Plantoil/diesel conversion basics
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danalinscott

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Reply with quote  #1 
Coolant/fuel heat exchangers do exactly what their name implies. They take heat from hot coolant and transfer it to the cooler (VO/PO) fuel. Since coolant heat is essentially waste heat produced by the engine  transferring some of this "free"  heat to the VO..(which must be warmed to lower its viscosity).. is the most efficient way to accomplish this. In addition to being "free" it is also essentially self regulating. The VO/PO passing through a Coolant/Fuel heat exchanger cannot possibly become hotter than the coolant passing through it.  Depending on fuel and coolant flow volume and temperature as well as interface surface area VO/PO fuel can be as hot as 180°F when leaving a Coolant/Fuel heat exchanger....but more commonly is a temperature closer to 140°F.

Two types of Coolant/Fuel heat exchangers exist:

"Shell and Tube"  heat exchangers are exactly what the name implies....one or more tubes through which fuel flows surrounded by a larger shell which creates a "coolant jacket" surrounding the the fuel filled tube(s) . Heat is transferred through the surface of the fuel filled tubes into the fuel.

and

Flat Plat Heat Exchangers - Where a series of flat plates are stacked creating a series of thin, flat passages. Coolant and fuel are flowed through alternating passages and heat is transferred through the plates separating the counter flowing coolant and fuel. Flat Plate Heat Exchangers can pack an incredible amount of surface are in a small package and is fast becoming the standard component in modern VO/PO conversions.

 

Externally most resemble the image above and internally they function as illustrated below.


 These are the most commonly used coolant/fuel heat exchangers in VO conversions.  For links to sources for FPHEs go HERE and for more info on them go HERE.

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danalinscott

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Posted 28 June 2006 08:55 PM
What size coolant line are folks using on their FPHE? 5/8" seems to be popular, anyone using 3/8"?

IP>Vegtherm>6-port Pollak(looped return)>wrapped vw filter>tank with heated pickup.

2 different scenarios:

1. Adding the FPHE between the tank and the filter (very cold climate). **Everything but the valve and vegtherm in the trunk.** This is to get things flowing nicely through the filter. My concern is that the 3/8" lines may not make it worth it. Also, am I taking to much heat away from the tank, when I need to melt that oil in -20F weather?

2. Put FPHE before the filter in the engine compartment, Run the 3/8" line to the filter and then back to the tank, and a separate 3/8" or 5/8" line to the FPHE (split the tap off the heater lines.)

3. FPHE after filter, but with the vegtherm this seems redundant.

My main concern is to keep the tank flowing, since the veg-therm wll bring things up to final temp.

I'm thinking out loud.. anyone have an opinion?


1981 1.6NA VW Pickup
1994 1.6TD FrankenJEtta
VEG-THERM based WVO system
Appleseed Processor
Chugiak, AK
http://www.alaskabiodiesel.org
 
Posts: 20 | Location: Chugiak, AK USA | Registered: 13 April 2003 Reply With QuoteReport This Post
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Posted 28 June 2006 10:48 PM
Hey, I lived in Chugiak AK for 15 years or so. Allways nice to run into an Alaskan.

I don't have much else to say about your questions, though, except that I would try to front load the heat as much as possible. You need the heat most going through filter and into IP. The oil cant take all the heat out of the coolant so i would think there would be plenty left over for the heated fuel pick and tank.

I'd be interested to know if anybody has data on how much heat transfer they are able to get in their system. I mean, the difference between initial coolant temp and return temp after it has gone through all the heat exchangers. Coolant ought to flow a lot more than fuel and I would be surprised if someone had a heat transfer of more than 30F or 40F. I am just guessing though. But I mean, when the engine is cold so is the WVO, and as the coolant heats, so does the WVO, so basically I don't think you have to worry about "Taking too much heat away from the tank".


Jackson

pre-SVO 84 300d
 
Posts: 7 | Location: Chicago | Registered: 04 May 2006 Reply With QuoteReport This Post
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Posted 29 June 2006 12:23 AM
Using 3/8" coolant line on a FPHE will severely limit its ability to raise VO to as high a temp as possible. Mount these as close to he filter as possible.

Use a heated coolant heated fuel pickup to liquify VO in your tank, HOH or HIH lines to keep it liquid and flowing easily and the FPHE to add the majority of heat to the VO.


Dana
danalinscott@yahoo.com
http://vegoilconversions.netfirms.com/
VegOil Conversions by Dana Linscott- VO Conversion
Consultation for large and small trucks, VO fuel related businesses, and co-generation(power/heat)projects
 
Posts: 3802 | Location: Central MN..Brrrrrr! | Registered: 06 November 2001 Reply With QuoteEdit or Delete MessageReport This Post
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Posted 29 June 2006 02:33 AM
Thanks, Dana for the input.

I'm struggling with the series or parallel FPHE installation.

(There seem to be some technical series-parallel discussions on the forum, but I haven't found any practical ones. I've read the FPHE installation thread twice, but it's so long I'm sure I've missed a few things.)

Anyway, I need a 5/8" flow through the FPHE, and my HOH is 3/8" back to the tank, so if this is installed in series, (Coolant >5/8"> FPHE >5/8"> wrapped filter >3/8"> HOH>tank >3/8"> return) then am I not constricting the flow through the FPHE?

