Journey of Life

MODEL QUESTION PAPER

Question paper

Air enters a nozzle steadily at 2. 21 kg/m3 and 30 m/s and leaves at 0. 762 kg/m3 and 180 m/s. If the inlet area of the nozzle is 80 cm2 , determine the mass flow rate and the exit area of the nozzle.

A frictionless piston cylinder device initially contains 200L of saturated refrigerant-134a.

The piston is free to move and its mass is such that it maintains a pressure of 800kPa on the refrigerant. The refrigerant is now heated until its temperature rises to 500C. Calculate work done during the process. A steam power plant receives heat from the furnace at a rate of 280GJ/h. Heat losses to the surrounding air from the steam as it passes through the components of the power plant is 8GJ/h. The waste heat transferred to the cooling water is 145GJ/h.

Determine the net power out put of the plant and the thermal efficiency of the plant.

Air enters an adiabatic nozzle steadily at 300 kPa, 200oC and 30 m/s. It leaves at 100 kPa and 180 m/s. The inlet area of the nozzle is 80 cm2. Find the mass flow rate through the nozzle, temperature at the exit of the nozzle and the area of the nozzle at its exit. Air is heated in a circular duct by a 15 KW electric heating system placed inside the duct.

Air enters the duct at 100 kPa and 170C with a mass flow rate of 150 m3/ min. If the heat lost from the duct to the surroundings is at a rate of 200 J/s, determine the exit temperature of the air. Steam enters an adiabatic turbine at 10MPa and 5000C at a rate of 3 kg/s and leaves at 200kPa. If the power out put of the turbine is 2MW, determine the temperature of the steam at the exit. Neglect the changes in kinetic and potential energy.