Impact of Cold and Hot Exhaust Gas Recirculation on Diesel Engine
Today most of the transport vehicles in countries like India where cost effective is the predominant criteria utilize diesel engines rather than petrol engines. From past 5 years usage of diesel engines was rapid which can be addressed from the sales report of many automobile companies. The reason behind this could be cost of diesel fuel and efficiency of the diesel engine when compared to petrol engine. But when we look on the worse side of diesel engine, emissions from diesel engine are high especially NOx. So there is a need for a technique which could reduce the emissions without affecting the performance of engine. One such technique could be Exhaust gas recirculation. Present paper aims to find the impact of cold and hot EGR on emissions of diesel engine.
Effect of exhaust gas recirculation and ethyl hexyl nitrate additive on biodiesel fuelled diesel engine for the reduction of NOx emissions
Cetane improvers reduce the ignition delay, which in turn reduces the combustion temperatures thereby reduce NOx emissions. Exhaust gas recirculation (EGR) proved to be an effective way to reduce the NOx emissions. In this present experimental work, a combination of exhaust gas recirculation and cetane improver ethyl hexyl nitrate (EHN) is used to investigate the performance and exhaust emissions of a single cylinder four stroke naturally aspirated direct injection and air cooled diesel engine. Test results show that the brake thermal efficiency increases with the increase in the percentage of EGR which is accompanied by a reduction in brake specific fuel consumption and exhaust gas temperatures, and that biodiesel with cetane improver under 20% EGR reduces NOx emissions by 33% when compared to baseline fuel without EGR. However carbon monoxide (CO), hydro carbon (HC) and smoke emissions increase with an increase in percentage of EGR.
Analysis of Combustion in Diesel Engines Fueled by Directly Injected Natural Gas
A single-cylinder two-stroke (DDC 1-71) diesel engine has been fueled with natural gas directly injected at high pressure into the engine cylinder. Prior to injection of the natural gas, a quantity of diesel fuel is injected into the cylinder (from the same injector) to provide for gas ignition. Tests have been conducted at medium load and speed over a wide range of injection timing, and with both conventional diesel and gas/diesel operation. With natural gas fueling, significant reduction in nitrogen oxide emissions have been measured without significant loss in efficiency, relative to conventional diesel operation. Using measurements of cylinder pressure development, a new method of combustion analysis has been used to estimate mass burning rate, burned gas temperature, and rate of nitrogen oxide (NO) generation. The method uses a nonlinear regression technique to determine the distribution with crank angle of the cylinder heat loss rate. The method assumes that NO formation takes place within one turbulent mixing time following combustion of each fuel-air increment. Comparison of measured and calculated NO concentration in the exhaust over the whole range of injection timing shows that for both conventional diesel and gas/diesel operation the effective turbulent mixing period is equivalent to 4 degreesmore » of crank angle at 1,250 RPM. The results demonstrate that a mass burned method can be used to infer cylinder temperature distributions and NO formation rate as well as the progress of combustion.« less