 #1
 19
 0
Homework Statement
I've attached a Jpeg with the question in, laid out much more clearly than I could expect to type it here. I hope the attachment is ok.
Homework Equations
The Attempt at a Solution
So far I have:
(1) dS = dQ / T
Entropy is a measure of a system's disorder.
(2) I've drawn a flow diagram but can't get a picture of that on here. Suffice to say I have tried to do this part quite hard but can't get it to work.
(3)
(a) dS = dQ /T ... dQ = 3/2 N K dT ... so dS = 3/2 N K dT/T. Then I can work out the integral and do this first part for temperature going from 293 to 273? Does mass not matter here?
(b) dS = dQ/T ... We know Q from the question as 333kJ/kg so S = Q/T goes to S = 333 * 1 kilogram of water / 273 Kelvin. Is this right?
(c) I have no idea how to do this.
The entropy change of the universe will increase during this process, as it will do for all processes above 0 Kelvin.
(4) Coefficient of Performance = Qh / Work = Qh / Qh  Qc ... this can then be written as Th / Th  Tc = 323K / 323K  273K = 6.46.
To improve the coefficient of performance of the icemaker you could decrease the temperature of the hot reservoir???? This doesn't seem to make sense...
If anyone has the time to look at this and help me I would very much appreciate it as I have lost all my second year notes on thermodynamics and can't see how to do this question properly.
DoubleB
Attachments

45.9 KB Views: 301