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BARC 2019: Thermodynamics Nuclear Quiz-4

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Question 1

A piston – cylinder device contains helium gas initially at 150 kPa, 20, and 0.5 m3. The helium is now compressed in a polytropic process to 400 kPa and 140. Determine the heat loss or gain during the process.
RHe = 2.0769 kJ/kgK; Cv = 3.1156 kJ/kgK.

Question 2

Three litres of water initially at 30 is to be heated to 90 in a teapot fitted with a 1200 watt electric heating element inside, and the rate of heat loss from the water to surroundings is 100 watt for 30 to 60 and 200 watt for 60 to 90. The time required will be approximately ____ seconds.
(Take specific heat of water as 4.18 kJ/kg)

Question 3

An otto cycle engine having a clearance volume of 250 cc has a compression ratio of 5. The ratio of pressure rise at constant volume is 4. If the initial pressure is 1 bar, the theoretical mean effective pressure is _____ bar.
Take = 1.4

Question 4

A heat engine is operating between two temperatures having 60% efficient. If a refrigerator is used to work under similar temperature and is required to have a refrigeration effect of 2 ton then find the work input to the refrigerator in Kw

Question 5

A refrigerator is used to cool water from 35to 20 and water is flowing through tubes. If one ton of refrigeration is required for this process. Specific heat of water is 4.187 kJ/kg K. If the diameter of the tube is 300 mm and density of water is 992 kg/m3. Find the velocity of water flowing in the tube in mm/s.

Question 6

A 3 stage refrigerator compressor with perfect intercooling is operated with overall pressure ratio of 8. If the intermediate pressures are 3 bar and 1.5 bar. Find the minimum and maximum pressure of the compression in bar.

Question 7

The inlet temperature of the otto cycle during compression is 400K and maximum temperature of the cycle is 900K. If the heat supplied during constant volume is 300kJ/kg. Find the compression ratio for maximum work output.

Question 8

The inlet temperature and pressure of a diesel cycle is 1 bar and 100 degree celcius and maximum temperature of the cycle is 1800K, compression ratio is 16. Find heat added (kJ/kg) at constant pressure.

Question 9

A stationary mass of gas is compressed without friction from an initial state of 0.3 and 0.105 MPa to a final state of 0.15 and 0.105
MPa the pressure remains constant throughout the process. There is a transfer of 47.6 kJ of heat from the gas during the process. How much
does the internal energy of the gas changes

Question 10

In a sample of moist air at standard atmospheric pressure of 101.325 kPa and 26 °C, the partial pressure of water vapour is 1.344 kPa. If the saturation pressure of water vapour is 5.36 kPa at 26 °C,  then what are the humidity ratio and relative humidity of moist air sample?
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