 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
slyck(at)frontiernet.net
Guest
|
 Posted: Sun Dec 03, 2006 6:38 am Post subject: cooling |
 |
|
Although aimed at rotary engines, this is a very comprehensive
(and lengthy) report on cooling:
http://www.rotaryeng.net/how-to-cool12.html
I have a couple of hose connections that will get beading this winter.
BB
| | - The Matronics Kolb-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kolb-List |
|
|
|
| Back to top |
|
 |
jbhart(at)onlyinternet.ne
Guest
|
| Posted: Sun Dec 03, 2006 8:35 am Post subject: cooling |
|
|
From: robert bean <slyck(at)frontiernet.net>
Although aimed at rotary engines, this is a very comprehensive
(and lengthy) report on cooling:
http://www.rotaryeng.net/how-to-cool12.html
......................................................
Bob,
It looks like I am using the wrong approach. Thanks.
As I am running the Victor 1+ with a small radiator, I have looked into different coolants. I tried out water, water with WaterWetter, and 50/50 water/glycol and a product called "Engine Ice". WaterWetter was purchased from AutoZone and the Engine Ice I found on the web.
The results from initial testing this summer gave the following:
WaterWetter and H20 <-BEST
H2O
Engine Ice and WaterWetter
Engine Ice
Half H2O and Glycol <-WORST
WaterWetter when added to water lowers water surface tension. If you have
ever watched water start to boil in a pan on the stove you may have noticed
that little bubbles filled with steam begin to form and remain attached to
the pan bottom. As the water continues to heat the bubbles break loose and
float to the surface. These bubbles attached to the heated surface actually
reduce heat flow to the water. By reducing the water surface tension, the
bubbles break away from the metal surface earlier in their formation
allowing liquid water to re-attach to the surface and improves heat flow.
WaterWetter is not an anti-freeze solution, but Engine Ice is. Engine Ice
is expensive, and it is claimed that it will lower coolant temperatures by
50 degrees. I did not find this to be true. Now that cooler air
temperatures are here, I do not see that much improvement over glycol/water
solution.
Next Spring after the date for last frost, I will go back to WaterWetter and
distilled water.
I left the Engine Ice in for this winter and I expected it to be much better
in the cooler air, but this does not seem to be the case.
Jack B. Hart FF004
Winchester, IN
| | - The Matronics Kolb-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kolb-List |
|
|
|
| Back to top |
|
|
Jim Baker
Joined: 30 Mar 2006
Posts: 181
Location: Sayre, PA
|
| Posted: Sun Dec 03, 2006 10:48 am Post subject: cooling |
|
|
| Quote: | By reducing the water surface tension, the
bubbles break away from the metal surface earlier in their formation
allowing liquid water to re-attach to the surface and improves heat flow.
|
If you're running a pressure coolant system that gets hot enough
to form bubbles in operation........
Jim Baker
580.788.2779
Elmore City, OK
| | - The Matronics Kolb-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kolb-List |
|
|
|
| Back to top |
|
|
jbhart(at)onlyinternet.ne
Guest
|
| Posted: Mon Dec 04, 2006 8:20 pm Post subject: cooling |
|
|
At 12:48 PM 12/3/06 -0600, you wrote:
| Quote: |
> By reducing the water surface tension, the
> bubbles break away from the metal surface earlier in their formation
> allowing liquid water to re-attach to the surface and improves heat flow.
If you're running a pressure coolant system that gets hot enough
to form bubbles in operation........
|
Jim,
There is a temperature drop across the cylinder and head surface walls to
the water. The reason for this due to the fact that the thermal
conductivity or heat transfer rate of aluminum is about 250 times greater
than that for water. So steam bubbles will form on the high temperature
aluminum surface even though the apparent water temperature is much less
than the water boiling temperature. As the steam bubbles migrate further
away from the aluminum surface hot spot into the cooler water they
collapse.
This can easily be shown. Place a small pan filled with about two inches of
cold water on a stove. Turn on the burner to a medium heat. Hold a candy
thermometer so that the bulb is about one inch below the waters surface.
Watch the bottom of the pan. In a few minutes you will notice small steam
bubbles forming on the bottom of the pan. The thermometer will read about
100 degrees F. To form the steam bubbles, the metal to water interface has
to be at least 212 degrees F.
