This paper evaluates the performance of Nafion 211 at elevated temperatures up to 120 °C using an... more This paper evaluates the performance of Nafion 211 at elevated temperatures up to 120 °C using an experimentally validated model. Increasing the fuel cell operating temperature could have many key benefits at the cell and system levels. However, current research excludes this due to issues with membrane durability. Modelling is used to investigate complex systems to gain further information that is challenging to obtain experimentally. Nafion 211 is shown to have some interesting characteristics at elevated temperatures previously unreported, the first of which is that the highest performance reported is at 100 °C and 100% relative humidity. The model was trained on the experimental data and then used to predict the behaviour in the membrane region to understand how the fuel cell performs at varying temperatures and pressures. The model showed that the best membrane performance comes from a 100 °C operating temperature, with much better performance yielded from a higher pressure of ...
There are four strategies to combating global warming, namely by directly reducing greenhouse gas... more There are four strategies to combating global warming, namely by directly reducing greenhouse gas emissions, or indirectly through expanding renewable energy employment, more efficient use of energy, or a wide range of climate policies. This study reports a bibliometric analysis of direct carbon dioxide emission reduction through carbon capture. The research trend in carbon capture within the three main types of technologies, namely pre-combustion, post-combustion and oxy-fuel combustion, was investigated using publications from 1998 to 2018 retrieved from the Web of Science database. It was found that from 1998-2007 there was little or no research output on carbon capture, until 2008, when legislation on climate change abatement was introduced and public and industry awareness of clean fossil energy options grew. With these motivating factors, 55 countries engaged in carbon capture technologies and related research in which the United States has the most research output followed by the UK and, China. Among the carbon capture technologies commonly studied, the bibliometric analysis based on a network map showed that post-combustion capture is the most referenced carbon capture technology with about 80.9% of total publications retrieved. oxy-fuel combustion had the lowest number of publications (3.4%).
This paper demonstrates the significant and positive effect of applying a magnetic field on the p... more This paper demonstrates the significant and positive effect of applying a magnetic field on the performance of Proton Exchange Membrane Water Electrolysers (PEMWE). A magnetizer and a transparent PEMWE cell are used to observe the effect of the magnetic field at variable water flow rates on the PEMWE performance. The presence of the magnetic field introduces Lorentz force which results in a significant improvement in the electrolyser performance. The magnetic flux density is varied between 0 T and 0.5 T, while the water flow rate is varied from 100 ml min −1 to 300 ml min −1 to study the effect and relationship between the two parameters and the performance of the PEMWE. Under a 0.5 T magnetic field and 300 ml min −1 flow rate, a 33% increase in the cell performance is achieved compared to the conventional operation at the same flow rate. The positive effect is explained by the introduction of Lorentz force from the magnetic field to the operating PEMWE. The improvement here is due to the relaxation and pumping effect of the magnetic field on the electrode surface which results in enhancing oxygen bubbles removal and lowering mass transport polarisation. Moreover, the enhanced oxygen bubbles removal is expected to increase the lifetime of the electrolyser as a result of the reduced contact between the produced oxygen and the anode materials.
In this study, inkjet printing technology was adopted for the application of protective layer coa... more In this study, inkjet printing technology was adopted for the application of protective layer coatings on metallic Solid Oxide Fuel Cell (SOFC) interconnects. The study highlights the potential of the inkjet printing process to fabricate aqueous-based protective layer coatings over ferritic stainless steels, a novel, very flexible, and low-cost approach to coating. The work presented focusses on the formulation of aqueous-based spinel particulate inks for the inkjet printing process using an electromagnetic inkjet printer. An ink formulation route based on a two-stage ball milling technique was developed to produce a printable ink composition with Manganese Cobalt Oxide (MnCo 2 O 4 ,MCO) and Manganese Cobalt Ferrite (MnCo 1.8 Fe 0.2 O 4 , MCF) as the coating materials. Stability of the ink suspensions and particle size distribution were studied and characterised using zeta and a particle size analysis, respectively. Flow properties of the inks were analysed using a conventional rheometer at shear rates 1 to 1000 s À1 and Piezo Axial Vibrator rheometer at higher shear rates (10-6 s À1). Finally, printability of the inks was assessed theoretically based on the Ohnesorge number, Z. The formulated MCO and MCF inks with~25 wt% solid loading exhibited Z values of 4.17 and 6.77, satisfying the printability criteria of the inkjet inks. Printability of the inks was demonstrated by printing them on stainless-steel substrates. and printed layers were free of any visible defects after heat-treatment. The demonstrated ink formulation procedure provides a guide for inkjet inks development with respect to inkjet printer requirements. Furthermore, the outlined methodology can be employed to fabricate protective and other coatings for any kind of metallic components such as bipolar plates and heat-exchangers.
