HW#3(1) Air at 90 kPa and 10C enters an adiabatic diffuser steadily with a velocity of 180 m/s and leaves with a low velocity at a pressure of 100 kPa.The exit area of the diffuser is 4 times the inlet area.Determine (a) the exit temperature and (b) the exit velocity of the air. (2)Helium is to be compressed from 120 kPa and 310 K to 700 kPa and 430 KA heat loss of 20 kJ/kg occurs during the compression process.Neglectingkineticenergychanges,thepowerinput required for a mass flow rate of determine 90 kg/min. (3) Steam enters the condenser of a steam power plant at 20 kPa and a quality of 95% with a mass flow rate of 20,000 kg/h.It is to be cooled by water from a nearby river by circulating the water through the tubes within the condenser.To prevent thermal pollution, the river water is not allowed to experience atemperatureriseabove10C.Ifthesteamistoleavethe condenser as saturated liquid at 20 kPa, determine the mass flow rate of the cooling water required. Tw +10C Tw(4)A computer cooled by a fan contains eight PCBs, each dissipating 10 W power.The cooling air is supplied by a 25-W fan mounted at the inlet.If the temperature rise of air as it flows through the case of the computer is not to exceed 10C, determine (a) the flow rate of the air that the fan needs to deliver and (b) the fraction of the temperature rise of air that is due to the heat generated by the fan and its motor.

(5)A steam power plant with a power output of 150 MW consumes coal at a rate of 60 tons/h.If the heating value of the coal is 30,000 kJ/kg, determine the overall efficiency of this plant. (6)When a man returns to his well-sealed house on a summer day, he finds that the house is at 35C.He turns on the air conditioner, which cools the entire house to 20C in 30 min.If the COP of the air-conditioning system is 2.8, determine the power drawn by the air conditioner.Assume the entire mass within the house is equivalent to 800 kg of air for which cv = 0.72 kJ/kg-C and cp = 1.0 kJ/kg-C. (7)Refrigerant 134a enters the evaporator coils placed at the back of the freezer section of a household refrigerator at 100 kPa with a quality of 20% and leaves at 100 kPa and -26C.If the compressor consumes 600W of power and the COP of the refrigerator is 1.2, determine (a) the mass flow rate of the refrigerant and (b) the rate of heat rejected to the kitchen air.