Strike Calculators not asking for grain weight?

[Dextersmom]

Hey am I mental? what gives? even Palmer's explanation / equation doesn't actually include an actual grain weight. How can this be accurate when calculating initial strike temp?
Tw=(0.2/r)(T2-T1)+T2

i know the "r" is the grain weight ratio, but simply stating 1.250 in the equation doesn't account for whether you're using 10lbs or 20lbs of grain?

and what about heat loss to an insulated mash tun? what if I haven't pre heated.

I'm sure there's something simple i'm missing here.
I've been using beersmith with varying success depending on whether I'm using the PC or APP (which both have discrepancies).

This has prompted me to attempt these calculations long hand to confirm the calculations.

 

[Aaron Beers]

In the equation you're quoting, I presume r is the ratio by weight of grain to water. Since the ratio is provided, the exact weights are irrelevant.

 

[Dextersmom]

I think that's what I'm having a problem wrapping my head around.

 

[bitteritdown]

0.2 may be the constant used for the specific heat of barley? So instead of multiplying that by mass it is divided by the ratio?

http://howtobrew.com/book/section-3/the-methods-of-mashing/calculations-for-boiling-water-additions
https://www.homebrewtalk.com/forum/threads/specific-heat-of-grain.246356/

 

[Dextersmom]

good thread.
i think at this point i'll let the smarter folk engineer the calculators and i'll have to adjust my profiles to fit based on trial and error.

if it works, it works I suppose!

 

[beermanpete]

The Palmer formula (in the first post) is predicated on a water/grain ratio that has been predetermined by the brewer. You choose how many quarts of water you will use per pound of malt. That ratio is used in the formula to calculate the temperate the strike water should be. For traditional mashing the water to grain ratio ranges from about 1.25 qts per pound to 2 qts. per pound. For example; if you are mashing with 1.5 quarts per pound then r=1.5. If you are using 10 pounds of malt then you need 15 quarts of water (3.75 gals.) for mash-in.

 

[Dextersmom]

That much I get, but when determining heat energy needed I wasn't getting why it wasn't asking for a weight. I do somewhat get it now.

 

[beermanpete]

The formula is working with the specific energy of the water and grain, meaning that each pound of water has the same specific heat as does each pound of malt. One pound of water mixed with one pound of malt of a different temperature will equalize to a particular temperature. 10 pounds of water and 10 pounds malt will equalize to the same temp as the one pound example because the energy balance is the same.

 

[Dextersmom]

Now I'm getting it.
Thanks!

 

[wilserbrewer]

If it makes you happy, put total quarts water divided by total pounds grain into the formula rather than water to grain ratio.

Pounds of grain is in the formula, it’s just hidden [emoji13]

 

[Dextersmom]

I'm pickin up what you're puttin down