Welcome To UTPedia

We would like to introduce you, the new knowledge repository product called UTPedia. The UTP Electronic and Digital Intellectual Asset. It stores digitized version of thesis, dissertation, final year project reports and past year examination questions.

Browse content of UTPedia using Year, Subject, Department and Author and Search for required document using Searching facilities included in UTPedia. UTPedia with full text are accessible for all registered users, whereas only the physical information and metadata can be retrieved by public users. UTPedia collaborating and connecting peoples with university’s intellectual works from anywhere.

Disclaimer - Universiti Teknologi PETRONAS shall not be liable for any loss or damage caused by the usage of any information obtained from this web site.Best viewed using Mozilla Firefox 3 or IE 7 with resolution 1024 x 768.

Effect of Boost Pressure on Performance, Combustion and Exhaust Emissions in Direct Injection Compressed Natural Gas(CNG) Engine

Tadesse, Girma (2009) Effect of Boost Pressure on Performance, Combustion and Exhaust Emissions in Direct Injection Compressed Natural Gas(CNG) Engine. Masters thesis, UNIVERSITI TEKNOLOGI PETRONAS.

[img]
Preview
PDF
Download (2580Kb) | Preview

Abstract

There is an increasing interest in supercharging S.I. engines operating on natural gas mainly due to its superior knock resisting properties in comparison to traditional liquid fuels. With direct injection of gaseous fuel there is still some penalty in volumetric efficiency when injecting the fuel at early and partial direct injection. The present work reports the effect of low boost pressures on engine performance, combustion and exhaust emissions of CNG-DI engine. The experimental test was carried out in 4-stroke spark ignition CNG-DI engine with compression ratio of 14. The investigation was done at full load and homogenous piston for stoichiometric air-fuel ratio in order to assess the maximum output of the engine. The test includes variation of engine speed and boost pressure. Injection parameters are found to have significant influence on engine performance. Simulated port injection (Early injection) when inlet valves are still open (300BTDC) and partial direct injection in which part of the injection occurs after the inlet valves are closed (180BTDC) were varied at each operating speeds with variation of boost pressure from 2.5 to 10 kPa. Injection pressure was kept constant at 18 bars for all test points. Narrow angle injector (NAI) was used to get faster mixing rate at operating engine speeds of 2000 rpm to 5000 rpm. Ignition timing was set to get maximum brake toque (MBT). In order to examine effects of boost pressure experimental work was done for naturally aspirated engine and the results were compared to supercharging system. For boost pressure above 7.5 kPa, it is observed that there is better performance at all operating engine speeds compared to naturally aspirated engine. With increasing supercharging pressure there is better heat release and mass fraction burned resulting in better combustion efficiency. In-cylinder pressure and temperature is high with increasing boost pressure giving high NOx emission. Supercharging system is found to reduce the penalty of volumetric efficiency at port and partial direct injections. With supercharging, partial direct injection gives better performance for speeds 2000 to 4000 rpm compared to early injection timings, whereas early injection timing gives better performance for engine speeds 4000 to 5000 rpm. At high engine speed, early injection timing gives enough time for mixture preparation with penalty for volumetric efficiency loss reduced by supercharging.

Item Type: Thesis (Masters)
Subject: UNSPECIFIED
Divisions: Engineering > Mechanical
Depositing User: Users 5 not found.
Date Deposited: 04 Jun 2012 10:16
Last Modified: 25 Jan 2017 09:44
URI: http://utpedia.utp.edu.my/id/eprint/2895

Actions (login required)

View Item View Item

Document Downloads

More statistics for this item...