Simulation of performance and optimization for diesel engine fueled with higher biodiesel blend

Abstract

With global energy demand that keeps on increasing by 1.2% every year, CO2 was predicted to increase as well. A short-term solution to reduce CO2 is to switch to carbon-neutral fuels and one of them is biodiesel. However, biodiesel’s higher viscosity and lower calorific value compared to pure petroleum diesel lead to higher brake specific fuel consumption (BSFC) especially for higher biodiesel blend. Even though there are many ways to reduce the BSFC, to quantify how much these ways manage to reduce it requires experiments that are costly and time consuming. At the same time, a limited simulation model can be used as the alternative to the experiments. Therefore, the objective of this research is to develop a model based on the Yanmar L70N6 engine using GT-Suite simulation software, to predict engine performance, combustion, and emissions when using biodiesel. The engine model was then used to simulate a high biodiesel blend with a variation of injection timing (IT), injection pressure (IP), and preheat biodiesel fuel (PF). In this research, experimental work was conducted to obtain baseline data for validating the simulation study based on the manufacturer’s default setting of IP (206 bar), IT (14 ºbTDC), and ambient temperature for fuel which is around 30°C. In the experiment, B10 and B30 were tested at four different speeds (1500, 2000, 2500, and 3000 rpm) with five different loads (3, 5, 7.5, 10, and 11.5 Nm) at each speed. Then, B30, B50, B70, and B100 were simulated with variations of IP (206, 220, 240, 260, 280, and 300 bars), IT (10, 12, 14, 16, 18, 20, 22, and 24 ºbTDC) and PF (30, 40, 50, 60, 70, 80, and 100°C). For model validation, the engine speed was simulated at 2000 rpm with five different loads and comparison between the simulation and the experimental results showed less than 10% differences in the BSFC of B10 (8.8%) and B30 (5.1%). The results showed that by increasing IP to 300 bar, retarding IT to 12ºbTDC, and PF to 100ºC, reduction of the BSFC was recorded from 2.1% to 5.4% meanwhile CO2 emission reduction was recorded from 3.79% to 10.7% and by combining three optimized parameters, it helps reducing BSFC, and CO2 for all blends. Among all biofuels, B100 has the lowest BSFC (8.8%) and CO2 (22.3%) at 3000 rpm and 3 Nm load. In conclusion, the objective of the research, which is to develop a reliable simulation model and improve the performance of a high biodiesel blend, has been achieved successfully.