An availability analysis of dual-fuel engines at part loads: The effects of pilot fuel quantity on availability terms

Abstract It is well known that dual-fuel engines at part load inevitably suffer from lower thermal efficiency and higher emission of carbon monoxide and unburned fuel. A quasi-two-zone combustion model has been developed for studying the second-law analysis of a dual-fuel (diesel-gas) engine operating under part load conditions. This quasi-two-zone combustion model is able to establish the development of combustion process with time and associated important operating parameters, such as pressure, temperature, heat release rate, and species concentration. The present study is an attempt to investigate the combustion phenomenon from the second law point of view at part load and increasing pilot fuel quantity is considered to improve the above-mentioned problems. By employing different quantities of pilot fuel, it is found that increasing the pilot fuel quantity increases the work availability and reduces chemical availability of unburned fuels. Also, the results indicate that, compared to the baseline dual-fuel engine, increasing the pilot fuel quantity in about 12 per cent results in an increase of 23 per cent in availability destruction and 29 per cent in the second law efficiency. This enhancement is due to a better combustion progress and increased indicated work when a high amount of pilot fuel quantity is employed.