Friday, February 5, 2010

Day 34: The Freezer Experiment, Trial 1 - FAIL!!!

Megan: How's that freezer experiment coming, Tony?

Tony: Grrr...

After plugging the Kill-A-Watt power meter into the fridge, I thought we could easily figure out an answer to the question "Do water jugs in the freezer save energy?" I was wrong. For starters, the 10 milk jugs of water that I squeezed into the freezer expanded after freezing, and this was just enough expansion to crack the freezer door open a centimeter. Of course, not using the freezer a lot, we did not notice this for two days! Then, while we were visiting Washington, DC over the weekend, a power outage reset the meter.

While I hate throwing out data, I know that the power spikes from the start of the experiment (when I had the door open again and again to get the jugs in), and the spikes from the door being wedged open were anomalous. So I threw this data out. I also threw out the readings just after these events, since I wasn't sure if the fridge was back to its steady-state operation. (Incidentally, this made me empathize with the experimentalists that had to throw out some climate change data when they worried that someone might use corrupt data to "prove" climate change isn't real.)

As the spreadsheet of my freezer data shows, even with these data thrown out, the power consumption of the freezer changes a lot. The uncertainties in my "0 jug days" vs. my "8 jug days" is large enough that I can't really conclude anything. I am convinced that I am under-sampling the process of it cycling between idle and running states. I can either set a timer over the weekend to check the freezer every five minutes *or* try using one of Vernier's Watt's Up modules to log this for me.

Once Trial 2 is complete, I'll let you know.

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