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GATE 2022 ME: National Champion Quiz -2

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Question 1

The properties of mercury at 300 K are: density = 13529 kg/m3, specific heat at constant pressure = 0.1500 kJ/kg-K, dynamic viscosity = 0.1400 × 10-2 N.s/m2 and thermal conductivity = 5 W/m-K. The Prandtl number of the mercury at 300 K is _______.

Question 2

A refrigeration cycle working on the reversed Brayton cycle with isentropic expansion and compression processes has an operating pressure ratio of 5. The COP of the refrigeration cycle is ___________


Question 3

Insulation is provided over an electric power transmission cable to enhance the Heat transfer rate. The coefficient of thermal conductivity of the insulation is 0.2 W/m-K and to the air side is 50 W/m2-K. The optimum thickness of the insulation is

(Assume outer diameter of wire is 2 mm)

Question 4

If Prandtl number is 0.064 and friction coefficient is 0.64, Stanton number will be equal to___.

Question 5

I n a steam power plant operating on an ideal Rankine cycle, superheated steam enters the turbine at 3 MPa and 350. The condenser pressure is 75 kPa. The thermal efficiency of the cycle is ________ percent.
Given data:
For saturated liquid, at P = 75 kPa, hf = 384.39 kJ/kg, vf = 0.001037 m3/kg, sf = 1.213 kJ/kgK
At 75 kPa, hfg = 2278.6 kJ/kg, sfg = 6.2434 kJ/kgK
At P = 3 MPa and T = 350[Superheated steam], h = 3115.3kJ/kg, s = 6.7428 kJ/kgK

Question 6Multiple Correct Options

Which of following options is/are correct regarding efficiency of ideal regenerative Brayton cycle?

Question 7

Heat is generated uniformly in a long solid cylindrical rod (diameter = 10mm) at the rate of . The thermal conductivity of the rod material is 25W/m.K. Under steady state conditions, the temperature difference between the centre and the surface of the rod is _________ °C.

Question 8

In VCR system, the refrigeration capacity is 1800 kJ/min & Heat rejected in condenser is 2400 kJ/min. What will be the heat rejection factor is ____ (up to two decimal)

Question 9

The saturated water vapour pressure in atmospheric air is at 40° and 1.03bar with relative humidity of 70% is 6.342kPa. What is the specific humidity of air in g/kg of dry air?

Question 10

Two large parallel plates having a gap of 10 mm in between them are maintained at temperature T1= 1000 K and T2= 400 K. Given emissivity values, =0.5, =0.25 and Stefan-Boltzmann constant the heat transfer between the plates (in kW/m2) is ______

Question 11

A spherical body of diameter 75 mm of initial temperature 25 is immersed in the fluid at temperature 400. Thermo physical properties of the body are k=22W/m-K, c=400 J/kg and ρ=9000kg/m3 (Regular notations used). Determine the time (in seconds) when the temperature will become 390, given the convective heat transfer coefficient between body and fluid is 300W/m2-k.

Question 12

In a counter flow heat exchanger having an area of 50mand heat capacity of hot and cold fluid is 3.050kW/K. If the overall heat transfer coefficient is 250W/K, then find the effectiveness of heat exchanger if heat exchanger area is
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