Adding ice to lower pitching temp

[kelper]

You are forgetting the amount of heat needed to turn ice at 0 deg C to water at 0 deg C.

I'll come back with some figures later...

That amount of ice melting will lower the batch another 28 deg F.

 

[Drunkula]

You are forgetting the amount of heat needed to turn ice at 0 deg C to water at 0 deg C.

Rah - good lad. I was gunna say that. It takes 90 times the amount of energy to turn ice to water than it does to raise water temperature 1 degree C. Turning water into steam takes about 540 times - that's why when steam condenses on your skin that state change energy is returned in a fraction of a second, much worse than dunking your hand in boiling water.

 

[DavidDetroit]

If you have 3 gallons at 90°F and your goal is 5 gallons at 70°F.
then the 2 gallons of water to add will need to be at 40°F

No need for ice, just chill the 2 gallons in the fridge overnight.


to go down the ice route
if you have 3 gallon at 90°F
your tap water is at 70°
And the Ice temp from your freezer is -13°F

then you will need 0.73 gallons of ice at -13°F + tap water to make up to 70°F

Gotta like the math. Empirically, I was going to do 1 gallon of ice (so a little overkill). Good to know. Thanks.

 

[DavidDetroit]

I see the science wheels beginning to turn. That's good. I just know that the tap water isn't cool enough in July and August here to make the wort chiller that effective, time-wise.
Once I learned there was nothing wrong with adding ice directly, I was just going to eyeball it since I have a decent idea after seeing what it took to get the wort to 80F.

 

[Hopperty]

You are forgetting the amount of heat needed to turn ice at 0 deg C to water at 0 deg C.

I'll come back with some figures later...

That amount of ice melting will lower the batch another 28 deg F.

Rah - good lad. I was gunna say that. It takes 90 times the amount of energy to turn ice to water than it does to raise water temperature 1 degree C. Turning water into steam takes about 540 times - that's why when steam condenses on your skin that state change energy is returned in a fraction of a second, much worse than dunking your hand in boiling water.

Yes indeed, I forgot about the latent heat

ice to water at the same temperature reuuires about the same energy as raising it by about 8°C (14°F)


so 3 gallon wart at 90°
tap at 70°
0.62 gallon ice at -13°F

 

[kelper]

so 3 gallon wart at 90°

Is that a witches' brew?

 

[kelper]

0.62 gallons of WATER at -13F will cool your WORT from 90F to 72F

0.62 gallons of ice melting will cool it another 25F so final temp will be 47F

The melting has much more effect than you realise.

 

[Ghillie]

What kind of pump does that? It sounds like it would make warm weather a non-factor. Even though I've brewed quite a bit (only extract with grain), I've not familiar with any of the useful ancillary equipment.

I use a Robobrew which has a recirc pump. I've never used the method I described as my tap water is always cold. But it's very popular in Oz.

So I've no experience with any pumps other than what came with my Robo. But I'd image you have a couple of options (UK examples):

Cheap option:
https://www.ebay.co.uk/itm/DC12V-18...hash=item5220d9914d:m:mtY9YaN3iAukmCnDoCx7ycA

Flow rate is ~600L/hr.

More expensive, bigger capacity and likely more robust pump:
https://www.ebay.co.uk/itm/MP-15RM-...=14328125294593d0291df24b4f08b0c3ea91e75522a8

Flow rate is ~960L/hr

 

[Gerryjo]

I use a Robobrew which has a recirc pump. I've never used the method I described as my tap water is always cold. But it's very popular in Oz.

So I've no experience with any pumps other than what came with my Robo. But I'd image you have a couple of options (UK examples):

Cheap option:
https://www.ebay.co.uk/itm/DC12V-18...hash=item5220d9914d:m:mtY9YaN3iAukmCnDoCx7ycA

Flow rate is ~600L/hr.

More expensive, bigger capacity and likely more robust pump:
https://www.ebay.co.uk/itm/MP-15RM-Food-Grade-Magnetic-Drive-Water-Pump-Stainless-Steel-Brewery-Beer-220V/143281252945?hash=item215c3a6a51&_trkparms=ispr=1&enc=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&checksum=14328125294593d0291df24b4f08b0c3ea91e75522a8

Flow rate is ~960L/hr

If you're going to use a pump to cool make sure it has a lower flow rate so sa to help dissipate the heat as you are looking for as much heat to transfer to the cooler and get taken away though this can also be throttled at the pump with a lever valve

 

[kelper]

deleted

 

[Ghillie]

If you're going to use a pump to cool make sure it has a lower flow rate so sa to help dissipate the heat as you are looking for as much heat to transfer to the cooler and get taken away though this can also be throttled at the pump with a lever valve

This is something I've often pondered about...

