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Old 05-02-13, 02:29 PM   #5
AC_Hacker
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Quote:
Originally Posted by stevehull View Post
I guess I don't understand. You are using the EPA estimate as the prior standard? I would suggest running the unit as is, without the modified thermostat, and NOT using the EPA estimate. Then you have a true baseline allowing an apples to apples comparison.
SH,

I supplied two graphs, the first one was used as a baseline. The yellow bar indicated to me that the asymptote would fall pretty close to the EPA number. That was close enough for me. There is a reason that I used 'hasty' in the title.

If you'd like greater certainty, please try the experiment yourself. That's the way science works.

Quote:
Originally Posted by stevehull View Post
It could be that the new thermostat is better - but why? The insulation is the same, the compressor is the same - what is different?
The difference is that I'm not demanding the unit to chill the box down to 0 degrees F, I'm only asking it to go to 38 degrees F.

It all has to do with Carnot's Efficiency Theorem.

It a matter of delta-T and the work required to achieve some delta-T.

As a freezer, asking a box to get 60 - 0 = 60 degrees colder is an act against nature. To perform this act, considerable work is required.

As a refrigerator, asking a box to get 60 - 38 = 22 degrees colder is a lesser act against nature. To perform this lesser act, less work is required.

Es claro?

Also, I've heard people wondering as to why a converted freezer was so much more efficient...

Some say that it is because you don't dump air every time you open the door. I doubt that this is such a great factor, because the energy to chill down a freezer full of air is not so much.

Some say it is because the insulation is thicker. This would be a pretty large factor. That was one of the reasons I jumped on this unit, because it didn't have much more insulation than a refrigerator.

Some say that it is because the freezer is built to be more efficient, else the cost of operation would deter people from owning one. I think that this actually might be true. At least comparing my conversion and what I estimate it's energy use to be, to a refrigerator of the same size. So with a converted freezer, you're taking a fairly high efficiency refrigeration system and lowering the physical demands on it.

Thicker insulation would be better...

Not dumping air would be better...

Not stooping over to get a cantaloupe is not so bad.

-AC
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Last edited by AC_Hacker; 05-08-13 at 01:55 PM..
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