Nafion membranes are still the dominating material used in the polymer electrolyte membrane (PEM)... more Nafion membranes are still the dominating material used in the polymer electrolyte membrane (PEM) technologies. They are widely used in several applications thanks to their excellent properties: high proton conductivity and high chemical stability in both oxidation and reduction environment. However, they have several technical challenges: reactants permeability, which results in reduced performance, dependence on water content to perform preventing the operation at higher temperatures or low humidity levels, and chemical degradation. This paper reviews novel composite membranes that have been developed for PEM applications, including direct methanol fuel cells (DMFCs), hydrogen PEM fuel cells (PEMFCs), and water electrolysers (PEMWEs), aiming at overcoming the drawbacks of the commercial Nafion membranes. It provides a broad overview of the Nafion-based membranes, with organic and inorganic fillers, and non-fluorinated membranes available in the literature for which various main properties (proton conductivity, crossover, maximum power density, and thermal stability) are reported. The studies on composite membranes demonstrate that they are suitable for PEM applications and can potentially compete with Nafion membranes in terms of performance and lifetime. 1. Background During the last 100 years the world average temperature has increased by almost 0.8 • C [1], becoming the most critical environmental issue of our time. Even though there are many different factors responsible, the greatest concern is greenhouse gas emissions due to human activities linked to energy production and use. In this sense, governments worldwide are acting to take measures to revise their energy mix by reducing fossil fuels usage and promoting alternative sources. The European Union, with the objectives set in the 20-20-20 pack, put forward strict targets to be reached before 2020, namely 20% reduction of greenhouse gases, 20% primary energy production from renewables, and 20% of biofuels burned in transportation. Moreover, recently a medium-long term strategy was agreed, stating that the European energy efficiency should be improved by 27% and the renewables energy input should increase by up to the 27% of the total share before 2030. Within this overall framework, it is becoming increasingly important that research and development of new technologies are intensified to allow the penetration of more efficient energy conversion systems. In this context, polymer electrolyte membrane technologies can play an important role.
The corrosion behaviour and Cr retention ability of SS309, aluminised SS309, and AluChrom 318 hav... more The corrosion behaviour and Cr retention ability of SS309, aluminised SS309, and AluChrom 318 have been investigated at 850°C in air with 3 % H 2 O. The SS309 samples failed the specifications for application as cathode air preheater (CAPH) material due to a high Cr evaporation rate and massive scale spallation. The surface aluminisation dramatically decreased the Cr evaporation rate of SS309, but not in the long-term due to breakaway oxidation induced alumina scale spallation. The AluChrom 318 formed a γ-Al 2 O 3 /α-Al 2 O 3 layer scale and demonstrated the highest Cr retention ability and oxidation resistance among the tested alloy samples.
Two materials, polyaniline (PANI) and titanium nitride (TiN), used for bipolar plate (BPP) coatin... more Two materials, polyaniline (PANI) and titanium nitride (TiN), used for bipolar plate (BPP) coatings have each shown promise in improving the corrosion resistance and contact resistance, respectively, of metallic bipolar plates. Polyaniline was shown to provide a barrier for the bipolar plate and to effectively lower the corrosion currents observed in ex situ corrosion tests. However, the interfacial contact resistance (ICR) between poly-aniline coatings and gas diffusion layer (GDL) is high and results in high electrical losses. On the other hand, TiN is reported to achieve good conductivity and in some cases improved corrosion resistance. The two materials have also been investigated together in a composite coating and showed promising results, but the contact resistance of the coating was still too high for use in a commercial fuel cell. In this study, the application of an additional layer of TiN over the TiN-polyaniline composite coating (a bilayer coating) is investigated. Composite bilayered PANI TiN coatings were deposited upon SS316L substrates. The optimized coating achieved U.S. Department of Energy (DoE) targets with potentiostatic corrosion currents of~0.024 μA cm-2 and ICR values of 11.2 mΩ cm 2. PANI polymerization was confirmed , using Fourier-transform infrared (FTIR) spectroscopy and TiN loadings were investigated with energy dispersive X-ray (EDX) spectroscopy.
