Experimental and numerical analysis of the performance of a diesel engine retrofitted to use LPG as secondary fuel

Improvements in life expectancy and standards of living, along with population growth, have contributed to the depletion of the planet's traditional energy sources. Such current dependence suggests that fossil fuels will continue to dominate the powering of internal combustion engines. Nevertheless, because of their adverse environmental impacts, stringent environmental legislation is in place today to regulate industries which use conventional fossil fuels. Hence, there is the necessity to seek viable, sustainable alternatives to power diesel engines. Therefore in this study, performance and emission characteristics are investigated using a diesel engine modified to function in dual-fuel mode (with diesel and liquefied petroleum gas). Engine cylinder pressure is obtained experimentally. A single-zone, zero-dimensional model is then developed and validated under different engine operating conditions. The performance and emission characteristics of the retrofitted diesel engine are investigated and analysed for various diesel-LPG ratios. The study reveals that, generally, the higher the engine speed, the higher the maximum in-cylinder pressure and vice versa. Also, increasing the LPG mass fraction from 50% to 60% at each operating regime, will lead to improvement in engine performance (efficiency, power, torque) and reduce NOx and HC emissions.