all aluminum hoh or tot

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

Moderators: SunWizard, coachgeo

all aluminum hoh or tot

Postby jram » Thu Apr 24, 2008 2:18 pm

has anyone tried making a hoh line with all aluminum lines soldered together? it seems this would offer the conductivity of aluminum (via solder) and the simplicity and safety of traditional hoh. it would just have to be insulated well so that all the coolant heat does not radiate off.
thanks for thoughts
83 300D: FPHE>unheated filter>ILH>looped
jram
 
Posts: 1
Joined: Wed Mar 05, 2008 2:16 pm

Postby coachgeo » Thu Apr 24, 2008 8:46 pm

one of the advantages of using rubber coolant lines around a metal (or rubber) fuel line is you can squash them together tight thus increasing the area of actual survace contact.

sorta like 0o0

this seems to be why rubber HOH seems to get as hot as some TIH. Least that's what I've read. now with metal TOT that does not get squashed thus the contact patch is rather small and is said to maybe be not as efficeint as the rubber HOH.


Also that would be a shiat load of soddering. Does not soddering weaken the metal too? By the time you got done I bet you could have built two vehicles worth of rubber HOH espeially if its Hoses on metal fuel line
Life; It's all in the Balance

Moderator
coachgeo
 
Posts: 569
Joined: Thu Mar 06, 2008 10:46 am
Location: North Texas

Postby SunWizard » Thu Apr 24, 2008 9:34 pm

coachgeo wrote:this seems to be why rubber HOH seems to get as hot as some TIH. Least that's what I've read.

Not true at all. Its a bad idea to repeat something you read somewhere that is that far from reality. Please point me to where you read it, I would like to give them the following engineering info:

8' of 3/8" alum. tube in hose (TiH), 100F delta temp between coolant and VO transfers 21,946,000 BTU/hr of heat.
8' of 3/8 alum. tube sandwiched between 2 rubber hoses (HoT), 100F delta, transfers 4592 BTU/hr of heat. Rubber HoH is about half this.

Formulas and numbers here:
http://www.marshall.k12.wi.us/mhs/teachers/mirus/20002001/PrinEngr/PrinEngrInfo/RValues.html
The key number to note is the U value, heat conductance:
1/16" of Alum.= 279571
1/8" of Rubber=117

Besides the thermodynamics above, I have done actual heat transfer tests with rubber hose on metal, and TiH, and the results agree with the expected numbers above, of 1000s of times more heat transfer with TiH. Rubber HoH is slightly less heat transfer than the HoT calcs above.

HoH may be enough to keep your VO liquid in the hose, but its not much heat in comparison. Whether it would be enough would mainly depend on how well you insulate the HoH, and how cold it is outside, and how you plumb your rig, and how much heat you need before your filter.

I agree that soldering 2 alum. tubes would be a tough job. It would make for good heat transfer. How about just have 2 or 3 alum. tubes bundled and insulated (ToT), it would be far better heat transfer than rubber HoH or HoT.

I am glad your post inspired me to do those calculations, since it shows how useful a TiH can be, in some cases eliminating the need for FPHE and at much lower cost. I think I will start a new post about that issue.

Edit: U calcs were off due to inches to meters conversion, calcs revised.
Last edited by SunWizard on Fri Apr 25, 2008 9:14 am, edited 1 time in total.
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: 1723
Joined: Mon Dec 11, 2006 2:53 pm
Location: N. Colorado

Postby leftcoastjeff » Fri Apr 25, 2008 12:43 am

8' of 3/8" alum. tube in hose (TiH), 100F delta temp between coolant and VO creates 558000 BTU/hr of heat, more than most FPHE.
8' of 3/8 alum. tube sandwiched between 2 rubber hoses (HoT), 100F delta, creates 98 BTU/hr of heat.

Formulas and numbers here:
http://www.marshall.k12.wi.us/mhs/teach ... alues.html
The key number to note is the U value, heat conductance:
1/16" of Alum.= 7101
1/8" of Rubber=3

This is very relavant to other thread, rubber coolant line=3,
Add air bubbles in the rubber? neoprene! check it out. great insulation.
Maybe a couple of more testers.......anybody know the "u or R" value of 6.5mm neoprene foam?

LCjeff
'87F-250 stock, minus that pesky water seporator/air inlet, bone stock for now.

Thomas Edison says it best, “Opportunity is missed by most people because it is dressed in overalls and looks like work”.
leftcoastjeff
 
Posts: 196
Joined: Thu Apr 17, 2008 6:35 pm
Location: Monterey, cal.

Postby BMW Fan » Fri Apr 25, 2008 6:12 am

Slowly, SUN, slowly.
Don’t scare the coach.
He is correct in saying that the flexibility of rubber hose allows for more contact area.
If you compare 3/8 rubber hose and 3/8 metal hose you can easily create more contact area by squeezing the rubber hose together.
Meaning the coach is right… for this part.

If it comes to heat transfer every technician with a clear mind knows that your numbers speak for themselves. HOH rubber hose simply can’t reach the same figures because of the so much lower heat conductance.
IMHO opinion a FPHE just in front of the IP is the safest and most reliable insurance for optimum heat supply. Don’t need to spread the heat all along from tank to engine and franticly try to insulate against heat loss.
I don’t care much of all the theory if I got the result where I need it and that’s in front of the IP.

BMW Fan

http://www.crawldog.com/klausold/
BMW Fan
 
Posts: 225
Joined: Sat Mar 08, 2008 6:48 am
Location: Nova Scotia, Canada

Postby Jake Palmer » Fri Apr 25, 2008 7:15 am

SunWizard wrote:
coachgeo wrote:this seems to be why rubber HOH seems to get as hot as some TIH. Least that's what I've read.

