Isaac Chukwuemezu Okereke, Mohammed S. Ismail, Derek Ingham, Kevin J. Hughes, Lin Ma and Mohamed Pourkashanian
This paper aims to numerically investigate the impact of gas diffusion layer (GDL) anisotropic transport properties on the overall and local performance of polymer electrolyte…
Abstract
Purpose
This paper aims to numerically investigate the impact of gas diffusion layer (GDL) anisotropic transport properties on the overall and local performance of polymer electrolyte fuel cells (PEFCs).
Design/methodology/approach
A three-dimensional numerical model of a polymer electrolyte fuel cell with a single straight channel has been developed to investigate the sensitivity of the fuel cell performance to the GDL anisotropic transport properties – gas permeability, diffusivity, thermal conductivity and electrical conductivity. Realistic experimentally estimated GDL transport properties were incorporated into the developed PEFC model, and a parametric study was performed to show the effect of these properties on fuel cell performance and the distribution of the key variables of current density and oxygen concentration within the cathode GDL.
Findings
The results showed that the anisotropy of the GDL must be captured to avoid overestimation/underestimation of the performance of the modelled fuel cell. The results also showed that the fuel cell performance and the distributions of current density and oxygen mass fraction within the cathode GDL are highly sensitive to the through-plane electrical conductivity of the GDL and, to a lesser extent, the through-plane diffusivity, and the thermal conductivity of the GDL. The fuel cell performance is almost insensitive to the gas permeability of the GDL.
Practical implications
This study improves the understanding of the importance of the GDL anisotropy in the modelling of fuel cells and provides useful insights on improving the efficiency of the fuel cells.
Originality/value
Realistic experimentally estimated GDL transport properties have been incorporated into the PEFC model for the first time, allowing for more accurate prediction of the PEFC performance.
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Jinbei Tian, Mohammed S. Ismail, Derek Ingham, Kevin J. Hughes, Lin Ma and Mohamed Pourkashanian
This paper aims to investigate the impact of three different flow channel cross sections on the performance of the fuel cell.
Abstract
Purpose
This paper aims to investigate the impact of three different flow channel cross sections on the performance of the fuel cell.
Design/methodology/approach
A comprehensive three-dimensional polymer electrolyte membrane fuel cell model has been developed, and a set of conservation equations has been solved. The flow is assumed to be steady, fully developed, laminar and isothermal. The investigated cross sections are the commonly used square cross section, the increasingly used trapezoidal cross section and a novel hybrid configuration where the cross section is square at the inlet and trapezoidal at the outlet.
Findings
The results show that a slight gain is obtained when using the hybrid configuration and this is because of increased velocity, which improves the supply of the reactant gases to the catalyst layers (CLs) and removes heat and excess water more effectively compared to other configurations. Further, the reduction of the outlet height of the hybrid configuration leads to even better fuel cell performance and this is again because of increased velocity in the flow channel.
Research limitations/implications
The data generated in this study will be highly valuable to engineers interested in studying the effect of fluid cross -sectional shape on fuel cell performance.
Originality/value
This study proposes a novel flow field with a variable cross section. This design can supply a higher amount of reactant gases to the CLs, dissipates heat and remove excess water more effectively.
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Zhenxiao Chen, Derek Ingham, Mohammed Ismail, Lin Ma, Kevin J. Hughes and Mohamed Pourkashanian
The purpose of this paper is to investigate the effects of hydrogen humidity on the performance of air-breathing proton exchange membrane (PEM) fuel cells.
Abstract
Purpose
The purpose of this paper is to investigate the effects of hydrogen humidity on the performance of air-breathing proton exchange membrane (PEM) fuel cells.
Design/methodology/approach
An efficient mathematical model for air-breathing PEM fuel cells has been built in MATLAB. The sensitivity of the fuel cell performance to the heat transfer coefficient is investigated first. The effect of hydrogen humidity is also studied. In addition, under different hydrogen humidities, the most appropriate thickness of the gas diffusion layer (GDL) is investigated.
Findings
The heat transfer coefficient dictates the performance limiting mode of the air-breathing PEM fuel cell, the modelled air-breathing fuel cell is limited by the dry-out of the membrane at high current densities. The performance of the fuel cell is mainly influenced by the hydrogen humidity. Besides, an optimal cathode GDL and relatively thinner anode GDL are favoured to achieve a good performance of the fuel cell.
