Strike water temp calculating

[JR]

I got sick of the slightly hit and miss approach I was taking to mash temperatures so I'm geeking it up and figuring out exactly what temp my strike water should be for a given volume / grain amount / temp of grain and mash tun.
I started by doing a few tests with different volumes of water at different temps to figure out how much energy it takes to heat up my mash tun and its rate of energy loss for different volumes of water.

Now I am about to add grain into the equasion - can anyone tell me how much energy it takes to heat up 1kg of crushed grain 1 degree?

If I cant find a published value I will try to figure out the answer from the online calculators that calc strike water temp. (and possibly do a test at home to confirm.)

[Andrew]

I,ve been furiously going through some note but can't find exact figures. If your losing alot of temp its more likely to be from you mash tun than the malt. Maybe you could "pre-sparge" your mash tun with water 1 or 2 degrees above your desired strike temp to heat it up before you mash in. Adding malt shouldn't take much more than 1-2 degrees out of your mash liqour.

[James P]

Add strike water at 5C above mash temp, and wait for the temp to fall to mash in, which will heat your tun too.

[JR]

I have been using the approximate method for too long (and Im a bit of a geek who wants to derive a formula for my system)

Reverse calculating some online calculators gives me 0.3872Kj to raise 1kg grain 1 degree. (assuming that 1 degree of temp in a litre of water is a Kj)

I will stop wasting time at work and test the number on some other calculators when I get home.

The equasions I have found so far are for degrees f not celcius and they dont directly convert with a scale factor like pounds and quarts do.

anyway I better do some work.

[James P]

Try this on how to brew

NOTE: These equations also work for degrees Celsius, liters and kilograms. The only difference is that the thermodynamic constant of .2 changes to .41.

Initial Infusion Equation:
Strike Water Temperature Tw = (.2/r)(T2 - T1) + T2

Mash Infusion Equation:
Wa = (T2 - T1)(.2G + Wm)/(Tw - T2)

where:
r = The ratio of water to grain in quarts per pound.
Wa = The amount of boiling water added (in quarts).
Wm = The total amount of water in the mash (in quarts).
T1 = The initial temperature (¡F) of the mash.
T2 = The target temperature (¡F) of the mash.
Tw = The actual temperature (¡F) of the infusion water.
G = The amount of grain in the mash (in pounds).


The infusion water does not have to be boiling, a common choice is to use the sparge water at 170¡F. Then TB becomes 170 ¡F and more water (Wa) will be needed to make up the additional quantity of heat.

[JR]

Brilliant thanks for that

I also found a formula here http://pint.com.au/calculators/strikewatertemp/

which uses the constant 0.40

between me calcing it at .39 your book saying .41 and pint.com saying 0.40 then I think we have the answer. I will use 0.41 when I build my spreadsheet as your reference looks the most reliable.

[James P]

Do you not have Beersmith? At my normal chargeout rates, it is cheaper to pay beersmith and let it do the calculations for me! :)

[JR]

I do have beersmith but most of the temp calcs are for my large copper mash tun, the grain is the smaller correction.

I am also working on rate of energy loss from my mash tun so I know how often I need to add some hot water to stay within a couple of degrees. That changes with volume in the MT - big triple batches hardly move at all and small single batches need attention every 15 mins or so.

I will build one spreadsheet to rule them all so I wont have to think about it again. Then I can start worrying about whatever is next on my proirity list. (either water chemestry or exactish pitching rates)

[Martin townshend]

0.149x(required mash temp-grain temp)+required mash temp=strike temp- 0.5deg C for thermo dynamic wotsits and bingo de bongo. Spot on. (All figures in Deg C.)
OR, 0.149x(66-13)+66=73.9-0.5=74.4C

[James P]

That makes the job a lot easier! :)

[Mike Neilson]

Fucken hell its spot on!! shit thats a lot of mumbo jumbo x squarred for my simple brain!!

[Stu McKinlay]

Now I can see all your problems Martin - you should be mashing at 67c!!!!

[Martin Bridges]

You forgot to subtract your granny's birthday!