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Ambient Air Temperature/Room Air Temperature

Posted: Tue Nov 06, 2012 8:49 pm
by zelph
How important is ambient air temperature/room temperature in the testing of little DIY alcohol stoves?

You've seen it many times where someone gives the statistics during the course of testing their newly designed DIY alcohol stove.

Beginning water temperature, ambient air temperature, amount of fuel, amount of water etc.

What is your opinion and why?

Re: Ambient Air Temperature/Room Air Temperature

Posted: Tue Nov 06, 2012 10:08 pm
by realityguy
I'd say there is quite a difference in winter testing and summer testing..as much as 50-60 degrees..That's about 25-30 % of the the "raise" in heat needed between seasons(32 degrees to 212=180degrees verses 80 to 212=132degrees).That's got to make a large change,specially in getting alcohol pressurized for jetted stoves..or to burn more even in wicked ones..

Re: Ambient Air Temperature/Room Air Temperature

Posted: Wed Nov 07, 2012 10:48 am
by sudden
It is not important at all given the way I see it reported. The only comparison that matters to me is a side by side boil test of various designs. Unless you have control over the testing environment there is no point showing the conditions imo.

Re: Ambient Air Temperature/Room Air Temperature

Posted: Wed Nov 07, 2012 10:53 am
by zelph
Ok, I can see how it can determine how fast a side jetted stove like the White Box Stove will have the jets ignite. (approx. 1 min. under ideal conditions?)

Wick stoves are not affected by ambient air temps. The alcohol is right at the surface of the wick and as soon as a match is touched to the wick it ignites. Hot air from the stove begins to rise and surround/engulf the pot of water. Once the pot is engulfed it no longer can be affected by ambient air temps.

"Tony" showed us a clear example of how the pot is surrounded by a layer of heat during the duration of a test boil. Here is a quote from a previous thread:

Studying fluid dynamics is what I do for a living.

If you look closely at this shadow graph image of a flame from a cat can side burner stove under a pot you can see the flame coming out of the side of the stove, there is no sign of turbulence until the flame goes up the side of the pot and starts to mix with the (or entrains) surrounding air.

I have also included some shadow graph pictures of the flames from other alcohol stoves and until the flame goes up the side of the pot in my opinion there is no sign of turbulence.

Tony

Image
Side jet burner

Image
My volcano which has a fairly high velocity flame jet for an alcohol stove

Image
Zelphs Starlyte

Image
Open top burner


Laminar Flow versus Turbulant Flow
viewtopic.php?f=25&t=1086

It is not important at all given the way I see it reported. The only comparison that matters to me is a side by side boil test of various designs. Unless you have control over the testing environment there is no point showing the conditions imo.


I'm inclined to agree with "sudden"


.

Re: Ambient Air Temperature/Room Air Temperature

Posted: Wed Nov 07, 2012 12:04 pm
by realityguy
Side by side testing is important..testing s a stove a stove on 90-100 degree days and "claiming "it'll boil water at xnumber of minutes with no other factors involved is what i was talking about.There are a lot of claims thrown around of "quick boils" without any water starting temperatures.Hell yeah I can get a 3 minute boil when my water starts at 1509 degrees.. ;)
99% of the test results I view online I ignore..I don't do stove testing on my own anymore and just use them.It's not all that important to me whether a stove boils water in 5 minutes or 10.I'm out to relax and enjoy myself.Besides,my stoves pretty much get left on their own to get the job done. ;)

Re: Ambient Air Temperature/Room Air Temperature

Posted: Sat Jan 12, 2013 10:29 pm
by steamjam
realityguy wrote:Side by side testing is important..testing s a stove a stove on 90-100 degree days and "claiming "it'll boil water at xnumber of minutes with no other factors involved is what i was talking about.There are a lot of claims thrown around of "quick boils" without any water starting temperatures.Hell yeah I can get a 3 minute boil when my water starts at 1509 degrees.. ;)
99% of the test results I view online I ignore..I don't do stove testing on my own anymore and just use them.It's not all that important to me whether a stove boils water in 5 minutes or 10.I'm out to relax and enjoy myself.Besides,my stoves pretty much get left on their own to get the job done. ;)


Yes. Even though my stove tests are always using the same pot, and using water starting at the same temp with the same thermometer.. Its still in an office under idea 65 degree-no wind conditions, therefore its NOT a 100% accurate test...

Re: Ambient Air Temperature/Room Air Temperature

Posted: Sun Jan 13, 2013 10:47 pm
by zelph
we design on the bench inside under controlled conditions to test the stove.

Once we get a stove to boil 2 cups with 1/2 ounce of denatured alcohol then it's time to take it outside and test our skills at protecting the stove from the elements. We use windscreens to help it along, use an umbrella to protect it from rain ;) When the barometric pressure is low we can expect an increase in time to reach a boil.

Once the stove is on fire and producing the massive amount of heat going up the side of the pot that we can see in the shadow graphs, ambient air temperature won't matter.