The paper shows CFD activity concerning an innovative hydrogen direct-injection system, characterized by low fuel rail pressure. The system allows combining the benefits of hydrogen direct injection, mainly consisting in high specific power and in backfire prevention, with the typical ones of indirect injection, mainly consisting in the almost complete utilization of the on-board stored hydrogen, as well as in low cost and reliability. The injection is split in two steps: first an electroinjector meters hydrogen and feeds a small intermediate chamber, then the hydrogen stored in the chamber is injected into the cylinder with proper timing by a mechanically-actuated valve. A prototype was derived from a production single-cylinder motorcycle engine on the basis of previous CFD predictions and, despite important limitations in design freedom, proved to run correctly, without the typical drawbacks of hydrogen engines. Maximum power was higher than with gasoline. Present CFD activity is aimed at designing a new engine originally intended for hydrogen. Axisymmetric analyses have been carried out for several valve and seat-valve profiles, proving that proper geometrical details allow quite satisfactory fuel distribution at the ignition time for every engine speed and load.
NUMERICAL INVESTIGATION OF AN INNOVATIVE LOWPRESSURE DIRECT-INJECTION SYSTEM FOR HYDROGEN ENGINES
Frigo S;
2011-01-01
Abstract
The paper shows CFD activity concerning an innovative hydrogen direct-injection system, characterized by low fuel rail pressure. The system allows combining the benefits of hydrogen direct injection, mainly consisting in high specific power and in backfire prevention, with the typical ones of indirect injection, mainly consisting in the almost complete utilization of the on-board stored hydrogen, as well as in low cost and reliability. The injection is split in two steps: first an electroinjector meters hydrogen and feeds a small intermediate chamber, then the hydrogen stored in the chamber is injected into the cylinder with proper timing by a mechanically-actuated valve. A prototype was derived from a production single-cylinder motorcycle engine on the basis of previous CFD predictions and, despite important limitations in design freedom, proved to run correctly, without the typical drawbacks of hydrogen engines. Maximum power was higher than with gasoline. Present CFD activity is aimed at designing a new engine originally intended for hydrogen. Axisymmetric analyses have been carried out for several valve and seat-valve profiles, proving that proper geometrical details allow quite satisfactory fuel distribution at the ignition time for every engine speed and load.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
