Improved Stove Efficiency Calculator/Spreadsheet

[James Marco]

Well, Methanol will boil off at a lower temp than ethanol. So, this means that less water will carry over. I would guess about 2% or so. As far as fuel line de-icer, it can all mix with water, lowering the freezing point. So it still works, regardless of 5% water content or 2% water content.

BTW: I believe most methanol is from industrial processes, not distilled.

[Andrew Williams]

If you want to get really serious about measuring your time to boil, you should get a usb temperature logger like this: http://www.vernier.com/products/sensors/temperature-sensors/go-temp. Watch the temperature vs time graph and when it levels out you know you've reached the boiling point at your specific local pressure.

[Ben H.]

I fixed a few of the errors that were pointed out to me and now v.3 has hit the newsstand:

https://drive.google.com/file/d/0BwVBql46i9hbUE9HUm0xN3MwTWs/edit?usp=sharing

As I mentioned to Delmar, if you select a cannister gas fuel (isobutane, propane, butane) and then select a fuel amount in ml or fl oz you will get a DIV/0 error because density is not entered into the applicable field on the fuel tab. I don't think this is a problem, because I can't imagine how you would measure the gas you burned volumetrically.

[Ben H.]

"… http://www.vernier.com/products/sensors/temperature-sensors/go-temp…" -Andrew W

That's a neat little gadget and a pretty good price. If they had a cheap usb scale that worked with the same software you could get real time efficiency calculations throughout your burn.

[Delmar O’Donnell]

> I don't think this is a problem, because I can't imagine how you would measure the gas you burned volumetrically.

Agreed; I had not thought this through.

Thanks for V3 Ben!!

[Troels L]

Very cool approach to meassuring stove efficiency ! I am new to this and has been using my own simplied methods.

Is Ben’s spreadsheet the most used efficiency calculator or is their some kind of standard method used in on BPL?

[Ben H.]

Well, I am not unbiased, but I think my spreadsheet is the most often used if people don’t use there own.  Most people who measure efficiency use a method similar to mine.  I haven’t seen other spreadsheets passed around other than people to modified mine to there own liking.  I certainly didn’t invent the method; I just tried to put together an easy to use option to simplify and standardize the process.  I felt too many people were using proxies for efficiency (if I make this tweak I used a little less fuel).  Formalizing it makes seeing the impact easier IMO.  I still see people using proxies for efficiency, but it seems to have become less common.  I am glad you like and still enjoy feedback.

[Troels L]

Love it – thanks!

[James Marco]

> I don’t think this is a problem, because I can’t imagine how you would measure the gas you burned volumetrically.
Agreed; I had not thought this through.

If you weigh the fuel, you can calculate amount of input oxygen. Around 1 fifth of our air is O2, so you can calculate the amount of air needed for burning.

Calculating exhaust gasses through the flue (just warmed air rising) can get a bit difficult. But knowing the diameter of the wind screen and the output vents along with the input vents should give you a rather reasonable flue output. Flue output is combustion byproducts + warmed air, but this will change as the water & pot warm up over the burn time. Anyway, a spread sheet can handle all that…

[Ben H.]

Reviving a somewhat dead thread. A couple years back, I received a notice of changes to Google Drive sharing rules and then I occasionally received individual requests to share the spreadsheet. I always approved them blindly. One such requestor yesterday tipped me off to the fact that the spreadsheet was corrupted. It looks like it was converted to a Google Sheets file and wiped out all of the drop down menus I labored over. This rendered the sheet nonfunctional. It looks like I was blindly giving people the ability to edit the spreadsheet on the drive and they were trying to use it like an online tool. That kind of capability wasn’t well developed 8 years ago when I made this sheet.

I re-uploaded the file and switched everyone’s rights to viewer only. Hopefully this will force people to download the file and use it on Excel (or possibly Open Office). That file is still here:

https://docs.google.com/spreadsheets/d/0BwVBql46i9hbUE9HUm0xN3MwTWs/edit?usp=sharing&ouid=105475109096819072638&resourcekey=0-u7TVbWWEBR9bUbETZKrUZg&rtpof=true&sd=true

 

I stripped out much of the functionality with that more advanced sheet and verified it works on Google Sheets. It is only in SI units so you have to specify fuel in grams and temperatures in deg C. This is an editable sheet so it may get destroyed by users but in theory you could use it as an online efficiency calculator.

https://docs.google.com/spreadsheets/d/1zRAyvl4zLgucK_9_kb-akcTofAdVkPk9jtV2pWi17RU/edit?usp=sharing

If I have time I may try to develop something more complex that can be used online.

 

 

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