Abstract :
In this experimental study, the performance, combustion and emission parameters of single cylinder, fourstroke,
air-cooled, naturally aspirated, compression ignition (CI) engine with a compression ratio of 17.5 was
modified to operate in the liquefied petroleum gas (LPG)-diesel dual fuel mode of operations. Diesel being injected
into the cylinder and LPG being inducted in the intake manifold of an engine in the dual fuel mode at a constant
BMEP of 4 bar with a fixed engine speed of 1500 rpm. It was seen from the experimental data that the maximum
possible operating range of energy ratio (LPG to diesel) was limited by misfire and the corresponding values of the
energy ratio ranges from 0% to 89.5% at this operating condition. The concentration of nitric oxide (NO) emission
was significantly decreased from 550 ppm to 50 ppm with introduction of LPG as the contribution of diesel that was
injected reduced in order to maintain the same energy ratio. It was noticed that the lower peak in-cylinder pressure
at higher energy ratios signifying the low in-cylinder gas temperature. As the energy ratio increases, the level of
hydrocarbons (HC) emissions raises from 23 ppm to 824 ppm. Brake thermal efficiency reduces with increase in
energy ratio because of poor ignition quality of air-fuel mixture that was used with lesser amounts of diesel.
Keyword :
Liquefied petroleum gas (LPG), energy ratio, Dual fuel mode, Engine emissions