Mechanical, thermo dynamical and environmental comparison of engines using natural gas and gasoline

Abstract

This paper shows experimental results of a Toyota Hilux 2400 swept volume, compression ratio 9:1 engine, operating with La Guajira natural gas and petrol. Also shows a thermodynamic study of those fuels in a normalized, variable compression ratio ASTM-CFR monocylinder engine. When using natural gas, Hilux engine increases its fuel consumption around 20% for the same power. Volumetric efficiency increases 10% and CO emissions decrease around 40%. When comparing thermodynamic parameters in CFR engine operating at a compression ratio of 9:1, it was found a 12,5% decrease in indicated power and 17% in maximum combustion pressure, which is proportional to temperature diminish of around 20%. Convective heat transfer coefficient decreases around 28% respect to petrol. First laminar combustion phase is duplicated when using the same spark advance as petrol, nevertheless this is maintained almost constant when spark is advance 15º over petrol spark advance.

Keywords

• natural gas
• petrol
• combustion
• fuel consumption
• emissions