Effect of Design Parameters on the Internal Steam Reforming of Methane in Solid Oxide Fuel Cell Systems
Issue:
Volume 3, Issue 3, June 2017
Pages:
38-49
Received:
10 May 2017
Accepted:
26 May 2017
Published:
30 June 2017
Abstract: The operation of solid oxide fuel cell systems with the internal steam reforming of methane over supported nickel catalysts is studied. A mathematical model including heterogeneous chemistry, electro-chemistry, mass transport, and porous media transport is developed to explore the thermal energy coupling between the steam reforming and the electrochemical reactions, independent of the geometrical structure. The role of catalyst activity, inlet temperature, current density, and operating pressure in the system behavior is evaluated. A sensitivity analysis is also performed for different design parameters. The effect of flow configuration on the operation of the system is analyzed and compared based on multiple performance criteria. It is shown that the internal steam reforming within the fuel cell system can result in an overall auto-thermal operation which increases efficiency and simplifies the design process. However, a local cooling effect may occur close to the entrance of the reformer. The use of less active catalysts can cause the slippage of the methane. To reduce both the overall temperature increase across the fuel cell and the local cooling caused by the endothermic steam reforming reactions, increasing the operating pressure is found to be an effective approach. High system efficiency is obtained with increasing the operating pressure or decreasing the current density. The more efficient system is found for a co-flow configuration, while significant temperature gradients near the entrance of the reformer are not desirable for ceramic solid oxide fuel cell systems.
Abstract: The operation of solid oxide fuel cell systems with the internal steam reforming of methane over supported nickel catalysts is studied. A mathematical model including heterogeneous chemistry, electro-chemistry, mass transport, and porous media transport is developed to explore the thermal energy coupling between the steam reforming and the electroc...
Show More
Bioenergy Potential of Under-Utilized Solid Waste Residues from Oil Palm Mills in Nigeria
Sylvester Chibueze Izah,
Adesola Stephen Ojesanmi
Issue:
Volume 3, Issue 3, June 2017
Pages:
50-57
Received:
13 May 2017
Accepted:
6 June 2017
Published:
14 July 2017
Abstract: This study estimated bioelectricity potentials of under-utilized oil palm processing solid wastes (chaff, empty fruit bunch, palm press fibre and palm kernel shell) in Nigeria. The potential challenges of bio-power production from these solid wastes were also evaluated. Quantitative approach was employed for data generation. Historical data study of oil palm growth rate between 2004 to 2013 was used and projections at three scenarios (high, low and current status) were made. The findings showed that bioelectricity from total possible gatherable under-utilized oil palm processing solid wastes in Nigeria were 3.234 to 5.175 MWh in 2004, which could have reached 3.796 to 6.073 MWh in 2013. Based on projections at high, low and current growth rate scenarios, 5.728 to 9.165 MWh (high growth rate), 4.720 to 7.536 MWh (low growth rate) and 4.242 to 6.787 MWh (current growth rate) of electricity at efficiency of 80% (for combustion), 65% (for pyrolysis) and 50% (for gasification) could be achieved by 2029. After considering all the challenges associated with each type of conversion process, only 40% of these values are attainable. The study identified technological, policy/political and economic framework as potential challenge of bioelectricity generation in Nigeria. Hence the study concludes by suggesting means of overcoming the hurdles under Nigeria setting.
Abstract: This study estimated bioelectricity potentials of under-utilized oil palm processing solid wastes (chaff, empty fruit bunch, palm press fibre and palm kernel shell) in Nigeria. The potential challenges of bio-power production from these solid wastes were also evaluated. Quantitative approach was employed for data generation. Historical data study o...
Show More