This work investigates life cycle costing analysis as a tool to estimate the cost of hydrogen to ... more This work investigates life cycle costing analysis as a tool to estimate the cost of hydrogen to be used as fuel for Hydrogen Fuel Cell vehicles (HFCVs). The method of life cycle costing and economic data are considered to estimate the cost of hydrogen for centralised and decentralised production processes. In the current study, two major hydrogen production methods are considered, methane reforming and water electrolysis. The costing frameworks are defined for hydrogen production, transportation and final application. The results show that hydrogen production via centralised methane reforming is financially viable for future transport applications. The ownership cost of HFCVs shows the highest cost among other costs of life cycle analysis.
Using the residual heat from the engine exhaust and of late from the fuel cell exhaust to drive a... more Using the residual heat from the engine exhaust and of late from the fuel cell exhaust to drive a refrigeration or air conditioning unit on-board a vehicle has been the interest of many research groups worldwide. Umpteen number of modelling studies and a few prototypes have been built in this area. In this paper, an up to date review of the heat driven absorption refrigeration/air conditioning systems specifically meant for transport applications is given. This is followed by a discussion on the major challenges involved in implementing such a technology for the transport sector, the ways in which such a technology can be developed further and why using heat driven refrigeration/air conditioning systems could be a game changer in the automotive industry. From the study carried out two things are apparent-there is currently no VARS unit that can readily be used on-board vehicles and linking VARS units with engine exhaust leads to drop in engine efficiency and thus overall vehicle performance. Fuel cells (SOFCs in particular), if used as APUs can reduce the load on the engine and also supply a constant heat load to the VARS and thus be more effective.
Increasing Polymer Electrolyte Fuel Cells' (PEFCs) operating temperature has benefits on the perf... more Increasing Polymer Electrolyte Fuel Cells' (PEFCs) operating temperature has benefits on the performance and the ease of utilisation of the heat generated; however, efforts for high temperature PEFCs have resulted in high degradation and reduced life time. In the literature , conventional low temperature (T < 80 C) and high temperature (140e200 C) regimes have been extensively studied, while the gap of operating at intermediate temperature (IT) (100e120 C) has been scarcely explored. The main bottleneck for operating at IT conditions is the development of a suitable proton exchange membrane with comparable performance and lifetime to the commercially used Nafion operating at conventional conditions. In this work, composite membranes of Graphene Oxide (GO) and Nafion of varied thickness were fabricated, characterised and assessed for in-situ single cell performance under automotive operating conditions at conventional and intermediate temperatures. The material characterisation confirmed that a composite GO-Nafion structure was achieved. The composite membrane demonstrated higher mechanical strength, enhanced water uptake, and higher performance. It was demonstrated that by utilising GO-Nafion composite membranes, an up to 20% increase in the maximum power density at all operating temperatures can be achieved, with the optimum performance is obtained at 100 C. Moreover, the GO-Nafion membrane was able to maintain its open circuit voltage values at increased temperature and reduced thickness, indicating better durability and potentially higher lifetime.
