An air compressor takes in air at standard conditions (use 14.7 psia and 70°f) at a negligible velocity. the air is discharged at 115 psia and 125°f with a den- sity of 0.5 lbm/ft 3. the mass fl ow rate out of the 0.5 ft2 discharge pipe is 12 lbm/s. if the compressor input horsepower is 800, find the magnitude and direction (in words) of the heat transfer to/from the compressor in units of btu/s. assume a steady flow. draw a control surface for the calculation.

Consider a power plant with water as the working fluid that operates on an ideal rankine cycle. it has a net power output of 45mw. superheated steam enters the turbine at 7mpa and 500°c (h=3411.4 kj/kg; s=6.8 kj/kg k) and is cooled in the condenser at a pressure of 10 kpa by running cooling water from a lake through the tubes of the condenser at a rate of 2000 kg/s. (a) show the cycle on a t-s diagram (a right schematic is fine - you do not need to calculate the temperatures at each point); (b)-determine the work done by the turbine and the pump in kj/kg; (c)-the mass flow rate of water used by the power plant; (d)-the thermal efficiency of the cycle; (e)-the temperature rise of the cooling water. assume the cooling water is incompressible with cp 4.18 kj/kg°c.