Jet Relationships

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DarenN
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Joined: Wed Feb 06, 2008 11:46 am
Location: Surrey, B.C. Canada

Jet Relationships

Postby DarenN » Tue Mar 09, 2010 11:40 am

I've always been interested in how changes in the number of jets and jet sizes affect the efficiency of soda can burners.
I built a bunch of identical burners with different numbers of jets and different jet sizes and tested them.

Image

testing was done in my kitchen with an ambient temperature of 70*F.
fuel load in all tests was 18ml of Methyl Hydrate.
no windscreen.
each set of results is the average of three tests.

i first tested only the time to bloom and total burn time without potstand or pot.

the first collum is the jet size in decimal inches.
second is the time to bloom.
the third is the flame out time.



Size - Bloom - Flame Out

24 jets
.0315 - 0:49 - 3:13
.039 - 0:47 - 3:06
.046 - 0:45 - 3:05
.062 - 0:43 - 3:10

12 jets
.0315 - 0:45 - 4:46
.039 - 0:42 - 4:26
.046 - 0:37 - 4:04
.062 - 0:38 - 3:46

6 jets
.0315 - 0:39 - 6:22
.039 - 0:35 - 6:04
.046 - 0:31 - 5:44
.062 - 0:31 - 5:26

I then went through the entire series of tests again to record bloom, boil, and burn times under a pot.
boil is a rolling boil. 212*F.
the pot used was aluminum, 4.25" in diameter by 4" tall. with lid.
the distance from the top of the burner to the bottom of the pot was just over 1/2".
ambient temp, 70*F.
2 cups of water at 70*F was used in all tests.
no windscreen.
18ml of Methyl Hydrate for fuel.
the procedure was as follows:
light the stove and start the timer simultaneously.
quickly place the pot of water on the potstand.
record the time when the jets bloomed.
record the time when the water boiled.
record the time at flame out.

number of jets.
Jet Size - Bloom - Boil - Flame Out


24 Jets
.0315 - 1:08 - 7:44 - 7:45
.039 - 1:01 - 7:14 - 7:33
.046 - 1:03 - 7:00 - 7:29
.062 - 1:03 - 6:55 - 7:16

12 Jets
.0315 - 0:52 - 7:01 - 7:33
.039 - 0:52 - 6:57 - 7:12
.046 - 0:51 - 6:53 - 7:12
.062 - 0:47 - 6:30 - 6:38

6 Jets
.0315 - 0:58 - 7:58 - 9:03
.039 - 0:51 - 8:14 - 8:33
.046 - 0:49 - 8:09 - 8:39
.062 - 0:40 - 8:00 - 9:00

discussion on this topic can be found at:

viewtopic.php?f=41&t=4295

DarenN........
"I'd rather be happy than right." Slartibartfast

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