In light of stricter emissions regulations and depleting fossil fuel reserves, fuel cell vehicles... more In light of stricter emissions regulations and depleting fossil fuel reserves, fuel cell vehicles (FCVs) are one of the leading alternatives for powering future vehicles. An open-cathode, air-cooled proton exchange membrane fuel cell (PEMFC) stack provides a relatively simple electric generation system for a vehicle in terms of system complexity and number of components. The temperature within a PEMFC stack is critical to its level of performance and the electrochemical efficiency. Previously created computational models to study and predict the stack temperature have been limited in their scale and the inaccurate assumption that temperature is uniform throughout. The present work details the creation of a numerical model to study the temperature distribution of an 80-cell Ballard 1020ACS stack by simulating the cooling airflow across the stack. Using computational fluid dynamics, a steady-state airflow simulation was performed using experimental data to form boundary conditions where possible. Additionally, a parametric study was performed to investigate the effect of the distance between the stack and cooling fan on stack performance. Model validation was performed against published results. The temperature distribution across the stack was identical for the central 70% of the cells, with eccentric temperatures observed at the stack extremities, while the difference between coolant and bipolar plate temperatures was approximately 10 C at the cooling channel outlets. The results of the parametric study showed that the fan-stack distance has a negligible effect on stack performance. The assumptions regarding stack temperature uniformity and measurement were challenged. Lastly, the hypothesis regarding the negligible effect of fan-stack distance on stack performance was confirmed. K E Y W O R D S airflow simulation, coolant temperature, fuel cell vehicles, PEM fuel cells, stack temperature, thermal management
There are four strategies to combating global warming, namely by directly reducing greenhouse gas... more There are four strategies to combating global warming, namely by directly reducing greenhouse gas emissions, or indirectly through expanding renewable energy employment, more efficient use of energy, or a wide range of climate policies. This study reports a bibliometric analysis of direct carbon dioxide emission reduction through carbon capture. The research trend in carbon capture within the three main types of technologies, namely pre-combustion, post-combustion and oxy-fuel combustion, was investigated using publications from 1998 to 2018 retrieved from the Web of Science database. It was found that from 1998-2007 there was little or no research output on carbon capture, until 2008, when legislation on climate change abatement was introduced and public and industry awareness of clean fossil energy options grew. With these motivating factors, 55 countries engaged in carbon capture technologies and related research in which the United States has the most research output followed by the UK and, China. Among the carbon capture technologies commonly studied, the bibliometric analysis based on a network map showed that post-combustion capture is the most referenced carbon capture technology with about 80.9% of total publications retrieved. oxy-fuel combustion had the lowest number of publications (3.4%).
A vapour absorption refrigeration system (VARS) coupled with a solid oxide fuel cell (SOFC) is pr... more A vapour absorption refrigeration system (VARS) coupled with a solid oxide fuel cell (SOFC) is proposed for different types of refrigerated trucks (large, medium and small) as a favourable alternative to conventional diesel engine driven vapour compression refrigeration systems. An SOFC-supported VARS has the novel attributes of negligible environmental impact and the ability to keep the refrigeration system running while the vehicle engine is switched off. In addition, the SOFC system produces electricity which can be utilised for other operations on the vehicle. This in turn reduces the load on the main diesel engine of the vehicle. This research paper presents a comprehensive thermo-economic study for two different SOFC system configurations namely; series and parallel to optimise the SOFC sub-system layout. Moreover, a benefit function to optimise the SOFC stack size and operating conditions has been identified considering four performance parameters, namely; thermodynamic efficiency, mass of the system, greenhouse gas (GHG) emissions, and cost of cogeneration. The analysis was conducted on various categories of refrigerated trucks. The results show that a parallel configuration has an enhanced thermo-economic performance and requires a 45–65% lower number of SOFC cells to obtain the required refrigeration load in comparison to the series configuration. Simulation results indicated that the proposed SOFC-VARS for large, medium and small refrigerated trucks can provide an output of 3.3 kW, 12.8 kW and 18.7 kW of electric power and 1 kW, 4 kW and 6 kW of refrigeration load respectively. It was also found that the SOFC-coupled VARS is able to supply the required refrigeration load with negligible emissions of GHGs compared to other refrigerated transportation technologies.
... Polymer Electrolyte Fuel Cell Degradation Matthew M. Mench Emin Caglan Kumbur T. Nejat Veziro... more ... Polymer Electrolyte Fuel Cell Degradation Matthew M. Mench Emin Caglan Kumbur T. Nejat Veziroglu AMSTERDAM l BOSTON l ... in Vehicles Summary and Future Challenges Acknowledgments Nomenclature 4. Gas Diffusion Media and their Degradation Ahmad El-kharouf ...
