Experimental studies and numerical modelling of the combustion, performance and emission characteristics of a diesel engine fuelled with biodiesel mixture and alcohol blends

Abstract

The increase in energy demand, air pollution, and the decrease of fossil fuels globally has led to the partial substitution of diesel fuel with biodiesel in diesel engines. Biodiesel is known to have some properties like high density and viscosity which makes it difficult to use in such engines. One of the methods used to decrease the density and viscosity and decrease engine emissions is to blend it with alcohol. Due to its renewable nature and oxygen component, ethanol has become a good additive to biodiesel. Most literature focus on the use of blends of single biodiesel. However, there exists a knowledge gap in the use of biodiesel mixture, its blends with alcohol, and engine performance, combustion, and emission characteristics of these mixtures. The biodiesel mixture was produced from waste vegetable oil and soybean oil. The fuel property test results showed that the biodiesel mixture-ethanol blends exhibited decreased viscosity and density compared to WVB100, SB100, and BM100. The heating value of BM100 was superior to the individual biodiesels and the BME blends. The engine and combustion parameters, and emissions of the individual biodiesels, BM100 and BME blends were tested in a single-cylinder diesel engine. The experimental results were compared with predicted results obtained from Diesel-RK software. The experimental results for performance and combustion parameters of biodiesel mixture were better compared to individual biodiesels and BME blends. In terms of emissions, CO, NO, HC, and smoke for the BME blends decreased compared to the individual biodiesels and BM100 at maximum speed. The simulation results for ICP and HRR of BM100 were higher than those of BME and individual biodiesels. BME attained a longer ignition compared to other fuels tested while the STP values of BME were lower compared to the other fuels. BM100 exhibited better engine performance parameters compared to individual biodiesels and biodiesel mixture-ethanol blends. At maximum speed, BM100 had the highest value of NOx while BME had decreased NO, CO2, PM, and smoke emissions. BME15 emits lower CO2, NO, and smoke by 29.1%, 75.9%, and 35.7% compared to diesel. There were marginal differences between the experimental and simulation results.