Chapter 8, Problem 164P

Refrigerant-134a at 700 kPa and 120°C enters an adiabatic nozzle steadily with a velocity of 20 m/s and leaves at 400 kPa and 30°C. Determine (a) the exit velocity and (b) the ratio of the inlet to exit area A1/A2.

In a power plant, water vapor with a flow rate of 35 kg / s enters the adiabatic turbine at a pressure of 10 MPa and a temperature of 500° C, and comes out at a pressure of 150 kPa and 92% dryness at a speed of 200 m / s. The velocity at the turbine inlet is negligibly small compared to the outlet. The water coming out of the turbine is cooled in the condenser by cooling water whose inlet temperature is 20° C. At the condenser outlet, the cooling water temperature rises to 40 ° C, the steam pressure is 100 kPa, the temperature is 60 ° C. Coolant can be regarded as compressed liquid.a) Power generated in the turbineb)Heat transferred to the cooling water in the condenserc)Calculate the cooling water flow

Electric heating systems used in many homes consist of a simple duct with resistance heaters. As it flows over the resistance wires, the air is heated. Consider a 25 kW electric heating system. Air enters the heating section with an air flow rate of 120 m3 / min at 100 kPa and 12 ° C. If 150 W of heat is lost from the air in the duct to the environment, determine the exit temperature of the air.

In large steam power plants, the feedwater is frequently heated in a closed feedwater heater by using steam extracted from the turbine at some stage. Steam enters the feedwater heater at 1 MPa and 200°C and leaves as saturated liquid at the same pressure. Feedwater enters the heater at 2.5 MPa and 50°C and leaves at 10°C below the exit temperature of the steam. Determine the ratio of the mass flow rates of the extracted steam and the feedwater.

In a steady flow apparatus, 135 KJ of work is done on each kg of fluid. The specific volume of the fluid, pressure and speed at the inlet are 0.37 m3/Kg, 600KPa, and 160 m/s. The inlet is 32 m below the floor, and the discharge pipe is at floor level. The discharge conditions are 0.62 m3/kg, 100KPag and 27 m/s. The total heat gained between the inlet and discharge is 9 KJ/Kg of fluid. In the flowing through this apparatus, by how much does the specific internal energy increase or decrease?

The stators in a gas turbine are designed to increase the kinetic energy of the gas passing through them adiabatically. Air enters a set of these nozzles at 300 psia and 700°F with a velocity of 80 ft/s and exits at 250 psia and 645°F. Calculate the velocity at the exit of the nozzles.

The fan on a personal computer draws 0.3 ft3 /s of air at 14.7 psia and 70°F through the box containing the CPU and other components. Air leaves at 14.7 psia and 83°F. Calculate the electrical power, in kW, dissipated by the PC components.

Air at 200 kPa and 950 K enters an adiabatic nozzle at low velocity and is discharged at a pressure of 110 kPa. If the isentropic efficiency of the nozzle is 92 percent, determine the exit temperature.

Water is heated in an insulated, constant-diameter tube by a 7-kW electric resistance heater. If the water enters the heater steadily at 20°C and leaves at 75°C, determine the mass flow rate of water.