Improving thermal efficiency by reducing cooling losses in hydrogen combustion engines |
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Authors: | Toshio Shudo |
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Affiliation: | Applied Energy System Group, Division of Energy and Environmental Systems, Hokkaido University, N13 W8, Kita-Ward, Sapporo, Hokkaido 060-8628, Japan |
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Abstract: | Hydrogen can be readily used in spark ignition engines as a clean alternative to fossil fuels. However, the higher burning velocity and shorter quenching distance of hydrogen compared with hydrocarbons cause a larger heat transfer from the burning gas to the combustion chamber walls. Because of this cooling loss, the thermal efficiency of hydrogen-fueled engines is sometimes lower than that of conventionally fueled engines. Therefore, reducing the cooling loss is a crucial element in improving the thermal efficiency of hydrogen combustion engines. Previous research by the author and others has proposed the direct injection stratified charge as a technique for reducing the cooling loss in hydrogen combustion and shown its effect in reducing cooling loss through experiments in a constant volume combustion vessel. However, it is known that a reduction in cooling loss does not always improve thermal efficiency due to a simultaneous increase in the exhaust heat loss. This paper explains the relation between cooling loss reduction and thermal efficiency improvements by the direct injection stratified charge in hydrogen combustion engines. |
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Keywords: | Hydrogen engine Thermal efficiency Cooling loss Exhaust loss Stratified charge Combustion |
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