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YILMAZ, İLKER TURGUT

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İLKER TURGUT

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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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    Experimental Evaluation of Performance and Combustion Characteristics in a Hydrogen-Methane Port Fueled Diesel Engine at Different Compression Ratios
    (AMER CHEMICAL SOC, 2020) YILMAZ, İLKER TURGUT; Sanli, Ali; Yilmaz, Ilker Turgut; Gumus, Metin
    This paper investigates the performance and combustion characteristics of a common-rail diesel engine fueled with methane and hydrogen enrichment of methane under different loads (2.15, 4.3, 6.45, and 8.6 bar) and compression ratios (CRs) (18.25, 16.9, and 15.8). Traditional diesel fuel is used as the pilot fuel and is injected twice as pre- and main injections. Results of the usage of gaseous fuels are compared with each other and the single diesel mode. Accordingly, brake thermal efficiency (BTE) and brake specific energy consumption (BSEC) are highly deteriorated at low loads, but they improve with load. Hydrogen substitution results in slightly higher BTE and lower BSEC. The average exhaust temperature with gaseous fuels is enhanced compared to that with diesel. Peak cylinder pressures of dual-fuel operations are higher, and an earlier heat release is observed; moreover, combustion noise of dual-fuel operations is further enhanced under a high CR-high load condition. Finally, combustion durations substantially change with loads and CRs.
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    Investigation of the effect of biogas on combustion and emissions of TBC diesel engine
    (ELSEVIER SCI LTD, 2017) YILMAZ, İLKER TURGUT; Yilmaz, I. T.; Gumus, M.
    In this study, the effect of biogas on the thermal barrier coated (TBC) dual-fuel engine was experimentally investigated. Experiments were carried out on a four cylinder, water cooled, turbocharged, common-rail coated and uncoated diesel engine under dual-fuel (biogas-diesel) mode and single fuel (neat diesel) mode. Combustion chambers of the pistons were coated with 400 mu m thickness 8% yttria stabilized zirconia main coat over a 100 mu m thickness Ni-Al bond coat using atmospheric plasma spray method. Combustion (cylinder gas pressure, rate of pressure rise), heat release (rate of heat release, cumulative heat release, duration and center of heat release) exhaust emission (HC, NOx and smoke emissions) parameters were investigated. Results showed that homogenous mixture of gaseous fuel and air caused high cylinder pressures. TBC can be used for decreasing smoke emissions under dual-fuel (biogas-diesel) mode. TBC had not a significant effect on NOx emission of single fuel mode. (C) 2016 Elsevier Ltd. All rights reserved.