A refrigeration cycle rejects QH 500 Btu per cycle to a hot

A refrigeration cycle rejects Q_H = 500 Btu per cycle to a hot reservoir at T_H = 540degreeR, while receiving QC = 375 Btu per cycle from a cold reservoir at a temperature of T_c. For 10 cycles of operation, determine: a. The net work input in Btu, and b. The minimum theoretical temperature T_c in degreeR.

Solution

a)

Net work done = heat rejected - heat received

= 10*(500 - 375)

= 1250 btu <-answer

b)

For a refigerator:

Heat received/Th = Heat rejected/Tc

So, 500/(540) = 375/Tc

So, Tc = 405 deg R <----------answer