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Effect of water injection on spark ignition engine with 98-Octane as fuel

Diwakar, Vinodh (2017). Effect of water injection on spark ignition engine with 98-Octane as fuel. Master of Engineering Thesis, Charles Darwin University.

Document type: Thesis
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Author Diwakar, Vinodh
Title Effect of water injection on spark ignition engine with 98-Octane as fuel
Institution Charles Darwin University
Publication Date 2017
Thesis Type Master of Engineering
Supervisor Lugg, Chris
Klaric, Stefanija
Subjects 0913 - Mechanical Engineering
Abstract Higher octane fuels act significantly in avoiding self-ignition that occurs in engine. When self-ignition occurs, it leads to a repeated noise called, knock. Water injection system in the internal combustion engines, plays a major role in optimizing the engine performance. It is also termed as Anti-Knocking injection. As the heat energy is absorbed during combustion, the temperature inside the cylinder will be reduced and helps in supressing detonation. The engine control unit (ECU) can take advantage of advancing the ignition timing and increased volumetric efficiency. Due to the cooler and denser air charges, higher thermal efficiency is also predicted.

This study experimentally investigates the effect of water injection on torque output, air intake temperature and exhaust gas temperature, in a naturally aspirated spark ignition engine, where water was injected at intake just before the throttle body and 98-Octane is used as fuel throughout the cycle. Further, this study investigates the effect of water injection as a knock resistance and reducing the emissions. The experiment is conducted to test water to fuel mass flow ratios at various levels of 0%, 10%, 15% and 20% at constant engine speed set at 3000rpm and at Wide Open Throttle (WOT). Previous experiments found that, with increasing the water-fuel mass ratios, there has been a reduction found in intake air and exhaust gas temperatures.

In addition, this research gives a valid comparison between a previous study using 91-Octane as its base fuel. It concludes 98-Octane has better combustibility and less brake specific fuel consumption compared to lower octane fuels. The findings also say that there is a better combustion efficiency and literature also indicates in practical situations, NOx, CO, CO2, soot and other emissions are reduced. Therefore, higher octane fuels are beneficial on high compression ratio engines (high performance cars).
Keyword 98-Octane
water injection
anti-knocking
emission reduction
high thermal efficiency
higher torque
higher power
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Created: Mon, 31 Jul 2017, 10:35:57 CST by Jessie Ng