Air as an ideal gas flows through the compressor and heat exchanger shown in the figure. A separate liquid stream also flows through the heat exchanger. The data given are for operation at steady state. Stray heat transfer to the surroundings can be neglected, as can all kinetic and potential energy changes. Determine the compressor power, in kW, and the mass flow rate of the cooling water, in kg/s.

Air (Rair = 0.287 ) as an ideal gas flows through the turbine and heat exchanger arrangement kg-K, shown below. Steady-state data are given on the figure. Stray heat transfer and kinetic and potential energy effects can be ignored. Sketch a T - s diagram of processes 1-4 and determine: (a) The entropy production of turbine 1 [3.2 kW /K] (b) The isentropic efficiency of turbine 1 [75%] (c) The exit temperature of turbine 2 if its isentropic efficiency is nr, = 0.85 [960 K] (d) The entropy production within the intermediate heat exchanger [3.2 kW/K] W1 = 10,000 kW Wn= ? Turbine Turbine P3= 4.5 bar T3 = ? T = 1100 K P2=5 bar P4 = 1 bar Air wwww www 2 4 T = 1400 K Pi = 20 bar Ts = 1480 K 5 Ps = 1.35 bar ms = 1200 kg/min Heat exchanger V T = 1200 K P6 =1 bar %3D Air in

Refrigerant 134a enters a horizontal pipe operating at steady state at 40°C, 300 kPa, and a velocity of 25 m/s. At the exit, the temperature is 50°C and the pressure is 240 kPa. The pipe diameter is 0.055 m. Determine: (a) the mass flow rate of the refrigerant, in kg/s, (b) the velocity at the exit, in m/s, and (c) the rate of heat transfer between the pipe and its surroundings, in kW.

Water stored in a large, well-insulated storage tank at 21oC, and atmospheric pressure is being pumped at steady state from this tank by a pump at the rate of 40m3/h. The motor driving the pump supplies energy at the rate of 8.5 k.W. The water is used as a cooling medium and passes through a heat exchanger where 255 k.W of heat is added to the water. The heated water then flows to a second large, vented tank, which is 25 m above the first tank. Determine the final temperature of the water delivered to the second tank.