Not true at all. Its a bad idea to repeat something you read somewhere that is that far from reality.

Please point me to where you read it, I would like to give them the following engineering info:

Heck, he may have read that from me! I have used HoH and TiH in the same car and had the same heat output. That was a VW 1.6 Jetta, with the lines run inside the car.

Was it an abberation? Perhaps. But it was enough to convince me that HiH was hard to justify for my needs... which was simply to deliver WARM oil to the final heat exchanger at the front of the car.

SunWizard wrote:8' of 3/8" alum. tube in hose (TiH), 100F delta temp between coolant and VO creates 558000 BTU/hr of heat, more than most FPHE.
8' of 3/8 alum. tube sandwiched between 2 rubber hoses (HoT), 100F delta, creates 98 BTU/hr of heat.


Hmmm
Just a couple observations when I compare your formula to what my setup was:
-Even in a Jetta, my HoH run is almost 20' by the time it makes it circuituous route in the trunk, around the strut tower, around the seat back, under the rocker, up behind the dash and through the firewall.
-I was able to get ~45-50*C fuel out of my HiH, and got the same out of the HoH.

A couple other considerations that make my experience a bit less than scientific:
-I'm positive my HiH was shorter than my HoH. Probably by 5' or so.
-My heated fuel pickup usually added ~15*C to the fuel temp... meaning the HoH/HiH was not the ONLY source of heat being measured
-At some point in there, I did change my thermostat because the car wasn't heating up enough. In retrospect, that alone would skew things a lot. But what are ya gonna do when it's winter and your daily driver has no heat? Momma don't care about science when her feet are cold.

SunWizard wrote:HoH may be enough to keep your VO liquid in the hose, but its not much heat in comparison. Whether it would be enough would mainly depend on how well you insulate the HoH, and how cold it is outside, and how you plumb your rig, and how much heat you need before your filter.
[snip]
I am glad your post inspired me to do those calculations, since it shows how useful a TiH can be, in some cases eliminating the need for FPHE and at much lower cost. I think I will start a new post about that issue.


I agree 100% with all of that. There is no question that stand-alone, HiH would give hotter temps than HoH. I guess the question is whether or not it needs to. In my experience, with a good heated fuel pickup to boost temps and well insulated lines, HoH works great... as long as you're happy with 50*C output. That's more than sufficient if you're just using the HoH to get the fuel to a final heat exchnager, be it an FPHE or a Vegtherm.

But if you want to eliminate an FPHE & Vegtherm, then HoH is not the way to go. A long length of HiH can probably supplant a final heat exchanger, if there's a need to do that. HoH can't

Side note: I want to say again what a great venue this is, Sunwizard. This is the kind of discussion I like to have on a forum. thanks again for setting this up
Jake Palmer
 
Posts: 69
Joined: Tue Mar 04, 2008 11:12 pm
Location: New Brunswick

Postby SunWizard » Fri Apr 25, 2008 9:12 am

leftcoastjeff wrote:This is very relavant to other thread, rubber coolant line=3,
Add air bubbles in the rubber? neoprene! check it out. great insulation.
Maybe a couple of more testers.......anybody know the "u or R" value of 6.5mm neoprene foam?

I searched on it and found few references, but the ones I found said neoprene was about the same as rubber, for 1/8" thick neoprene R=0.0085, U=117. (My U=3 was off due to inches to meters conversion, calcs revised.)
This doesn't take into account the air in wetsuit neoprene which has to make it much better. Most foams are about 10x more insulating than rubber, so that would be a guess of R=0.085, U=11.7 for 1/8" thick.
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: 1723
Joined: Mon Dec 11, 2006 2:53 pm
Location: N. Colorado

yep, same story

Postby coachgeo » Fri Apr 25, 2008 11:46 am

Yep, this is the same way I recall the other discussions on this to go. By the numbers it does not make since. In reality on the road it seems to work out differently for some folk. Eventually the science will catch up with reality and figure out where the misscalculations were.

Funny how it works out sometimes.

Sounds like better insulation around a TIT should surpase the temps created by HOH. It all will eventually come down to...

. how much is enough temp for the job
. how much time and the pocket book one wants to spend to reach that point
. how much time and the pocket book one wants to spend on going beyond that point.
Life; It's all in the Balance

Moderator
coachgeo
 
Posts: 569
Joined: Thu Mar 06, 2008 10:46 am
Location: North Texas

Postby WD8CDH » Tue May 27, 2008 2:50 pm

How hot rubber HoH gets depends mostly on fuel flow. With return to tank, the flow rate is too high for the fuel to get very close to the coolant temperature. If the flow rate is low enough, like in a looped system, the fuel may get to 95% of the coolant temperature in 5 or so feet. With aluminum tube in Hose, the fuel would get to about 99.9% of the temperature of the Coolant. But that is only a few degrees better with a 100degree delta T.

HoH is fine at low flow rates but HiH or TiH is much better at higher flow rates.
Ron Schroeder
WD8CDH
'85 MB 300DT 2 Tank
Since '81 former WVO conversions:
'83 240D
'80 Audi 4000D
'83 Isuzu Pup
'86 Golf
'76 Honda Civic with Kubota engine
Prior to the cars, several generators
Kubota Tractor
WD8CDH
 
Posts: 103
Joined: Tue May 27, 2008 11:44 am
Location: NY


Return to 2 Tank veggie oil conversion and General discussion

Who is online

Users browsing this forum: No registered users and 0 guests