FUELS WITH A HIGH ENTHALPY OF EVAPORATION IN SI ENGINE

The increasing use of fuels derived from oil, grows concern over the point that non-fossil fuels have to be considered as the future fuels. Among the alternatives, hydrogen seems to be one of the best since it can be produced from the abundant sources of water, but it suffers the drawbacks regarding combustion, storage and transportation view points. The other non-hydrocarbon alternative is ammonia, produced from unlimited sources of air and water [۱]. It can be introduced into the engine in the form of liquid or vapor. Methanol can be produced from coal to provide a motor fuel and ethanol from agricultural sources gives a non-oil source of fuel. For operation of the internal combustion engine, lower air- fuel mixture temperature or higher air-fuel mixture pressure are often preferred, because they provide efficiency and consequently a higher power output. The air-fuel mixture temperature is highly affected by evaporation enthalpy of the liquid fuel introduced into the inlet manifold of a spark- ignition engine. Due to a very low air-fuel mixture temperature for a fuel such as ammonia, change of state for the fuel may be observed in the inlet manifold. This has a significant role in the operation of the engine. These have been examined in this paper using related theoretical and experimental results.