Practical implications
The current study improves the understanding of the effect of the hydrogen humidity in air-breathing fuel cells and this new model can be used to investigate different component properties in real designs.
Originality/value
The hydrogen relative humidity and the GDL thickness can be controlled to improve the performance of air-breathing fuel cells.
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Mohammed S. Ismail, Mohamed R. Berber, Ziyad A. Alrowaili and Mohamed Pourkashanian
This paper aims to numerically solve fully developed laminar flow in trapezoidal ducts with rounded corners which result following forming processes.
Abstract
Purpose
This paper aims to numerically solve fully developed laminar flow in trapezoidal ducts with rounded corners which result following forming processes.
Design/methodology/approach
A two-dimensional model for a trapezoidal duct with rounded corners is developed and conservation of momentum equation is solved. The flow is assumed to be steady, fully developed, laminar, isothermal and incompressible. The key flow characteristics including the Poiseuille number and the incremental pressure drop have been computed and tabulated for a wide range of: sidewall angle (θ); the ratio of the height of the duct to its smaller base (α); and the ratio of the fillet radius of the duct to its smaller base (β).
Findings
The results show that Poiseuille number decreases, and all the other dimensionless numbers increase with increasing the radii of the fillets of the duct; these effects were found to amplify with decreasing duct heights or increasing sidewall angles. The maximum axial velocity was shown to increase with increasing the radii of the fillets of the duct. For normally used ducts in hydrogen fuel cells, the impact of rounded corners cannot be overlooked for very low channel heights or very high sidewall angles.
Practical implications
The data generated in this study are highly valuable for engineers interested in estimating pressure drops in rounded trapezoidal ducts; these ducts have been increasingly used in hydrogen fuel cells where flow channels are stamped on thin metallic sheets.
Originality/value
Fully developed laminar flow in trapezoidal ducts with four rounded corners has been solved for the first time, allowing for more accurate estimation of pressure drop.
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Priyajit Mondal, Dhritishree Ghosh, Madhupa Seth and Subhra Kanti Mukhopadhyay
The purpose of this article is to provide information about interactions between pink-pigmented facultative methylotroph (PPFM) organisms and plants, their molecular mechanisms of…
Abstract
Purpose
The purpose of this article is to provide information about interactions between pink-pigmented facultative methylotroph (PPFM) organisms and plants, their molecular mechanisms of methylotrophic metabolism, application of PPFMs in agriculture, biotechnology and bioremediation and also to explore lacuna in PPFMs research and direction for future research.
Design/methodology/approach
Research findings on PPFM organisms as potent plant growth promoting organisms are discussed in the light of reports published by various workers. Unexplored field of PPFM research are detected and their application as a new group of biofertilizer that also help host plants to overcome draught stress in poorly irrigated crop field is suggested.
Findings
PPFMs are used as plant growth promoters for improved crop yield, seed germination capacity, resistance against pathogens and tolerance against drought stress. Anti-oxidant and UV resistant properties of PPFM pigments protect the host plants from strong sunshine. PPFMs have excellent draught ameliorating capacity.
Originality/value
To meet the ever increasing world population, more and more barren, less irrigated land has to be utilized for agriculture and horticulture purpose and use of PPFM group of organisms due to their draught ameliorating properties in addition to their plant growth promoting characters will be extremely useful. PPFMs are also promising candidates for the production of various industrially and medicinally important enzymes and other value-added products. Wider application of this ecofriendly group of bacteria will reduce crop production cost thus improving economy of the farmers and will be a greener alternative of hazardous chemical fertilizers and fungicides.
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V.W.J. Anand, S. Ganesh and Seripah Awang Kechil
The purpose of this study to analyze the unsteady magneto hydrodynamic incompressible viscous fluid flow along the porous parallel plates in which constant periodic…
Abstract
Purpose
The purpose of this study to analyze the unsteady magneto hydrodynamic incompressible viscous fluid flow along the porous parallel plates in which constant periodic suction/injection takes place at lower and upper plate, respectively. By the proper choice of stream function, they obtained exact solution analytically. Velocity components are obtained from exact solution.
Design/methodology/approach
Emissions of the pollutants from the aviation sectors are doubled compared to 2000. There are many recent developments that are actively developed to combat the emission by increasing the performance of the Jet engines. The role of the computational fluid dynamics and the numerical approaches are crucial in terms of research and development.
