A Simple Hand Fired Stove Efficiency Thought Experiment

windyhill4.2 wrote:a bumblebee has too little wing span to body mass to be able to achieve lift off ,yet it flies very well.Some people have been educated beyond any earthly good,&try to reason that the bumblebee can't fly.

Ive been told that Igor Sikorsky had something like this painted on a sign hanging in his first helicopter factory.

lsayre wrote:In order to feel like Atlas I would have to first morph into being Sting!

And lest anyone misconstrue, this is a credit to his character and his knowledge and his methods of replying to posts.

And when I perceive condescension and disrespect pop up where none was given, then it's time to move on in that event.

Carbon12 wrote:I thought humidified air made you feel warmer???

I should have been more specific... It does when it's warm out and you're trying to cool off. At some point, I think there's a crossover ~75 degrees for me. Cold and dry feels way better than cold and damp. That was coming from my perspective in a house that runs between 55 & 60 degrees because I'm saving to buy a base heater.

wsherrick wrote:By the figures from the posted table my stove is producing 1,115,832 BTU's out of the total possible.
This leaves a loss of 54, 168 BTU,s out of the total possible 1,170,000 BTU,s.
How is this stated as a percentage?

William,
To answer your question: Qout/Qin = 1,115,832 / 1,170,000 = 95.4%

Sunny Boy wrote:William,
For clarification.

Is all 41 square feet producing 450 degrees ?

If I understand this correctly, if you have to put 30 pounds of coal in every 24 hours, that's how much it's burning in any 24 hour period, not 60, or 90 pounds.

Paul

Yes, that's true but the total amount of coal burning is 60 pounds at any time so you are getting the heat of the whole 60 pounds. So 30 pounds gets taken away during the period you have to add the new 30 pounds to the total. So it basically takes two days to cycle 60 pounds through the stove at 450 degrees from loading it to shaking it out. So if the total is 60 pounds the table posted is over estimating how many BTU's are produced at 450 degrees. Of course the whole stove isn't that hot from top to bottom nor is any stove uniform in temperature.
I wanted to plug in those numbers to see how it came out.

If anyone else wants take a crack at it they are welcome. I was very bad at Calculus when I was in college.

Sunny Boy wrote:That chart got me wondering if I could use it to get a total for my range.

I figured the best way was to measure the total area, then divide up the stove into square foot areas, . . and using my IR gun, scan each square foot to get an average temp for each square foot.

I got as far as measuring and totaling up all the heat radiating surfaces. That's how I came up with that 45+ square feet for my range. Next step is to start scanning and writing down the averages. Then use that chart to see how many BTU's each is, then total that.

The real challenge is to figure out coal use at that temp total.

What the heck, there's nothing good on cable anyway !

Paul

That is exactly the method I suggested at the beginning of this thread. I would love for a baseburner to be 90% or better but my engineering mind keeps having alarms going off as to why it should not be. So it makes me curious if it could be.

As far as the 60 lbs. burning and needing to add 30 lbs. a day then you only get the heat of 30 lbs. The amount in process is unimportant and adds nothing. Consider a pot of water on a stove that holds 2 gallons and you add 1 gallon every day to refill it. That means you consumed 1 gallon a day and adding 1 gallon of water to the air.

if being skeptical is being rude then time for me to exit this discussion as well.

ddahlgren wrote:

Sunny Boy wrote:That chart got me wondering if I could use it to get a total for my range.

I figured the best way was to measure the total area, then divide up the stove into square foot areas, . . and using my IR gun, scan each square foot to get an average temp for each square foot.

I got as far as measuring and totaling up all the heat radiating surfaces. That's how I came up with that 45+ square feet for my range. Next step is to start scanning and writing down the averages. Then use that chart to see how many BTU's each is, then total that.

The real challenge is to figure out coal use at that temp total.

What the heck, there's nothing good on cable anyway !

Paul

That is exactly the method I suggested at the beginning of this thread. I would love for a baseburner to be 90% or better but my engineering mind keeps having alarms going off as to why it should not be. So it makes me curious if it could be.

As far as the 60 lbs. burning and needing to add 30 lbs. a day then you only get the heat of 30 lbs. The amount in process is unimportant and adds nothing. Consider a pot of water on a stove that holds 2 gallons and you add 1 gallon every day to refill it. That means you consumed 1 gallon a day and adding 1 gallon of water to the air.

if being skeptical is being rude then time for me to exit this discussion as well.

Being skeptical is good as long as you are fair. The actual truth is what's important. I firmly believe that these stoves can and do achieve these levels of efficiency, if you don't accept it, who am I to be insulting to you about it. I won't turn into a condescending ass to make fun of you. If I believe something then I have to try and find out if it is really true or not and then show the proof to you the skeptic. That's how truth is discovered.
The 30 pounds a day to maintain a 450 barrel temp. on the stove is a fact. If I idle the stove at 250-300, it barely uses any coal at all. How much at these low temperatures, I don't know, I haven't measured it
I guess to be exact about it I am going to get a scale and measure exactly how much coal is used in a 24 hour period at different operating temperatures and then there will be some hard data to work from.

lsayre wrote:

wsherrick wrote:Someone answer the question. If on average stove A uses half the coal to produce the same BTU's per hour as stove B, how much more efficient is stove A on percentage scale.

