Gaseous fuels have always been established as an assuring way to lessen emissions in Spark Ignition engines. In particular, LPG resolved to be an affirmative fuel for SI engines because of their efficient combustion properties, lower emissions and higher knock resistance. This paper investigates performance, emission and combustion characteristics of a microcontroller based electronic LPG gaseous phase port injection system. Experiments were carried out in a single cylinder diesel engine altered to behave as SI engine with LPG as fuel at a compression ratio of 10.5:1. The engine was regulated at 1500 rpm at a throttle position of 20% at diverse equivalence ratios. The test results were compared with that of the carburetion system. The results showed that there was an increase in brake power output and brake thermal efficiency with LPG gas phase injection. There was an appreciable extension in the lean limit of operation and maximum brake power output under lean conditions. LPG injection technique significantly reduces hydrocarbon and carbon monoxide emissions. Also, it extremely enhances the rate of combustion and helps in extending the lean limit of LPG. There was a minimal increase of NOx emissions over the lean operating range due to higher temperature. On the whole it is concluded that port injection of LPG is best suitable in terms of performance and emission for LPG fuelled lean burn SI engine. © Published under licence by IOP Publishing Ltd.

Porpatham E

Department of Automotive Engineering

School of Mechanical Engineering

Vellore Campus

Pradeep Bhasker J

Fulltext

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

LPG gaseous phase electronic port injection on performance, emission and combustion characteristics of Lean Burn SI Engine

IOP Conference Series: Earth and Environmental Science

A single cylinder diesel engine was modified to operate as a Compressed Natural Gas (CNG) fuelled lean burn Spark Ignition (SI) engine. The engine was tested at 1500 rpm under wide open throttle condition at different compression ratios over varying equivalence ratios. The optimized compression ratio for CNG operation was found to be 12.5:1 which was further investigated for hydrogen substitution at 5% and 10% on energy basis to study and compare the performance, emission and combustion behavior of CNG fuelled lean burn SI engine. The brake thermal efficiency and brake power output increases with rise in compression ratio and achieved a peak brake thermal efficiency of 30.2% with 12.5:1 compression ratio and above a critical value of 12.5:1, the improvement was small when compared to the increase in emissions. Wide flammability limits of hydrogen enable ultra-lean combustion thereby extends the lean limit of operation to an equivalence ratio of 0.42 with 10% hydrogen addition as compared to 0.50 with neat CNG operation and its anti-knock enhancement makes it advantageous compared to increasing the compression ratio under low load conditions. Hydrogen addition also enhanced the combustion rate, heat release rate and reduced cyclic variations. On the emissions front, hydrogen addition showed reduction in hydrocarbon emissions from 65 g/kWh to 6.9 g/kWh at an equivalence ratio of 0.5 alongside carbon monoxide and carbon dioxide reduction. Due to retarded ignition timing to avoid knock, the Oxides of Nitrogen (NOx) emission increase was not significant. © 2017 Elsevier Ltd

Fuel

Effects of compression ratio and hydrogen addition on lean combustion characteristics and emission formation in a Compressed Natural Gas fuelled spark ignition engine

Experiments were conducted to study the effects of piston squish area on the performance, emissions and combustion characteristics of a Liquefied Petroleum Gas (LPG) fuelled lean burn Spark Ignition (SI) engine at a compression ratio of 10:1 under 25% throttle condition. A single cylinder diesel engine was modified to operate as LPG fuelled SI engine at a constant speed of 1500 rpm. The test was conducted at different squish areas of 25, 30, 35 and 40% on the total piston area at different equivalence ratios maintaining a constant squish velocity of 4 m/s. The ignition timing was set to MBT (Minimum advance for best Torque). It has been found that there is no significant change in lean limit in all the squish areas. An appreciable difference in brake power and brake thermal efficiency was noticed between equivalence ratios 0.7 and 0.9. The piston with 30% squish area showed good results followed by 25, 35 and 40%. The HC emission level at 30% squish area is less compared to other areas. At mid equivalence ratios the NO emission increased in 30% and 25% when compared to 35% and 40% due to increase in temperature and pressure. But NO emissions at maximum power in 25% and 30% were lower compared to 35% and 40% squish area. The Co-efficient of Variation (COV) of Indicated Mean Effective pressure (IMEP) increased sharply when the lean limit is reached. The heat release pattern shows that the rate of heat release was lowered at lean condition. On the whole it is concluded that 30% squish area is best suitable in terms of performance and emissions for LPG fuelled lean burn SI engine. Copyright © 2016 SAE International.

SAE Technical Paper Series

Investigations on the effect of Piston Squish Area on Performance and Emission Characteristics of LPG fuelled Lean Burn SI Engine

Applied Thermal Engineering

Enhancing the heavy load performance of a gasoline engine converted for LPG use by modifying the ignition timings

Controlling LPG temperature for SI engine applications

A novel strategy of using twin injectors mounted on the cylinder barrel of a two-stroke spark ignition (2S-SI) engine for direct injection of Liquefied petroleum gas (LPG) is developed and compared with manifold injection. Gaseous LPG at a low pressure of about 4-4.5 bar was used and the injectors were located opposite each other and above the transfer ports. Experiments were conducted at the best injection and spark timings at 3000 rpm. Results at 25% and 100% throttle positions over different overall equivalence ratios are presented. The twin direct injection system led to significant reductions in hydrocarbon (HC) emissions of about 80% at both the throttle positions as compared to the manifold injection method due to reduction in short-circuiting losses. The best brake thermal efficiency was also improved from 19.7% to 25.2% at full throttle. Oxides of Nitrogen (NO) emissions were lower and carbon monoxide (CO) levels were higher due to charge non homogeneity. Experiments were also done with a single injector mounted on the cylinder barrel. The twin direct injection system resulted in significantly lower HC emissions and allowed operation under wider range of equivalence ratios with later injection timings as compared to the single injector strategy indicating its superior mixture preparation characteristics. © 2015 Published by Elsevier Ltd.

Journal	Data powered by TypesetIOP Conference Series: Earth and Environmental Science
Publisher	Data powered by TypesetIOP Publishing
ISSN	1755-1307
Open Access	No