Actually the air is also on the external part of the slab. So, why we should take it into account on the external side and not on the internal part? Thanks
I finally lend to some good or at least "meaningful" results with my simplified toy model.
Let's assume to put 500Kg of potatoes inside the fridge.
The cp for the potatoes is cp=4184x0.84=3514.56 J/Kg degree C
So, to cool down 500Kg of potatoes from 18 to 8 degrees we would take:
Q = 3514.56 x...
We had in mind to estimate how much the cooling system will be stressed to be activated on a given DeltaT. So if it has to switch on every 4m is really too much and the isolation would not be enough. But putting some water inside shows the Tau is actually bigger, since the air does not contain...
As told I've Just 3l of water inside making It a bit more real and raising the Tau to 28m. I Need an approximation, not the real temperature profile. However I Will try with your suggestions. Thanx
As you can sere from my original post: The aim is to estimate the time needed by the internal air to reach 18 degrees.
Actually that time Is infinite so let's keep It real: when I stop the cooling, how Much the air inside Will take to go from 8 to 10 degrees?
As told above putting 3liters of...
Currently this is an "ideal" fridge, with nothing inside so, yes we are seeking here for a box of cold air inside. This number we are looking for (see my post below: 4m is the time to reach the 62.3% of deltaT, so roughly 6 degrees) is the number the cooler would restart to cool again down to 8...
OK, thanks to your suggestion I probably approximating better the problem. As you claimed, what I found is the time constant of the problem, not the real solution. That said we can claim:
T(t) = T1 + (T2-T1)(1 - e^(-t/CT))
where CT is the time constant you are talking about. Specifically, this...
Thanks for your replay, It makes Sense to me. I know the real temperature profile Will be exponential. Not clear when you claim "Will change that Number a lot"
Probably a normale fridge has some better isolation than a set of polystyrene of 4 cm. We are talking here abour formulas and Physics, so please motivate tour corcerns by that. Thanks
Hello,
I'm trying to build a custom made fridge made by a cube by 120cm on each side.
The material used to isolate the cube will be some polystyrene panels, with thickness s=4cm.
Let's imagine to cool the dry air inside in order to reach the internal temperature of 8 degree Celsius, while the...
Thanks for your opinion. Actually is by far more complex than this. The PI/2 trick, gotten from applying the "i" is actually working on 2D, i.e. when you relate a 2D vector to a complex number. Here we are in 4D, and it's totally different.
Actually I found partially an answer to this accessing...