On the other hand, a parallel system (5/8">FPHE>5/8">return AND 3/8">wrapped filter>HOH>tank>3/8") tee'd off of the heater lines may not have enough pressure (??) from the water pump to flow well (vw rabbit pickup), or one side may get all the flow, then requiring some type of valve to slow/divert the flow.

ANYWAY, this is all very academic. What are folks really doing?


1981 1.6NA VW Pickup
1994 1.6TD FrankenJEtta
VEG-THERM based WVO system
Appleseed Processor
Chugiak, AK
http://www.alaskabiodiesel.org
 
Posts: 20 | Location: Chugiak, AK USA | Registered: 13 April 2003 Reply With QuoteReport This Post
Member
Posted 29 June 2006 04:09 AM
Yes, the series connection will limit the flow through the FPHE. A parallel connection would be better.
 
Posts: 1129 | Location: AK/YT | Registered: 03 May 2005 Reply With QuoteReport This Post
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Posted 29 June 2006 10:25 AM
I concurr.
If the FPHE is insulated (which adds teh equivalent of at least 2 more plates in output) and installed in the cooolant line that flows to the (cab) heater core the coolant througput will be highest.

And to date I have not experienced (or heard of anyone) else experiencing any noticable diminished heat output from the Cab heater when a FPHE is installed this way.


Dana
danalinscott@yahoo.com
http://vegoilconversions.netfirms.com/
VegOil Conversions by Dana Linscott- VO Conversion
Consultation for large and small trucks, VO fuel related businesses, and co-generation(power/heat)projects
 
Posts: 3802 | Location: Central MN..Brrrrrr! | Registered: 06 November 2001


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Swany

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Reply with quote  #3 

It seems that most folks are plumbing their heat exchangers with 3/8 for the vo and 5/8 for the coolant.  The line I'm using is 3/4".  Is there any reason to reduce to 5/8 for the FPHE?


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Swany

99 Jetta TDI, Linscott hotrod, hoh, fphe, jacketed filter, inline heaters. Coolant plumbed in series with parallel loops for fphe and rest of rig.
danalinscott

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Reply with quote  #4 
No.

If you have 3/4" id hose and an FPHE with 3/4" ports you can use 3/4" fittings for a higher flow through rate. The cost is a bit higher and except in extreme situations there is no advantage. If you have a 1/2" port FPHE the cost  is higher and there is no possibility of higher flow though.

Do you have a FPHE with 3/4" ports?


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Glen_in_NZ

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Reply with quote  #5 

Heat exchangers - Tube or Flat Plate?


I’m looking into fitting a heat exchanger to a 1996 Toyota Hilux Surf SSR-X  3ltr Turbo Diesel.


I have two questions……..for now


Which is better (Tube or Flat Plate) and why?


The Tube style looks pretty straight forward – cut through the coolant hose and the fuel line (after the filter / before the injector) and fit the heat exchanger.  The Flat Plate on the other hand looks a whole lot more complicated. How and where does this fit / attach to the fuel / coolant system – the wholes don’t look big enough!!


Any assistance, information or pointing in the right direction would be gratefully received.


Many thanks

Glen

 

danalinscott

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Reply with quote  #6 
FPHEs are generally much more compact and less exepensive. They come with male or female threaded ports to which hose barb type adaptors can be fitted. And the ports are generally more than sufficiently sized for automotive coolant and fuel flow rates.

They are both installed in the same way in conversions. There are schematics on the options for tapping into the coolant system posted on this forum at: http://www.websitetoolbox.com/tool/post/voconversionbasics/vpost?id=2273794



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rickrexor

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Reply with quote  #7 

           With the economy in the shape that it is in, I had no patience or time to waste time.  As times became harder on my family, I did a survey over the entire house to see where we could cut back, or at least, save some money.  I noticed that my heating bill was unusually higher than it typically was.  After some investigating, I found that I was losing heat, as the hot water was transferred from the boiler to different parts of the house.  My neighbor recommended heat exchangers that would save my family money with higher quality piping.  Two months later, my heating bill was exactly where I thought it should have been and took the money that we saved and was actually able to afford a vacation for the family.  To save money, you really need to check out http://www.fluorotherm.com  

danalinscott

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Reply with quote  #8 

Quote:

           With the economy in the shape that it is in, I had no patience or time to waste time.  As times became harder on my family, I did a survey over the entire house to see where we could cut back, or at least, save some money.  I noticed that my heating bill was unusually higher than it typically was.  After some investigating, I found that I was losing heat, as the hot water was transferred from the boiler to different parts of the house.  My neighbor recommended heat exchangers that would save my family money with higher quality piping.  Two months later, my heating bill was exactly where I thought it should have been and took the money that we saved and was actually able to afford a vacation for the family.  To save money, you really need to check out http://www.fluorotherm.com  



This type of heat exchanger is not suitable for use in VO conversions.

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kristinthomas21

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Reply with quote  #9 
I ordered 26 of the plate Omar. I m going to go get the ball valve to the heater core. I already have my HOH established and its hotfox in my spare tank would be a huge pita to change now. My car is turned off during the month, I tried to upgrade components.

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