#### A pressure cooker contains 1.5 kg of saturated steam at 5 bar. Find the quantity of heat which must be rejected so as to reduce the quality to 60% dry. Determine the pressure and temperature of the steam at the new state.

A pressure cooker contains 1.5 kg of saturated steam at 5 bar. Find the quantity of heat which must be rejected so as to reduce the quality to 60% dry. Determine the pressure and temperature of the steam at the new state.

1. 1000 kg of steam at a pressure of 16 bar and 0.9 dry is generated by a boiler per hour. The steam passes through a superheater via boiler stop value where its temperature is raised to 380°C. If the temperature of feed water is 30°C, determine :

(i) The total heat supplied to feed water per hour to produce wet steam.

(ii) The total heat absorbed per hour in the superheater.

Take specific heat for superheated steam as 2.2 kJ/kg K.

2. Using steam tables, determine the mean specific heat for superheated steam :

(i) at 0. 75 bar, between 100°C and 150°C ;

(ii) at 0.5 bar, between 300°C and 400°C.

3. A pressure cooker contains 1.5 kg of saturated steam at 5 bar. Find the quantity of heat which must be rejected so as to reduce the quality to 60 % dry. Determine the pressure and temperature of the steam at the new state.

4. A spherical vessel of 0.9 m^{3} capacity contains steam at 8 bar and 0.9 dryness fraction. Steam is blown off until the pressure drops to 4 bar. The valve is then closed and the steam is allowed to cool until the pressure falls to 3 bar. Assuming that the enthalpy of steam in the vessel remains constant during blowing off periods, determine :

(i) The mass of steam blown off ;

(ii) The dryness fraction of steam in the vessel after cooling ;

(iii) The heat lost by steam per kg during cooling.

5. If a certain amount of steam is produced at a pressure of 8 bar and dryness fraction 0.8. Calculate :

(i) External work done during evaporation.

(ii) Internal latent heat of steam.

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