30103Re: SS wall heat conduction math

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• Jun 1, 2005
Andrew, a mash temperature will typically vary inbetween 90C (~17%) -
99C (~1%) during operation. IMO you'll get missleading results by
using 78C for mash temperature.

- Riku

--- In Distillers@yahoogroups.com, Andrew Forsberg <andrew@u...>
wrote:
> Hi all,
>
> The internet has provided me with far too many conflicting rates and
> formulae for calculating whether an external water bath for a
stainless
> steel boiler will or will not provide sufficient heat.
>
> I'd very much appreciate it if an engineer on the list would give
this a
> once over:
>
> T1 = 105 degC (water + table salt jacket)
> T2 = 78 degC (mash)
> Heat transfer coefficient = no idea... Ignoring it for the moment.
> K = approx 14 W(m2 . K) (I have seen more figures for SS than I
care to
> poke sticks at. This is the most conservative, and is for 270K, so
> anything better would be super).
> Q = Watts
> A = Area = .64m2
> D = thickness of the SS wall = approx 2 mms
>
> Q/A = (T1 - T2) / (D . 1/K)
>
> Q/A = (27) / (.002 / 14)
> = 27 . 7000
> = 189,000
>
> Q = 189,000 . 0.64
> = 120.96 kW
>
> So, what I'd like to know is -- will a 2mm stainless steel wall for
an
> area of .64m2 allow heat to pass through at a rate of up 120kW for
that
> temperature differential? Even approximately? As long as it's higher
> than 3 or 4kW I'm happy. Unfortunately some formulae I've found
> suggested the figure would be closer to 800W...
>
> Cheers and thanks,
> Andrew
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