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This paper aims to investigate the impact of three different flow channel cross sections on the performance of the fuel cell.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.

The hydrogen relative humidity and the GDL thickness can be controlled to improve the performance of air-breathing fuel cells.

The purpose of this paper is to numerically investigate the effects of the shape on the performance of the cathode catalyst agglomerate used in polymer electrolyte fuel cells (PEFCs). The shapes investigated are slabs, cylinders and spheres.

Three 1D models are developed to represent the slab like, cylindrical and spherical agglomerates, respectively. The models are solved for the concentration of the dissolved oxygen using a finite element software, COMSOL Multiphysics®. “1D” and “1D axisymmetric” schemes are used to model the slab like and cylindrical agglomerates, respectively. There is no one-dimensional scheme available in COMSOL Multiphysics® for spherical coordinate systems. To resolve this, the governing equation in “1D” scheme is mathematically modified to match that of the spherical coordinate system.

For a given length of the diffusion path, the variation in the performances of the investigated agglomerates is dependent on the operational overpotential. Under low magnitudes of the overpotentials, where the performance is mainly limited by reaction, the slab-like agglomerate outperforms the spherical and cylindrical agglomerates. In contrast, under high magnitudes of the overpotentials where the agglomerate performance is mainly limited by diffusion, the spherical and cylindrical agglomerates outperform the slab-like agglomerate.

The current advances in the nano-fabrication technology gives more flexibility in designing the catalyst layers in PEFCs to the desired structures. If the design of the agglomerate catalyst is to be assessed, the current micro-scale modelling offers an efficient and rapid way forward.

The current micro-scale modelling is an efficient alternative to developing a full (or half) fuel cell model to evaluate the effects of the agglomerate structure.

The librarian and researcher have to be able to uncover specific articles in their areas of interest. This Bibliography is designed to help. Volume IV, like Volume III, contains features to help the reader to retrieve relevant literature from MCB University Press' considerable output. Each entry within has been indexed according to author(s) and the Fifth Edition of the SCIMP/SCAMP Thesaurus. The latter thus provides a full subject index to facilitate rapid retrieval. Each article or book is assigned its own unique number and this is used in both the subject and author index. This Volume indexes 29 journals indicating the depth, coverage and expansion of MCB's portfolio.

Wonders whether companies actually have employees best interests at heart across physical, mental and spiritual spheres. Posits that most organizations ignore their workforce – not even, in many cases, describing workers as assets! Describes many studies to back up this claim in theis work based on the 2002 Employment Research Unit Annual Conference, in Cardiff, Wales.

This article traces the development of ideas and policies linked to the shifting definitions of crime reduction, prevention and community safety. The conceptual changes are often difficult to define due to imprecision and breadth. Community safety is sufficiently broad to be concerned with a range of harms and hazards beyond crime and disorder, which may become the focus of the emerging new forms of government.

The paper questions aspects of the UK government’s policy to target small firm support on fast‐growing firms – to maximise its employment impact. The paper explores the tension between advice likely to increase growth and risk‐taking and advice likely to ensure firm survival in the turbulent small and medium‐sized enterprises sector. The research data derive from 24 semi‐structured interviews and a group interview of ten business advisers in the West Midlands region collected between autumn 1996 and spring 1997, and a national survey of 175 Business Link personal business advisers (PBAs) conducted in April 1998. Interviewees responded to a prompt asking for advice to a fast‐growing firm. The paper compares qualitative interview responses from a wide variety of West Midlands business advisers with questionnaire responses from PBAs. The paper suggests that the advice given by accountants and bank managers differs little from that given by Business Link’s PBAs. The paper will argue that advisers including PBAs, offer risk‐averse advice and support to small firms. Present business advice might reduce insolvency rather than increase the number of fast‐growth firms. The risk‐averse nature of advice, reflecting the adviser’s clientele, undermines policies designed to increase the number of fast‐growth companies. It concludes that advice will often be inconsistent with the growth‐oriented aim of government policy.

Intercollegiate athletics is a tremendous part of today’s society and encompasses numerous American lives. Its wide spectrum attracts various people from gender, race, ethnicity, cultures, religion, and sexuality. Black male student-athletes, a target of higher education institutions, are affected by sociological, institutional, and athletic factors. This population is highly sought after by college coaches due to their athletic abilities and ability skills in their specific sport in order to elevate their respective sports team, athletics’ department, and university into the national limelight. Current institutional and intercollegiate athletics’ trends that are incorporated to recruit Black male student-athletes are explored. Specific recruiting techniques utilized by college coaches to persuade this population are examined. The sociological issues in current intercollegiate athletics are analyzed with their direct effect on the college selection choice of Black male student-athletes.

Organizational approaches to racial inequality have provided contextual insight into a host of traditional stratification outcomes (e.g., hiring, earnings, authority). This chapter extends the organizational approach by drawing on the health-stress framework to explore how organizational context affects experiential and health-related outcomes – discrimination, social support, and psychological distress. Drawing on a sample of Black workers in the United States, we examine the relationship between workplace racial composition and psychological distress, as well as two potential mediators – racial discrimination and workplace social support. Our findings reveal that psychological distress is similar for Black workers in token (<25% Black coworkers), tilted other race (25–49.99% Black coworkers), and tilted same race (50–74.99% Black coworkers) job contexts. Workers in Black-dominated jobs (>75% Black coworkers), however, experience significantly less psychological distress than other compositional thresholds, net of individual, job, and workplace characteristics. This relationship is not explained by either racial discrimination experiences or supervisor and coworker social support. This finding suggests that researchers need to theorize and examine other protective factors stemming from coworker racial similarity.