EXPERIMENTAL INVESTIGATIONS ON CI ENGINE WITH VARYING AIR GAP AND YTTRIUM OXIDE AS HEAT RESISTING MATERIAL

Abstract

In the present day to day life each and every work involves travelling and transportation as a result of this usage of automobile vehicles increases day by day rapidly for heavy duty works and for heavy transportation. DI Diesel Engine is used because of its higher power outputs. But in this Diesel Engine in the suction stroke, inlet air which is entering in to the engine cylinder is compressed to higher pressure and temperature, which sometimes is not sufficient to mix with the fuel injected, and some of the fuel particles are burnt incompletely in this process and it gets released into atmosphere from exhaust stroke. Due to these circumstances there is a loss of fuel and also it produces less power output than the required. Improving engine performance and reducing the exhaust emissions are the most important issues. The thermal efficiency of an engine increases by the amount of heat present in the combustion chamber which mainly depends on heat transfer rate through the piston. Thermal efficiency is increased by reducing heat loss through
piston by providing air insulations between the piston crown and skirt. In the present work, three different strategies of air insulation (air gap) of 1.5mm, 2mm, 2.5mm between the aluminium piston skirt and conical brass crown which is of low thermal conductivity and low specific heat are attempted on the test engine, with an objective to identify the best one in terms of performance and emissions. Among them 2mm air gap insulated piston has the better performance characteristics. And then it is coated with yttrium oxide as heat resisting material and the engine tests are carried out and the performance and emissions are evaluated and compared with the performance of other pistons.