|View single post by Samurai Appliance Repair Man|
|Posted: Sat Apr 23rd, 2005 02:21 am||
Samurai Appliance Repair Man
|This is a good heat transfer problem, worked many like this in Heat Transfer class in undergrad. The temp of the freezer doesn't tell you the temp of the icecream. It will take some determinate period of time for the icecream to pull down. That time is calculated by:
q= the rate of heat transfer in joules/sec or BTUH
k= the appropriate heat transfer coefficient
A= the surface area of the object being chilled
Delta(T)= the change in time from state 1 to state 2, in seconds
This is simplistic, of course, because it allows only for conductive cooling. In a freezer, convective cooling would be a significant factor and would further reduce the pull down time.
Go ahead and make a first-brush calculation, state all assumptions, and I'll check your work.
P.S., as anyone who's made homemade icecream knows, you have to get the icecream slurry to 27F or below before it begins to harden.
Last edited on Sat Apr 23rd, 2005 02:29 am by Samurai Appliance Repair Man