1. The Effect of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection António L. N. Moreira João Carvalho Miguel R. O. Panão IN+, Center for Innovation, Technology and Policy Research Mechanical Engineering Department Instituto Superior Técnico

2. The Effect of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection 16% of total HC emissions due to liquid films. - Cheng et al. (1993) - 15% of injected fuel remains liquid inside combustion chamber  1.5 increase factor in HC emissions between engine cold-start and heated engine. - Meyer and Heywood (1999) - COLD STARTAFTER WARM UP

3. The Effect of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection Nu = a Re m Pr n We p Arcoumanis and Chang, Experiments in Fluids, vol. 16, pp. 105-119, 1993. Film Evaporation Vaporization/ Boiling Transition Leidenfrost

4. The Effect of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection 1.To quantify the effects of all surface, flow and fluid properties on the heat transferred in PFI systems Nu = a Re m Pr n We p Ja q Ec w

5. The Effect of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection Resistance = 8 – 12   t response  10  s Signal gain = 300 Temperature acquired at 50kHz Electronic noise =  0.3ºC Simultaneous measurements of droplet dynamics and surface thermal behaviour

6. The Effect of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection Nu = a Re m Pr n We p Ja q Ec w New Correlation Film Evaporation Vaporization/ Boiling TransitionLeidenfrost Panão and Moreira, Thermo- and fluid dynamics characterization of spray cooling with pulsed sprays, Experimental Thermal and Fluid Science, in Press.

7. The Effect of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection 1.To quantify the effects of all surface, flow and fluid properties on the heat transferred in PFI systems; 2.To quantify spatial and injection conditions effects in systems with simultaneous fuel injector activation (cold start and acceleration enrichment).

8. The Effect of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection 20 - 20 (mm)  r = 2 mm Working Conditions Injection frequency = 10, 15, 20 and 30 Hz Duty Cycle = 0.05, 0.075, 0.1 and 0.15 (  t inj = 5ms) Wall temperature = 125, 150, 175, 200 and 225ºC

9. The Effect of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection N series  Step 1 – Calculate Ensemble-Average Series Average over  70 Series ensemble-average series

10. The Effect of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection Step 2 – Phase-Average Wall Temperature -5% of T w (t=0) valid injections (N vinj ) ensemble-average series

11. The Effect of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection Step 3 – Total Average Heat Flux Phase-Average Wall Temperature Transient Profile Reichelt et al., Int. J. Heat Mass Transfer 45 (2002), pp579. instantaneous heat flux CALCULATION

12. The Effect of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection Reichelt et al., Int. J. Heat Mass Transfer 45 (2002), pp579. T w = 125ºC f inj = 10Hz time-average heat flux

13. The Effect of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection Panão and Moreira, Thermo- and fluid dynamics characterization of spray cooling with pulsed sprays, Experimental Thermal and Fluid Science, in Press. f inj = 30 Hz  t inj = 5 ms r = 0 mm

14. The Effect of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection 1.To quantify the effects of all surface, flow and fluid properties on the heat transferred in PFI systems; 2.To quantify spatial and injection conditions effects in systems with simultaneous fuel injector activation (cold start and acceleration enrichment); 3.To develop a methodology to describe the overall thermal interaction acounting for the complex non-linear interactions within the area of impact.

15. The Effect of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection Step 3 – Total Average Heat Flux total average heat flux T w = 125ºC f inj = 10Hz OVERALL BOILING CURVE

16. The Effect of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection Step 4 – Spray Cooling Efficiency spray cooling efficiency

17. The Effect of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection Overall Boiling Curves

18. The Effect of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection Spray Cooling Efficiency

19. The Effect of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection

21. A novel methodology is developed to quantify the heat removed a pulsed spray. Total average heat flux increases with injection frequency due to the associated increase of net mass flux. Nukiyama temperature is independent of injection frequency. Spray cooling efficiency is larger for CHF and lower injection frequencies. A new correlation for the heat transfer coefficient has been developed based on simultaneous measurement of the spray characteristics and surface thermal behaviour: