Superheated steam at 20 mpa, 5608c enters the turbine of a vapor power plant. the pressure at the exit of the turbine is 0.5 bar, and liquid leaves the condenser at 0.4 bar at 758c. the pressure is increased to 20.1 mpa across the pump. the turbine and pump have isentropic efficiencies of 81 and 85%, respectively. cooling water enters the condenser at 208c with a mass flow rate of 70.7 kg/s and exits the condenser at 388c. for the cycle, determine (a) the mass flow rate of steam, in kg/s. (b) the thermal efficiency.

The temperature of air decreases as it is compressed by an adiabatic compressor. a)- true b)- false

Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?

The higher the astm grain-size number, the coarser the grain is. a)-true b)-false