How many gallons of boiling water to heat 5000 gal 10 degrees?

[Spades]

How many gallons of boiling water (212°) must one add to get a 5000 gallon pool with 75°F water up (+10°) to 85°F

 

[gwegan]

All at once or over time? Is the pool covered or uncovered?

 

[tucsontico]

Energy balance:

m1*Cp*(Tf - Ti) = m2*Cp(Tb-Tf)

m1 = mass of water in pool/tub
Cp = heat capacity (assumed constant)
Tf = 85F
Ti = 75f
m2 = mass of water needed
Tb = 212

The equation reduces to:

m2 = m1*(Tf - Ti)/(Tb - Tf)

a cool thing about this eq is that it as long as the volume is not a funtion of temperature (you can assume it is not) you can use any units you want to use for the temp. You can also interchange volume and mass (using any units) and get the same answer.

Sooooo, with your numbers:
m2= 5000*(85-75)/(212-85)
m2=393.7 gallons
:study::uhh:

 

[Spades]

Awesome!! Even better is the formula provided to plug-in other values. One other question... Does this take into account the new volume that you will now arrive at? It was 5000 gallons, and now it will have 5394.7 gallons. Or do you first subtract 394.7 gallons to arrive back at 5000 gallons?

gwegan - Yes all at once

 

[JamesW]

It assumes that the new volume will be 5,393.7 gallons.

Is this something that you're planning to do?

Also, note that the answer is different depending on the starting temperature. Going up 10 degrees takes more boiling water as the starting temperature increases.

For example, starting at absolute zero (not possible, but just for example and not including ice). It would take 75.5 gallons of boiling water to increase the temperature 10 degrees.

To go from 201 f to 211 f , it would take 50,000 gallons.

It would not be possible to go from 202 f to 212 f by adding water at 212 f (it would take an infinite amount).

If you used steam at 212 degrees Fahrenheit, then it would only take about 52 lbs of steam, which wound condense into about 6 gallons of water.

 

[tucsontico]

It assumes that the new volume will be 5,393.7 gallons.

Is this something that you're planning to do?

Also, note that the answer is different depending on the starting temperature. Going up 10 degrees takes more boiling water as the starting temperature increases.

For example, starting at absolute zero (not possible, but just for example and not including ice). It would take 75.5 gallons of boiling water to increase the temperature 10 degrees.

To go from 201 f to 211 f , it would take 50,000 gallons.

It would not be possible to go from 202 f to 212 f by adding water at 212 f (it would take an infinite amount).

If you used steam at 212 degrees Fahrenheit, then it would only take about 52 lbs of steam, which wound condense into about 6 gallons of water.

Everything you mention is true. However, at the temperatures we're discussing water will not appreciably change its volume. At lower temps (below 34ºF or 1ºC), water begins to expand in volume which renders this equation invalid. I totally agree using steam is the most efficient way to increase the temp of a large volume of water. Unfortunately, producing steam and injecting into a big tub of water (5000 gal) is beyond most consumer-level devices.

 

[JamesW]

[Edit] It would be 384 lbs of steam. Which would condense into 46 gallons of water. [End edit]

 

[JohnT]

I'm not sure I'd want to be part of nearly 400 gallons of boiling water.

 

[Spades]

It assumes that the new volume will be 5,393.7 gallons.

Is this something that you're planning to do?

Also, note that the answer is different depending on the starting temperature. Going up 10 degrees takes more boiling water as the starting temperature increases.

For example, starting at absolute zero (not possible, but just for example and not including ice). It would take 75.5 gallons of boiling water to increase the temperature 10 degrees.

To go from 201 f to 211 f , it would take 50,000 gallons.

Well it has certaiinly crossed my mind on several occassions where i was in a pinch with people wanting to come over to swim without notice. And now that i have some actual figures i can better assess whether i would do it And yes i completely follow the logic that as the water temp progressively increases it will take either more water and/or higher temps to raise the temp

 

[mas985]

I don't know how you were planning to generate the boiling water but because heat loss rate increases with water temperature the number of BTUs to heat the water to 75F using boiling water would be quite a bit more than just using a standard pool heater. So if you are interested in heating the water as quickly as possible and more cost effectively, a 400k BTU pool heater will probability be the best choice.

 

[ps0303]

I wouldn't recommend any other way to heat any pool but by using the correct equipment to do so. I had a hotel maintenance guy tell me that when his heater breaks down he uses water from their boiler to fill the spa. That is a liability. No matter if this is even a resident, heating a pool this way as the OP is asking is not safe nor efficient.

 

[Spades]

This was an idea that crossed my mind when i was in a pinch, not be the standard method id use on a day to day basis.

 

[JohnT]

This was an idea that crossed my mind when i was in a pinch, not be the standard method id use on a day to day basis.

Do you have a plan for boiling over 3000 pounds of water? I can't even think of a way to do it other than a large commercial boiler.

 

[needsajet]

Come on down and boil it on the road in front of my house. We can scramble some eggs while we wait.

Today is a bit cool, but I'll let you know when the right day is coming Last Friday would have been perfect.

 

[JamesW]

It's an interesting thought experiment, but not a realistic or safe option. As noted above, invest in a pool heater if you want to heat the pool.

 

[JoyfulNoise]

Personally I'd like to setup a giant magnifying glass above my pool with the focal point of the lens set to approximately 3/4 of the depth of the deep end just over the bottom drains....just be careful not to swim to close to the beam waist....ZAP!

 

[needsajet]

Might have been watching too much James Bond, but what about a parabolic trough mirrors on solar tracking gimbals...

 

[JamesW]

They use those in solar power plants. Sometimes they use molten salt to transfer the energy.

 

[JoyfulNoise]

Might have been watching too much James Bond, but what about a parabolic trough mirrors on solar tracking gimbals...

I've got lots of extra roof space on the casita next to the pool ... will check with wife, aka chief financial officer, on the family budget line for "hair brained pool ideas"

They use those in solar power plants. Sometimes they use molten salt to transfer the energy.

Yes, very neat. Molten fluorides I believe. They also have molten salt based nuclear reactors too....lots of excess heat in a reactor core.



Sent from my iPhone using Tapatalk

 

[gwegan]

The solar plants with mirrors have a bad habit of turning birds into dust.

Report: Ivanpah solar project kills 3,500 birds

So you jump off Matt's diving rock and never hit the water. Just some ashes.