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The aim of this paper is to investigate performance improvements of a monolithic solid oxide fuel cell geometry through an entropy generation analysis.

The analysis of entropy generation rates makes it possible to identify the phenomena that cause the main irreversibilities in the fuel cell, to understand their causes and to propose changes in the design and operation of the system. The various contributions to entropy generation are analyzed separately in order to identify which geometrical parameters should be considered as the independent variables in the optimization procedure. The local entropy generation rates are obtained through 3D numerical calculations, which account for the heat, mass, momentum, species and current transport. The system is then optimized in order to minimize the overall entropy generation and increase efficiency.

In the optimized geometry, the power density is increased by about 10 per cent compared to typical designs. In addition, a 20 per cent reduction in the fuel cell volume can be achieved with less than a 1 per cent reduction in the power density with respect to the optimal design.

The physical model is based on a simple composition of the reactants, which also implies that no chemical reactions (water gas shift, methane steam reforming, etc.) take place in the fuel cell. Nevertheless, the entire procedure could be applied in the case of different gas compositions.

Entropy generation analysis allows one to identify the geometrical parameters that are expected to play important roles in the optimization process and thus to reduce the free independent variables that have to be considered. This information may also be used for design improvement purposes.

In this paper, entropy generation analysis is used for a multi‐physics problem that involves various irreversible terms, with the double use of this physical quantity: as a guide to select the most relevant design geometrical quantities to be modified and as objective function to be minimized in the optimization process.

Improved nuclear reactor configurations that address major concerns of environmentalists and safety analysts are discussed. In addition to social acceptance, these new modes of power generation have economic potential to become the dominant producers of energy in the twenty‐first century. The class of power generation with this promise is the high temperature gas reactor (HTGR); the variant we focus on is the pebble‐bed modular reactor (PBMR). We also focus on using nuclear power as an energy source for desalinating seawater. Finally, the case is made that HTGR reactors are ideal for supplying the high‐temperature heat needed for manufacturing molecular hydrogen, a leading candidate for clean fuel consumption. These three themes are developed in a broad context with the objective of recommending policy actions dealing with global warming, public health, and economic opportunity.

THE trials of R 100 and R 101, with the consequent revival of interest in airship technical matters, makes the present time not inappropriate for reviewing the alternative methods by which such craft can be propelled.

The purpose of this paper is to propose and compare two energy management strategies (EMSs). First, a classic method based on frequency separation with fixed limits on fuel cell (FC) power is presented and tested. Then, the improvement of the classic strategy is developed and implemented when the main enhancements are its ease of implementation, hydrogen economy and extending hybrid source lifetime.

The proposed EMS is developed using an online variable power limitation of the FC depending on the battery state of charge while ensuring that the energy of batteries remains in its operating depth of discharge (DOD) range.

In the objective to show the benefits of the developed strategy, a comparative analysis was conducted between two strategies. The simulation and experimental results show the effectiveness and gains obtained by the improved energy management system (IEMS) in terms of fuel economy (13 per cent) and decreasing the applied stress on the FC (22 per cent) which leads to a longer life span of the whole system.

The proposed approach is developed and tested by simulation. To confirm it, a test bench has been assembled as hardware in the loop (HIL) real-time system. The presented experimental results confirm the efficiency and show the providing gains of the IEMS.

The purpose of this paper is to optimize the design and power management control fuel cell/supercapacitor and fuel cell/battery hybrid electric vehicles and to provide a comparative study between the two configurations.

In hybrid electric vehicles (HEVs), the power flow control and the powertrain component sizing are strongly related and their design will significantly influence the vehicle performance, cost, efficiency and fuel economy. Hence, it is necessary to assess the power flow management strategy at the powertrain design stage in order to minimize component sizing, cost, and the vehicle fuel consumption for a given driving cycle. In this paper, the PSO algorithm is implemented to optimize the design and the power management control of fuel cell/supercapacitor (FC/SC) and fuel cell/battery (FC/B) HEVs for a given driving cycle. The powertrain and the proposed control strategy are designed and simulated by using MATLAB/Simulink. In addition, a comparative study of fuel cell/supercapacitor and fuel cell/battery HEVs is analyzed and investigated for adequately selecting of the appropriate HEV, which could be used in industrial applications.

