Experimental Investigation on Usage of Palm Oil as a Lubricant to Substitute Mineral Oil in CI Engines

Due to growing environmental concerns, vegetable oils are finding their way into lubricants for industrial and transportation applications. The substitution of mineral oil with vegetable oil as a base stock for an environment friendly lubricant in a CI engine is explored in this study without adding any additives. The experiments have been conducted with a mixture of palm oil and mineral oil, at different compositions. Blends of palm oil and mineral oil in different compositions, 0, 25, and 50 (by vol %) were added to base SAE20W40 mineral oil to obtain different lubricant blends. The parameters evaluated include brake thermal efficiency, brake specific fuel consumption, volumetric efficiency, and mechanical efficiency and exhaust emissions. The engine performance and emission tests were carried out on a single cylinder, water cooled, 4-stroke CI engine. Compared to mineral oil, the palm oil-based lubricant revealed appreciable expedience on engine and emission performance. 1. Introduction Vegetable oil lubricants provide a renewable source of environmentally friendly lubricants, relating to the lubricant’s ability to biodegrade into harmless products. Recently there has been an increased concern in enhancing the use of biodegradable vegetable oils in lubricants, mostly by environmental as well as health and safety issues, emerging due to changes in economic and supply factors. From the viewpoint of emissions, biodegradable lubricants are expected to behave differently from conventional lubricants, mainly with respect to SOF emissions (soluble organic fraction of particulate emissions). Polycyclic aromatic hydrocarbons, which are absent in vegetable oils, pose a great contingency to human health. Vegetable oils are also low in potential pollutants like sulphur-containing compounds which can damage both environment and catalytic converter. The advantages of vegetable oils as base oil in lubricants as compared to mineral oils are nontoxicity, biodegradability, resource renewability, affordable application cost, high viscosity index, and so forth. Vegetable oils are usually much cheaper than ester based oils and therefore provide more potential for the successful implementation as lubricants in base oil. 1.1. Literature Review Many researchers have worked on these methods, with positive results. Cheenkachorn and Fungtammasan [1] investigated the use of palm oil as base oil for an environmentally friendly lubricant for small four-stroke motorcycle engines. Their study showed that, compared to mineral-based commercial oil, the palm oil-based lubricant showed