waterinjection.info  

Go Back   waterinjection.info > Forum policy and contents > Water/alcohol supplementary technical papers

Reply
 
Thread Tools Display Modes
  #1  
Old 07-04-2016, 05:25 PM
rotrex rotrex is offline
Senior Member
 
Join Date: Jan 2014
Location: Germany
Posts: 187
Default "Knock Limits in Spark Ignited Direct InjectedEngines Using Gasoline/Ethanol Blends"

https://dspace.mit.edu/bitstream/han...pdf?sequence=2

"Knock Limits in Spark Ignited Direct InjectedEngines Using Gasoline/Ethanol Blends"

This is very interesting as it compares the influence of chemical and evaporative effects on forced induction engines by examining the knock threshold via a change in intake air temperature using the engine either with port injection or with direct injection. This way you can observe what happens to fuel evaporating before the intake valve closes, port injection, or after the intake valve has closed, direct injection.

It also contains diagrams stating droplet lifetimes of isooctane vs temperature and crank degree. At about 400K or about 130C, a 100 µl fuel droplet has a lifetime of 100 Milliseconds! At 530C, we still talk some 30 ms.
So much for water spray with its 100 µm droplets significantly evaporating in the inlet tract.

A signifikant fraction of the fuel actually evaporates on the walls, intake, valve, cylinder and piston unless you pay a lot of attention to fuel spray dynamics for a direct fuel injection system. With the walls receiving cooling, you lose the charge cooling effect.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 09:22 AM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.