Quickie post: Freezer experiment

About this time yesterday, I unplugged the new freezer in order to see how well it contained the coolness.  Once I got back home from work, I checked the thermometer--- 40 degrees Farenheit.  The Dr. Pepper bottles were still frozen, especially on the bottom.  The one closer to the lid was slightly melted.  Upon inspection this morning, the temperature is holding and the ice is melting, but is still abundant.  So, this says that the ice will remain for at least 24 hours, and likely to last longer.

Calculations show that the bottles should have about a million joules of energy stored in them.  That's about a third of a kilowatt hour.  This means that the energy loss can be said to be less than this over the course of how much time it takes to melt the ice inside this freezer.  This can tell me how much energy has to be replaced by the freezer's operation, and thus, how much it will take to keep things frozen inside.  Perhaps not exactly correct, but a fair estimate.  We are NOT rocket scientists here, doncha know.

But it might as well be a moon shot, just the same.

Update:

48 hours and counting.  The closer you get to the lid, the warmer it is.  This makes sense.  It is holding at 46 degrees.  A little too warm for food storage, but the thermometer is near the lid.  Moving the food down to the bottom would enable it to keep cold enough for near term storage.  I am estimating 72 hours like this before it gets useless.

Given that there's 1 megajoule to freeze the (6) 2-liter bottles, that means that there is a loss of 1 mj/72 per hour heat loss to the environment.  This works out to about 14 k joules per hr, or about a third of a kilowatt-hour per day.

As a thought experiment, what would something 30 times as large calculate out to: about 116 watts per hour.

The above is a thought experiment for da trailer, in case you didn't get it.  What does the BTU calculator say?

Considerably more.  You'd have to use a dehumidifier in conjunction with a swamp cooler in order to get temps down to within 10 degree Farenheit of the target.

This means that even with good insulation, there will be significant heat gain on very hot days.  Something to consider.

The little generator that I got will output about 20 kilowatt-hours per day if run continuously.  However, you'd like to have someone monitor it while you are asleep.  That case, by the way, would be worst case scenarios.  It wouldn't get this bad very often, if at all.

This post goes into the off-the-grid subseries for electricity and power.  It will be the first of the subseries posts.

Previous ( main series post ) Next (power subseries post )

Previous  ( construction post )  Next  ( construction post )