Doctoral Dissertations (FEAS)

Permanent URI for this collectionhttps://hdl.handle.net/10155/401

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Analysis of the thermal hydraulics of a multiphase oxygen production reactor in the Cu-Cl cycle
(2016-06-01) Abdulrahman, Mohammed W.; Agelin-Chaab, Martin; Wang, Zhaolin
In the thermochemical water splitting process by Cu-Cl cycle, oxygen gas is produced by an endothermic thermolysis process in a three-phase reactor. In this thesis, the required heat for the thermolysis process is provided by adopting the idea of heating some of the stoichiometric oxygen gas by using a nuclear reactor heat source. Then, the gas is re-injected into the reactor from the bottom, to transfer heat directly to the slurry bed of molten salt and solid reactant. In this thesis, the thermal hydraulics of the oxygen slurry bubble column reactor (SBCR) is investigated experimentally and numerically. In the experiments, lower temperature alternative materials, such as helium gas at 90°C and water at 22°C, are used to mimic the actual materials of the oxygen gas at 600°C and molten CuCl at 530°C. From the experimental studies, new forms of empirical equations are formulated for the overall gas holdup and the volumetric heat transfer coefficient in terms of the design and input parameters of the SBCR, such as; the superficial gas velocity, reactor height, and solid particles concentration. The empirical equations are obtained for both bubbly and churn-turbulent flow regimes. It is also determined experimentally the flow regime transition point between bubbly and churn-turbulent flow regimes. Furthermore, it is found experimentally that the solid particle diameter has insignificant effect on the overall gas holdup. To better understand the thermal hydraulics of the oxygen SBCR, a computational fluid dynamics (CFD) models are developed by using the ANSYS FLUENT software. All CFD simulation results are validated by the experimental results of the alternative materials system with good agreements. From the CFD simulations, it is also found that the gas temperature decreases dramatically near the bottom of the reactor, and the effects of the superficial gas velocity, reactor height, and solid concentration on the gas temperature are negligible. Finally, a simple correlation is obtained to calculate the number of oxygen reactors in terms of the superficial gas velocity of the oxygen gas and the oxygen production rate.
Design and investigation of renewable natural gas and methane production systems
(2024-04-01) Bolt, Andre; Dincer, Ibrahim; Agelin-Chaab, Martin
This thesis presents the design and investigation of renewable natural gas and methane production systems. The thesis comprises a theoretical and an experimental portions. The experimental portion of the thesis includes the design, construction, and experimental testing of a new helical fixed-bed reactor, as well as a production system to support and monitor the reactor. Additionally, the experimental system integrates gas bending and the recycling of the coolant working fluid to pre-heat the reactant molecules prior to entering the reactor. The experimental tests include studying the effects of pressure variability at the inlet of the reactor, variations in the reactor starting temperature, and variations in the mole ratio between reactants. Most notably, the system is able to achieve a maximum CH4 production rate of 10.61 L/h. This equates to overall energy and exergy efficiencies of 13.36% and 12.46%, respectively. However, during the simulation aspect of the thesis, computational fluid dynamics (CFD) analyses are conducted. These analyses consider the design of four unique fixed-bed natural gas reactor concepts. Additionally, each of the reactor concepts is presented as having three unique configurations. The analyses show that Concept 4’s helical reactor design presents the greatest potential to mitigate elevations in the reactors’ temperature due to more of its surface area being exposed compared to the other reactor concepts. Additionally, Configuration 1 of Concept 4 is able to achieve a yield of 86.7%. The theoretical portion also investigates four novel multigeneration systems capable of synthesizing natural gas while simultaneously producing several useful outputs. System 1 considers a target location of Alberta, Canada, and uses biomass and solar energy as its source. The system achieves energy and exergy efficiencies of 61.0% and 28.6%, respectively, during heating mode. The other three multigeneration systems reduce CO2 emissions from industries that produce substantial amounts of greenhouse gas emissions (cement, steel, and glass industries), through the integration of chemical absorption techniques, the CO2 that is extracted can be used to synthesize CH4 renewably. These systems also harness solar, wind, hydro, and tidal as the energy sources.
