Abstract    The standard design parameters of a compression ignition engine fail to give specified performance with strait vegetable oil (SVO) from different origins. This study is performed to find the effect of compression ratio on emission characteristics such as carbon monoxide (CO), carbon dioxide (CO2), hydrocarbon (HC), nitrogen oxides (NOx) and smoke opacity with all the tested fuels in a single cylinder, four stroke VCR engine fueled with neat Karanja oil blends (10% and 20%) with diesel (on volume basis) and Karanja oil methyl ester (KOME) blends (20%, 40% and 60%) and the results are compared with diesel. Experiment has been conducted at compression ratios of 16:1, 17:1, 18:1. At higher CR minimum value CO is recorded 0.04% for 20% blend of KOME (B20), while it show maximum CO2 recorded 4.45%. Lowest HC and NOx emission recorded 22 ppm and 552 ppm respectively for 40% blend of KOME (B40). Emissions are marginally higher for K10 and K20 than diesel. Overall observation shows that B40 shows lowest emissions than other blends of KOME at higher compression ratio.

Keywords    Karanja oil, Karanja oil methyl ester, Variable compression ratio engine, Emission

چکیده    پارامترهای طراحی استاندارد یک موتور احتراق تراکمی با سوخت روغن​های گیاهی خالص از گیاه​های مختلف قادر به تامین کارایی مشخص شده نیستند. در این مطالعه اثر ضریب تراکم بر ویژگی​های انتشار گازهایی مانند مونوکسید کربن (CO)، دی اکسید کربن (CO2)، هیدروکربن (HC)، اکسیدهای نیتروژن (NOx) و کدورت دود با در یک موتور دیزل تک سیلندر چهار زمانه با سوخت روغن Karanja تمیز مخلوط شده با سوخت دیزل به نسبت​های حجمی 10 و 20 درصد و Karanja و همچنین متیل استر به نسبت​های حجمی 20 ، 40 و 60 درصد (KOME) بررسی و با سوخت دیزل مقایسه شده است. آزمون​ها در ضریب​های تراکم 16:01، 17:01 و 18:01 انجام شده است. در ضریب تراکم​های بالاتر، حداقل مقدار CO برای KOME 20درصدی (B20) به 0.04 به دست آمده است، در حالی که حداکثر CO2 45/4٪ بوده است. پایین ترین مقدار هیدروکربن و NOx منتشر شده برای KOME 40 درصدی ( (B40به ترتیب 22 و 552 پی پی ام است. تولید این گازها توسط سوخت​های K10 و K20 فقط اندکی بیشتر از دیزل است. نتایج این پژوهش به طور کلی نشان می​دهد که تولید گازها از سوخت با ترکیب B40 در نسبت​های تراکم بالاتر، کمترین مقدار در میان سوخت​های KOME است.

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