Energy Fuels 2009, 23, 5394–5400 Published on Web 09/09/2009
: DOI:10.1021/ef900569a
Effect of Preheating on Firing Behavior of a Spark-Ignition Methanol-Fueled Engine during Cold Start Jun Li,†,‡ Changming Gong,*,† Yan Su,† Huili Dou,‡ and Xunjun Liu† †
State Key Laboratory of Automobile Dynamic Simulation, Jilin University, Changchun 130022, China, and ‡Research and Development Center, China First Automobile Works Group Corporation, Changchun 130011, China Received June 3, 2009. Revised Manuscript Received August 27, 2009
To overcome the difficulty in the cold start of the spark-ignition (SI) methanol-fueled engine with inlet port fuel injection (PFI) at low ambient temperatures, the effects of several auxiliary preheating measures, including the intake air preheating, the methanol fuel preheating, the resistance wire, which heats the inlet manifold, and the glow plug, which heats the methanol-air mixture, on the firing behavior of the methanol-fueled engine were studied experimentally by means of a single-cycle methanol injection strategy. The results showed that, with the ambient temperatures below 16 °C, the methanol-fueled engine cannot be started reliably without an auxiliary start aid even at a large amount of methanol injected per cycle. Both the intake air preheating and the methanol fuel preheating cannot ensure the reliable firing of the methanol-fueled engine during the cold start, but the resistance wire and the glow plug will do. Under the glow-plug preheating, the amount of methanol injected per cycle for reliable cold start is by 30% less than that of the resistance wire and the maximum combustion pressure in the cylinder is 180% higher. The preheating by the glow plug is better than that by the resistance wire.
rate of the catalytic converter.5 Many measures have been taken, such as intake air heating, fuel heating, heated spark plug, fuel reforming, supplementary fuel, blend fuel, etc.6-10 For a port fuel injection (PFI) gasoline engine, 60-95% of tailpipe HC emissions over the Federal Test Procedure (FTP) cycle are emitted during the cold-start and warm-up period.11 A dominant source of these emissions is the need for overfueling. Typically, the injector is aimed at the back of the intake valve head because this is the hottest surface in the intake system. However, this surface is at ambient temperature during the cold start. Chen et al.12 in 1996 found that only 20% of gasoline evaporates under this condition, in reasonable agreement with equilibrium calculations that 10-20% of the fuel vaporizes during the first few cycles of a cold start.13,14 Swindal et al.15 note that multicomponent fuel evaporation may complicate. They proposed that droplet evaporation is a batch distillation process for cold operation and during the early part of the intake stroke. In batch distillation, the lighter
1. Introduction Because of the shortage of petroleum and the stringency of exhaust emission standards, the alternative fuel engine has become more and more attractive. Methanol (CH3OH), also known as methyl alcohol, is considered to be one of the favorable fuels for the engine.1 It can be produced from synthesis gas [a mixture of carbon monoxide (CO) and hydrogen] that is formed by steam reforming of natural gas, gasification of coal, or biomass, all of which are available in abundance or renewable.2 Methanol is a colorless liquid, completely miscible with water and organic solvents, and has a high octane number, indicating excellent antiknock performance, high latent heat of vaporization, allowing for a denser fuel-air charge, and good lean burn capability. These properties make methanol a good fuel for spark-ignition (SI) Otto-cycle engines.3 Although methanol is the simplest aliphatic alcohol, its boiling point (65 °C) is higher than the initial boiling point of gasoline (about 40 °C). The low vapor pressure and high latent heat of vaporization of methanol may cause cold-start difficulties for a methanol engine at low ambient temperatures.4 In view of environmental protection, a major difficulty in meeting rigorous emission standards is the initial cold-start transient, where the hydrocarbon (HC) emitted remains at a high level because of the richer fuel-air mixture supplied, as well as the lower conversion
(5) Henein, N. A.; Tagomori, M. K. Prog. Energy Combust. Sci. 1999, 25, 563–593. (6) Suga, T.; Kitajima, Y.; Hamazaki, A. Proceedings of the 9th International Symposium on Alcohol Fuels, Firenze, Italy, 1991; pp 532-537. (7) Karpuk, M. E.; Scott, W. C. SAE Tech. Pap. 881678, 1988. (8) Pan, K. R.; Zhai, H.; Xie, R. M.; Yan, Y.; Zhu, J.; Zhang, R.; Zhao, R. L.; Decker, G.; Steinke, D. Proceedings of the 9th International Symposium on Alcohol Fuels, Firenze, Italy, 1991; pp 768-772. (9) Liao, S. Y.; Jiang, D. M.; Cheng, Q.; Huang, Z. H.; Wei, Q. Energy Fuels 2005, 19, 813–819. (10) Bielaczyc, P.; Merkisz, J. SAE Tech. Pap. 980401, 1998. (11) Kim, C.; Foster, D. E. SAE Tech. Pap. 852120,1985. (12) Chen, K. C.; Cheng, W. K.; Van Doren, J. M. SAE Tech. Pap. 961955, 1996. (13) Boyle, R. J.; Doam, D. J.; Finlay, I. C. SAE Tech. Pap. 930710, 1993. (14) Santoso, H.; Cheng, W. K. SAE Tech. Pap. 2002-01-2805, 2002. (15) Swindal, J. C.; Dragonetti, D. P.; Hahn, R. T.; Furman, P. A.; Acker, W. P. SAE Tech. Pap. 950106, 1995.
*To whom correspondence should be addressed: State Key Laboratory of Automobile Dynamic Simulation, Jilin University, Changchun 130022, China. E-mail:
[email protected]. (1) Gong, C. M.; Deng, B. Q.; Wang, S.; Su, Y.; Gao, Q.; Liu, X. J. Energy Fuels 2008, 22, 2981–2985. (2) Hu, T. G.; Wei, Y. J.; Liu, S. H.; Zhou, L. B. Energy Fuels 2007, 21, 171–175. (3) Frank, B. SAE Tech. Pap. 912413, 1991. (4) Bassem, H. R.; Fakhri, J. H.; Charles, L. G.; Karl, H. H.; Harold, J. S. SAE Tech. Pap. 2002-01-2702, 2002. r 2009 American Chemical Society
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pubs.acs.org/EF
Energy Fuels 2009, 23, 5394–5400
: DOI:10.1021/ef900569a
Li et al.
Table 1. Engine Specifications bore (mm) stroke (mm) displacement (cm3) compression ratio maximum power (kW)/speed (rpm) maximum torque (N m)/speed (rpm) cooling system intake valve opening (IVO) intake valve closing (IVC) exhaust valve opening (EVO) exhaust valve closing (EVC)
52.4 57.8 125 10.55:1 6.5/7500 9/6000 air cooled 15 °CA BTDC 35 °CA ABDC 35 °CA BBDC 15 °CA ATDC
components evaporate first, leaving smaller droplets that are enriched in behavior fuel components. For warm operation and late in the compression stroke, they proposed that droplet evaporation is probably a combination of batch distillations and is diffusion-limited. If the thermal diffusivity is much greater than the mass diffusivity, all components evaporate at similar rates and the fuel droplet has essentially constant composition. They also found that the low boiling-point tracers (