So when I use my immersion chiller, I open the tap fully; the faster the water flows through the chiller the better the cooling effect. I've heard mutterings of improved heat transfer with a lower flow rate due to improved heat transfer, but I feel it's incorrect?

Increased flow rate always results in an increased cooling effect. Heat transfer does decrease in terms of inlet vs outlet differential; but this is more to do with efficiency rather than rate/speed of cooling. If you throttle back the flow rate you will eventually maximise heat transfer, but it won't speed up cooling. It will slow cooling down. Technically you'll make the cooling aspect more efficient by using less water. But when not on a water meter it's a non-issue. For me (no water meter), water usage is moot - therefore speed is all that's considered.

I've also heart mutterings about thermal barriers around the coils with a higher flow rate, but periodic stirring/whirlpooling will eradicate that.

 

[kelper]

As a marine engineer, I can expand on this. If you pump hot wort through a coil immersed in cold water to a separate vessel it would be more effective to pump slowly. You should control the pumping rate to get the final temperature you require. But if you are pumping cold water through a coil which is immersed in your wort it will be more effective to have as much flow as possible.

 

[Ghillie]

As a marine engineer

Where do you work?

 

[kelper]

Where do you work?

I used to work on cruise ships but am now retired. PM me if you want specifics.

 

[mathorp]

My strategy for hot weather cooling of wort with an immersion chiller coil is:
Stage 1: Pump tap water or swimming pool water through the coil, dumping the returns until temperature drop fizzles out. This might be at 30 deg C.
Stage 2: Partially fill a tub (e.g. insulated "Esky") with an ice/water mix. Use a small pump (e.g. fish tank pump) to circulate the 0 deg C through the coil with returns going back into the tub. (The returns are likely to be cooler than tap water). Add more ice as necessary.

Start with just enough water to cover the pump. A couple of bags of ice is usually plenty to bring a 25 litre batch down from 30C to below 20C quickly.

I have never tried the frozen/sanitised bottle method but it has the beauty of simplicity. If ever I live in a hot climate again I will try it out.

 

[DavidDetroit]

stirring/whirlpooling

I didn't know they were called "thermal barriers" but I do also stir but out of observation.

 

[Hopperty]

0.62 gallons of WATER at -13F will cool your WORT from 90F to 72F

0.62 gallons of ice melting will cool it another 25F so final temp will be 47F

The melting has much more effect than you realise.

you're right! I seemed to have thought that the latent heat of water ice represented about 8 degrees Celsius, when in fact it is about 80 degrees. Think I have been wrong on that one for a very long time (so can't blame the home brew)

It's a lot of energy isn't it - typically boiling a kettle (from room temp) is the same amount of energy to change water ice from zero °C to water at zero °C

 

[kelper]

Hopperty, where do you live?

I can't show you the calculations, because I used metric units.

There's a handy calculator here http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/cice.html

If you add 700g of ice to 1 kg of water at 90 deg C, the final temp would be 20 deg C.

So work out the weight of wort and add about 70% of that in ice.


Here's another where you can work in ounces and Fahrenheit.

http://www.onlineconversion.com/mixing_water.htm

 

[Ghillie]

I didn't know they were called "thermal barriers" but I do also stir but out of observation.

Stirring/whirlpooling isn't referred to as a thermal barrier.

The concept is in relation to the wort in contact with the coils being cold and not allowing for thermo transfer to the rest of the wort. This is why stirring/whirlpooling helps as you technically allow for more of the wort to come into contact with the coils. In very basic and poor terms...

 

[Hopperty]

Hopperty, where do you live?

I can't show you the calculations, because I used metric units.

There's a handy calculator here http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/cice.html

If you add 700g of ice to 1 kg of water at 90 deg C, the final temp would be 20 deg C.

So work out the weight of wort and add about 70% of that in ice.


Here's another where you can work in ounces and Fahrenheit.

http://www.onlineconversion.com/mixing_water.htm

It wasn't me that asked the question !

I made a rather silly decimal point error on the latent heat, not the method of calculation.

And for what its worth your own method is also deeply flawed by assuming the ice would be at 0°C. In a typical domestic freezer the ice will be more like -25°C, so with the quantities you used above you would end up with a final temperature of 9.3°C

I have derived a formula below that would work
Using Celius and GoalTemp being the desired temperature of the wort, the following formula would give the volume of ice needed.

IceVolume = ((WortVolume x WortTemp) - (WortVolume x GoalTemp)) / (GoalTemp - (IceTemp - 79.5))

So as per your figures but amusing ice temperature of -25°C here is a working example (you have to get you head round that two minuses makes a positive)

IceVolume = ((1000 x 90) - (1000 x 20)) / (20 - (-25-79.5))
IceVolume = (90,000 - 20,000) / (20 - -104.5)
IceVolume = 70,000 / 124.5
IceVolume = 562 grams