The world faces problems with depleting energy resources and the harmful impact of present energy consumption patterns on the environment, and consequently on the global climate and humanity. The concerns regarding global climate change are serious and have resulted in extensive research and developments on alternative, clean energy sources. While many of the available natural energy resources are limited due to their reliability, quality, quantity and density; nuclear energy has the potential to contribute a significant share of large scale energy supply without or little contributing to climate change. Hydrogen production via thermochemical water decomposition is one of the key potential processes for direct utilization of nuclear thermal energy. Thermochemical water splitting with a copper-chlorine (Cu-Cl) cycle is a promising process that could be linked with nuclear reactors to decompose water into its constituents, oxygen and hydrogen as a net result, through intermediate copper and chlorine compounds with a net input of water and heat. The process involves a series of closed-loop chemical reactions that does not contribute to any greenhouse gas emissions into the environment. Although some preliminary technical studies of the Cu-Cl cycle have been reported and some small lab scale experiments of individual reactions in the cycle have been carried out, there is still a need to link all the sub-steps of the cycle and build a pilot plant, to facilitate eventual commercialization. Such an experimental set up of overall cycle is lacking, especially to evaluate characteristics of the complete cycle such as energy, exergy and cost effectiveness. Simulation packages, such as Aspen Plus, are useful tools to provide the system designer or operator with design, optimization and operation information before building a pilot plant. In this thesis, process analysis is performed and simulation models are developed using the Aspen Plus simulation package, based on experimental work carried out at the University of Ontario Institute of Technology (UOIT), the Argonne National Laboratory (ANL), the Atomic Energy of Canada Limited (AECL) and other sources. The energy and mass balances, stream flows and properties, the heat exchanger duties and shaft work are calculated. Heat recovery options are assessed to improve thermal management and hence overall efficiency of the Cu-Cl cycle. An integrated heat exchange network is designed to use heat from the process streams efficiently and decrease the external heat demand. The efficiency of the process, based on three, four and five-step cycles, is examined in this thesis. The thermal efficiency of the five-step thermochemical process is calculated as 44%, of the four-step process is 43% and of the three-step process is 41%, based on the lower heating value of hydrogen. Sensitivity analyses are performed to study the effects of various operating parameters on the efficiency, yield, and cost. A parametric study is conducted, and possible efficiency improvements are discussed. The manner is investigated in which exergy-related parameters can be used to minimize the cost of a Cu-Cl thermochemical cycle for hydrogen production. The iterative optimization technique presented requires a minimum of available data and provides effective assistance in optimizing thermal systems, particularly in dealing with complex systems and/or cases where conventional optimization techniques cannot be applied. The principles of thermoeconomics, as embodied in the specific exergy cost (SPECO) and exergy-cost-energy-mass (EXCEM) methods, are used here to determine changes in the design parameters of the cycle that improve the cost effectiveness of the overall system. It is found that the cost rate of exergy destruction varies between $1 and $15 per kilogram of hydrogen produced; and the exergoeconomic factor between 0.5 and 0.02 as the cost of hydrogen rises from $2.8 to $20 per kg of hydrogen produced. The hydrogen cost is inversely related to the exergoeconomic factor, plant capacity and energy/exergy efficiencies. Based on the cycle’s design parameters and conditions the hydrogen production cost is calculated as $3.8/kg hydrogen. Also, an integrated Cu-Cl cycle hydrogen production system, based on nuclear and renewable energy sources, is investigated. Nuclear and renewable energy sources are reviewed to determine the most appropriate option to couple with the Cu-Cl cycle. An environmental impact assessment is conducted and compared to the conventional methods using fossil fuels and other options. Some cost assessment studies of hydrogen production are presented for this integrated system. The results show that hydrogen production cost could drop down to as low as 2.8 $/kg. The results are expected to assist ongoing efforts to increase the economic viability of the Cu-Cl cycle, and to reduce product costs of potential commercial versions of this process. / UOIT

