Lean-burn hydrogen spark-ignited engines: the mechanical equivalent to the fuel cell
Abstract
Fuel cells are considered as the ideal power source for future vehicles, due to their high efficiency and low emissions. However, extensive use of fuel cells in light-duty vehicles is likely to be years away, due to their high manufacturing cost. Hydrogen-fueled, spark-ignited, homogeneous-charge engines offer a near-term alternative to fuel cells. Hydrogen in a spark-ignited engine can be burned at very low equivalence ratios, so that NO[sub x] emissions can be reduced to less than 10 ppm without catalyst. HC and CO emissions may result from oxidation of engine oil, but by proper design are negligible (a few ppm). Lean operation also results in increased indicated efficiency due to the thermodynamic properties of the gaseous mixture contained in the cylinder. The high effective octane number of hydrogen allows the use of a high compression ratio, further increasing engine efficiency. In this paper, a simplified engine model is used for predicting hydrogen engine efficiency and emissions. The model uses basic thermodynamic equations for the compression and expansion processes, along with an empirical correlation for heat transfer, to predict engine indicated efficiency. A friction correlation and a supercharger/turbocharger model are then used to calculate brake thermal efficiency. The model is validatedmore »
- Authors:
- Publication Date:
- Research Org.:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Org.:
- USDOE, Washington, DC (United States)
- OSTI Identifier:
- 402294
- Report Number(s):
- UCRL-JC-124095; CONF-961017-9
ON: DE96011453
- DOE Contract Number:
- W-7405-ENG-48
- Resource Type:
- Conference
- Resource Relation:
- Conference: American Society of Mechanical Engineers (ASME) and Metals materials week, Cincinnati, OH (United States), 6-10 Oct 1996; Other Information: PBD: [1996]
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 33 ADVANCED PROPULSION SYSTEMS; VEHICLES; SPARK IGNITION ENGINES; HYDROGEN FUELS; COMBUSTION; NITROGEN OXIDES; EMISSION; THERMODYNAMIC MODEL; HYDROCARBONS; ANTIKNOCK RATINGS; IGNITION QUALITY; SUPERCHARGERS; TURBOCHARGERS; EFFICIENCY; FUEL-AIR RATIO; HYBRID SYSTEMS
Citation Formats
Aceves, S M, and Smith, J R. Lean-burn hydrogen spark-ignited engines: the mechanical equivalent to the fuel cell. United States: N. p., 1996.
Web.
Aceves, S M, & Smith, J R. Lean-burn hydrogen spark-ignited engines: the mechanical equivalent to the fuel cell. United States.
Aceves, S M, and Smith, J R. 1996.
"Lean-burn hydrogen spark-ignited engines: the mechanical equivalent to the fuel cell". United States. https://www.osti.gov/servlets/purl/402294.
@article{osti_402294,
title = {Lean-burn hydrogen spark-ignited engines: the mechanical equivalent to the fuel cell},
author = {Aceves, S M and Smith, J R},
abstractNote = {Fuel cells are considered as the ideal power source for future vehicles, due to their high efficiency and low emissions. However, extensive use of fuel cells in light-duty vehicles is likely to be years away, due to their high manufacturing cost. Hydrogen-fueled, spark-ignited, homogeneous-charge engines offer a near-term alternative to fuel cells. Hydrogen in a spark-ignited engine can be burned at very low equivalence ratios, so that NO[sub x] emissions can be reduced to less than 10 ppm without catalyst. HC and CO emissions may result from oxidation of engine oil, but by proper design are negligible (a few ppm). Lean operation also results in increased indicated efficiency due to the thermodynamic properties of the gaseous mixture contained in the cylinder. The high effective octane number of hydrogen allows the use of a high compression ratio, further increasing engine efficiency. In this paper, a simplified engine model is used for predicting hydrogen engine efficiency and emissions. The model uses basic thermodynamic equations for the compression and expansion processes, along with an empirical correlation for heat transfer, to predict engine indicated efficiency. A friction correlation and a supercharger/turbocharger model are then used to calculate brake thermal efficiency. The model is validated with many 1345 experimental points obtained in a recent evaluation of a hydrogen research engine. The experimental data are used to adjust the empirical constants in the heat release rate and heat transfer correlation. The adjusted engine model predicts pressure traces, indicated efficiency and NO,, emissions with good accuracy over the range of speed, equivalence ratio and manifold pressure experimentally covered.},
doi = {},
url = {https://www.osti.gov/biblio/402294},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Oct 01 00:00:00 EDT 1996},
month = {Tue Oct 01 00:00:00 EDT 1996}
}