Knock prevention of CHP engines by addition of N-2 and CO2 to the natural gas fuel

G Brecq , Jérôme Bellettre , Mohand Tazerout (1, 2) , T Muller

1 Mines Nantes - Mines Nantes
2 GEPEA - Laboratoire de génie des procédés - environnement - agroalimentaire

This work focuses on the prevention of knock in the case of spark ignition (SI) engines supplied by natural gas network. The effects of the addition of two inert gases (N-2 and CO2) are experimentally studied. The added volumetric quantities are between 0% and 25% for N-2 and between 0% and 15% for CO2. The thermal efficiency and the emissions of the engine are very slightly affected by the addition, whereas a significant increase of the knock limited spark timing (KLST) is always measured. A twice-higher augmentation of KLST is noted when CO2 is added compared to N2 for an equivalent volumetric concentration. The overall augmentation varies between +1 and +6 degreesCA depending on engine operation. Finally, a law for predicting the KLST augmentation implied by the addition of inert gases is deduced from all the measurements. (C) 2003 Elsevier Science Ltd. All rights reserved.

Domaines: Sciences de l'ingénieur [physics]

G Brecq, Jérôme Bellettre, Mohand Tazerout, T Muller. Knock prevention of CHP engines by addition of N-2 and CO2 to the natural gas fuel. Applied Thermal Engineering, 2003, 23 (11), pp.1359-1371. ⟨10.1016/S1359-4311(03)00063-2⟩. ⟨hal-00935944⟩