Findings
Velocity profiles like axial and radial have been drawn for various values of M, D, α and θ. The exact solutions have been solved by differential transformation method. The closed form analytical solutions are obtained for the stream function, axial and radial velocities and flow velocity.
Originality/value
The effects of Darcy parameter, magnetic parameter, Suction Reynolds number and frequency parameter on lower and upper plates are discussed through graphs.
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The purpose of the paper is to showcase the significant achievements of Egypt's scientists in the 20th century across various fields of study such as medicine, physics, chemistry…
Abstract
Purpose
The purpose of the paper is to showcase the significant achievements of Egypt's scientists in the 20th century across various fields of study such as medicine, physics, chemistry, biology, math, geology, astronomy and engineering. The paper highlights the struggles and successes of these scientists, as well as the cultural, social and political factors that influenced their lives and work. The aim is to inspire young people to pursue careers in science and make their own contributions to society by presenting these scientists as role models for hard work and dedication. Ultimately, the paper seeks to promote the importance of science and its impact on society.
Design/methodology/approach
The purpose of this review is to present the scientific biographies of Egypt's most distinguished scientists, primarily in the field of Natural Sciences, in a balanced and comprehensive manner. The work is objective, honest and abstract, avoiding any bias or exaggeration. The author provides a clear and concise methodology, including a brief introduction to the scientist and their field of study, an explanation of their major contributions, the impact of their work on society, any challenges or obstacles faced during their career and their lasting legacy. The aim is to showcase the important achievements of these scientists, their impact on their respective fields and to inspire future generations to pursue scientific careers.
Findings
The group of outstanding scientists in 20th century Egypt were shaped by various factors, including familial upbringing, education, society, political and cultural atmosphere and state support for scientific research. These scientists made significant contributions to various academic disciplines, including medicine, physics, chemistry, biology, mathematics and engineering. Their impact on their communities and cultures has received international acclaim, making them role models for future generations of scientists and researchers. The history of these scientists highlights the importance of educational investments and supporting scientific research to foster innovation and social progress. The encyclopedia serves as a useful tool for students, instructors and education professionals, preserving Egypt's scientific heritage and honouring the scientists' outstanding accomplishments.
Research limitations/implications
The encyclopedia preserves Egypt's scientific heritage, which has been overlooked for political or other reasons. It is a useful tool for a variety of readers, including students, instructors and education professionals, and it offers insights into universally relevant scientific success factors as well as scientific research methodologies. The encyclopedia honours the outstanding scientific accomplishments of Egyptian researchers and their contributions to the world's scientific community.
Practical implications
The practical implications of this paper are several. First, it highlights the importance of education, family upbringing and societal support for scientific research in fostering innovation and social progress. Second, it underscores the need for continued funding and support for scientific research to maintain and build upon the accomplishments of past generations of scientists. Third, it encourages young people to pursue scientific careers and make their own contributions to society. Fourth, it preserves the scientific heritage of Egypt and honors the contributions of its outstanding scientists. Finally, it serves as a useful tool for students, instructors and education professionals seeking to understand the factors underlying scientific success and research methodologies.
Social implications
The social implications of the paper include promoting national pride and cultural identity, raising awareness of the importance of education and scientific research in driving social progress, inspiring future generations of scientists and researchers, reducing socioeconomic disparities and emphasizing the role of society, politics and culture in shaping scientific researchers' personalities and interests.
Originality/value
The paper's originality/value lies in its comprehensive documentation of the scientific biographies of Egypt's most prominent scientists in the 20th century, providing unique insights into the factors that contributed to their development and their impact across various academic disciplines. It preserves Egypt's scientific heritage and inspires future generations of scientists and researchers through the promotion of educational investments and scientific research. The encyclopedia serves as a useful tool for education professionals seeking to understand scientific success factors and research methodologies, emphasizing the importance of supportive and inclusive environments for scientific development.
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Mohammed Ismail El-Adly, Nizar Souiden and Arusa Khalid
This study aims to investigate the impact of emotional perceived value on hotel guests’ satisfaction, affective commitment and loyalty.
Abstract
Purpose
This study aims to investigate the impact of emotional perceived value on hotel guests’ satisfaction, affective commitment and loyalty.
Design/methodology/approach
Data were collected from 348 respondents living in the United Arab Emirates, and hypotheses were tested using AMOS 28 and structural equation modeling.
Findings
This study’s unique contribution lies in its revelation that emotional perceived value directly impacts guests’ satisfaction, affective commitment and loyalty. Furthermore, it uncovers that emotional-perceived value indirectly influences loyalty through satisfaction and affective commitment.
