LP gas conversion in petrol engines
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Date
1998-11-07
Authors
Sumanasiri, K. E. D.
Journal Title
Journal ISSN
Volume Title
Publisher
University of Peradeniya
Abstract
Conversion of Petrol engine to run by Liquified Petroleum (LP) gas is becoming
increasingly common in Sri Lanka due to the high price of petrol compared to cheaper LP
gas option. Even though the diesel engines can be converted, it has not been paid much
attention due to the low price of diesel. Many petrol vehicle owners are still searching for
advantages and disadvantages of different conversion systems for which the cost varies
from Rs. 10,000 to 50,000 depending on the conversion system. The paper presents a study
which involves identifying the differences of the engine performance when converted to
run from petrol to LP gas, rather than the cost effectiveness.
The Nissan petrol engine test bed (carburettor system) available at the Department
of Mechanical Engineering was converted to be operated using gas from a domestic LP gas
cylinder. Different arrangements were tested to understand the engine performance by
changing the air: fuel ratio, by heating of gas supply, by changing cylinder pressure etc.
Indicator diagrams were obtained to study the pressure variation inside the engine cylinder
when petrol and LP gas are combusted. Exhaust gas emissions were analysed using the
Orsat's apparatus.
It was found that the volumetric consumption of LP gas is higher than that of
petrol. Heating of the gas supply reduced the gas consumption and reduced the engine
temperature. No significant difference in the exhaust emission was identified perhaps due
to the accuracy of the gas analyser. The ignition advance angle should be altered for better
performance of the engine when running using LP gas which are preset for best
performance when running with petrol.
The trails were made in a test engine with variation of brake loads and the
performance during actual running conditions of vehicles should be studied separately. It
is to be pointed out that the facilities of an advanced carburettor are not fully utilised when
the engine is converted to run on LP gas. The engine performance could be enhanced if
petrol and LP gas are used together to run the engine.
Description
Keywords
LP Gas , Carburettor system , Petrol engines , Energy and environmental sciences
Citation
Proceedings & Abstracts of the Annual Research Sessions,1998,University of Peradeniya, peradeniya, Sri Lanka, pp 68