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GÜMÜŞ, METİN

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Start date: 2020 × Subject: Compression ratio ×

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    Assessment of combustion and exhaust emissions in a common-rail diesel engine fueled with methane and hydrogen/methane mixtures under different compression ratio
    (PERGAMON-ELSEVIER SCIENCE LTD, 2020) YILMAZ, İLKER TURGUT; Sanli, Ali; Yilmaz, Ilker Turgut; Gumus, Metin
    This study investigates the potential usage of the methane and hydrogen enriched methane in a turbocharged common-rail direct injection diesel engine. Methane and hydrogen/methane mixtures are sent through the air intake manifold of the engine. The engine is operated at four different loads and three different compression ratios. Results are compared amongst single diesel and dual-fuel operations at different compression ratios and load conditions. Compared to diesel, dual-fuel operations mostly generate higher and advanced peak in-cylinder gas pressure, more combustion noise, late pilot injection and start of combustion, advanced combustion center, substantial variations at ignition delay and combustion duration, a significant increase in cyclic variations at low and medium loads, and earlier heat release. Hydrogen enrichment decreases evidently specific fuel consumption. Concerning emissions, compared to diesel operation, dual-fuel operations produce higher total hydrocarbon (THC) and nitrogen oxides (NOx) but lower carbon dioxide (CO2). Hydrogen substitutions decrease THC and CO2 emissions of methane dual-fuel operations approximately between 9-29% and 1-32%, respectively. Smoke emission of dual-fuel operations is less than that of diesel at low and medium loads, whereas it sharply increases at high load. Knocking occurs at high compression ratio and load conditions with dual-fuel operations and dramatically increases with increasing hydrogen ratio. Decreasing the compression ratio notably reduces the combustion noise as well as some emissions, such as NOx, CO2 and smoke, for entire load ranges of dual-fuel and diesel operations. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Investigation of heat transfer in combustion chamber of a direct injection diesel engine under different compression ratios and engine torques
    (2022-01-01) GÜMÜŞ, METİN; Sanli A., GÜMÜŞ M.
    The heat transfer between gases and combustion chamber walls is an important issue because of affecting the emissions and engine performance. On the other hand, there are a number of engine operation parameters impacting on the in-cylinder heat transfer. Of these parameters, compression ratio and engine torque are of significant influence on the engine heat transfer. For this reason, in this study the effects of compression ratio and engine torque on the heat transfer between gases and combustion chamber walls in a compression ignition engine were studied. The most used correlations such as Hohenberg, Woschni, Nusselt, Eichelberg, and Sitkei-Ramanaiah were used to calculate the overall convective heat transfer coefficient in the combustion chamber. Moreover, various heat transfer characteristics (heat flux, heat loss in combustion chamber parts, heat transfer rate) were evaluated in this study. In the performed study, it was shown that compression ratio and engine torque affected significantly the heat transfer coefficient and heat flux. While heat transfer characteristics calculated by Sitkei-Ramanaiah correlation had the highest value, Eichelberg correlation had the lowest values. The most transferred heat among the combustion chamber parts occurred in the piston.