Effect of ambient temperature and density on the transition of hot temperature combustion to low temperature combustion of commercial diesel and waste plastic diesel in an optical access machine

Abstract

Alternative diesel production from mixed waste plastic pyrolysis is an effective method for the management of waste plastic and its related costs. The low temperature combustion (LTC) of diesel enables the reduction of nitrogen oxides and soot simultaneously. However, because of the high quantity of unburned hydrocarbon (UHC) and carbon monoxide (CO) emissions, LTC has a low combustion efficiency. This paper investigated the combined effect of low ambient temperature and high density (LATHD) on the transition from hot temperature combustion (HTC) to LTC by using commercial diesel (CD) and waste plastic diesel (WPD) without exhaust gas recirculation (EGR) and low cetane fuels. The results showed that NOx and soot concentrations were decreased and integral heat release was increased. For a given unit heat release, the NOx emissions of CD and WPD decreased 60% and 38%, respectively, by decreasing the ambient temperature from 1050 K to 750 K. Furthermore, integral heat release is a more influential parameter on NOx than heat release rate. After that, soot concentrations of CD and WPD were significantly decreased by 85% and 81% with a reduction in ambient temperature from 1050 K to 750 K. At the same ambient temperature, the NOx and soot concentrations of WPD were higher than that of CD for all cases. With the same ignition delay, however, the NOx and soot concentrations of WPD/high cetane fuel decreased dramatically compared to CD. This information will be useful for determining compression ratio and combustion phasing when considering engine designs.