Premixed Low Temperature Combustion of Biodiesel and Blends in a High Speed Compression Ignition Engine

2009 ◽  
Vol 2 (1) ◽  
pp. 28-40 ◽  
Author(s):  
William F. Northrop ◽  
Stanislav V. Bohac ◽  
Dennis N. Assanis
2005 ◽  
Vol 6 (5) ◽  
pp. 475-486 ◽  
Author(s):  
S-C Kong ◽  
Y Ra ◽  
R D Reitz

An engine CFD model has been developed to simulate premixed charge compression ignition (PCCI) combustion using detailed chemistry. The numerical model is based on the KIVA code that is modified to use CHEMKIN as the chemistry solver. The model was applied to simulate ignition, combustion, and emissions processes in diesel engines operated to achieve PCCI conditions. Diesel PCCI experiments using both low- and high-pressure injectors were simulated. For the low-pressure injector with early injection (close to intake valve closure), the model shows that wall wetting can be minimized by using a pressure-swirl atomizer with a variable spray angle. In the case of using a high-pressure injector, it is found that late injection (SOI = 5 ° ATDC) benefits soot emissions as a result of low-temperature combustion at highly premixed conditions. The model was also used to validate the emission reduction potential of an HSDI diesel engine using a double injection strategy that favours PCCI conditions. It is concluded that the present model is useful to assess future engine combustion concepts, such as PCCI and low-temperature combustion (LTC).


Author(s):  
Valentin Soloiu ◽  
Marvin Duggan ◽  
Henry Ochieng ◽  
David Williams ◽  
Gustavo Molina ◽  
...  

In this study, the in-cylinder soot and NOx trade off was investigated in a Compression Engine by implementing Premixed Charge Compression Ignition (PCCI) coupled with Low Temperature Combustion (LTC) for selected regimes of 1–3 bars IMEP. In order to achieve that, an omnivorous (multi-fuel) single cylinder diesel engine was developed by injecting n-butanol in the intake port while being fueled with biodiesel by direct injection in the combustion chamber. By applying this methodology, the in-cylinder pressure decreased by 25% and peak pressure was delayed in the power stroke by about 8 CAD for the cycles in which the n-butanol was injected in the intake manifold at the engine speed of 800 rpm and low engine loads, corresponding to 1–3 bars IMEP. Compared with the baseline taken with ultra-low sulfur diesel no. 2 (USLD#2), the heat release presented a more complex shape. At 1–2 bars IMEP, the premixed charge stage of the combustion totally disappeared and a prolonged diffusion stage was found instead. At 3 bars IMEP, an early low temperature heat release was present that started 6 degrees (1.25 ms) earlier than the diesel reference heat release with a peak at 350 CAD corresponding to 1200 K. Heat losses from radiation of burned gas in the combustion chamber decreased by 10–50% while the soot emissions showed a significant decrease of about 98%, concomitantly with a 98% NOx reduction at 1 IMEP, and 77% at 3 IMEP, by controlling the combustion phases. Gaseous emissions were measured using an AVL SESAM FTIR and showed that there were high increases in CO, HC and NMHC emissions as a result of PCCI/LTC strategy; nevertheless, the technology is still under development. The results of this work indicate that n-butanol can be a very promising fuel alternative including for LTC regimes.


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