Laser-assisted homogeneous charge ignition in a constant volume combustion chamber

• Published in: Optics and lasers in engineering Vol. 47; no. 6; pp. 680 - 685
• Main Authors: Srivastava, Dhananjay Kumar, Weinrotter, Martin, Kofler, Henrich, Agarwal, Avinash Kumar, Wintner, Ernst
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.06.2009; Elsevier
• Subjects: Auto-ignition; Biological and medical applications; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Homogeneous charge compression ignition; Laser ignition; Optics; Physics; Plasma; Resonant absorption; Plasma; Homogeneous charge compression ignition; Resonant absorption; Laser ignition; Auto-ignition; Water; Pulse width; Laser beam applications; Absorption coefficients; Pulsed lasers; Exhaust gas recirculation; Internal combustion engines; Combustion chambers
• ISSN: 0143-8166; 1873-0302
• DOI: 10.1016/j.optlaseng.2008.12.002

Homogeneous charge compression ignition (HCCI) is a very promising future combustion concept for internal combustion engines. There are several technical difficulties associated with this concept, and precisely controlling the start of auto-ignition is the most prominent of them. In this paper, a novel concept to control the start of auto-ignition is presented. The concept is based on the fact that most HCCI engines are operated with high exhaust gas recirculation (EGR) rates in order to slow-down the fast combustion processes. Recirculated exhaust gas contains combustion products including moisture, which has a relative peak of the absorption coefficient around 3 μm. These water molecules absorb the incident erbium laser radiations ( λ=2.79 μm) and get heated up to expedite ignition. In the present experimental work, auto-ignition conditions are locally attained in an experimental constant volume combustion chamber under simulated EGR conditions. Taking advantage of this feature, the time when the mixture is thought to “auto-ignite” could be adjusted/controlled by the laser pulse width optimisation, followed by its resonant absorption by water molecules present in recirculated exhaust gas.