlZahrani, Abdullah; Dincer, Ibrahim
The current work is a thermodynamic-based design and analysis of a solar-based integrated system for power production. In this regards, a reheat supercritical carbon dioxide (S-CO2) Rankine cycle is proposed. This cycle is then integrated with a parabolic trough collector (PTC) solar field, a thermal energy storage system and an absorption refrigeration system (ARS). A parametric study is then conducted, involving energy and exergy analyses of each subsystem and the overall integrated system. The system performance under different operating conditions is evaluated through energy and exergy efficiencies as well as energy and exergy based coefficients of performance (COP) for the absorption system. The heat energy losses and exergy destruction rates are also evaluated for different components. The effects of changing some radiation properties and operating conditions on the performance of the PTC solar field are investigated. This includes beam radiation incidence angle, receiver emittance and glass cover emittance. In addition, the impacts of changing these parameters on the overall integrated system energy and exergy efficiencies are illustrated. The energy and exergy efficiencies of the PTC are found to be 66.35% and 38.51%. The energy and exergy efficiencies of the reheat S-CO2 Rankine power cycle are examined under various operating conditions of the concentrated solar power (CSP) plants. The exergy destruction rates through the cycle components are determined and evaluated. The results show that the S-CO2 Rankine power cycle is expected to achieve energy and exergy efficiencies of 31.6%, and 57.5%, respectively. Under the same operating conditions, the energetic COP for ARS is about 0.7 and the exergetic COPex is 0.27. Accordingly, the overall integrated system energy (heat-to-electric) and exergy efficiencies become 11.73%, and 12.36%, respectively.
Investigation of a novel high temperature solid oxide electrolyzer for solar hydrogen production
(2017-04-01) AlZahrani, Abdullah; Dincer, Ibrahim
This thesis proposes and investigates a new generation of photoelectrochemical cells for solar hydrogen production based on high temperature Solid Oxide Electrolysis Cells. Therefore, a set of experiments are designed to develop and select the most promising materials and configurations. Furthermore, the study includes a design of a novel testing station built to accommodate the various parameters to be tested in order to assess the performance of the proposed Photoelectrochemical Solid Oxide Cell (PSOC). As part of the design process, a material survey was conducted to screen potential semiconductors that are capable of operating at high temperatures. Subsequently, promising materials are selected and applied through specific chemical processes which can provide the required structure and surface properties. The material processing strategies to develop a light absorbing surface are made on commercial button cells; which has been tested and its performance is well-characterized under different operating conditions. Thus, improvements brought about by the developed photoactive layer can be detected under different types of light. The research further includes the thermodynamic and electrochemical modeling of a Solid Oxide Electrolysis Cell (SOEC). In this regard, the energy and exergy aspects of a single cell performance, as well as the performance of Solid Oxide Electrolysis (SOE) stack, are investigated. The exergoeconomic aspects of utilizing SOE plant at a large-scale is also considered through a detailed exergoeconomic analysis. Last, the models are used to examine the SOE performance sensitivity to variation in operating parameters and conduct an exergetic optimization to highlight the trade-offs between economic and technical performance optimums. In addition, the integration of SOE in solar tower power plant for hydrogen production is examined considering continuous operating by using thermal energy storage and a high efficiency supercritical carbon dioxide (S-CO2) power cycle. The findings of this thesis are expected to make a new solar hydrogen production pathway that is efficient, environmentally friendly, and in near-future expected to be economically competitive.