Emissions From Refined Coconut Oil Ethyl Ester-Diesel Blends – a Preliminary Study

Abstract

Abstract –    The study describes the production of ethyl ester biodiesel from refined coconut oil. It aimed to replace the toxic methanol by a renewable and relatively safe ethanol and to determine whether the product properties conform to Philippine National Standard (PNS) specifications for B100 fatty acid methyl ester biodiesel. Emission characteristics of the biodiesel were also studied using a single-cylinder engine generator set fueled with neat diesel, B1, B2, and B5 biodiesel blends, at 61%, 77%, and 93% electrical loads, which are low, medium, and high load respectively. Successful conversion via base-catalyzed transesterification was carried at process conditions of 1% (weight to oil) KOH catalyst, 59% excess ethanol, 1.5 hours reaction time and ambient temperature at mixer setting of about 4500 rpm with a yield of 93.64% ester. Several properties of the produced coconut ethyl ester conformed to PNS specifications with the exception of cetane index, acid value, water content, and total glycerine content. The calculated cetane index was 46.327 which is close to US and Brazil standards for cetane number. Emission tests revealed that the B1 blend had the optimal emission characteristics with most of the parameters while B2 blend had the most significant decrease in CO emission. B1 reduced CO2 emission by 8%, NOx at 7% and THC by 2.5% at high load when compared to base petro diesel. B2 blend reduced CO emission significantly by 46% at low load and 22% at medium load when compared to base petro diesel. The remaining B2 and B5 blends had an average increase of about 10% and 16% NOx emissions respectively, a typical characteristic for most biodiesels.

Keywords—biodiesel, ethanol, ethyl ester, coconut oil, biodiesel emissions