Rajiv Gandhi Proudyogiki Vishwavidyalaya 2010 B.E Mechanical Engineering MODEL - , , Bhopal, ThermalEngg. - exam paper

(A) A tank whose quantity is unknown is divided into 2 parts by a separating partition. 1 side of the tank contains 0.01 m3 of refrigerant 134a as a saturated liquid at 0.8 MPa. The other side is evacuated. The partition is removed and tank fills the entire quantity of the tank. If the final state of the refrigerant is 25 oC and 200 kPa, then
(1) The initial temperature of the refrigerant is --------------0C
(2) The initial specific quantity of the tank is -------------m3/kg
(3) The mass of the refrigerant is ------------kg
(4) The final condition of the refrigerant is -------------------------
(5) The final specific quantity of the refrigerant is ----------------- m3/kg
(6) The quantity of the full tank is ----------------------- m3
(12 marks)

(B) Complete the table

T,oC P,kPa v,m3/kg u,kJ/kg liquid Quality, x
? 400 ? 1825 water ?
220 ? ? ? water 1
110 ? ? ? R-134a 0.5
? 4000 ? 3650 R-134a ?
(12 marks)

© A 20m3 tank contains nitrogen at 250C and 800 kPa. a few nitrogen escapes the tank through a leakage. The leakage is stopped. The final temperature and pressure of the nitrogen in the tank is 200C and 600 kPa respectively.
(1)The initial mass of the nitrogen is -----------kg
(2)The final mass of the nitrogen is -------------kg
(3)The mass of nitrogen that leaked is ----------kg.
(6 marks)

(D) five kgs of hydrogen are heated from 400 K to 100 K
(1)Using constant values of Cp and Cv,
(a) the change in internal energy of hydrogen is -------kJ
(b) change in enthalpy of hydrogen is --------------kJ.
(2) Using avg. values of Cp and Cv,
(a) the change in internal energy of hydrogen is -------kJ
(b) change in enthalpy of hydrogen is --------------kJ.
(4 marks)

(E) Fill in the blanks. (1 mark each)
(a) The pressure gage connected to a tank reads 400 kPa at a location where barometer reads 760 mm of mercury. The absolute pressure in the tank is ----kPa.


(b) The vacuum gage on a tank reads 35 kPa at a location where barometer reads 760 mm of mercury. The absolute pressure in the tank is ----kPa.
(c) A 800 L rigid tank contains 10kg of oxygen at 250C. The pressure in the tank is ------------kPa. If the atmospheric pressure is 97 kPa, then the studying of the pressure gage attached to the tank is _____kPa.
(d) The difference in the open system and closed system is that the --------- crosses the boundaries of the open system.
(e) A tank contains a gas at 100 kPa. It is heated so that the temperature modifications by 100C. The corresponding change in Kelvin scale is -------------

Earning:   Approval pending.