Olsson, Jan-Ola, Tunestål, Per, Johansson, Bengt, Fiveland, Scott, Agama, J. Rey, and Assanis, Dennis N.
SAE World Congress & Exhibition, 2002,Detroit, Mich., United States,-- SAE Transactions, Journal of Engines. 111(3):442-458
Performance, Compression Ratio, CNG, Natural Gas, HCCI, Engine, Teknik, Maskinteknik, Energiteknik, Engineering and Technology, Mechanical Engineering, and Energy Engineering
This paper discusses the compression ratio influence on maximum load of a Natural Gas HCCI engine. A modified Volvo TD100 truck engine is controlled in a closed-loop fashion by enriching the Natural Gas mixture with Hydrogen. The first section of the paper illustrates and discusses the potential of using hydrogen enrichment of natural gas to control combustion timing. Cylinder pressure is used as the feedback and the 50 percent burn angle is the controlled parameter. Full-cycle simulation is compared to some of the experimental data and then used to enhance some of the experimental observations dealing with ignition timing, thermal boundary conditions, emissions and how they affect engine stability and performance. High load issues common to HCCI are discussed in light of the inherent performance and emissions tradeoff and the disappearance of feasible operating space at high engine loads. The problems of tighter limits for combustion timing, unstable operational points and physical constraints at high loads are discussed and illustrated by experimental results. Finally, the influence on operational limits, i.e., emissions peak pressure rise and peak cylinder pressure, from compression ratio at high load are discussed.
Olsson, Jan-Ola, Tunestål, Per, and Johansson, Bengt
SAE World Congress, 2001 ,Detroit, MI, United States,-- SAE Transactions, Journal of Engines. 110(3):1076-1085
Control, Combustion, HCCI, Engine, Teknik, Maskinteknik, Energiteknik, Engineering and Technology, Mechanical Engineering, and Energy Engineering
This paper presents a strategy for closed-loop control of a multi-cylinder turbocharged Homogeneous Charge Compression Ignition (HCCI) engine. A dual fuel port injection system allows control of combustion timing and load individually for each cylinder. The two fuels used are isooctane and n-heptane, which provides a wide range of autoignition properties. Cylinder pressure sensors provide feedback and information regarding combustion. The angle of 50% heat release is calculated in real time for each cycle and used for timing feedback. Inlet air preheating is used at low loads to maintain a high combustion efficiency.