[Homeroast] A (somewhat surprising) test for empirical data of heat loss on the CCD
ken at onlykenssite.com
Sun Feb 7 11:42:27 CST 2010
Ok, I see a lot of talk in the list and on the forums about heat loss
when brewing with the CCD, but I have seen no empirical data to support
the theory that there is significant heat loss occurring.
So I set up an experiment to see what the differences really were.
The experiment will be water brought to a boil in a whistling tea kettle
until the whistle is choppy (full boil), with 12 oz poured into a
measuring cup and then poured over 22 grams of coffee in the CCD with a
Melita #4 filter. Coffee will be brewed for 4 minutes with temperature
points taken as below.
The temperature measuring points will be:
1) After pour into the measuring cup
2) After pour into the coffee in the CCD
3) 1 minute after initial pour (standard 30 second stir after initial pour)
4) 2 minutes after initial pour
5) 3 minutes after initial pour
6) 4 minutes after initial pour
7) Temperature in the cup
tc used is accurate +/- 1c
temperatures are in degrees Fahrenheit
Baseline: Measuring cup and Bodum 10 oz cup at ambient temperature. No
cover on the CCD. Ambient temperature: 69 f
Measuring cup and Bodum 10 oz cup at ambient temperature. Plastic cover
on the CCD. Ambient temperature: 70 f
Baseline: Measuring cup and Bodum 10 oz cup at ambient temperature.
Porcelain plate cover on the CCD. Ambient temperature: 72 f
(this shows a slight drop over the plastic cover at some points, but is
within the error range of the tc)
Baseline: Measuring cup and Bodum 10 oz cup preheated with boiling
water. Plastic cover on the CCD. Ambient temperature: 72 f
Based on heat loss observation above, I built a cozy for the CCD from
thermal bubblewrap and preheated the CCD with hot tap water.
1) Even though this is a very small sample, it would appear that the
largest heat loss is not from the top of the CCD, but from it's sides.
2) The second largest loss is in heating the cup if it is not already
hot. The best results (temperature wise) was with a preheated CCD with
a cozy on it, topped with a plastic cover, drained into a preheated cup.
This resulted in a measured net gain in cup temperature of 11 degrees f
over the next warmest combination.
3) There was little (if any) difference between a plastic cover and a
porcelain cover for the CCD.
If any of you wish to repeat these experiments, I would be very
interested in the results.
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