The results have demonstrated that it is possible to significantly improve the hydrogen consumption in fuel cell hybrid electric vehicles (FCHEVs) by applying the PSO approach. Furthermore, by analyzing and comparing the results, the FC/SC HEV has slightly higher fuel economy than the FC/B HEV.

The addition of electrical energy storage such as supercapacitor or battery in fuel cell‐based vehicles has a great potential and a promising approach for future hybrid electric vehicles (HEV). This paper is mainly focused on the optimal design and power management control, which has significant influences on the vehicle performance. Therefore, this study presents a modified control strategy based on PSO algorithm (CSPSO) for optimizing the power sharing between sources and reducing the components sizing. Furthermore, an interleaved multiple‐input power converter (IMIPC) is proposed for fuel cell hybrid electric vehicle to reduce the input current/output voltage ripples and to reduce the size of the passive components with high efficiency compared to conventional boost converter. Meanwhile, the fuel economy is improved. Moreover, a comparative study of FC/SC and FC/B HEVs will be provided to investigate the benefits of hybridization with energy storage system (ESS).

The endurance of small unmanned air vehicles (UAVs) is directly associated with the energy density of the propulsion system used. As the batteries commonly used in small UAVs have a relatively low energy density, they are not sufficient for long-term endurance tasks. The purpose of this paper is to offer a solution to increase the endurance of a concept small UAV with combination of different power sources. The design, construction and ground tests of fuel cell-powered hybrid propulsion systems are presented in this paper.

The power requirements of a concept UAV were calculated according to aerodynamic calculations and then, hybrid propulsion system sources are determined. The hybrid system consists of a 100 W scale proton-exchange membrane (PEM) type fuel cell stack, lithium-polymer battery, solar cells and power management system (PMS). Subsequently, this hybrid power system was integrated with the new design of PMS and then series of ground tests were carried out.

This experimental study proved that it is theoretically possible to obtain an endurance of around 3 h for concept UAV with the proposed hybrid system.

The research study shows that fuel cell-based hybrid propulsion system with the proposed PMS can be widely used to obtain extended endurance in small UAVs.

A hybrid propulsion system with a novel PMS unit is proposed for small UAVs and the ground tests were implemented.

The purpose of this paper is to propose two energy management strategies (EMS) for hybrid electric vehicle, the power system is an hybrid architecture (fuel cell (FC)/battery) with two-converters parallel configuration.

First, the authors present the EMS uses a power frequency splitting to allow a natural frequency decomposition of the power loads and second the EMS uses the optimal control theory, based on the Pontryagin’s minimum principle.

Thanks to the optimal approach, the control objectives will be easily achieved: hydrogen consumption is minimized and FC health is protected.

The simulation results show the effectiveness of the control strategy using optimal control theory in term of improvement of the fuel consumption based on a comparison analysis between the two strategies.

This paper aims to clarify the corrosion behavior of two famous structural steels in sour environment. These steels have a vast application in oil and gas industries. The study aims to find the effect of different concentrations of sour solution on the origin of crack in these steels.

After preparation of specimens, different sour solutions were made using the synthetic brine (according to National Association of Corrosion Engineers [NACE], Technical Committee Report 1D182) and various amounts of Na₂S.9H₂O and CH₃COOH. The polarization test was done by Potansiostat apparatus model Zahner-IM6 at two temperatures, 25°C and 50°C. The corrosion current densities were obtained from the polarization curves. Finally, the corrosion products and hydrogen-induced cracking (HIC) were investigated by Tescan Vega II XMU scanning electron microscope (SEM) linked to a Rontec energy-dispersive X-ray spectroscopy (EDS) system.

API 5L-X70 steel showed smaller corrosion current values than A516-Gr70 steel. The HIC cracks propagated parallel to the surface of A516-Gr70 steel in three solutions and confirmed the inappropriateness of this steel for sour environment applications.

This paper studies the effect of sour environment on the behavior of two famous industrial steels at two temperatures by new method.

WHILE the general principles of gas‐fuel propulsion for airships have been enunciated in a former article, there remain to be considered both the gases available and the means whereby they can be procured.