10 litre boil up time

[emptyglass]

One of those things that always seems difficult for us gas guys is judging the performance of a burner. At the end of the day, its all about how fast the wash boils.
For the electric guys, its pretty easy to say "I used 3200 watts for that run" making comparisons are easy, for gas comparisons are harder. If I had a 3 ring banjo style burner and say, BT1 had a mongolian and if crow had a jumbo jet (BD747), its hard to say "I put 32MJ in and put ot 15,000btu's, how much are you using".

But I've been thunking bout this.
If you were to put 10 litres of water in your boiler, put the burner on and time how long it took to boil, the out put of the burner could be calculated. The only variables I see are water start temp, and altitude (for them there up in dose hills). It could probably be a smaller amount, but if it was 10 litres, that would let most of the electric guys jump on board so long as 10 litres covered their elements.
Boiler size and shape may influence the calculation, but probably not enough to matter.

An electric boiler that was capable of 4800w on a controller with a meter in WA could be compared to a 2 ring gas burner in QLD, regardless of what the meter said, or how many rings were running at what pressure. All that matters is the time. If they both boiled 10 litres in 10 mins, its a pretty good bet that similar stills will work the same using the same recipie. Pretty safe bet most ground water would be between 14 and 20 C (minus extremes)
This would be helpful for comparing the performance of plated columns, or a new still, knowing that you have got your gas burner running at the right heat or the elements going as hard as they should.

I dunno, its just an idea. Probably heaps of reasons why it wont work, and I'm not able to do the sums that the brains of the forum could. It still needs work, and if I'm being brain dead, please break it to me gently, I'm very sensative :laughing-rolling:

[Brendan]

Sounds feasible EG...

Like dragging the quarter mile of stillin'! :auto-layrubber:

[googe]

. Your brain dead :teasing-tease: good idea empty, me and uzzabeth were suppose to do that about a year ago lol. Warm water from the tap and let it cool to a certain degree could be an easy way to start equal?. You go first ;-)

[emptyglass]

Thats a fair call Googe, possibly a good way to eliminate the variables, start with a temp thats a bit above the avaerage.
Edit; now I'm upset Googe :teasing-neener:

Sort of Breandan, not much different, except its more for the purpose of comparison rather than outright performance (although there could be a few bragging rights up for grabs there)

Probably pretty safe to say that starting water temp for most of us would be below 40C, sorry you guys in Marble Bar.
Could even make it so the its timed from 40c to boiling, since you have to run it to time it, and your on your way to 100c anyway (a bit under where I am, 400m above sea level).

[Brendan]

I'm out of this as it takes a fair bit more than 10 litres to cover my second element :handgestures-thumbdown:

Someone else can measure for the 4.8kW or 6kW crew :D

[emptyglass]

Sorry brendan, I forgot your still only holds 4.99 litres.

[kelbygreen]

ouch :laughing-rolling:

[Brendan]

Sorry brendan, I forgot your still only holds 4.99 litres.

Haha, but I only distill dirty water and make lavender oil :shhh:

[MacStill]

Sorry brendan, I forgot your still only holds 4.99 litres.

Haha, but I only distill dirty water and make lavender oil :shhh:

Navnt you done rose water yet, it's divine :D

[emptyglass]

Next chance I get I'll give it a try and post results.

I'm using a 3 ring india banjo style burner, a good adjustable reg with gauge and a 50 litre boiler.
I usually use the middle ring only, set at 1/2 stick to get the mixture right (still get some soot) and usually on about 90-110kpa.
I use the outer ring sometimes for quick heat up.

I'll do 10 litre times for both settings, balls out heat up time and general run time.
I'm guessing my run setting would be about equivilent to 3 - 3.5kva electric.

Besides, I need some boiled water for dilution soon, so it wont get wasted.

[blond.chap]

Hey EG,

I have a suggestion on how to make this easier. You could work out the time it takes to increase 10L of water from one temperature to another, say from 30degC to 40degC.

The total energy required to increase 10L of water by 10 degrees is:
10*10*4.18=418kJ (4.18 is the amount of heat (in kJ) required to heat 1L of water up by 1°C)

Then if you divide that energy by the time taken in seconds you get the effective heat input of the boiler. Say it took 174 seconds, then 418/174=2.4kW. This would mean your heat input actually going into the water is the same as a 2.4kW element (assuming the element didn't lose any heat to the surroundings.

Electric boilers could also use this to compare how effective their insulation is.

A few quick notes:
- Larger temperature difference and/or bigger temperature change would give better accuracy
- The tests should be done at a reasonably consistent ambient temperature
- The temperature difference would need to be between the same range each time, as heat capacity is a function of temperature.

[emptyglass]

Good point blondy, it would take a lot less fuel/electricity to do that.

I was just thinking that if you started timing once you hit 40C, most effects of ambient temp are nullafied a bit, and if you went to boiling its one less temp to take :D
Besides that, I often find myself boiling up water anyway, so for me it works.

