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Thread: Exam question
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10-10-2009, 02:14 PM #1
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Exam question
Does anyone know how much BTU heat needed for 15000lbs water at 10C to turn into ice at -7.8C?
What is the proper set temperature for Ice rink?
Your help is appreciated!!
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10-10-2009, 02:59 PM #2
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You do know the answers are in your text books, don't you.
How many BTUs does it take to lower 1 pound of water 32°F.
How many BTUs to turn 1 pound of water to ice.
Multiply by 15,000 and you will have the answer.
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10-10-2009, 03:11 PM #3
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What helps me is to draw out the sensible/latent chart. Latent heat of fusion is 144 BTUs and latent heat of evaporation is 970 BTUs.
The formula we get is Q=SH*W*TD for sensible heat. Being your Sensible heat*weight*temperature difference. Latent heat in your case would be the latent heat of fusion. So as beenthere stated multiply that (144)*15000.
Remember SH for ice and steam is 0.5 and water is 1.
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