BTU of a stove

[swright81076]

Any guys out there able to help.

I'm trying to work out the BTU of my stove, I've seen many only advertising 12000 btu's and more. How can I work out mine.

Here are what I've got to go on.
Volume - 0.5l.
Start temp 20c.
End temp 100c.
Time 1.56 minutes.
Fuel used - 90g pine.

Sent from my Galaxy Nexus using Tapatalk 2

 

[swright81076]

Does 152.35 BTU sound right

Sent from my Galaxy Nexus using Tapatalk 2

 

[udamiano]

Not sure what you need, but a BTU is the amount of energy needed to increase the temperature of 1lb water at sea level by 1 degree Fahrenheit, not sure if that helps any

 

[Sappy]

BTU's measure how good the wood is, you'll only be working out the BTUu's of 90 g of pine in your stove, with such a small amount the next 90 g could have twice the btu count.

Firewood is measured in a cord( a pile 8 by 4 by foot) and you can get an estimate of the btu count is given, but every cord is different, my cord of pine could have a couple of million more BTU's than yours.

BTU count is an estimate, you could work it out but everytime you used it itd be different.

Add into that countless variables and its pointless. If your comparing stoves the time it takes to a specific amount of water, plus a rough estimate of fuel used, ie a handful will give a much better comparison than working out the BTU's

 

[santaman2000]

...Firewood is measured in a cord( a pile 8 by 4 by foot)...

You left out one dimension; 8 ft X 4 ft X4 ft. (128 cubic feet)

 

[johnboy]

Any guys out there able to help.

I'm trying to work out the BTU of my stove, I've seen many only advertising 12000 btu's and more. How can I work out mine.

Here are what I've got to go on.
Volume - 0.5l.
Start temp 20c.
End temp 100c.
Time 1.56 minutes.
Fuel used - 90g pine.

Sent from my Galaxy Nexus using Tapatalk 2

What you can calculate is the the size of your fire box in say cm3 then how much wood can fit in the fire box realistically and still have room to combust.

Then you need to know how much energy potential that type of wood has for a given volume. Generally calculated when the wood is dry or at a specific moisture percentage.

This is in nasty imperial but it might help....


http://www.engineeringtoolbox.com/wood-combustion-heat-d_372.html



So a rough example would be...

Useable Fire box size is 100cm3

Burning dry pine with a theoretical energy potential of 200btu per 50cm3

Gives an energy potential of say 400 btu for the firebox... However depending on the design of the fire box it might not be that efficient at converting the potential heat energy of the wood to actual heat energy. You get a lot of unburnt gases going up the flue soot etc... So you could make an estimation of how efficient the stove is say 55% and use that in your calculations....


Or just keep chucking logs in and enjoy the flames....

 

[ged]

I'm trying to work out the BTU of my stove, I've seen many only advertising 12000 btu's and more. How can I work out mine.

Here are what I've got to go on.
Volume - 0.5l.
Start temp 20c.
End temp 100c.
Time 1.56 minutes.
Fuel used - 90g pine.

The power output of a stove cannot be measured in BTU. Power must be measured in BTU per hour.

For this kind of measurement the SI units are far more useful. I would use kiloWatts (kW). One kW is about 3414 BTU per hour if you really need Imperial figures.

The numbers that you have given do not give enough information to work out the power output of the stove. You have given nothing to even estimate the efficiency of transfer of heat from the stove to the container. One stove could be producing ten times as much as another, but ninety percent of the heat might be wasted. That's where windshields and things like the JetBoil and other heat-exchanger pots win big. Strictly speaking, we can't even work out the power input into the volume because you haven't said what it's a volume of! Can we assume it's water?

Do you really need to know? There's an almost pathological interest here in how long it takes to boil enough water for a brew, but more numbers than that are almost meaningless in our context. Much more important is can it be used to do what you want it to do? Will it burn the desired fuels effectively, efficiently? Can you control and refuel it easily? Does it heat the pot evenly? Can you cook a decent meal without burning the food?

As a general guide, dry wood gives you roughly between three and five kilowatt hours per kilo, so if you're burning half a kilo per hour you're getting about 1.5 to 2.5 kW (or about 5000 to 8500 BTU per hour).

The question then arises: What are you doing with it all?

 

[santaman2000]

...Do you really need to know? There's an almost pathological interest here in how long it takes to boil enough water for a brew, but more numbers than that are almost meaningless in our context...

I think he wants to know so as to be able to compare it with/against other camp stoves. Most of them (the ones available over here anyway) list their capabilities in BTUs so it would be useful for such a stove to stove comparison. That said, I think since he has the stove in question, a simple test (actually using the stove) might prove both easier and more useful.

 

[swright81076]

I think he wants to know so as to be able to compare it with/against other camp stoves. Most of them (the ones available over here anyway) list their capabilities in BTUs so it would be useful for such a stove to stove comparison. That said, I think since he has the stove in question, a simple test (actually using the stove) might prove both easier and more useful.

That's exactly right. I'm just curious and want to compare. I know I can can compare boil times for a fixed amount of water at a constant start temperature using the same amount of fuel. But the only stoves I have at present are my experimental wood gas, modified alcohol can stove and an old IKEA type stove. The wood gas is the fastest and considering its only wood as fuel seems amazing.

Sent from my Galaxy Nexus using Tapatalk 2