Quaternary blends of diesel, biodiesel, higher alcohols and vegetable oil in a compression ignition engine

Abstract

Vegetable oils, biodiesel and alcohols are important alternative fuel resources for diesel engines. Prominent fuels of the three types include: soybean oil which has efficient amount of productivity, biodiesel made of waste oils which do not affect food security and alcohols with high number of carbons. There is potential to use quaternary blends of diesel fuel, waste oil methyl ester, soybean oil and higher alcohols, such as propanol and pentanol, in diesel engines for the purpose of increasing the use of biofuels and decreasing fossil fuel consumption. In this work, diesel fuel (D) was mixed with biodiesel (B), and biodiesel-vegetable oil (VO)-alcohol blends using the higher alcohols of propanol (Pro) and pentanol (Pen). Test fuel blends of DB (50 vol% D-50 vol% B), DBVOPro (40 vol% D-40 vol% B-10 vol% VO-10 vol% Pro), DBVOPen (40 vol% D-40 vol% B-10 vol% VO-10 vol% Pen) were prepared through the splash blending method and tested in a diesel engine. The key fuel properties such as density, lower heating value, viscosity and cetane number were measured. Engine performance and exhaust emission tests of the blends were carried out on a four-cylinder, four-cycle diesel engine generator at various loads (0, 3, 6, 9 kW) with fixed engine speed of 1800 rpm. According to engine test results, mean brake specific fuel consumptions (BSFCs) of DBVOPro increased compared to DB and DBVOPen at all engine loads. As compared to DB blend, DBVOPro presented the best mean oxides of nitrogen (NOx) with a reduction of 11.9%. However, formation of carbon monoxide (CO) and hydrocarbon (HC) emissions have been increased with the addition of each of the higher alcohol to DB.