Re: Second rapid boiling test - Jim Ross

[Reedtb2@cs.com]

Dear Jim, Crispin and all:

Hot dog!  We seem to be getting some real science and engineering experimentation into this list rather than a lot of interesting talk.  I could picture the experiment described very well, since I have run many of similar nature here at BEF or CPC on our Turbo and WoodGas stoves.

I recommend the format you have used to others aspiring to quantitative tests or winning coiling contests.  

A few questions and comments:

1) I envy you your 2 gm precision on your (digital?) balance.  It is so much better to have a continuous reading balance.

2) I presume the data was taken "by hand" rather than recording from the balance and 

3)  thermometer or thermocouple?

4)  What did you use as a heating value for the wood/paper?  Looks like 4.44 MJ/.326 kg = 13.6 MJ/kg, seems low even for wet wood. 

5)  It would be particularly useful if you could give the moisture content of the wood.  It only requires a thermostated oven (electric or gas) that you can maintain at 105C +/- 5 C.  Most electric or gas stoves achieve this.  Weigh, dry for 1-2 hours, depending on fuel size, weigh again and calculate.  I'm guessing you might be 15-20% moisture (wet basis) in your high humidity environment.  This would significantly affect your calculation in the heating value of the wood. 

                                                               ~~~~~~

We also monito time to boil as a useful criterion for real world cook stoves.  However, an equally important criterion is "turndown" if you are interested in fuel efficiency.  Your ability to boil in 3 minutes is excellent for the contest, but may imply difficulty in achieving long slow heat.  

How is the Basintuthu for simmering? 

ONward,           TOM REED               BEF STOVEWORKS


In a message dated 1/8/02 8:51:23 AM Mountain Standard Time, crispin@newdawn.sz writes:


> Dear Stovers
>
> Jim Ross has given the rapid boil a go.  He cut the wood into large squarer
> chunks though he did take them from the same plank I used.
>
> He used newspaper which was a bit damp today and he was given 6 gms to work
> with.  This is half a sheet from a small newspaper.
>
> Details:
>
> Date of Test  8 January 2002, 5:15PM
> Mean air temperature 19 deg C and raining slightly
> Mass of water    1000gm
> Mass of aluminum pot    514gm (the test was done with a closed pot)
> Mass of water + pot    1514gm
> Mass of paper used to ignite kindling    6gm
> Mass of pine fuel put into the basket grate    320gm
> Mass of all fuel in the basket grate    326gm
> Mass of fuel added during the test    None
> Mass of fuel and ash remaining after removing the pot (est)    30gm
> Mass of water + pot at 4 minutes 15 seconds    1402gm
> Initial Water temperature 22 deg C
> Final water temperature    98 deg C
>
> With the two of us present we were able to lift the assembled stove up to
> light the fire and start the clock as soon as the damp newspaper was lighted.
> The fact that is was raining seemed to affect the initial combustion quite a
> bit and the secondary burning did not kick in until quite a bit later than
> it did yesterday.  I feel that this was due to the lower surface area of the
> pine pieces (being thicker in section) and the paper bing so humid.  The
> lower ambient temperature was a factor in this, as was the very high
> relative humidity.
>
> Sincerely,
> Crispin
>
> ++++++++++++
>
> Time    Temp
> Sec      Deg C
> 0            22
> 5            24
> 10          25
> 15          26
> 20          27
> 25          28
> 30          29
> 35          29
> 40          30
> 45          32
> 50          33
> 55          35
> 60          35
> 65          36
> 70          39
> 75          39
> 80          40
> 85          41
> 90          41
> 95          42
> 100        43
> 105        47 (secondary combustion kicked in)
> 110        49 (this normally happens at 50-80 seconds)
> 115        52
> 120        55
> 125        61
> 130        66
> 135        70
> 140        71
> 145        78
> 150        81
> 155        86
> 160        88
> 165        90
> 170        95
> 175        97
> 180        97
> 185        98    Full Boil @ 3:05
> 190        98
> 195        98
> 200        98
> 205        98    Fuel subtantially consumed
> 210        98
> 215        98
> 220        98
> 225        98
> 230        98
> 235        98
> 240        98
> 245        98
> 250        98
> 255     End
>
> Water heated:    1000gm from 22 to 98 deg C
> Water boiled:    113 cc @ 98 Deg C
> Boiling rate avg 1.6 cc per second (1.65 KJ/sec)
> Total energy applied over 4:15    4.44MJ
> Water absorbed    1000x (98-22) + 113*1025 = 192,825 J
> Efficiency    4.3%
>
> +++++++++++++++
>
> Experimenter: Jim Ross
> 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, cylindrical, open grated lower end,
> made from 1.2mm stainless steel.
> Pot:    230mm aluminum pot weighing 514 gm, tested with the lid.
> Fuel:    Pine, air dried in summer.
> Clearance between the pot and the fire passages:    25mm
> Fuel consumed during the test:    296 gm (est).