Simultaneous Reduction of NOx and Smoke Emissions in Dual Fuel and HCCI Engines Operated on Biogas

Abstract

Biogas has emerged as a promising alternative to fossil fuels in internal combustion engines in recent times. It could be used as the primary fuel in Compression Ignition (CI) engines in combination with a small quantity of a high cetane fuel in two modes – dual fuel or Homogeneous Charge Compression Ignition (HCCI). This chapter compares the performance, combustion, and emission parameters of a CI engine operated with biogas in dual fuel and HCCI modes vis-à-vis conventional diesel operation. The effects of biogas composition (quantified in terms of the methane content), location of secondary fuel injection and engine load are investigated. It is observed that the use of biogas has the potential to reduce both NOx and smoke emissions simultaneously, with HCCI mode offering ultra-low emissions. Operating the engine in dual fuel mode can provide high thermal efficiency and significant diesel substitution.