7 A refrigerator maintains a cold environment at 2 C The ref

7) A refrigerator maintains a cold environment at 2 C. The refrigerator steadily removes 370W from where the food is stored and discharges heat to the room through a radiator at 45 C.

a) How much current would a reversible refrigerator draw from a 120V power suplly under these conditions?

b) What is the coefficient of performance for a reversible refrigerator under these conditions?

c) How much heat does the reversible refrigerator dischage to the room?

d) If you opened the door to a reversible refrigerator and let it run, would the room get warmer or colder? What would be the net rate of Q for the room that results from running the refrigerator with the door open?

e) If the real refrigerator has a COP of 4.5, calculate how much heat it would discharge into the room under the same conditions as in (c) - i.e. with the door closed?

f) Compare and discuss the results of (c) and (e).

g) Determine the rate of entropy generation for the reversible refrigerator in part (a) and the real refrigerator in part (e).

Solution

solution

P = VI

I = P / V

= 370 / 120

= 3.083 Amperes

COP_R,rev = 1/((T_H/T_L)-1)

= 1/ ((318/275) -1)

= 6.4