Limited cooling space

Chew, Aaron aaronc at rsacom.com
Wed May 19 21:37:56 GMT 1999


I would reply the following.  I know I could be wrong, but here's my
thinking:

I think the coffee cup analogy more closely represents comparing the water
temp of car with a radiator and a car without it.  Of course, the car with
the radiator is cooler.

I too have trouble believing that the radiator trick results in cooler
temps.  Sure the water travels through a longer distance, but it sure
travels a lot quicker (less time for heat transfer) if the new water pump
flow rate can match the original configuration.

-----Original Message-----
From: Frederic Breitwieser [mailto:frederic at xephic.dynip.com]
Sent: Wednesday, May 19, 1999 3:46 PM
To: diy_efi at efi332.eng.ohio-state.edu
Subject: Re: Limited cooling space


> The way I see it, the coolant now "sees" a radiator that is 1/3 as high
and
> 3 times longer.  Why does this cool better than normal.  The log delta T
is
> the same, no?  Is it a flow turbulence thing?  That is the only change I
> see.

Here would be my <cough> guess...

If you increase the width of the radiator, the coolant has to move
further to reach the other side and be sucked back into the system,
therefore its exposed to the ambient (and hopefully cooler) air
temperature, which reduces the temperature of the coolant going back
in.

While my dilbert-cube-mates think I'm insane, I just tried something
that you can do that will illustrate the point.

Run the hot water on your faucet for a few minutes, until the
temperature is constant.  Stick a thermometer into a coffee mug, then
fill it with hot water.  Record temperature.

Then, using a second thermometer, or cool off the first one to room
temperature, repeat the experiment, however use the hose with the
spray gun, which typically has 5-6 feet of hose under it.  The
temperature in the mug is consistantly 5-6 degrees colder.  I did this
3 times to make sure.

Longer hose, more distance traveled, more energy (heat) lost or
radiated into "space".

-- 

Frederic Breitwieser
Bridgeport CT 06606

1993 Supercharged Lincoln Continental
1989 HWMMV w/turbocharged 500cid Caddy
1975 Dodge D200 Club Cab soon to have 431 stroker + turbos
2000 (I hope) Buick GTP (Mid-Engined Sports Car)



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