Marvin Duggan

Investigation of Low Temperature Combustion Regimes of Biodiesel With N-Butanol Injected in the Intake Manifold of a Compression Ignition Engine

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 (multifuel) 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. t 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 deg (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 an be a very promising fuel alternative including for LTC regimes.

RCCI Operation With PFI of n-Butanol and DI of Biodiesel Compared With DI of Binary Mixtures of n-Butanol and Biodiesel

In this study the Reactive Controlled Combustion Ignition (RCCI) obtained by early port fuel injection (PFI) of n-butanol and direct injection (DI) of biodiesel were compared with in cylinder direct injected binary mixture of n-butanol and biodiesel with the same mass ratio of 3:1 in both fuelling strategies. The combustion and emissions characteristics were investigated at 5 bars IMEP at 1400 rpm. The ignition for DI of n-butanol-biodiesel binary blends showed a delay by approximately 7.5°CAD compared with the PFI case. For the binary mixture, n-butanol-biodiesel, the combustion pressure has decreased by 50% compared to the PFI of butanol. The maximum in cylinder gas temperature decreased by 100K for the n-butanol-biodiesel mixture versus ULSD#2 and has also experienced a 10° CAD delay. The premixed charge combustion has been split into two regions of high temperature heat release, an early one BTDC, and a second stage, ATDC for the PFI strategy. Increasing the load to 7.5 bars IMEP, heavy knock occurred for the PFI case. The soot emissions showed a 90% decrease with n-butanol injection PFI and by 98% reduction for DI of n-butanol binary mixture with the biodiesel, while the NOx emissions were reduced by 40% in both cases. The aldehyde emissions exhibited a significant 95% decrease for the n-butanol-biodiesel binary mixture compared with the n-butanol PFI. The mechanical efficiency at 80% and thermal efficiency and 38% were found similar, for both fuelling strategies.The results of this work suggest that the DI of n-butanol-biodiesel binary mixtures is more effective in reducing emissions than PFI of n-butanol combined with DI of biodiesel and also less likely to produce knock.Copyright

Cotton Seed FAME Combustion and Emissions Research in a DI Diesel Engine

This study investigates the combustion characteristics of cotton seed fatty acid methyl esters (FAME), with C100 (100% cotton seed biodiesel) and C20 (20% cotton seed biodiesel, 80% ultra-low sulfur diesel #2), in a direct injection diesel engine and compares the results with ultra-low sulfur diesel #2 (ULSD#2). The dynamic viscosity of C100 was found to meet the American Society for Testing and Materials (ASTM) standard. The lower heating value obtained for C100 was 37.7 MJ/kg, compared to 42.7 MJ/kg for ULSD#2. ULSD#2 and C100 displayed ignition delays of 9.6 crank angle degrees (CAD) and 7 CAD representing 1.14 ms and 0.83 ms respectively and a combustion time of 4ms (35 CAD) at 1400 rpm and 8 bar indicated mean effective pressure (IMEP) (100% load). The apparent heat release of the tested fuels at 8 bar IMEP showed both a premixed and diffusion phase and produced maximum values of 122 and 209 J/CAD for C100 and ULSD#2 respectively, with a decreasing trend occurring with increase in percentage of FAME. The 50% mass burnt (CA50) for 100% biodiesel was found to be 3 CAD advanced, compared with ULSD#2. The maximum total heat flux rates showed a value of 3.2 MW/m2 for ULSD#2 at 8 bar IMEP with a 6% increase observed for C100. Mechanical efficiency of ULSD#2 was 83% and presented a 5.35% decrease for C100, while the overall efficiency was 36% for ULSD#2 and 33% for C100 at 8 bar IMEP. The nitrogen oxides (NOx) for C100 presented an 11% decrease compared with ULSD#2. Unburned hydrocarbons value (UHC) for ULSD#2 was 2.8 g/kWh at 8 bar IMEP, and improved by 18% for C100. The carbon monoxide (CO) emissions for C100 decreased by 6% when compared to ULSD#2 at 3 bar IMEP but were relatively constant at 8 bar IMEP, presenting a value of 0.82 g/kWh for both fuels. The carbon dioxide (CO2) emissions for C100 increased by 1% compared with ULSD#2, at 3 bar IMEP. The soot value for ULSD#2 was 1.5 g/kWh and presented a 42% decrease for C100 at 8 bar IMEP. The results suggest a very good performance of cotton seed biodiesel, even at very high content of 100%, especially on the emissions side that showed decreasing values for regulated and non-regulated species.Copyright