This paper evaluates the performance of Nafion 211 at elevated temperatures up to 120 °C using an... more This paper evaluates the performance of Nafion 211 at elevated temperatures up to 120 °C using an experimentally validated model. Increasing the fuel cell operating temperature could have many key benefits at the cell and system levels. However, current research excludes this due to issues with membrane durability. Modelling is used to investigate complex systems to gain further information that is challenging to obtain experimentally. Nafion 211 is shown to have some interesting characteristics at elevated temperatures previously unreported, the first of which is that the highest performance reported is at 100 °C and 100% relative humidity. The model was trained on the experimental data and then used to predict the behaviour in the membrane region to understand how the fuel cell performs at varying temperatures and pressures. The model showed that the best membrane performance comes from a 100 °C operating temperature, with much better performance yielded from a higher pressure of ...
There are four strategies to combating global warming, namely by directly reducing greenhouse gas... more There are four strategies to combating global warming, namely by directly reducing greenhouse gas emissions, or indirectly through expanding renewable energy employment, more efficient use of energy, or a wide range of climate policies. This study reports a bibliometric analysis of direct carbon dioxide emission reduction through carbon capture. The research trend in carbon capture within the three main types of technologies, namely pre-combustion, post-combustion and oxy-fuel combustion, was investigated using publications from 1998 to 2018 retrieved from the Web of Science database. It was found that from 1998-2007 there was little or no research output on carbon capture, until 2008, when legislation on climate change abatement was introduced and public and industry awareness of clean fossil energy options grew. With these motivating factors, 55 countries engaged in carbon capture technologies and related research in which the United States has the most research output followed by the UK and, China. Among the carbon capture technologies commonly studied, the bibliometric analysis based on a network map showed that post-combustion capture is the most referenced carbon capture technology with about 80.9% of total publications retrieved. oxy-fuel combustion had the lowest number of publications (3.4%).
This paper demonstrates the significant and positive effect of applying a magnetic field on the p... more This paper demonstrates the significant and positive effect of applying a magnetic field on the performance of Proton Exchange Membrane Water Electrolysers (PEMWE). A magnetizer and a transparent PEMWE cell are used to observe the effect of the magnetic field at variable water flow rates on the PEMWE performance. The presence of the magnetic field introduces Lorentz force which results in a significant improvement in the electrolyser performance. The magnetic flux density is varied between 0 T and 0.5 T, while the water flow rate is varied from 100 ml min −1 to 300 ml min −1 to study the effect and relationship between the two parameters and the performance of the PEMWE. Under a 0.5 T magnetic field and 300 ml min −1 flow rate, a 33% increase in the cell performance is achieved compared to the conventional operation at the same flow rate. The positive effect is explained by the introduction of Lorentz force from the magnetic field to the operating PEMWE. The improvement here is due to the relaxation and pumping effect of the magnetic field on the electrode surface which results in enhancing oxygen bubbles removal and lowering mass transport polarisation. Moreover, the enhanced oxygen bubbles removal is expected to increase the lifetime of the electrolyser as a result of the reduced contact between the produced oxygen and the anode materials.
In this study, inkjet printing technology was adopted for the application of protective layer coa... more In this study, inkjet printing technology was adopted for the application of protective layer coatings on metallic Solid Oxide Fuel Cell (SOFC) interconnects. The study highlights the potential of the inkjet printing process to fabricate aqueous-based protective layer coatings over ferritic stainless steels, a novel, very flexible, and low-cost approach to coating. The work presented focusses on the formulation of aqueous-based spinel particulate inks for the inkjet printing process using an electromagnetic inkjet printer. An ink formulation route based on a two-stage ball milling technique was developed to produce a printable ink composition with Manganese Cobalt Oxide (MnCo 2 O 4 ,MCO) and Manganese Cobalt Ferrite (MnCo 1.8 Fe 0.2 O 4 , MCF) as the coating materials. Stability of the ink suspensions and particle size distribution were studied and characterised using zeta and a particle size analysis, respectively. Flow properties of the inks were analysed using a conventional rheometer at shear rates 1 to 1000 s À1 and Piezo Axial Vibrator rheometer at higher shear rates (10-6 s À1). Finally, printability of the inks was assessed theoretically based on the Ohnesorge number, Z. The formulated MCO and MCF inks with~25 wt% solid loading exhibited Z values of 4.17 and 6.77, satisfying the printability criteria of the inkjet inks. Printability of the inks was demonstrated by printing them on stainless-steel substrates. and printed layers were free of any visible defects after heat-treatment. The demonstrated ink formulation procedure provides a guide for inkjet inks development with respect to inkjet printer requirements. Furthermore, the outlined methodology can be employed to fabricate protective and other coatings for any kind of metallic components such as bipolar plates and heat-exchangers.
