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In order to verify the possibility of representing the local heat transfer characteristics within the combustion chamber by flow-based zonal modelling, cycle simulation and finite element (FE) analysis for the temperature distribution in the piston and cylinder block were performed. Convective heat transfer coefficient was calculated using flow-based zonal model and compared with that using Woschni's Correlation. Calculated temperature distribution of the piston and the cylinder block showed that the flow- based zonal model is far more logical because of its capability to reflect in-cylinder flow, combustion chamber configuration, and engine operating condition. The shape of isothermal line and the highest temperature region location by flow-based zonal modelling are affected by the magnitude of heat loaded from combustion chamber. The results obtained from Woschni's correlation, however, do not show any change in the isothermal line shape and the highest temperature region location.

Natural gas vehicle's (NGV's) hydrocarbon (HC) emission is mostly methane, and it is very hard to get rid of methane using conventional Pt/Rh based three-way catalytic converter since methane(CH4) is one of the most stable hydrocarbon species. In countries where HC is regulated in non-methane hydrocarbon (NMHC), CH4 emission is not a problem, but in other countries where HC is regulated in total hydrocarbon (THC), more effort is needed to meet the HC emission level of a NGV. In addition, methane is known to be responsible for global worming, and there is a movement to regulate CH4 emission in North America. Recent research showed that Pd/Rh based catalyst is an effective means of reducing CH4. Other research showed that the dispersion of noble metals instead of crystalization on substrate is also an effective means of reducing CH4.