Lets assume that stove B is a lowly 60% efficient and it burns 50 lbs of coal per day. Lets also assume that the coal being used has 12,500 BTU's per pound:

50lbs. x 0.60 x 12,500 = 375,000 BTU's per day required to heat the home

Now lets assume that Stove A requires only half the coal to accomplish the same heating task:

375,000 BTU's required / 25 lbs coal per day = 15,000 BTU's delivered into the home per pound of coal burned

But the coal at its very best (I.E, at an impossible to achieve in the first place 100% efficiency) can only give up 12,500 BTU's per pound.

Therefore Stove A is an impossibility.

I know from my personal experience and from the testimony of several others who have switched stove types or have both at same time that a savings of 1/2 the coal has been commonly reported.
Therefore, the assumption (i.e incorrect premise) that stove B is operating at an average of 60% is probably incorrect, it has to be lower. Therefore until definite observable proof of said premise is shown, I submit that stove A is what is possible and it is stove B that needs to be tested. So far all of the demand for evidence has rather one sided in the other direction.

While I do find this to be an interesting discussion, I also feel the we are quite limited in our knowledge of coal, BTUs, and actual calculations of efficiency. There seems to be an eternal debate on just how good or bad the old stoves are, with vocal/adamant proponents on both sides of the divide. Additionally, proponents of the old stoves feel that these older designs are not only good, but "far" superior to the new stoves...

With my limited knowledge and experience, I feel there are excellent stoves made in all eras; past and present as well as a lot of bad stoves made, perhaps even more so in the past than the present. That is more likely due to the fact there were hundreds of stove manufactures in the past, while there are far fewer today and those that are currently manufacturing can only survive if they are, at a minimum, fairly competitive within the current market.

As to the question if the old stoves are superior to the new designs, I caution that there are currently a lot of assumptions being made and seemingly a large amount of missing information. As an example of missing information, I'm including a few pages from the book by Babcock & Wilcox "Steam its Generation and Use" which has a fairly extensive description of coal, coal combustion, coal classifications and the BTU rankings of various coals and their methods. Just by looking at the various BTU calculation methods, Williams calculations show his stove running anywhere from about 95% efficient (using his numbers) to about 48% efficient - using a different set of BTU calculations that may be more appropriate for BTU calculation for heating devices.

I'd imagine the reality lies somewhere in between.

The pages included show that BTUs calculated in the laboratory are not set in stone, but rather quite open to interpretation and different methods of doing the analysis may be applicable to different applications for the coal.

Just some food for thought...

dj

I know from my personal experience and from the testimony of several others who have switched stove types or have both at same time that a savings of 1/2 the coal has been commonly reported.
Therefore, the assumption (i.e incorrect premise) that stove B is operating at an average of 60% is probably incorrect, it has to be lower. Therefore until definite observable proof of said premise is shown, I submit that stove A is what is possible and it is stove B that needs to be tested. So far all of the demand for evidence has rather one sided in the other direction.

That is exactly what I plan on doing when I finish the god forsaken broken hinge pins on my Crane 404. The only problem is the back bottom and 25% of sides and top are covered with an air gap so a blower can force air through.

ddahlgren wrote:

I know from my personal experience and from the testimony of several others who have switched stove types or have both at same time that a savings of 1/2 the coal has been commonly reported.
Therefore, the assumption (i.e incorrect premise) that stove B is operating at an average of 60% is probably incorrect, it has to be lower. Therefore until definite observable proof of said premise is shown, I submit that stove A is what is possible and it is stove B that needs to be tested. So far all of the demand for evidence has rather one sided in the other direction.

That is exactly what I plan on doing when I finish the god forsaken broken hinge pins on my Crane 404. The only problem is the back bottom and 25% of sides and top are covered with an air gap so a blower can force air through.

Me too, I am going to start a journal and keep exact records of temperature and coal consumption using a 24 hour interval as the constant.
On another note, having spent decades running steam locomotives, I have several exhaustive books pertaining to our subject here. These books are very informative as they are filled with steam tables, whole chapters on the science of coal combustion.
Turn of the Century home and sanitary (plumbing) magazines are also full of information. Out of one of these from around 1909-1910 a laboratory testing of three base burners was conducted by the Detroit Stove Works. It was found that they averaged about 85% combustion efficiency and that the average for all types of coal stoves at the time was around 70%. The study said nothing about thermal efficiency. I have never seen or heard of any studies concerned with the thermal efficiency of a heating stove. Of course, I can't find this anywhere to show you.
So I guess we might break new ground here.