Prediction of performance and emissions of ammonia-diesel dual-fuel engine using response surface methodology

Ammonia is a zero-carbon fuel with great prospects for engine applications. In this research work, an experiment was carried out to analyze the effects of single factor parameters like injection-pressure, injection-timing and ammonia substitution rate (ASR) on combustion, performance and emission of an ammonia-diesel dual-fuel (ADDF) engine. The experimental results showed that advancing the injection-timing and increasing the injection-pressure both can enhance braking thermal efficiency (BTE) and reduce brake specific fuel consumption (BSFC) and unburned ammonia emissions. Between the two, advancing the injection-timing led to greater improvement in combustion in ADDF engines. However, increasing the ammonia substitution rate reduced thermal efficiency and increased unburned ammonia emissions while decreasing NOx emissions. Besides, multi-factor interaction effects among injection-pressure, injection-timing, and ASR for the ADDF engine were analyzed using response surface methodology. Employing the optimizer, optimization was performed aiming to minimize NOx and NH3 emissions and simultaneously maximum BTE and minimum BSFC. Results indicated under conditions of the ASR at 30 %, the diesel injection-pressure of 120 MPa and the injection-timing of 4°CA BTDC, responses obtained were found to be optimum, showing the corresponding values of BTE, BSFC, THC, CO, NOx, and NH3 emissions were 38.3 %, 225.9 g/(kW·h), 35.1 ppm, 61.6 ppm, 381.6 ppm, and 6313.6 ppm, respectively. These findings provide valuable insights for optimizing the operation of ADDF engines to achieve better performance and reduced emissions.