Development and analysis of thermal management strategies to improve Lithium-ion battery performance
(2024-01-01) Shahid, Seham; Agelin-Chaab, Martin
The transportation industry contributes more than a quarter of the global greenhouse gas emissions and transportation electrification was introduced as a means to decarbonize the industry. One of the major challenges related to the electrification of technologies are the thermal challenges associated with Lithium-ion batteries which are the leading candidate for electric batteries. In this research, these thermal challenges have been investigated with the objective of effective cooling and increased thermal uniformity within cylindrical Lithium-ion batteries. To achieve this, novel hybrid thermal management strategies have been proposed that combine air, liquid, and phase change material cooling systems. Several configurations of the proposed strategies are designed and analyzed through both experimental and numerical studies. The proposed hybrid strategies were able to limit the maximum temperature of the battery module to below ~29 °C. The developed battery module also achieved the desired temperature uniformity to less than 5 °C. Furthermore, the proposed hybrid strategies eliminate the requirement of a pump and reservoir system since there is no flow of liquid coolant within the battery module. This reduces the energy required for the operation of the thermal management system, thereby increasing the available energy for propulsion. Therefore, the proposed hybrid strategies and battery modules are capable of maintaining the thermal environment required by the Lithium-ion batteries for effective performance and can also be scaled to an entire battery pack for a range of applications.
Development and assessment of integrated powering systems with alternative fuel choices for clean transportation
(2023-04-01) Seyam, Shaimaa Fouad Mohamed Abdelhamid; Dincer, Ibrahim; Agelin-Chaab, Martin
This thesis presents novel engine systems using alternative fuels for aviation, rail, and marine transportation as follows: (i) alternative powering systems, such as fuel cells, on-board hydrogen production (ii) alternative fuel choices with hydrogen, methane, methanol, ethanol, and dimethyl ether; and (iii) different methods for waste retrieval energy, such as absorption refrigeration systems, desalination system, and thermoelectrical generators. The systems are analyzed by three methods: thermodynamic, exergoenvironmental, and exergoeconomic analyses. Besides, the multi-objective particle swarm optimization (MOPSO) is applied for different operating conditions to choose the optimal design characteristic of the transportation systems. For aviation transportation, the base turbofan produces a power of 9144 kW and thrusting energy of 38 MW, with 43.4% and 52% energetic and exergetic efficiency, respectively, under cruising conditions. However, the maximum power of SOFC-turbofan is 48MW, including 7.3 MW of turbofan power, 39.8 MW of thrust energy, and 0.94 MW of the SOFC. The overall energetic and exergetic efficiencies of the hybrid turbofan are 48.1% and 54.4%, respectively. For rail transportation, the traditional rail engine produces a power of 3355 kW with 45 % energetic and 57% exergetic efficiency. A new design of gas turbine combined with SOFC and PEMEC produces about 5590 kW with 90% energy efficiency and 50% exergy efficiency. This engine is optimized to produce a power of 7502 kW with exergetic efficiency of 82% with reducing specific fuel and product exergy cost to 11.5 $/GJ and 14.5$/GJ, respectively. For marine transportation, the traditional marine engine produces a power of 10,524 kW with 23% energetic efficiency. However, a stream Rankine cycle combined with a hybridized gas turbine produces a power of 15546 kW with 61% energetic efficiency and 43% exergetic efficiency. This engine is optimized to produce a power of 16725 kW with exergetic efficiency of 70% and reducing specific fuel and product exergy cost of 18 and 28 $/GJ, respectively. In addition, all five fuel blends in the eight engines were able to reduce carbon emissions by more than 60% compared to traditional fuels. Also, the specific fuel consumption was reduced by 10-20% compared to the utilization of traditional fuels.
Experimental and numerical investigation of the flow structures at the rear of three-dimensional bluff bodies
(2023-05-01) Siddiqui, Naseeb A.; Agelin-Chaab, Martin
Flows around bluff bodies have complex structures, which create drag, surface contamination and stability issues for transportation systems. The standard Ahmed body (SAB) is a simplified representative three-dimensional (3D) bluff body that is known to produce the essential features of complex bluff bodies. This thesis studies the flow structures at the rear end of 3D bluff bodies to aid the development of flow control strategies. In the first method, a modified SAB with a 25° slant angle is proposed that uses elliptical curvature at the rear end and is denoted as the elliptical Ahmed body (EAB). The particle image velocimetry (PIV) technique is used to provide the detailed flow structure. The PIV study is conducted at a Reynolds number of 4.31 ×104 based on the model height. This experimental study is complemented by detached eddy simulations at Reynolds numbers of 1.47 × 104, 4.31 × 104 and 1.90 × 105. In the second method, the effect of a hydrophobic coating on the flow structure of the SAB and EAB is investigated experimentally using the PIV technique and for the same Reynolds numbers stated above. For both methods, the coherent structures are evaluated using advanced analysis techniques, such as frequency analysis, proper orthogonal decomposition, dynamic mode decomposition, Q-criterion and λ2-criterion. For the Reynolds numbers and specific conditions investigated, the results show that the elliptical curvature creates significant reorganization of the flow structures, where the slant separation bubble, longitudinal C-vortices and lower recirculation bubble are eliminated, whereas the upper recirculation bubble shifts toward the slant surface. This flow restructuring provides ~10.4% drag reduction and reduces surface contamination. In addition, the hydrophobic coating increases the slant separation bubble and the Strouhal number at the slant surface of the SAB, while the wake recirculation length is not significantly affected. However, the shear stress, turbulent kinetic energy, and Strouhal numbers are reduced over the EAB with the coating. Overall, the results show that elliptical curvature and hydrophobic coating have the potential for drag reduction and the mitigation of surface contamination. However, further investigation is required before generalized conclusions can be drawn.