Nafion membranes are still the dominating material used in the polymer electrolyte membrane (PEM)... more Nafion membranes are still the dominating material used in the polymer electrolyte membrane (PEM) technologies. They are widely used in several applications thanks to their excellent properties: high proton conductivity and high chemical stability in both oxidation and reduction environment. However, they have several technical challenges: reactants permeability, which results in reduced performance, dependence on water content to perform preventing the operation at higher temperatures or low humidity levels, and chemical degradation. This paper reviews novel composite membranes that have been developed for PEM applications, including direct methanol fuel cells (DMFCs), hydrogen PEM fuel cells (PEMFCs), and water electrolysers (PEMWEs), aiming at overcoming the drawbacks of the commercial Nafion membranes. It provides a broad overview of the Nafion-based membranes, with organic and inorganic fillers, and non-fluorinated membranes available in the literature for which various main properties (proton conductivity, crossover, maximum power density, and thermal stability) are reported. The studies on composite membranes demonstrate that they are suitable for PEM applications and can potentially compete with Nafion membranes in terms of performance and lifetime. 1. Background During the last 100 years the world average temperature has increased by almost 0.8 • C [1], becoming the most critical environmental issue of our time. Even though there are many different factors responsible, the greatest concern is greenhouse gas emissions due to human activities linked to energy production and use. In this sense, governments worldwide are acting to take measures to revise their energy mix by reducing fossil fuels usage and promoting alternative sources. The European Union, with the objectives set in the 20-20-20 pack, put forward strict targets to be reached before 2020, namely 20% reduction of greenhouse gases, 20% primary energy production from renewables, and 20% of biofuels burned in transportation. Moreover, recently a medium-long term strategy was agreed, stating that the European energy efficiency should be improved by 27% and the renewables energy input should increase by up to the 27% of the total share before 2030. Within this overall framework, it is becoming increasingly important that research and development of new technologies are intensified to allow the penetration of more efficient energy conversion systems. In this context, polymer electrolyte membrane technologies can play an important role.
The corrosion behaviour and Cr retention ability of SS309, aluminised SS309, and AluChrom 318 hav... more The corrosion behaviour and Cr retention ability of SS309, aluminised SS309, and AluChrom 318 have been investigated at 850°C in air with 3 % H 2 O. The SS309 samples failed the specifications for application as cathode air preheater (CAPH) material due to a high Cr evaporation rate and massive scale spallation. The surface aluminisation dramatically decreased the Cr evaporation rate of SS309, but not in the long-term due to breakaway oxidation induced alumina scale spallation. The AluChrom 318 formed a γ-Al 2 O 3 /α-Al 2 O 3 layer scale and demonstrated the highest Cr retention ability and oxidation resistance among the tested alloy samples.
Two materials, polyaniline (PANI) and titanium nitride (TiN), used for bipolar plate (BPP) coatin... more Two materials, polyaniline (PANI) and titanium nitride (TiN), used for bipolar plate (BPP) coatings have each shown promise in improving the corrosion resistance and contact resistance, respectively, of metallic bipolar plates. Polyaniline was shown to provide a barrier for the bipolar plate and to effectively lower the corrosion currents observed in ex situ corrosion tests. However, the interfacial contact resistance (ICR) between poly-aniline coatings and gas diffusion layer (GDL) is high and results in high electrical losses. On the other hand, TiN is reported to achieve good conductivity and in some cases improved corrosion resistance. The two materials have also been investigated together in a composite coating and showed promising results, but the contact resistance of the coating was still too high for use in a commercial fuel cell. In this study, the application of an additional layer of TiN over the TiN-polyaniline composite coating (a bilayer coating) is investigated. Composite bilayered PANI TiN coatings were deposited upon SS316L substrates. The optimized coating achieved U.S. Department of Energy (DoE) targets with potentiostatic corrosion currents of~0.024 μA cm-2 and ICR values of 11.2 mΩ cm 2. PANI polymerization was confirmed , using Fourier-transform infrared (FTIR) spectroscopy and TiN loadings were investigated with energy dispersive X-ray (EDX) spectroscopy.
