PhD and Masters by research theses (SoE)
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Browsing PhD and Masters by research theses (SoE) by Supervisor "Badr, Ossama"
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Item Open Access Development of a cascaded latent heat storage system for parabolic trough solar thermal power generation(Cranfield University, 2014-09) Muhammad, Mubarak Danladi; Badr, Ossama; Yeung, HoiConcentrated solar power (CSP) has the potential of fulfilling the world’s electricity needs. Parabolic-trough system using synthetic oil as the HTF with operating temperature between 300 and 400o C, is the most matured CSP technology. A thermal storage system is required for the stable and cost effective operation of CSP plants. The current storage technology is the indirect two-tank system which is expensive and has high energy consumption due to the need to prevent the storage material from freezing. Latent heat storage (LHS) systems offer higher storage density translating into smaller storage size and higher performance but suitable phase change materials (PCMs) have low thermal conductivity, thus hindering the realization of their potential. The low thermal conductivity can be solved by heat transfer enhancement in the PCM. There is also lack of suitable commercially-available PCMs to cover the operating temperature range. In this study, a hybrid cascaded storage system (HCSS) consisting of a cascaded finned LHS and a high temperature sensible or concrete tube register (CTR) stages was proposed and analysed via modelling and simulation. Fluent CFD code and the Dymola simulation environment were employed. A validated CFD phase change model was used in determining the heat transfer characteristics during charging and discharging of a finned and unfinned LHS shell-and-tube storage element. The effects of various fin configurations were investigated and heat transfer coefficients that can be used for predicting the performance of the system were obtained. A model of the HCSS was then developed in the Dymola simulation environment. Simulations were conducted considering the required boundary conditions of the system to develop the best design of a system having a capacity of 875 MWhth, equivalent to 6 hours of full load operation of a 50 MWe power plant. The cascaded finned LHS section provided ~46% of the entire HCSS capacity. The HCSS and cascaded finned LHS section have volumetric specific capacities 9.3% and 54% greater than that of the two-tank system, respectively. It has been estimated that the capital cost of the system is ~12% greater than that of the two-tank system. Considering that the passive HCSS has lower operational and maintenance costs it will be more cost effective than the twotank system considering the life cycle of the system. There is no requirement of keeping the storage material above its melting temperature always. The HCSS has also the potential of even lower capital cost at higher capacities (>6 hours of full load operation).Item Open Access Development of a Hybrid Powerplant for Kuwait: The Simultaneous Production of Power, Fresh Water and Cooling(Cranfield University, 2010-03) Hussain, Hussain J.; Badr, OssamaThe harsh summer months of Kuwait combined with massive urbanisation projects, population growth and generous subsidies resulted in a rapid increase in electricity and freshwater consumption over the past 30 years. This led the government to invest heavily in large and capital intensive cogeneration powerplants that generate electricity via steam turbines and produce desalinated seawater through the utilisation of the multi-stage flash (MSF) desalination process. Air-conditioning (A/C) load accounts for about 70% of electric peak-load during summer. As a result, Kuwait consumes annually millions of barrels of oil and tons of natural gas that can be otherwise exported or saved for the future as a strategic commodity. The main objective of this research is to develop, model and recommend an optimum hybrid powerplant configuration and operation strategy for Kuwait that can simultaneously satisfy the demand for electricity, freshwater and cooling based on minimum fuel consumption. This is achieved by modelling and simulation of steam Rankine cycle, MSF water desalination and absorption refrigeration systems (ARSs) in Matlab to estimate their steam consumption. Reverse osmosis (RO) desalination and vapour-compression A/C are linked to the hybrid simulation program via their electricity consumption. Simulations show that during the hybrid configuration power-RO-AR is the most viable for Kuwait. During the winter months of January, February and December the optimum operation strategy with minimum fuel cost is the power-RO. On the other hand, operating the powerplant in the power-RO-AR hybrid mode during summer results in minimum fuel cost. The total annual fuel cost savings resulting from modifying the Doha West (DW) powerplant configuration and operation strategy are estimated to be about $363 million. This amounts to savings of about 8 million barrels of oil and 114 million m3 of natural gas per year. Furthermore, the payback period of hybridising the DW powerplant by adding RO desalination and AR system is one year with net savings of $127 million in the second year of operation.Item Open Access A Model for sustainable biomass electricity generation in Bangladesh(Cranfield University, 2005-09) Hossain, A. K. M. S.; Badr, OssamaBangladesh, where only 20% of the total population are connected to grid electricity, has a promising scope to utilise biomass for decentralised electricity generation. In this study, sustainable biomass electricity generation model was developed for the country, by combining tech no-econometric and optimisation modelling techniques. The developed model addresses the biomass generation and availability, feasible technologies, cost and efficiency correlations, economic plant size, plant economics and sensitivity, and environmental and social impacts. In 2003, the national total annual available biomass energy potential in Bangladesh varies from 183.848 to 223.776 TWh. The feasible technologies are: gasification based ICE-generator, anaerobic digestion based ICE-generator and direct combustion based steam turbine or Stirling engine-generator. Correlations of capital investment costs and overall conversion efficiencies with the plant electricity generating capacity have been developed. Direct combustion technology shows the highest electricity generation potential of 20.21 TWh/year; followed by gasification, of 14.30 TWh/year. Economic radius of biomass collection and size of the plants has been determined for maximum profitability. The biomass electricity plants economics have been estimated and compared with the diesel and dual-fuelled plants. Analysis shows that, anaerobic digestion and gasification-based electricity generation plants are economically feasible. Biomass electricity plant is highly sensitive to changes in biomass price, selling price of electricity, investment cost, plant lifetime, conversion efficiency and operating hours. The employment of the biomass electricity instead of diesel generator saves significant amount of the greenhouse gas emissions. It creates more employment than conventional and presents other socio-economic benefits as well. Due to the combination of electricity generation potential, promising economics and low greenhouse gas emissions; gasification-based biomass electricity plant is recommended for the country. Biomass availability and plant economics vary between districts to districts. Computer programmes have been developed for district wise biomass electricity plant analysis.