Hydrogen is known as a clean energy carrier which has the potential to play a major role in addressing the climate change and global warming, and thermochemical water splitting via the copper-chlorine cycle is a promising method of hydrogen production. In this research, thermal management of the copper-chlorine cycle for hydrogen production is investigated by performing analytical and experimental analyses of selected heat recovery options. First, the heat requirement of the copper-chlorine cycle is estimated. The pinch analysis is used to determine the maximum recoverable heat within the cycle, and where in the cycle the recovered heat can be used efficiently. It is shown that a major part of the potential heat recovery can be achieved by cooling and solidifying molten copper(I) chloride exiting one step in the cycle: the oxygen reactor. Heat transfer from molten CuCl can be carried out through direct contact or indirect contact methods. Predictive analytical models are developed to analyze a direct contact heat recovery process (i.e. a spray column) and an indirect contact heat recovery process (i.e. a double-pipe heat exchanger). Characteristics of a spray column, in which recovered heat from molten CuCl is used to produce superheated steam, are presented. Decreasing the droplet size may increase the heat transfer rate from the droplet, and hence decreases the required height of the heat exchanger. For a droplet of 1 mm, the height of the heat exchanger is predicted to be about 7 m. The effect of hydrogen production on the heat exchanger diameter was also shown. For a hydrogen production rate of 1000 kg/day, the diameter of the heat exchanger is about 3 m for a droplet size of 1 mm and 2.2 m for a droplet size of 2 mm. The results for axial growth of the solid layer and variations of the coolant temperature and wall temperature of a double-pipe heat exchanger are also presented. It is shown that reducing the inner tube diameter will increase the heat exchanger length and increase the outlet temperature of air significantly. It is shown that the air temperature increases to 190oC in a heat exchanger with a length of 15 cm and inner tube radius of 10 cm. The length of a heat exchanger with the inner tube radius of 12 cm is predicted to be about 53 cm. The outlet temperature of air is about 380oC in this case. The length of a heat exchanger with an inner tube diameter of 24 cm is predicted to be about 53 cm and 91 cm for coolant flow rates of 3 g/s and 4 g/s, respectively. Increasing the mass flow rate of air will increase the total heat flux from the molten salt by increasing the length of the heat exchanger. Experimental studies are performed to validate the proposed methods and to further investigate their feasibility. The hazards involving copper(I) chloride are also investigated, as well as corresponding hazard reduction options. Using the reactant Cu2OCl2 in the oxygen production step to absorb CuCl vapor is the most preferable option compared to the alternatives, which include absorbing CuCl vapor with water or CuCl2 and building additional structures inside the oxygen production reactor. / UOIT

Nuclear-based hydrogen production via thermochemical water decomposition using a copper-chlorine cycle consists of a series of chemical reactions that split water into hydrogen and oxygen. This is accomplished through reactions involving intermediate copper and chlorine compounds, which act as catalysts that are recycled in the process. In this thesis, analytical and numerical solutions are developed to predict the behaviour of aqueous cupric chloride droplets in a solution undergoing spray-drying in the Cu-Cl cycle. The aqueous CuCl2 is present as a slurry within the cycle, which will later generate oxygen and hydrogen as a net result. The efficiency of the cycle can be increased by utilizing low-grade waste heat from any industrial source or nuclear power plant to assist in the drying process. There are many different methods employed in industry for drying of solutions. Each method has its own advantages and disadvantages, depending on the application and conditions. In this thesis, analytical correlations of heat and mass transfer are developed for the aqueous solution, subject to various drying conditions. The analysis is performed for moist air in contact with a sprayed aqueous solution of CuCl2(2H2O). Validation of the model is performed by comparisons with experimental results obtained from a Niro-spray dryer for CuCl2 and previous experimental and theoretical data for different fluids, on the basis of non-dimensional analysis. / UOIT

The SuperCritical Water-cooled nuclear Reactor (SCWR) is one of six Generation-IV nuclear-reactor concepts currently being designed. It will operate at pressures of 25 MPa and temperatures up to 625°C. These operating conditions make a SuperCritical Water (SCW) Nuclear Power Plant (NPP) suitable to support thermochemical-based hydrogen production via co-generation. The Copper-Chlorine (Cu‒Cl) cycle is a prospective thermochemical cycle with a maximum temperature requirement of ~530°C and could be linked to an SCW NPP through a piping network. An intermediate Heat eXchanger (HX) is considered as a medium for heat transfer with operating fluids selected to be SCW and SuperHeated Steam (SHS). Thermalhydraulic calculations based on an iterative energy balance procedure are performed for counter-flow double-pipe design concept HXs integrated at several locations on an SCW NPP coolant loop. Using various test cases, design and operating parameters are recommended for detailed future research. In addition, predicted effects of heat transfer enhancement on HX parameters are evaluated considering theoretical improvements from helically-corrugated HX piping. The effects of operating fluid pressure drop are briefly discussed for applicability in future studies. / UOIT