Numerical investigation of the effect split injection scheme on exergy terms in an IDI (indirect injection) diesel engine by three dimensional modeling

• The percentage of fuel mass in first pulse increases from 75% to 90%.
• The accumulative heat loss exergy increases by 5.74%.
• The accumulative work loss exergy increases by 6.54%.
• The accumulative fuel burn exergy increases by 5.39%.
• The irreversibility changes slightly.

The investigations suggest that it is possible to control the injected masses between two subsequent injections in split injection schemes by modern injection systems. It offers the opportunity to optimize the injection system. During this investigation, therefore, the exergy analysis is carried out under various two-step injection schemes in which the percentage of total fuel injected in the first pulse is changed from 75% to 100%, and the value of dwelling time duration is 20°CA (crank angle) for all cases. The calculations were performed on a Lister 8.1 IDI (indirect injection) diesel engine at full load operation. The energy analysis for these schemes was performed during a closed cycle by utilizing a three-dimensional CFD (computational fluid dynamics) code. The cylinder pressure results of the baseline engine were compared with the corresponding experimental data which showed a good agreement. For the exergy analysis, an in-house computational code was developed, which uses the results of the energy analysis at various cases. With crank angle position and the percentage of total fuel injected in the first pulse under different injection schemes, various rates of exergy and cumulative exergy components are identified and calculated separately. The results showed that the values of work exergy and exergy efficiency increase by 11.1% when the mass ratio injected in first pulse is changed from 75% to 100%.