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Old 08-11-2008, 11:38 AM   #41 (permalink)
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Quote:
Originally Posted by donee View Post
Hi Blackjackel,,

In a radiator application, I do not think the difference between copper and aluminum is significant.

Actually, in large truck applications, Copper/Brass radiators are still king. Aluminum radiators are basically 100% of all passenger cars AFAIK. I can't say for certain but I believe this is due to the improved heat rejection.

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Old 08-13-2008, 02:06 PM   #42 (permalink)
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funny!

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Originally Posted by Tango Charlie View Post
Too funny!
Have you ever had hot dogs warmed on the exhaust manifold? It's a cheap way to eat on the road!
Yep,had many a hot meal thanks to the 75% thermal heat loss wonders of the IC engine! Stouffer's has no idea what a freak like me can do with one of their TV dinners!!!!!!!!!!!!!!!
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Old 08-13-2008, 02:28 PM   #43 (permalink)
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cooling system

2.25% of your fuel's energy is lost to the cooling system.If modified to Walter Korff's specifications of 1963,those losses can be reduced to zero,and with low-technology.------------------------------------------------------------- 75% of your fuel's energy is lost in the coolant and exhaust.---------------------------------- If one were inclined to re-invent the cooling system,one might consider recovering,and doing useful work with, this 75% of energy currently being wasted(the elephant in the living room ) by all motor vehicles.---------------------------------- A person might look to Israeli solar vapor-cycle-turbo-generators,which use hermetically-sealed turbo-machinery,which capture solar pond heat( your car's engine) via heat exchangers,to run compound-turbine electric generators,using superheat"steam" created from a working fluid much like 134-A.------------------------------------------ Electricity produced,can be used to power all electric loads,provide air conditioning,and power for electric motor traction drive.------------------------------- First one's there's a billionaire!
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Old 08-16-2013, 09:39 AM   #44 (permalink)
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Just a few thoughts.

Taken out flat the same surface area of a radiator would need significantly more flat space to achieve the same heat transfer... that's why they do it that way.

My OEM Gen-1 ICE radiator has air flow frontal area of about roughly ~1.5 square feet ... but if I unrolled all the fins and everything out flat ... it has roughly ~9 square feet of surface area.

Cooling at idle is not an issue as the ICE usually doesn't run at idle.

Sense the body style effectively looses the ability to run a fan to increase the air flow rate ... larger surface area may be needed for fringe events like very hot ambient temperatures.

It would seem to me the body flat style may need a large portion of the surface area around the engine compartment ... hood , sides , etc.
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Old 08-16-2013, 11:44 PM   #45 (permalink)
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The thread is 5 years old. How did you find it?

I haven't read all five pages, but surface radiators and corrugated skins went in and out of fashion in the aircraft industry in the 1930s.

How cooling is done:

A fan but no radiator, all in the wake.
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Old 08-17-2013, 11:27 AM   #46 (permalink)
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Originally Posted by freebeard View Post
The thread is 5 years old. How did you find it?
I was going to post some thoughts about it ... but figured I'd do a site search first for a similar older thread before starting a new one.

And wa-la ... found one ... some of the things I would have posted were already covered ... this way if discussion does continue , it's all together in one place.

Speaking of which ... one thing I didn't see posted about yet ... the other aerodynamic benefit separate from body shell getting tightened up ... is that the heating of the air will reduce it's density , which will reduce the drag to push it out of the way ... even if this density change is a very small effect... still there, in addition to the other body shell.

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I haven't read all five pages, but surface radiators and corrugated skins went in and out of fashion in the aircraft industry in the 1930s.
there are pros and cons ... some of the major cons are significantly reduced with a modern HEV & PHEV system that doesn't idle , uses less or no ICE at low speeds , etc.

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How cooling is done:

A fan but no radiator, all in the wake.