Experimental investigation and modeling of lithium-ion battery cells and packs for electric vehicles
(2016-01-01) Panchal, Satyam; Dincer, Ibrahim; Agelin-Chaab, Martin
The greatest challenge in the production of future generation electric and hybrid vehicle (EV and HEV) technology is the control and management of operating temperatures and heat generation. Vehicle performance, reliability and ultimately consumer market adoption are dependent on the successful design of the thermal management system. In addition, accurate battery thermal models capable of predicting the behavior of lithium-ion batteries under various operating conditions are necessary. Therefore, this work presents the thermal characterization of a prismatic lithium-ion battery cell and pack comprised of LiFePO4 electrode material. Thermal characterization is performed via experiments that enable the development of an empirical battery thermal model. This work starts with the design and development of an apparatus to measure the surface temperature profiles, heat flux, and heat generation from a lithium-ion battery cell and pack at different discharge rates of 1C, 2C, 3C, and 4C and varying operating temperature/boundary conditions (BCs) of 5ºC, 15°C, 25°C, and 35°C for water cooling and ~22°C for air cooling. For this, a large sized prismatic LiFePO4 battery is cooled by two cold plates and nineteen thermocouples and three heat flux sensors are applied to the battery at distributed locations. The experimental results show that the temperature distribution is greatly affected by both the discharge rate and BCs. The developed experimental facility can be used for the measurement of heat generation from any prismatic battery, regardless of chemistry. In addition, thermal images are obtained at different discharge rates to enable visualization of the temperature distribution. In the second part of the research, an empirical battery thermal model is developed at the above mentioned discharge rates and varying BCs based on the acquired data using a neural network approach. The simulated data from the developed model is validated with experimental data in terms of the discharge temperature, discharge voltage, heat flux profiles, and the rate of heat generation profile. It is noted that the lowest temperature is 7.11°C observed for 1C-5°C and the highest temperature is observed to be 41.11°C at the end of discharge for 4C-35°C for cell level testing. The proposed battery thermal model can be used for any kind of Lithium-ion battery. An example of this use is demonstrated by validating the thermal performance of a realistic drive cycle collected from an EV at different environment temperatures. In the third part of the research, an electrochemical battery thermal model is developed for a large sized prismatic lithium-ion battery under different C-rates. This model is based on the principles of transport phenomena, electrochemistry, and thermodynamics presented by coupled nonlinear partial differential equations (PDEs) in x, r, and t. The developed model is validated with an experimental data and IR imaging obtained for this particular battery. It is seen that the surface temperature increases faster at a higher discharge rate and a higher temperature distribution is noted near electrodes. In the fourth part of the research, temperature and velocity contours are studied using a computational approach for mini-channel cold plates used for a water cooled large sized prismatic lithium-ion battery at different C-rates and BCs. Computationally, a high-fidelity turbulence model is also developed using ANSYS Fluent for a mini-channel cold plate, and the simulated data are then validated with the experimental data for temperature profiles. The present results show that increased discharge rates and increased operating temperature results in increased temperature at the cold plates. In the last part of this research, a battery degradation model of a lithium-ion battery, using real world drive cycles collected from an EV, is presented. For this, a data logger is installed in the EV and real world drive cycle data are collected. The vehicle is driven in the province of Ontario, Canada, and several drive cycles were recorded over a three-month period. A Thevenin battery model is developed in MATLAB along with an empirical degradation model. The model is validated in terms of voltage and state of charge (SOC) for all collected drive cycles. The presented model closely estimates the profiles observed in the experimental data. Data collected from the drive cycles show that a 4.60% capacity fade occurred over 3 months of driving.

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Browsing Doctoral Dissertations (FEAS) by Author "Agelin-Chaab, Martin"