Wavelet analysis of combustion characteristics and numerical validation of CI engine with novel water emulsified fuels

Abstract

This study examined the dependability of running a diesel engine on a novel water-emulsified diesel fuel with prolonged phase stability investigation. In order to develop a stable water emulsified fuel, experiments were conducted to standardize the composition ratios. The water-in-diesel emulsions were prepared using the surfactant named “Propylene Glycol Monostearate” along with Tween80 and Octanol was also chosen as co-emulsifier in order to enhance the phase stability. Using water-emulsified diesel fuel with the designations E0, E10, E20, E30, E40, and E50, the combustion stability using statistical and wavelet method were assessed on a 1-cylinder, 4-stroke CI engine. Even after being prepared for 100 days at room temperature, all water-in-diesel emulsions were discovered to be stable and homogenous. Moreover, to validate the combustion metrices such as in-cylinder pressure and HRR, a MATLAB-based single-zone thermodynamic model was developed. The combustion stability analyses using statistical method showed that the COV was found below 5 % at all loading conditions except E0 emulsion fuel whereas, the wavelet approach revealed that the E0 emulsion fuel's wavelet power spectrum (WPS) result showed a major intensity variance at high frequencies and lower frequencies for other emulsions and diesel 25 and 50 % loading condition. The analysis of the Global Wavelet Spectrum (GWS) results revealed that E0 exhibited higher peak power compared to diesel and other test fuels at 25 % and 50 % load conditions. The WPS and GWS results for E30 and E50 emulsion showed a similar trend as diesel fuel at all tested loading conditions implying a stable combustion with water-emulsified diesel. On the other hand, the prediction model anticipated the numerical values and was computed to be in strong conformity with the outcomes of the experiment. All numerical values lay within 95 % of the prediction band in regression analysis with an R2 value of 99.8 % and standard error (S = 0622) suggesting strong significant data and a better thermodynamic simulation model. In conclusion, PGM + Tween 80 could be used as a potential emulsifier to prepare stable water-in-diesel emulsion and Wavelet analysis proves to be a valuable tool for evaluating the cyclic variation observed in engine combustion. Additionally, the thermodynamic model is capable of providing accurate predictions of the engine combustion parameters.