Experimental studies on utilization of used transformer oil as an alternative fuel in a DI diesel engine

Reuse and recycling are better options to derive energy or value added products from waste substances and to minimize the disposal problems. Transformer oil is generally used as a coolant in welding transformers, power transformers and electromotive units. After a prolonged use in these devices, the transformer oil becomes waste and is disposed of. The disposal of used transformer oil (UTO) causes an environmental pollution. However, the UTO has properties that are similar to that of diesel fuel with a marginally higher viscosity and lower calorific value. The present investigation is aimed to reuse the UTO as a possible source of energy to run a small powered, single cylinder, four stroke, air cooled, direct injection (DI) diesel engine. Different techniques such as blending, operating the engine with different injection timings, nozzle opening pressures, compression ratios, preheating and dual fuel mode were adopted to study the engine behavior in terms of combustion, performance and emission when the engine is fueled with the UTO. The results are analyzed and compared with diesel operation of the same engine and presented in this thesis. Initially, UTO and six of its diesel blends on varying the UTO concentration from 10% to 60%, at a regular interval of 10% by volume basis was used. Increase in thermal efficiency with significant improvement in reduction of smoke was observed for UTO and its diesel blends compared to that of diesel. The nitric oxide (NO)emission was found to be higher for UTO and its diesel blends than that of diesel.Ignition delay was marginally shorter for the UTO and its diesel blends than diesel.The higher NO emission was due to advancement of injection timing as a result of bulk modulus characteristics of the UTO.Secondly, UTO was operated at different injection timings of advanced and retarded injection timings for maximum of 3 degree crank angle (oCA) at a regular interval of 1.5 oCA from the original injection timings of 23 oCA bTDC. When compared to the standard injection timing of 23obTDC and other injection timings tested for UTO, the retarded injection timing of 20obTDC resulted in a reduction in the NO emission by about 1.4% at an expense of smoke emission and brake specific energy consumption by about 6.7% and 1.1% respectively at full load. The ignition delay of UTO overal