Basintuthu Stove Flame temperature test 2

["Crispin" <crispin@newdawn.sz>]

Dear Stovers

Date of Test  19 January 2002, 2PM
Mean air temperature 23 deg C, humid and overcast, rain the night before
Mass of water    1000gm
Mass of tin can    212gm (the test was done with an open can)
Mass of paper used to ignite kindling    4gm
Mass of pine fuel put into the basket grate    196gm
Mass of all fuel in the basket grate    200gm
Mass of fuel added during the test    None
Mass of water + can at 2 minutes 45 seconds    1146gm
Initial Water temperature ? deg C (hot water)
Final water temperature     98 deg C

Method
This was a second test of the gas temperature directly under the bottom edge
of the tin can halfway between the can and the stove body.  This is probably
the highest temperature gas that reaches the can.  The flames do not always
pass over the thermocouple so the temperature is not as steady as the gasses
further away, though they are generally higher.  The fire was ignited with a
butane lighter.

Again, several people participated in the test as it required a stopwatch
holder, a temperature reader, a record taker (Blythe Walker) and a fire
lighter (me).

A fire shield around the pot was not present during this test which would
have increased the heat transfer to the pot sides, however the pot was
encased by a 3-paint can chimney protecting it from any wind while providing
additional draft.

The combustion 'went secondary' after about 25 seconds.

+++++++++++++++
Time in          Temp
Seconds      Degrees C
0                    39
5                    41
10                  50
15                  63
20                  78
25                  106    Secondary combustion started
30                  139
35                  231
40                  362
45                  500
50                  617
55                  620
60                  520    Flames presumed to have shifted
65                  371
70                  723
75                  748
80                  500
85                  666
90                  592
95                  641
100                758    Gas Temperature peak
105                762    "
110                639    "
115                570    "
120                757    "
125                738    Gas Temperature peak
130                715
135                674
140                636
145                616    Fuel pretty much exhausted
150                573
155                546
160                527

+++++++++++++++
Comments
We were operating the stove at its maximum potential heat output and these
are not considered to be representative of meal-cooking conditions.

The water in the can was already hot (70 deg?) and did boil but we were not
really interested in that as it was a flame temperature test.

We suspect the moisture content of the wood was not as high as in the
previous test as the secondary combustion started sooner.

The test was very brief (165 seconds) yet we feel the flame temperature was
measured accurately and is representative of a sustained fire condition.
There is a strong possibility that the flame temperature was held down by
copious quantities drawn through the system by the chimney.  Previous
measurements have routinely seen 850+ degrees in the flames when the
secondary air was given a chance to heat up more slowly.

+++++++++++++++
Description of the Stove
Name:    Basintuthu Single Pot Stove (pronounced bah-sin-DOO-too)
Class:    Bottom lighting with preheated primary and secondary air
Air Control:    None during this test.  All air passed throught the 5 x 40mm
air control holes unhindered.
Grate:    140mm diameter, 255mm long, 1.2mm thick stainless steel cylinder,
open grated lower end
Pot:    Tin can 127mm dia 195mm high.
Fuel:    Pine, air dried in summer.
Clearance between the pot and the fire passages: 25mm underneath, 78mm on
each side (cylindrical can in a cylindrical stove)
Fuel consumed during the test:   200 gm
Water boiled off    66cc
+++++++++++++++
END


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