I am in the final part of converting a chevy suburban diesel to run on veggie oil. I want to heat the injector lines to 220*F to give the veggie oil the viscosity of diesel fuel. This to get the proper atomization of the veggie oil upon injection into the combustion chamber. I got the heating system figured out. I like to monitor the temperature of the fuel injector line as close to the injectors as possible. I located a thermo couple that would be suitable. Where I run into problems is identifying/locating a four channel thermocouple readback fed by 12VDC. I looked high and low. The various veggie oil sites have been no help, surprisingly. Is there anyone on this forum that could put me in the right direction? In addition a temperature cutoff switch controlled by a thermocouple I have a hard time locating. If there is interest on this forum: I gladly post the ins and outs of this conversion with schematics, parts, pictures, etc. when the project is complete. Just let me know. Looking forward to any response. Thank you very much. Best regards, Hendrik.
A thermocouple generates a voltage based on heat. To display the temperature, all you need is a voltmeter. To control something based on the voltage from the thermocouple, build a high impedance comparator circuit.
Hey man, I just outfitted a VW with a veggie system. We used a termal switch that powered up the system once it hit about 84Degree C. or about 200degree F. I've research many graphs and did my own experiemtents and the visocity of veggie oil is about the same at 80Degrees. We just used a thermal switch system that gave an indicator light for the temp. A manual switch was then used to start the system (although a light modification could make it run automatically). The start switch power up a fuel pump and opened a solenoid valve.
The system monitored the temp at the fuel recycle (near the injectors) it turned on the light. A second temp point was taken off the heat exchanger. It went to an analog gauge to visually show the temp. We also had an off switch. Its important that you do that just incase there is a problem. Finally we added a pressure gauge just incase there was a leak. The final thing was a fuel level indicator.
The engine needs to be up to temp before the system starts. When the engine is hot any uncombusted veggie oil will float on the cylinder walls on a layer of vapour. That way you don't get carbon build up (like what you get on your BBQ or a cooking pan!
It is also good to have a shut off switch in the cabin with you. You should shut the system off about 5 to 10 minutes before you are done driving for a while. You need to purge out as much veggie oil from the fuel injectors and lines to prevent clogs! I've talked to a few guys who have had problems in this area. Mainly it happends on cold winter mornings but better do it just incase anyway eh?
I hope that gives you a bit of an answer. I don't have any circuit diagrams the owner of the car threw it together and I helped install it. All the parts came from a veggie oil society company thing for DIY... I can't seem to find the link to the site but they sell a kit... Anyway I have an email for a guy who has dones a few vehicle mods that could answer any of your question too. If you want it you have to give me a way to get it emailed to you. I don't feel right just sharing a guys emails on a forum for spam reasons.
Heating veggie oil in diesel injector lines
Posted - Jul 10 2008 : 2:16:22 PM
