LNG COCKTAILS AS ALTERNATIVE TRANSPORTATION FUELS
Liquid
hydrocarbon fuels may be extended by liquefying natural gas under pressure at
ambient temperature as a mixture with LPG (liquefied petroleum gas), gasoline,
diesel or other appropriate hydrocarbon fuel. Such mixtures may be described as
LNG (liquefied natural gas) cocktail fuels and would be marketed as a bottled
gas-type fuel. The liquefaction pressures required are quite high particularly
for the heavier fuels such as gas diesel oil. The minimum liquefaction
pressures at 38-40 °C for 30% W/W liquefaction of methane in propane, n-butane,
n-octane and cetane are approximately 90 (9.0), 120 (12), 260 (26) and 540 (54)
bar (MPa) respectively (1 bar = 0.1 MegaPascal). Experimental conversion kits
for LNG cocktail fuels need to be developed and tested for spark-ignition (SI)
and compression-ignition (CI) engines. The conversion kit for SI engines could
be based on commercially available LPG kits while that for CI engines would
require a more detailed investigation.