Evaluation of Ignition Quality of LPG with Cetane Number Improver

The objective of this study is to improve the ignition quality of LPG (liquefied petroleum gas) in order to utilize LPG as a diesel fuel. First, the relationship between the cetane numbers and ignition delay periods of primary standard fuels (mixtures of n-cetane and heptamethylnonane) and diesel fuels were investigated by measuring the ignition delay periods using a constant volume combustion chamber. As a result, it was found that a good relationship between the cetane numbers and ignition delay periods could be obtained for a 550°C combustion chamber temperature and 4MPa pressure. Also, the cetane number estimation equation was established using the ignition delay data of n-paraffins. Next, the constant volume combustion chamber was modified to evaluate the ignition delay period of LPG with a cetane number improver, and these cetane numbers were then estimated. The estimated cetane numbers of the LPG with a 15 wt % cetane number improver were more than 50 suggesting the possibility of utilizing LPG as a diesel fuel. Furthermore, the ignition quality of LPG with n-paraffins and a cetane number improver were evaluated. As a result, the ignition quality of LPG with 30wt% n-paraffin and 1wt% di-tert-butyl peroxide was equivalent to that of commercial diesel fuels. This result suggests that it is possible to develop an LPG-based diesel fuel containing a low cetane number improver.