• Issue 1 (2024)

Numerical and Experimental Sensitivity Study of a Direct Methanol Fuel Cell

IJTEE, Volume-21 , Issue 1 (2024), PP 47 - 54

Published: 09 Oct 2024

DOI: 10.5383/ijtee.21.01.006

by Haseeb Bin Yahya, Areeba Muhammad Imran, Yaser Al Swailmeen from Mechanical and Nuclear Engineering Department, Khalifa University of Science and Technology, Abu Dhabi, 127788, UAE

Abstract: This study investigates the sensitivity of open-circuit voltage (OCV) in a direct methanol fuel cell (DMFC) stack to variations in methanol flow rate, concentration, and operating temperature both experimentally and numerically. A fourcell DMFC stack with a crossflow inlet configuration was tested using methanol solutions of 0.5–2.0 M under ambient (23 °C) and elevated (80 °C) temperatures. The methanol flow rate was varied from 8 mL/min to 32 mL/min. Results showed that at 1.0 M concentration and 16 mL/min flow rate, the OCV peaked at 3.41 V under ambient conditions. The highest OCV observed overall was 3.48 V at 8 mL/min and 80 °C. However, OCV declined at higher concentrations and flow rates due to intensified methanol crossover. Numerical modeling using MATLAB produced polarization curves based on concentration-dependent exchange currents and limiting current densities. The model matched experimental trends but overestimated performance due to idealized assumptions. The theoretical maximum stack voltage calculated using the Nernst equation was 4.852 V. The corresponding 2nd law efficiency based on Gibbs free energy analysis reached a maximum of 71.7%. These findings underscore the importance of optimizing methanol delivery and thermal conditions to mitigate crossover losses and improve DMFC efficiency. The integrated experimental–numerical framework provides a low-cost method for evaluating practical DMFC performance limitations. read more... read less...

Keywords: Fuel Cell, DMFC, Sensitivity Study, PEM, Methanol Crossover, Open Circuit Voltage

Techno-Economic Assessment of Utility-Scale Wind Power Deployment in the UAE

IJTEE, Volume-21 , Issue 1 (2024), PP 39 - 46

Published: 09 Oct 2024

DOI: 10.5383/ijtee.21.01.005

by Areeba Imran and Isam Janajreh from Mechanical and Nuclear Engineering Department, Khalifa University of Science and Technology, Abu Dhabi, 127788, UAE

Abstract: Accurate wind resource assessment and turbine selection are essential for the successful integration of large-scale wind energy, particularly in island and coastal regions. This study investigates the techno-economic feasibility of deploying approximately 100 MW wind power installations at three strategically selected sites in the UAE: Masdar City, Sir Bani Yas Island, and Fujairah. Wind speed data collected at multiple elevations in Masdar were analyzed, and Weibull distributions were used to model site-specific wind regimes. Three turbines were evaluated: the 200kW Falkenberg 200 kW vertical-axis wind turbine (VAWT), the Vestas V44 600 kW, and the Bonus B54/1000 horizontal-axis wind turbine (HAWT). Performance was evaluated using key metrics such as capacity factors (CF), annual output, net present value (NPV), and internal rate of return (IRR). Fujairah showed the highest wind potential, with a mean wind speed of 9.17 m/s and a maximum CF of 45.4% using the 1 MW Bonus turbine. Sir Bani Yas demonstrates moderate wind potential with a CF of 32.7%, while Masdar City exhibits limited feasibility for large-scale wind projects with a CF of 25.1%. Economic analysis indicated that only the Vestas V44 turbine was financially viable at Sir Baniyas and Fujairah, with positive NPV and IRR. An optimized configuration of 173 Vestas V44 turbines at Sir Bani Yas and Fujairah (excluding Masdar) could generate over 270 GWh/year with an annual net cash flow of $7.3 million. This study highlights the importance of detailed site assessment and turbine matching to maximize cost-effective wind energy deployment and supports the UAE’s renewable energy goals. read more... read less...

Keywords: Wind energy, Sustainable development goals (SDG), Wind resource assessment, Techno-economic analysis

Investigating the Feasibility of Using Nuclear-Based PWR through Electrolysis for Hydrogen Production

IJTEE, Volume-21 , Issue 1 (2024), PP 27 - 37

Published: 09 Oct 2024

DOI: 10.5383/ijtee.21.01.004

by Mohamed AL Shehhi, Salem Al Shehhi from Mechanical and Nuclear Engineering Department, Khalifa University of Science and Technology, Abu Dhabi, 127788, UAE

Abstract: The world is currently grappling with the intensifying effects of climate change from harmful emissions of greenhouse gases. Additionally, there is a dire need to seek alternative fuel solutions due to the rapidly diminishing natural resources. Hydrogen emerges as an economically and environmentally viable and sustainable alternative fuel solution. This paper presents the outcomes of a project that investigated the feasibility of using nuclear-based Pressurized Water Reactors (PWRs) through the electrolysis technique for hydrogen production. The primary focus of the project is on the Advanced Pressurized Reactor rated 1400 Mwe (APR1400 type) due to the ready availability of hydrogen production facilities, which promise capacity for enhanced energy efficiency coupled with low-carbon emissions. The project thus examined two electrolysis technologies: low-temperature and high-temperature electrolysis, specifically evaluating their environmental and economic implications, as well as their scalability potential. Based on preliminary results, a combination of a nuclear plant’s waste heat and high-temperature electrolysis provides a considerable improvement in hydrogen production efficiency at significantly reduced operational costs. With 0.0324% of APR1400’s thermal capacity, the proposed nuclear plan can produce over 237 million kg of hydrogen annually. The plant’s LCOH of $1.44 involved CAPEX of $0.85 (59%), O&M of $0.45 (31%), and decommissioning of $0.14 (10%). The project thus comprehensively analyzed the economic and technological viability of the proposed nuclear-powered hydrogen production project, fundamentally contributing to and indicating the possibility of a possible shift towards a more sustainable energy solution. read more... read less...

