Dear Design News:
I'm turning to you in the hope that your readers may be able to shed some light on a fluids-related phenomenon that occurs in my fridge/freezer combo at home (see photos). My theory is that a complete ice shell forms over the top of the ice cube compartment. The as-yet-unfrozen water underneath comes under compression, which allows it to remain liquid, though it may actually be at the temperature of the freezer (around 0F). This "super-cooled" water creates an aperture through which it is suddenly forced, instantly solidifying. What we are seeing is a "jet" of water, frozen in place.
Head
work
Design News reader Richard King bought 200 lbs of beef during a "Mad Cow" special at his local grocery store. Since he can't possibly eat that many hamburgers right away, he plans to freeze the beef in his fridge that makes weird ice. The beef is currently at 80F, and will be maintained at a temperature of 0F. Beef freezes at 26F with a latent heat of fusion of 123 BTU/lb. Assume specific heats of 0.9 BTU/lb/degF above freezing and 0.45 BTU/lb/degF below freezing. What is the total heat in BTUs that must be removed from Richard's hamburgers-to-be?
A. 15,000
B. 20,000
C. 25,000
D. 30,000
E. 37,000
See answer below.
Adapted from "Fundamentals of Engineering Examination," Prentice Hall Press, Copyright 1986. |
But I could be wrong. So here are the parameters, should your readers wish to solve the mystery of the ice cube stalagmites:
1997 model fridge over freezer
Freezer set at 3 (a setting of 5 is coldest)
New, plastic ice cube tray (came with fridge)
City water to 1995 house
No evidence of water dripping from above (as is usual stalagmite formation)
Frequency of occurrence: 4-5 times in the last 2-3 years
The formations occur overnight or possibly more quickly
The accompanying images were taken several minutes apart.
Tray was transported from home to work for photo shoot, hence evidence of surface thawing
-Richard King, Designer, Accu-Fab Systems, Inc., Corvallis, OR
You got a solution?
If thermodynamics is your strong point, what are you waiting for? Send in your analysis of what's going on with Richard's weird ice (our associate art director has experienced the same thing!) by e-mail (kfield@cahners.com ) or snail mail (Weird Ice, Design News, 275 Washington St., Newton, MA 02458). We'll publish the most plausible, amusing, or witty entries in an upcoming issue of Design News.
You got a problem?
Losing sleep over why stalagmites are growing out of your ice cube tray or other weird stuff happening? Send us a photo (tif or jpeg) of the phenomenon, a description of the physical conditions associated with it, and your best guess on what you think is going on to kfield@cahners.com. If we publish it in an upcoming edition of Design News, you'll walk away with $50 and have 180,000 Design News readers working on a plausible scientific explanation for the phenomenon.
Headwork Answer: E
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