Effect of High Temperature Biodiesel Injection In Compression Ignition Engines

Abstract

Extensive research is being done to produce and utilise a variety of renewable fuels to meet the growing global energy demand and combat many issues such as environmental pollution, high costs of fossil fuels, and dependence on foreign energy sources. The current research aimed to extract and characterize Vateria indica and Karanja biodiesels through the transesterification process. The use of extracted biodiesels in a diesel engine leads to lesser brake thermal efficiency (BTE) and increased brake specific energy consumption (BSEC) due to higher viscosity and lower calorific value of biodiesels. This problem of higher viscosity is resolved by fuel preheating before injecting into the engine cylinder. The current research aims to evaluate the engine performance, emission, and combustion characteristics of Karanja oil methyl ester (KOME) and Vateria indica methyl ester (VIME) biodiesels blended with diesel at elevated fuel inlet temperatures ranging from 35 °C to 95 °C. The tests are carried out using two different engines, mainly the conventional DI engine (low-pressure injection at 180 bar) and CRDI engine (high-pressure injection at 1000 bar). In the CRDI engine, the effects of fuel injection timings and exhaust gas recirculation (EGR) rates on the engine parameters are also investigated. Results are obtained in terms of brake thermal efficiency, brake specific energy consumption, in-cylinder pressure, heat release rate, exhaust emissions of carbon monoxide (CO), hydrocarbon (HC), nitrogen oxide (NOX), carbon dioxide (CO2), and smoke opacity. It is observed from the findings of both the engines that the preheating of blends decreases viscosity which enhances engine performance, lower CO, HC, and soot emissions with a slight increase in NOX emissions. It is found that advancing the injection timing to 15° bTDC in a CRDI engine improves engine performance and reduces CO, and HC emissions with an increase in NOX emission compared to standard injection timing of 12° bTDC and retarded injection timing of 9° bTDC. As the EGR rate increases, engine performance decreases, and exhaust emissions like CO and HC increase with a reduction in NOX emission.