Practical implications
This research underscores the importance of hotel managers prioritizing guests’ emotional perceived value in their offerings. Managers can significantly enhance guests’ satisfaction, affective commitment and loyalty by highlighting self-gratification, aesthetics, prestige, transaction and hedonics.
Originality/value
This study brings a fresh perspective to understanding customer perceived value (CPV). It argues that the mere emphasis on the functional aspect of CPV would likely fall short of fully comprehending specific outcomes of their experience (e.g. satisfaction-dissatisfaction, loyalty, etc.). Assessing the emotional aspect of CPV, known as emotional customer perceived value (ECPV), adds further explanations and sheds light on the understanding of the CPV concept and its impacts on consumers’ experience. Furthermore, this study emphasizes that emotional perceived value is better comprehended as a multidimensional rather than a unidimensional construct. It adds that the concept of customer value as a multidimensional concept is context-specific (i.e. dimensions vary from one service sector to another), providing a unique and valuable perspective for the luxury hotel industry.
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Yahya Mohammed Al-Sayani, Ebrahim Mohammed Al-Matari, Mohamad Naimi Mohamad Nor, Noor Afza Amran and Mohammed Ahmed Alsayani
The purpose of this study is to look at the structure of the interactions between the board of directors’ chairman qualities such as chairman independence, tenure, ethnicity, age…
Abstract
Purpose
The purpose of this study is to look at the structure of the interactions between the board of directors’ chairman qualities such as chairman independence, tenure, ethnicity, age- and impression management (IM).
Design/methodology/approach
The research population consists of non-financial Malaysian companies listed on Bursa Malaysia’s Main Market, using data gathered via annual reports and DataStream. The study relies on the ordinary least square regression to test the direct relationships between the directors’ chairman characteristics and IM. Moreover, robustness and sensitivity tests were used to examine the effectiveness of chairman characteristics with IM. Furthermore, the results rely on the FGLS regression as an additional test. The study found that chairman independence, chairman ethnicity and chairman age have a significant impact on IM.
Findings
The results reveal that chairman independence has a negative association with qualitative IM (IMSC1). Moreover, chairman ethnicity has a positively significant relationship with qualitative IM (IMSC1) and quantitative IM (IMSC2). Also, the effectiveness of chairman characteristics has a negative and significant association with IMSC1.
Originality/value
The primary goal of this paper is to fill a gap in the literature and to open up opportunities for more in-depth research on the subject. So far, there has been no research into the impact of the board chairman’s (BC) personality on IM. This study serves as a warning to policymakers, businesses and their stakeholders, as well as researchers, about the importance of BC characteristics, which may impede the effectiveness of corporate governance mechanisms. The paper provides a framework for investigating these characteristics in the context of IM.
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Ismail Mohammed Budaiwi, Mohammed Alhaji Mohammed and Hammad Ali Harbi
Indoor environmental quality (IEQ) in buildings has an impact on people’s health, productivity and comfort. Maintaining the highest possible IEQ level in complex buildings, such…
Abstract
Purpose
Indoor environmental quality (IEQ) in buildings has an impact on people’s health, productivity and comfort. Maintaining the highest possible IEQ level in complex buildings, such as health care, is difficult due to economic and organizational constraints. This study aims to categorize the vicinities in a typical health-care facility in terms of importance and criticality in relation to the various IEQ factors, as well as to develop an IEQ assessment procedure.
Design/methodology/approach
A comprehensive literature review, established standards and structured interviews with industrial hygiene professionals in health-care settings were used in this study. To test the applicability of the developed IEQ assessment procedure, a pilot study was conducted in an existing health-care facility.
Findings
This study categorized health-care facilities into various vicinities and discovered three respondents group had varying IEQ perceptions (facility managers, environmental health specialists and nurses). According to the findings, indoor air quality is the most important and dominant factor influencing overall IEQ in health-care facilities. The trial application of the framework shows that much work is needed to improve the level of response and readiness of facility management and occupants to allow for the effective use of the developed procedure.
Originality/value
Previous research did not include a detailed categorization of vicinities in health-care buildings based on IEQ requirements. The findings of this study will help to close this knowledge gap and guide facility managers and operators in recognizing the relative importance of different IEQ factors, maintaining functional requirements and identifying priorities when developing maintenance and operational procedures and allocating resources.