What size heat exchanger should I use?

For discussing the modifications needed for diesel vehicles to run with 2 tank veggie oil conversions.

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Postby SunWizard » Sun Feb 27, 2011 9:05 am

harrisonm3 wrote:Maybe the lift pump is pushing fuel so fast that it doesn't heat up enough.

Looped return? If so the lift pump speed wouldn't matter, the WVO would simply loop around getting hotter and hotter.
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
Low fossil net zero house- 100% solar power and heat.
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Postby harrisonm3 » Sun Feb 27, 2011 9:48 am

I do have it T'd off before with only a little coolant going to the heater core.

I will re-route and see what happens.

It is a looped return.
Have an awesome day
Converted Dodge 2500 97 4x4,
3 valve looped return, Heated pickup, TIH, 31 FPHE.
http://veggiescout.blogspot.com/
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Postby SunWizard » Sun Feb 27, 2011 11:06 am

harrisonm3 wrote:I do have it T'd off before with only a little coolant going to the heater core.

I will re-route and see what happens.

Better than re-routing is to have a valve on the line to the heater core as I did on mine and you can close off or adjust how much heat goes to it. We need more details on your conversion, like a diagram or good description, or we are all just guessing about what it could be. Is your coolant flow like shown on my diagram?
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
Low fossil net zero house- 100% solar power and heat.
SunWizard
Site Admin
 
Posts: 1719
Joined: Mon Dec 11, 2006 2:53 pm
Location: N. Colorado

Postby harrisonm3 » Sun Feb 27, 2011 11:25 am

I have said valve.

My scheme is the same as yours with the following exceptions:

Hydraforce valves, and PEX tubing, Arctic Fox heated fuel pickup, in a 120 Gallon tank. 31 plate heat exchanger.
Have an awesome day
Converted Dodge 2500 97 4x4,
3 valve looped return, Heated pickup, TIH, 31 FPHE.
http://veggiescout.blogspot.com/
harrisonm3
 
Posts: 33
Joined: Wed Oct 29, 2008 9:54 am

Postby SunWizard » Sun Feb 27, 2011 12:08 pm

Pex is much worse heat transfer than aluminum, but I doubt that is the issue. That size FPHE should get the WVO to within 10F of coolant temps. If your coolant temps are dropping, its usually a bad tstat. My WVO stays >160F at all times, and coolant >170F, even down mountain passes. I have a stock 185F tstat.

Blocking the radiator doesn't change those temps much, it mostly makes for a quicker warmup and switchover. The tstat is what maintains the temp within a narrow range, by having no flow through the radiator much of the time in cold weather.

Check for restrictions or kinks in any of your coolant hoses. Air trapped in a hose could cause trouble too, try removing a hose from the highest point to see if you have air trapped there.
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
Low fossil net zero house- 100% solar power and heat.
SunWizard
Site Admin
 
Posts: 1719
Joined: Mon Dec 11, 2006 2:53 pm
Location: N. Colorado

Postby John Galt » Sun Feb 27, 2011 1:22 pm

I suspect that further investigation will show that the coolant flow through the FPHE is restricted by the long series circuit for the coolant. This is a common problem. The FPHE should have it's own coolant loop from the block to the return side of the engine coolant pump.
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