Note that the seal around the door is also leaking (slightly) on an ongoing
basis when the 'fridge is vertical and not leaking (as much) on a horizontal
unit. I'm not sure how much of a difference that actually makes, but the
point has not been considered in this thread so far.

I'll pay $50 for a well documented (pictures, description and data) study
comparing energy use on upright 'fridges when the door is being opened and
closed and when it is not. One fridge should do it, just check energy use
over a few hours with the door close and then open and close the door every
15 minutes for a few hours and done.

Another interesting study would be the temperature under the lower door seal
compared with ambient.

--
James.

-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of
Apptech
Sent: Thursday, February 21, 2008 06:30
To: Microcontroller discussion list - Public.
Subject: Re: [EE]: Thermal efficiency of Refigerators -- Air

> It takes 1 calorie (not food calorie) to heat 1 mL of 
> water (1cc) by 1
> degree celcius.  We need to drop 20 degrees, so 200 x 20 = 
> 4000 calories of
> coolth needed.  Say 25% efficiency, make it 16000.
>
> That's not much, in food terms (K calorie) that's a 
> jellybean or two.
>
> Aparently a calorie is about 0.00000116222222kWH, more 
> commonly known as
> 'not much'.
>
> My power bill says a kilowatt hour is worth $0.12AU, so 
> opening the fridge
> door costs me $0.0022, or less than a quarter of a cent.

Notably he says that he uses 100 Wh/day whereas typical 
fridges use kilowatt hours/day.
If he is correct then the difference between theory and 
practice may, as often happens, be greater in practice than 
in theory.

If door opening is the sole heat loss method (and it's 
not)(although his horizontal fridge concept emphasis 
suggests he things it matters) and if you and he are 
correct, then the average user opens their fridge 
0.12/0.0022 ~= 50 times / day.

It would be interesting to do some energy measurements (and 
some formal calculations) and determine whether door opening 
or decent freezer insulation predominates as the main power 
saver. The results from converting a vertical freezer to 
fridge use would be interesting.

Somebody could actually make some money out of this (and 
gain a few [ack] carbon credits) if they could be bothered.





            Russell

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