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A certain brand of freezer is advertised to use 730 kW ? h
Chapter 20, Problem 18E(choose chapter or problem)
Problem 18E
A certain brand of freezer is advertised to use 730 kW ⋅ h of energy per year. (a) Assuming the freezer operates for 5 hours each day, how much power does it require while operating? (b) If the freezer keeps its interior at - 5.0o C in a 20.0o C room, what is its theoretical maximum performance coefficient? (c) What is the theoretical maximum amount of ice this freezer could make in an hour, starting with water at 20.0o C?
Questions & Answers
QUESTION:
Problem 18E
A certain brand of freezer is advertised to use 730 kW ⋅ h of energy per year. (a) Assuming the freezer operates for 5 hours each day, how much power does it require while operating? (b) If the freezer keeps its interior at - 5.0o C in a 20.0o C room, what is its theoretical maximum performance coefficient? (c) What is the theoretical maximum amount of ice this freezer could make in an hour, starting with water at 20.0o C?
ANSWER:Solution 18E
Introduction
The total energy of the freezer is given. We can calculate the total time of operation using the given information. Then we can calculate the power of the freezer.
Operating temperature of the freezer is given, so we can calculate the working coefficient of the freezer.
We already know the required power (which is the work done on the freezer) and the coefficient of performance, we can calculate the amount of energy it will remove from the water and then we can calculate the mass of ice that can be formed in one hour.
Step 1
The total energy of the freezer is
And the total operating time of the freezer is
Hence the power of the freezer is