Jack B. Hart FF004
Winchester, IN
| | - The Matronics Kolb-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kolb-List |
|
|
|
| Back to top |
|
|
John Hauck
Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)
|
| Posted: Mon Dec 04, 2006 9:37 pm Post subject: cooling |
|
|
| The thermometer will read about
| 100 degrees F. To form the steam bubbles, the metal to water
interface has
| to be at least 212 degrees F.
|
| Jack B. Hart FF004
Jack/Gang:
Would you get the same results with a water pump rapidly circulating
the water?
john h
mkIII
| | - The Matronics Kolb-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kolb-List |
|
_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama |
|
| Back to top |
|
|
Jim Baker
Joined: 30 Mar 2006
Posts: 181
Location: Sayre, PA
|
| Posted: Mon Dec 04, 2006 9:51 pm Post subject: cooling |
|
|
| Quote: | >
>
>> By reducing the water surface tension, the
>> bubbles break away from the metal surface earlier in their formation
>> allowing liquid water to re-attach to the surface and improves heat flow.
>
>If you're running a pressure coolant system that gets hot enough
>to form bubbles in operation........
Jim,
There is a temperature drop across the cylinder and head surface walls to
the water. The reason for this due to the fact that the thermal
conductivity or heat transfer rate of aluminum is about 250 times greater
than that for water. So steam bubbles will form on the high temperature
aluminum surface even though the apparent water temperature is much less
than the water boiling temperature. As the steam bubbles migrate further
away from the aluminum surface hot spot into the cooler water they
collapse.
This can easily be shown. Place a small pan filled with about two inches of
cold water on a stove. Turn on the burner to a medium heat. Hold a candy
thermometer so that the bulb is about one inch below the waters surface.
Watch the bottom of the pan. In a few minutes you will notice small steam
bubbles forming on the bottom of the pan. The thermometer will read about
100 degrees F. To form the steam bubbles, the metal to water interface has
to be at least 212 degrees F.
|
You're talking about nucleation which is pressure dependent. As
an example, at the recommended 1.2 Bar pressure of a closed
Rotax cooling system (1.18 atm, or 900 mm/Hg) the boiling
point of pure water is raised to 104.75C, 220.46F, clearly not the
212F you cite in the open pan. Add ethylene glycol at 50/50 and
the temp goes up even further, my calcs show about 231F at 1.2
Bar. There is some evidence, however, that small bubbles may
promote heat transfer but most of that work was done under
microgravity conditions and not 1g conditions.
Jim Baker
580.788.2779
Elmore City, OK
| | - The Matronics Kolb-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kolb-List |
|
|
|
| Back to top |
|
|
jbhart(at)onlyinternet.ne
Guest
|
| Posted: Tue Dec 05, 2006 4:52 am Post subject: cooling |
|
|
| Quote: |
Would you get the same results with a water pump rapidly circulating
the water?
|
John,
In most cases yes because the water next to the hot aluminum surface is not
moving. Water has the same flow properties as air flowing over an airfoil,
in that the water next to the surface is not moving and then due to shearing
action the velocity picks up as the distance from the surface increases and
finally goes turbulent. One must remember that there are hot spots in the
system. Most likely they will be found next to the exhaust ports.
----------------------------------------------------------------------
| Quote: | You're talking about nucleation which is pressure dependent. As
an example, at the recommended 1.2 Bar pressure of a closed
Rotax cooling system (1.18 atm, or 900 mm/Hg) the boiling
point of pure water is raised to 104.75C, 220.46F, clearly not the
212F you cite in the open pan. Add ethylene glycol at 50/50 and
the temp goes up even further, my calcs show about 231F at 1.2
Bar. There is some evidence, however, that small bubbles may
promote heat transfer but most of that work was done under
microgravity conditions and not 1g conditions.
|
Jim,
You are correct that boiling temperature increases with pressure. If one
could pressurize the pan, you would see the same effect of bubbles forming
on the bottom of the pan. The pan surface temperature would be higher than
212 degrees F.
Yes, steam bubbles will help promote heat transfer with in a pool of water
such as in a pan. But at the hot metal surface with the water the heat
transfer rate decreases due to the combination of water and steam. This is
why the water is circulated. The moving water helps to shear off the steam
bubbles and to make room for more bubbles to form.
I use a coolant temperature gage, but a coolant pressure gage is a much
better indicator of what is going on at the head and cylinder aluminum and
water interface. The aluminum surface temperature will always be much
higher than the coolant temperature.
Jack B. Hart FF004
Winchester, IN
| | - The Matronics Kolb-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kolb-List |
|
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