This work investigates life cycle costing analysis as a tool to estimate the cost of hydrogen to ... more This work investigates life cycle costing analysis as a tool to estimate the cost of hydrogen to be used as fuel for Hydrogen Fuel Cell vehicles (HFCVs). The method of life cycle costing and economic data are considered to estimate the cost of hydrogen for centralised and decentralised production processes. In the current study, two major hydrogen production methods are considered, methane reforming and water electrolysis. The costing frameworks are defined for hydrogen production, transportation and final application. The results show that hydrogen production via centralised methane reforming is financially viable for future transport applications. The ownership cost of HFCVs shows the highest cost among other costs of life cycle analysis.
Using the residual heat from the engine exhaust and of late from the fuel cell exhaust to drive a... more Using the residual heat from the engine exhaust and of late from the fuel cell exhaust to drive a refrigeration or air conditioning unit on-board a vehicle has been the interest of many research groups worldwide. Umpteen number of modelling studies and a few prototypes have been built in this area. In this paper, an up to date review of the heat driven absorption refrigeration/air conditioning systems specifically meant for transport applications is given. This is followed by a discussion on the major challenges involved in implementing such a technology for the transport sector, the ways in which such a technology can be developed further and why using heat driven refrigeration/air conditioning systems could be a game changer in the automotive industry. From the study carried out two things are apparent-there is currently no VARS unit that can readily be used on-board vehicles and linking VARS units with engine exhaust leads to drop in engine efficiency and thus overall vehicle performance. Fuel cells (SOFCs in particular), if used as APUs can reduce the load on the engine and also supply a constant heat load to the VARS and thus be more effective.
Increasing Polymer Electrolyte Fuel Cells' (PEFCs) operating temperature has benefits on the perf... more Increasing Polymer Electrolyte Fuel Cells' (PEFCs) operating temperature has benefits on the performance and the ease of utilisation of the heat generated; however, efforts for high temperature PEFCs have resulted in high degradation and reduced life time. In the literature , conventional low temperature (T < 80 C) and high temperature (140e200 C) regimes have been extensively studied, while the gap of operating at intermediate temperature (IT) (100e120 C) has been scarcely explored. The main bottleneck for operating at IT conditions is the development of a suitable proton exchange membrane with comparable performance and lifetime to the commercially used Nafion operating at conventional conditions. In this work, composite membranes of Graphene Oxide (GO) and Nafion of varied thickness were fabricated, characterised and assessed for in-situ single cell performance under automotive operating conditions at conventional and intermediate temperatures. The material characterisation confirmed that a composite GO-Nafion structure was achieved. The composite membrane demonstrated higher mechanical strength, enhanced water uptake, and higher performance. It was demonstrated that by utilising GO-Nafion composite membranes, an up to 20% increase in the maximum power density at all operating temperatures can be achieved, with the optimum performance is obtained at 100 C. Moreover, the GO-Nafion membrane was able to maintain its open circuit voltage values at increased temperature and reduced thickness, indicating better durability and potentially higher lifetime.
