4. The thermal efficiency of a reversible heat engine operating between two given thermal reservoirs is 0.4. The device is used either as a refrigerator or as a heat pump between the same reservoirs. Then the coefficient of performance as a refrigerator (COP)R and the co-efficient of performance as a heat pump (COP)HP are
9. Air is to be heated by condensing steam. Two heat exchangers are available (i) a shell and tube heat exchanger and (ii) a finned tube heat exchanger. Tube side heat transfer area are equal in both the cases. The recommended arrangement is
Options
A. finned tube heat exchanger with air inside and steam outside.
B. finned tube heat exchanger with air outside and steam inside.
C. shell and tube heat exchanger with air inside tubes and steam on shell side.
D. shell and tube heat exchanger with air on shell side and steam inside tubes.