Keywords: Nuclear energy, Hydrogen Production, Electrolysis, Economic analysis, LCOH, KPI analysis

Performance Analysis of a Wind Tower Design for Greenhouse Application: A Case Study in UAE and KSA

IJTEE, Volume-21 , Issue 1 (2024), PP 15 - 24

Published: 09 Oct 2024

DOI: 10.5383/ijtee.21.01.003

by Hanna Yousef , Batool Khalaf from Department of Mechanical and Nuclear Engineering, Khalifa University of Science and Technology, Abu Dhabi, 127788, UAE

Abstract: This study investigates the performance of a passive evaporative cooling wind tower system for greenhouse applications in hot, arid climates. A simplified analytical model, based on Bahadori's framework, was employed to analyse airflow dynamics, heat transfer, and mass transfer within the tower. Climatic conditions from Abu Dhabi (UAE) and Riyadh (KSA) were considered, focusing on the effects of tower height, wind velocity, and ambient humidity. Results indicate that evaporative cooling is the dominant mechanism for temperature reduction, with tower height playing a critical role in performance. In Abu Dhabi, air reaches saturation at 10 m, limiting further cooling, while Riyadh's drier conditions allow continued evaporative cooling up to 15 m. Crop suitability was evaluated by mapping the resulting microclimates to agricultural requirements, providing design recommendations for optimal tower heights. These findings support the use of passive wind towers as sustainable climate control solutions in protected agriculture, tailored to specific regional conditions and align with the UAE and KSA's national sustainability agendas. The study highlights the potential of simple, low-energy cooling strategies to enhance agricultural productivity while reducing reliance on conventional, energy-intensive systems. read more... read less...

Keywords: Wind tower, Evaporative Cooling, Sustainability, Cooling effectiveness, Height optimization, Greenhouse climate

Dynamic Modeling, Simulation and Control of a Methanol Steam Reformer for Hydrogen Production

IJTEE, Volume-21 , Issue 1 (2024), PP 07 - 13

Published: 09 Oct 2024

DOI: 10.5383/ijtee.21.01.002

by Dimitris Ipsakis, Symeon Savvopoulos, Panagiotis Karageorgos, Dimitris Trigkas, Panos Seferlise , Simira Papadopoulou, and Spyros Voutetakis from School of Production Engineering & Management, Technical University of Crete, Chania, Greece - Chemical Process & Energy Resources Institute, Centre for Research & Technology Hellas, Thermi-Thessaloniki, Greece - Center for Membrane and Advanced Water Technology, Department of Mechanical Engineering, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates - Department of Industrial Engineering & Management, International Hellenic University, Sindos-Thessaloniki, Greece e Department of Mechanical Engineering, Aristotle University of Thessaloniki, Thessaloniki, Greece

Abstract: In this study a control-oriented mathematical model for a catalytic reactor suited for the steam reforming of methanol towards rich hydrogen production is presented. The model consists of partial differential equations that capture the concentration (or equivalently mass) and temperature time variation, by including a validated reaction kinetics scheme from a previous work. Based on this model, sensitivity analysis is performed with an aim to elucidate the effect of key process variables on the reformer’s temperature and hydrogen production. As will be shown, the feed ratios of steam/methanol and oxygen/methanol affect significantly the reformer’s temperature and hydrogen production and are selected as manipulated variables in our control analysis. The latter, is developed on the basis of comparing two PID controllers versus a model predictive controller (MPC) that is used to regulate simultaneously the operating temperature and hydrogen production (set-point tracking and disturbance rejection). Overall, this study can be used in control-oriented advanced schemes that can lead to the efficient production of energy carriers via cost friendly feedstock. read more... read less...

Keywords: dynamic modeling, model predictive control (MPC), PID control, hydrogen, autothermal steam reforming

Experimental and Computational Investigation of Jet Impingement Cooling for Gas Turbine Blades

IJTEE, Volume-21 , Issue 1 (2024), PP 01 - 05

Published: 09 Oct 2024

DOI: 10.5383/ijtee.21.01.001

by Mohammed Aldhaheri, Khamis Humaid, Abdulraman Al-Ali , Adel Sumjatha from Department of Mechanical Engineering, Khalifa University of Science and Technology, Abu Dhabi, UAE

Abstract: Gas turbines are widely used in power generation and aviation industries due to their high efficiency and reliability. However, their performance is significantly affected by thermal loads, making effective cooling strategies essential for maintaining operational integrity. This study explores state-of-the-art cooling techniques for gas turbine components, focusing on impingement jet cooling. Computer Fluid Dynamics (CFD) as well as experiments were performed to test the effect of mass flow rate, inlet jet width and its position on the cooling performance. Three key parameters were examined: average cavity wall temperature, outlet temperature, and the average Nusselt number. The model was exposed to a continuous heat flux and the cavity temperature measurements were recorded. Results indicated that the lowest average cavity wall temperature was achieved at the smallest inlet width and highest mass flow rate, with mass flow rate as the most significant factor. read more... read less...

Keywords: Gas turbines, Jet impingement Cooling, Turbine efficiency, CFD, Heat transfer enhancement