Love that.
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Old 08-17-2013, 02:22 PM   #47 (permalink)
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I have seen tube frame buggies that flow coolant through frame tubing, they still have a radiator, not sure how much the frame tube helps cooling as opposed to a rubber hose.
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Old 08-17-2013, 04:08 PM   #48 (permalink)
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Quote:
Love that.
Here's a design [on the left] that uses hot, pumped engine cooling air through a Coanda nozzle to pinch off and detach the low pressure wake bubble. Sort of a virtual boattail:
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Old 08-18-2013, 07:37 AM   #49 (permalink)
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I love crazy ideas ...

I've often thought fully shutting off the main grill and having small secondary radiator with highly optimized airflow ducting would be a neat trick - one that's not new. But then I saw this thread.

Obvious flaws usually have obvious solutions.

Inadequate suface area -> Obviously don't try to cool the engines entire thermal load with this, just highway cruising loads.
Hot surfaces -> Limit the temps from coolant.
Bellypan hitting something -> Seperate cooling loop. Lower pressure and flow rate, lower total liquid volume = less mess.

So I think you can't do away with your regular rad with electric fans.

So:

Keep the existing rad and coolant setup and only insert a small water-water exchanger to a secondary cooling loop that uses bellypan and/or hood, roof or even the rear lid/quarter panels.

If engine coolant is ~90 C the secondary coolant perhaps reaches ~80 C, if you flow control the fluid then you can control the surface temperature of the car down to safe levels. For a belly pan, frankly I wouldn't care if it got to 80C

A temperature vs flow controlled secondary cooling loop runs through a belly pan rad, where it cools to around 60C or below degrees, then a Aluminum hood or hood sections where it cools perhaps to +20 above ambient. This then returns to pick up heat from the exchanger in the main loop.

Why 60C? This would lead to a hood surface temperature of roughly 55-60 C. This feels hot enough to give you a start and make you stop leaning on that guy's weird looking hood, but takes about five to ten seconds to cause burns. Long enough for you to get your hand of it.

This system would run full time full flow once engine is at operating temp. It would do its work in a temp range below a thermostat that triggers opening of a movable grill block, which in turn would be below the temperature the thermo-fans kick in.

Given this much lower target of dissipating 10-20kw of heat it's much easier to make it work. I would bet that this could dissipate adequate heat for highway cruising that you could substantially shut the front grills except for a trickle of airflow in to the engine bay.

Someone want to take a guess at what a few square meters of aluminum at 55-80 C with highway speed airflow might achieve?

(Some cars have substantial amounts of aluminum body work and most of the chassis ...)

Interesting.
But the most interesting thing in this thread was the Meredith effect.

The Meredith Effect - AviationBanter

Probably negligible benefit below Formula 1 speeds and needless added weight. Sure but this tidbit intrigued me:

Quoting:

"the jet effect would be greatly enhanced if the exhaust system could
be piped to discharge within the exhaust ductwork that carried the
heated air from the radiator. This is because any additional heat
would expand the air, increasing the velocity of the discharge and
therefore the thrust attained."

"This does two things, 1. It accelerates the air through the ductwork.
2. It creates a negative pressure behind the radiator which sounds
like the same thing as 1, but really isn't. 3. It can produce
positive flow through the cooling ductwork even sitting on the ground
with tail to the wind. Ok, that's three things."

Crazy idea 1: Secondary cooling loop feeds an aluminum belly pad radiator that does double duty smoothing airflow. Probably not worth the extra weight and complexity?

Crazy idea 2: Radiator ductwork that uses an exhaust exit to move air through it. Probably a good use of otherwise wasted energy?
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Old 08-18-2013, 04:54 PM   #50 (permalink)
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...the idea is just crazy enough that it might work...
  1. Your aluminum bellypan could be one thin sheet with a bead-rolled, branching channel soldered or epoxied to a thicker aluminum sheet. There would be hot spots on the upper, inner face and a more uniform temp facing the air stream.
  2. I [unfortunately] don't have a reference, but in the 1950s someone built a Porsche racer that had the cooling duct end in a plenum about as big as a truck muffler that had the exhaust positioned inside as the only energy input into cooling. I don't know the result.

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