Performance of a Spark Ignition Engine Fueled by Natural Gas Using Oxygen Enriched Air

The purpose of this paper is to outline the effects of oxygen enrichment on the performance of a spark ignited single cylinder Ricardo research engine fueled with natural gas.

Substituting gasoline with natural gas, under stoichiometric conditions, brings about a decrease in power output of a dedicated gasoline engine. This reduction in power is quantified in this paper for both fuels under stoichiometric conditions as well as for different fueling rates, for natural gas.

Subsequently, the effects of oxygen enrichment are reviewed in terms of:

• volumetric efficiency,
• flame propagation velocity,
• coolant temperature, exhaust gas temperature,
• spark advance,
• brake mean effective pressure,
• brake horsepower.

The use of oxygen enriched air results essentially in:

1. 1
   a significant increase in brake horsepower,
2. 2
   improved lean limits and reduction of spark advance,
3. 3
   a lower brake thermal efficiency. However under all testing conditions, brake thermal efficiencies was higher on natural gas than on gasoline.