Author Topic: Talking Thermodynamics  (Read 99699 times)

Offline steam guy willy

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Re: Talking Thermodynamics
« Reply #1110 on: January 11, 2019, 03:19:04 AM »
Hi MJM,  thanks for the info.......

willy

Offline MJM460

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Re: Talking Thermodynamics
« Reply #1111 on: January 14, 2019, 08:39:36 AM »
Hi Admiral DK, thanks for joining in once again.  Itís interesting to see the diverse uses for these devices arising once they become available. 

Hi Willy always glad to have a reason to talk about the science and physics that keeps things turning.  There has been a lot of progress since those early experimenters discovered strange effects at the junction of dissimilar metals.

MJM460
The more I learn, the more I find that I still have to learn!

Offline steam guy willy

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Re: Talking Thermodynamics
« Reply #1112 on: February 10, 2019, 07:42:48 PM »
Hi MJM, just a quick digestion question from my hospital  bed. i missed a hot meal so they gave me some frozen sandwiches, They were sealed in plastic bags and i was wondering if they would get up to ambient quicker if they were removed from the bags ??? getting better slowly....

Willy

Online crueby

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Re: Talking Thermodynamics
« Reply #1113 on: February 10, 2019, 09:56:23 PM »
Hope the date on those was 2019, not 1919....

You must be doing a bit better to be asking thermodynamic questions! Keep that up!

Offline MJM460

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Re: Talking Thermodynamics
« Reply #1114 on: February 11, 2019, 12:28:55 AM »
Hi Willy, good to see you thinking about food and thermodynamics again, you must be on the mend.

As usual the question is a bit more complicated than it looks.  The plastic film makes a very thin insulating layer, and adds film coefficients for each side of the plastic.  Then, the air inside the wrap is somewhat restricted for convection.  I assume they are not vacuum packed.

The rough surface of the exposed bread has more surface area than the smooth plastic film, so that would help if unwrapped.  But the generally dry hospital air might make the sandwiches dry out while warming, so taking more time might not be the worst.  If they are like hospital sandwiches here, they donít need drying out!

All in all, I wouldnít want to predict the outcome on theoretical grounds, easier to determine by experiment.  You have the time, so perhaps one of your visitors could bring in your thermocouple probe and meter, and you could conduct the experiment, including the taste testing.  I am sure the nurses would let you use a sterile wipe to clean the probe before using it for a food application.  They would probably prefer that to your having someone bring in some saws, files and material for the next bit of your engine.

MJM460

The more I learn, the more I find that I still have to learn!

Offline steam guy willy

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Re: Talking Thermodynamics
« Reply #1115 on: February 11, 2019, 06:43:16 PM »
thanks MJM, yes there are a few variables as taste and texture come into it....next time i come into hospital that will be first on the list !!!!   except they wright down everything you bring !!!