Influence of Injection Timing on Performance and Emission Characteristics of Naturally Aspirated Twin Cylinder CIDI Engine Using Bio-diesel Blend as Fuel

--Stringent emission norms and environment degradation due to pollutants from the automotive vehicles lead us to find the suitable alternative for the petro-diesel. Among the alternatives the non-edible vegetable oil seems to be most promising one. When the vegetable oil is used as fuel in diesel engine, it does not cause any major problem if used for a short period. However in the long run it causes major problems such as injector coking, deposit build up in the combustion chamber, piston ring sticking and engine oil dilution. Hence vegetable oils are converted as biodiesels to reduce viscosity. The transesterification process has proved as one of the best method to achieve the same. It is evident from the literature that the major problem on utilization of blends of bio-diesel is the increase in NOx emission from diesel engines. To reduce the NOx emission from the diesel engines employing biodiesel blend as fuel, the injection timing of fuel is altered by either addition or removal of shims in the pump. The effect of changing the injection timing on BSEC, Brake Thermal Efficiency, CO, HC and NO emissions are studied at different injection timings such as 18°, 21°, 24°, 27° and 30° CA bTDC. From the experiments it is found that on retarding the injection to 18°CA bTDC from 24° CA bTDC, the original injection timing, the NOx emission reduced to about 35% while advancing to 30°CA bTDC, the NOx increased by 25%. The BSEC, CO, HC have been found to increase by about 3%, 12.65% and 10% respectively on retarding to 18°CA bTDC while decrease by 6.27%, 32%,and 14.44% respectively on advancing the injection to 30° CA bTDC. The brake thermal efficiency is reduced by 3.08% on retarding to 18°CA bTDC whereas it is improved by 5.09% on advancing the injection timing to 30° CA bTDC.