Optimal utilization of ZnO nanoparticles blended diesel-water emulsion by varying compression ratio of a VCR diesel engine

[Display omitted] •The increased concentration of nanoparticles improves the working characteristics of the engine.•The increase in the compression ratio improves engine performance.•The CO and HC emission levels were reduced by increasing the compression ratio.•Optimal results are noted for the DW10Z100 blend at compression ratio 18.5. The experimental study is performed to understand the effect of the ZnO nanoparticles blended diesel-water emulsion on the performance and emission characteristics of a VCR diesel engine at various compression ratios. The test fuels used for the investigation were neat diesel, diesel-water emulsion and ZnO nanoparticles incorporated diesel-water emulsion. The diesel-water emulsion consists of 88% neat diesel, 10% of distilled water and 2% surfactants. The dispersion of ZnO nanoparticles into the diesel-water emulsion varies by 50 ppm and 100 ppm with the help of ultrasonic agitation. During the investigation, the CR increased from 16.5 to 18.5 with one step, and load on the engine increased from 0% to 100% in the steps of 25. The test results showed a greater improvement in BTE and BSFC for ZnO nanoparticles blended test fuels compared to other test blends by increasing the CR of the engine. The emissions of CO, HC were reduced significantly whereas CO2 emissions were increased for ZnO nanoparticles blended test fuels with an increase in the CR. It is also observed that NOx emissions increase with increasing the CR, even though at all CR’s ZnO nanoparticles blended test fuel show lower NOx levels than other test blends. Based on the test the optimal results are observed at CR 18.5 for DW10Z100 blend.