I'll try to take times of every 10C rise when I get to doing it.

[db1979]

I reckon a combination of googes idea of heated water cooled to a certain temperature (say 30) and then heat on till it gets to a set temperature (40 maybe - blondes idea) would eliminate most sources of error. I think heated water would need to be added to a cool boiler so it would need to be straight from your hot water tap.

[Geoff]

I would a think good method is heating from a well stabilised ambient of any known temperature to boiling. I don't think that starting from some warm temperature and heating to a small temperature above this is reliable. My reasononing is that convection currents in hot water are quite significant, and will give an inaccurate measurement of water temperature if a simple spot measurement is taken. There is also likely to be similar large temperature gradients through the body of water.

If you start from some known well-settled ambient, then heat to boiling, the energy input will be esier to judge. Sure, the onset of boiling is somewhat hard to judge, but just wait for a racing boil. This is how you would time an electric system anyway. Then just use the formula

Q=mass*4180*(100-Tambient) to give total joules (correct for altitude by adjusting boiling point of 100 deg if needed), then use Q/time=power

mass in kg
T in degrees celcius
power in watts

[db1979]

I stand corrected. Good points.

[emptyglass]

I would a think good method is heating from a well stabilised ambient of any known temperature to boiling. I don't think that starting from some warm temperature and heating to a small temperature above this is reliable. My reasononing is that convection currents in hot water are quite significant, and will give an inaccurate measurement of water temperature if a simple spot measurement is taken. There is also likely to be similar large temperature gradients through the body of water.

If you start from some known well-settled ambient, then heat to boiling, the energy input will be esier to judge. Sure, the onset of boiling is somewhat hard to judge, but just wait for a racing boil. This is how you would time an electric system anyway. Then just use the formula

Q=mass*4180*(100-Tambient) to give total joules (correct for altitude by adjusting boiling point of 100 deg if needed), then use Q/time=power

mass in kg
T in degrees celcius
power in watts

I think you said what I was trying to say, but better.

[crow]

With all due respect , sound good til you take away one measurable factor. EG like myself uses gas and how to even roughly estimate the btu's on an adjustable hp reg would be near impossible, I guess if you could you could then equate that to wattage

[googe]

With all due respect , sound good til you take away one measurable factor. EG like myself uses gas and how to even roughly estimate the btu's on an adjustable hp reg would be near impossible, I guess if you could you could then equate that to wattage

Anything can be worked out by the right mind mate ;-) .

[Dominator]

Crow, the BTUs of your burner can be roughly calculated by using some simple measurements and the equations supplied.

Q=M*4180*(100-T ambient) to give total joules (correct for altitude by adjusting boiling point of 100 deg if needed), then use Q/time (s) = Power

Q = energy in joules
M = Mass in kg
T = Temp in degrees celcius
P = Power in watts
t = Time in seconds

So say you put 10L of water in your boiler at 20oC then run your burner flat out until the water boils an it takes 10mins.

Q = 10*4180*80
= 3,344,000 j

P = 3,344,000/600
= 5,573 W

1W = 3.4BTU
So 5,573W = 19,000BTU

While this does not exactly mean your burner puts out 5.5KW, (it likely puts out more but you will be loosing heat around the boiler that wont be included in your calculations) it does give you a ballpark figure and a comparison to the people running electric heaters.

[blond.chap]

I would a think good method is heating from a well stabilised ambient of any known temperature to boiling. I don't think that starting from some warm temperature and heating to a small temperature above this is reliable. My reasononing is that convection currents in hot water are quite significant, and will give an inaccurate measurement of water temperature if a simple spot measurement is taken. There is also likely to be similar large temperature gradients through the body of water.

If you start from some known well-settled ambient, then heat to boiling, the energy input will be easier to judge. Sure, the onset of boiling is somewhat hard to judge, but just wait for a racing boil. This is how you would time an electric system anyway. Then just use the formula

Q=mass*4180*(100-Tambient) to give total joules (correct for altitude by adjusting boiling point of 100 deg if needed), then use Q/time=power

mass in kg
T in degrees celcius
power in watts

You make some good points Geoff. I agree that a small temperature change won't have the level of accuracy that we're looking for (the 10degC thing was just a simple example). Also with the temperature difference through the boiler, you would really need to mix it up well which I can do with my boiler, but anyone just using a keg with a 2" connection would struggle.

My issue with heating to boiling point is that as you approach it more and more energy is spent on latent heat of vapourisation, so there's an inaccuracy in the time that you have water evaporating and when you get to a rolling boil where you can be certain it's at the boiling point.

If you could get a good degree of mixing going then timing from say 30degC to 90degC would be a good option.

If we can settle on a good standard approach it may be worth putting up a calculator (I can't upload excel), where you just enter in temperature change and time taken to give an output of "effective heat input", which would be the heat that is actually being used to change the liquid temperature. For the electric users you could also work out a % efficiency to see how effective your insulation is.