Study the effect of optimized input parameters on a CRDI diesel engine running with waste frying oil methyl ester-diesel blend fuel with ZnO nanoparticles: a response surface methodology approach

Fossil fuel use is a major issue to solve in the future, given its depleting nature as well as environmental concerns, about the global energy requirements. Therefore, even with the use of appropriate additives, such as nanoparticles, more diverse study is needed in other sources of fuel. Therefore, the major purpose of this paper is to investigate the combined effect of zinc oxide (ZnO) nanoparticles in waste frying oil methyl ester (WFME)/diesel fuel blend ratio (0%, 10%, 20%, 30%, and 40%), compression ratio (CR) (16, 17, 18, 19, and 20) and exhaust gas recirculation (EGR) rate (0%, 5%, 10%, 15%, and 20%) on the performance and emission properties of a single-cylinder 4-stroke common rail direct ignition variable compression ratio (CRDI VCR) diesel engine. Zinc oxide nanoparticles (60, 100, 140, 180, 220 ppm) were produced and applied to a diesel–biodiesel blend fuel as an additive. Following that, using the response surface approach (RSM), the interplay of factors on diesel engine emissions and performance was studied. The input factors like % blends, compression ratio, and EGR (%) with different concentrations of ZnO nanoparticles are examined to get improved responses. The main output responses are brake thermal efficiency (BTE), brake-specific energy consumption (BSEC), hydrocarbon (HC), carbon monoxide (CO), smoke level, and oxides of nitrogen (NOx). The results reveal that overall good engine performance is demonstrated by a mixture of WFME biodiesel 19.7980% at 18 CR, 129.5 ZnO (ppm), and 12.9 ≈13% EGR. The parameters (BTE, BSEC, HC, CO, smoking, and NOx) were shown to be 32%, 12.4566 kJ/kW-h, 29.5780 ppm, 0.1125%, 69.68%, and 468.263 ppm, respectively. The predictions of the RSM model were then compared to experimental results. BTE, BSEC, HC, CO, smoke level, and NOx had an average error of 2.25%, 1.80%, 1.43%, 2.75%, 2.32%, and 3.14%, respectively, which are within allowed limits. The findings of the experiments revealed that the addition of zinc oxide nanoparticles to WFME/diesel blends increases the BTE while reducing BSEC, CO, and HC along with a marginal increase in NOx emissions.