Analysis of experimental hydrogen engine data and hydrogen vehicle performance and emissions simulation
- Lawrence Livermore National Lab., CA (United States)
This paper reports the engine and vehicle simulation and analysis done at Lawrence Livermore (LLNL) as a part of a joint optimized hydrogen engine development effort. Project participants are: Sandia National Laboratory; Los Alamos National Laboratory; and the University of Miami. 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. 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 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 results indicate that hydrogen lean-burn spark-ignite engines can provide Equivalent Zero Emission Vehicle (EZEV) levels in either a series hybrid or a conventional automobile.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- OSTI ID:
- 456740
- Report Number(s):
- NREL/CP-430-21968-Vol.2; CONF-9605195-Vol.2; ON: DE97001438; TRN: 97:001171-0005
- Resource Relation:
- Conference: 1996 annual hydrogen peer review for DOE, Miami, FL (United States), 1-3 May 1996; Other Information: PBD: Oct 1996; Related Information: Is Part Of Proceedings of the 1996 US DOE hydrogen program review. Volume 2; PB: 268 p.
- Country of Publication:
- United States
- Language:
- English
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