Author Topic: Is there someway for me to find the exact specific heat for my mashtun?  (Read 5389 times)

atarlecky

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Hi,

I have a 15 gallon Hobby Beverage Equipment Company Mash Lauter Tun that is 7mm thick and constructed of HDPE. I hesitate to use the .3 specific heat recommended for plastic in the equipment section because I don't know thermodynamics enough to know if the thickness and chemical composition of the plastic material affects that number.

Is there a calculator that allows me to enter something like the ambient temp, the temp of the water added, etc... and spits out a SH number for me?

Thanks.

Offline Rootvonroot

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Re: Is there someway for me to find the exact specific heat for my mashtun?
« Reply #1 on: November 28, 2010, 12:43:40 PM »
Way old topic but I'm working on this issue myself

I'm just trying to use logic here
So last brewing session i took notes on all temperatures and volumes and realized a few things

my temps - weather 60F, grain 60F, MT 60F (all 'ish') and brewsmith called for 173F strike water temp
I'm using a 10 Gallon igloo for MT - it weights about 11lbs
i used 9lbs of grain

I used 186F for my strike water since i knew from past experience that beersmith has been prediciting low temps and i figured i'd aim high and stir down the mash to my mash in temp of 154F

once the MT and grain settled in - it was at 159F - a 27F difference

SOOOO - i read i needed to up my specific heat (SH) of my equipment

I made a dummy recipe and set my mash to single infusion with temps at 60F for MT and grain
then i'd go in to my equipment and up the SH a bit then re-add the equipment to the dummy recipe to recalculate the strike water temp

finally at SH 0.75 i reached strike water temp 182.2F which when I subtract the observed temp loss of 27F gets me 155.2F - a touch above what i'm aimin for at 154F and since I am using coolers I'd rather be higher than lower since i can just stir the temp down to what I'm aiming for....

In theory this idea seems like it should work and better help beersmith calculate a more accurate strike water/mash out temps....

although I haven't put the new calculations to a real-world test yet

« Last Edit: November 28, 2010, 12:46:43 PM by Rootvonroot »

Offline Rootvonroot

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Re: Is there someway for me to find the exact specific heat for my mashtun?
« Reply #2 on: November 28, 2010, 02:11:07 PM »
guess i should mention that the hot water is going through tubing and a pump at outside temps ... that'll make a difference i bet

so perhaps i'm aiming for a SH or my set-up as opposed to just the MT

Offline jomebrew

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Re: Is there someway for me to find the exact specific heat for my mashtun?
« Reply #3 on: November 28, 2010, 07:17:06 PM »
I am struggling with this too.   Rather than deal with figuring out the heat loss, I dumped 160f strike water in the mash tun for 10 minutes then drained it into the hot liquor kettle, dumped in my grains and went with the default heat loss.  I think I was close to my target temp.  Going with 156 and was shooting for 154.  I had 4 floating thermometers in the mash tun (48qt rubbermade cooler) and had 4 different temperatures.  Sigh :/

 

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