In light of stricter emissions regulations and depleting fossil fuel reserves, fuel cell vehicles... more In light of stricter emissions regulations and depleting fossil fuel reserves, fuel cell vehicles (FCVs) are one of the leading alternatives for powering future vehicles. An open-cathode, air-cooled proton exchange membrane fuel cell (PEMFC) stack provides a relatively simple electric generation system for a vehicle in terms of system complexity and number of components. The temperature within a PEMFC stack is critical to its level of performance and the electrochemical efficiency. Previously created computational models to study and predict the stack temperature have been limited in their scale and the inaccurate assumption that temperature is uniform throughout. The present work details the creation of a numerical model to study the temperature distribution of an 80-cell Ballard 1020ACS stack by simulating the cooling airflow across the stack. Using computational fluid dynamics, a steady-state airflow simulation was performed using experimental data to form boundary conditions where possible. Additionally, a parametric study was performed to investigate the effect of the distance between the stack and cooling fan on stack performance. Model validation was performed against published results. The temperature distribution across the stack was identical for the central 70% of the cells, with eccentric temperatures observed at the stack extremities, while the difference between coolant and bipolar plate temperatures was approximately 10 C at the cooling channel outlets. The results of the parametric study showed that the fan-stack distance has a negligible effect on stack performance. The assumptions regarding stack temperature uniformity and measurement were challenged. Lastly, the hypothesis regarding the negligible effect of fan-stack distance on stack performance was confirmed. K E Y W O R D S airflow simulation, coolant temperature, fuel cell vehicles, PEM fuel cells, stack temperature, thermal management
There are four strategies to combating global warming, namely by directly reducing greenhouse gas... more There are four strategies to combating global warming, namely by directly reducing greenhouse gas emissions, or indirectly through expanding renewable energy employment, more efficient use of energy, or a wide range of climate policies. This study reports a bibliometric analysis of direct carbon dioxide emission reduction through carbon capture. The research trend in carbon capture within the three main types of technologies, namely pre-combustion, post-combustion and oxy-fuel combustion, was investigated using publications from 1998 to 2018 retrieved from the Web of Science database. It was found that from 1998-2007 there was little or no research output on carbon capture, until 2008, when legislation on climate change abatement was introduced and public and industry awareness of clean fossil energy options grew. With these motivating factors, 55 countries engaged in carbon capture technologies and related research in which the United States has the most research output followed by the UK and, China. Among the carbon capture technologies commonly studied, the bibliometric analysis based on a network map showed that post-combustion capture is the most referenced carbon capture technology with about 80.9% of total publications retrieved. oxy-fuel combustion had the lowest number of publications (3.4%).
A vapour absorption refrigeration system (VARS) coupled with a solid oxide fuel cell (SOFC) is pr... more A vapour absorption refrigeration system (VARS) coupled with a solid oxide fuel cell (SOFC) is proposed for different types of refrigerated trucks (large, medium and small) as a favourable alternative to conventional diesel engine driven vapour compression refrigeration systems. An SOFC-supported VARS has the novel attributes of negligible environmental impact and the ability to keep the refrigeration system running while the vehicle engine is switched off. In addition, the SOFC system produces electricity which can be utilised for other operations on the vehicle. This in turn reduces the load on the main diesel engine of the vehicle. This research paper presents a comprehensive thermo-economic study for two different SOFC system configurations namely; series and parallel to optimise the SOFC sub-system layout. Moreover, a benefit function to optimise the SOFC stack size and operating conditions has been identified considering four performance parameters, namely; thermodynamic efficiency, mass of the system, greenhouse gas (GHG) emissions, and cost of cogeneration. The analysis was conducted on various categories of refrigerated trucks. The results show that a parallel configuration has an enhanced thermo-economic performance and requires a 45–65% lower number of SOFC cells to obtain the required refrigeration load in comparison to the series configuration. Simulation results indicated that the proposed SOFC-VARS for large, medium and small refrigerated trucks can provide an output of 3.3 kW, 12.8 kW and 18.7 kW of electric power and 1 kW, 4 kW and 6 kW of refrigeration load respectively. It was also found that the SOFC-coupled VARS is able to supply the required refrigeration load with negligible emissions of GHGs compared to other refrigerated transportation technologies.
... Polymer Electrolyte Fuel Cell Degradation Matthew M. Mench Emin Caglan Kumbur T. Nejat Veziro... more ... Polymer Electrolyte Fuel Cell Degradation Matthew M. Mench Emin Caglan Kumbur T. Nejat Veziroglu AMSTERDAM l BOSTON l ... in Vehicles Summary and Future Challenges Acknowledgments Nomenclature 4. Gas Diffusion Media and their Degradation Ahmad El-kharouf ...
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