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- Kassem, Nabil
(författare)
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Dynamic simulation of PEMFC stack for vehicular applications
- 2005
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Ingår i: Proceedings of the 1st European Fuel Cell Technology and Applications Conference 2005 - Book of Abstracts. - 0791842096 - 9780791842096 ; , s. 143-143
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Konferensbidrag (refereegranskat)abstract
- Fuel cells are considered the most versatile and environment friendly power sources to replace conventional internal combustion engines in future urban driving systems. Major automotive industries are carrying out comprehensive R&D programs supported by ample economic resources to develop hydrogen based fuel cells systems that are cheap, reliable with high efficiencies and almost near zero emissions. A number of prototypes are currently under road tests in many cities all over the world. In urban traffics, however, the fuel cells system will be running under dynamic conditions due to the possible variations in vehicular driving modes. Therefore, the objective of this work is to conduct transient analysis of the dynamic behaviour of a fuel cell stack performance under variable operating conditions that simulate the actual driving situations. In this work a dynamic model of a non-isothermal Polymer Electrolyte Membrane (PEM) fuel cell was developed based on the information available in the literature and has been realized in MATLAB/SIMULINK.® environment. The main components of the model are the Membrane Electrode Assembly (MEA) subsystems, thermal and water management subsystems. Main mechanisms involved in fuel cell operations are the electrochemical reactions, gas transport by convection and diffusion, and electrode losses. The input signals selected to excite the fuel cell dynamics are the load current, operating temperature, operating pressure, and hydrogen/oxygen inlet volumetric flows. The transients evolved for main cell outputs such as cell voltage, cell temperature, partial pressures of outlet gases, outlet flow rates, and diffusion flow of hydrogen and oxygen were studied. The results obtained show that sudden changes in current loads have direct impact on cell voltage and outlet gas partial pressures (concentration), and gas mass flows. For the applied current densities, temperature rise was observed. An increase in cell temperature, cell pressure or the hydrogen volumetric flow will lead to an increase in cell voltage and hence in the power output of the cell. Calculations carried out for a 400 fuel cell stack showed a power output of 70 K.W at an efficiency of about 50% (HHV of hydrogen).
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- Kassem, Nabil
(författare)
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Externalities affecting the viability of wind power for hydrogen production
- 2007
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Ingår i: 2004 New and Renewable Energy Technologies for Sustainable Development. - : World Scientific Publishing Co.. - 9789812707437 - 9789812705051 ; , s. 211-224
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Off-peak electricity from wind power farms is a valuable and cheap source of energy, which is hlly competitive, with fossil fuel and nuclear power generation. Wind power is one of the lowest-priced renewable energy technologies available today depending on the wind site, the type of wind turbines, and project financing. Coupling of wind turbines to high temperature steam electrolyzers would have the potential of providing low cost hydrogen source. For offshore wind farms to be economic, they have to be of sizes greater than 150 MW using large turbines (> 1.5 MW). The study uses methods of risk analysis to assess the economic viability of wind power and novel electrolytic processses to evaluate the simultaneous effect of multiple input uncertainties on system output. The results show that stochastic variations in wind speed, electricity prices, and interest rate have direct impact on investment capital requirements, and hence on the cost of hydrogen. © 2007 by World Scientific Publishing Co. Pte. Ltd. All rights reserved.
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- Osman, Marwan, et al.
(författare)
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Multidrug-resistant pathogens contaminate river water used in irrigation in disenfranchised communities
- 2024
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Ingår i: Journal of Global Antimicrobial Resistance. - : Elsevier. - 2213-7165 .- 2213-7173. ; 36, s. 175-180
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The contamination of fresh surface waters poses a significant burden on human health and prosperity, especially in marginalized communities with limited resources and inadequate infrastructure. Here, we performed in-depth genomic analyses of multidrug-resistant bacteria (MDR-B) isolated from Al-Oueik river water that is used for irrigation of agricultural fields in a disenfranchised area that also hosts a makeshift Syrian refugee camp.Methods: A composite freshwater sample was filtered. Faecal coliforms were counted and extended spectrum cephalosporins and/or ertapenem resistant bacteria were screened. Isolates were identified using MALDI-TOF-MS and analysed using whole-genome sequencing (WGS) to identify the resistome, sequence types, plasmid types, and virulence genes.Results: Approximately 106 CFU/100 mL of faecal coliforms were detected in the water. Four drug-resistant Gram-negative bacteria were identified, namely Escherichia coli, Klebsiella pneumoniae, Enterobacter hormaechei, and Pseudomonas otitidis. Notably, the E. coli isolate harboured blaNDM-5 and a YRIN-inserted PBP3, representing an emerging public health challenge. The K. pneumoniae isolate carried blaSHV-187 as well as mutations in the gene encoding the OmpK37 porin. Enterobacter hormaechei and P. otitidis harboured blaACT-16 and blaPOM-1, respectively.Conclusion: This report provides comprehensive genomic analyses of MDR-B in irrigation water in Lebanon. Our results further support that irrigation water contaminated with faecal material can be a reservoir of important MDR-B, which can spread to adjacent agricultural fields and other water bodies, posing both public health and food safety issues. Therefore, there is an urgent need to implement effective water quality monitoring and management programs to control the proliferation of antibiotic-resistant pathogens in irrigation water in Lebanon.
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