ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2013

Instructions

For the following questions answer them individually

Question 21

Ina thin cylindrical shell subjected to an internal pressure p, the ratio of longitudinal stress to the hoop stress is:

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Question 22

A hot plate transfers heat with a heat flux of 8000 W/m$$^2$$ into the ambientair at $$25^\circ C$$. if the surface of the hot plate is maintained at $$125^\circ C$$, calculate the heat transfer coefficient for the convection between the plate and the air:

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Question 23

Water at $$50^\circ C$$ flows over a hot plate maintained at temperature $$150^\circ C$$. The plate has a width of 50 cm and length of 100 cm. If the heat transfer coefficient between the water and the plate is 2100 W/m?-K, the thermal resistance of convection is:

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Question 24

An Aluminum sphere dipped into water at 10 degree centigrade, if temperature is increased, the force of bouncy will:

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Question 25

According to Lami’s theorem:

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Question 26

When a body of mass momentofinertia I (about a given axis) is rotated aboutthat axis with an angular velocity $$\omega$$, then the kinetic energy of rotation is:

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Question 27

In a boiler, feed water supplied per hour is 225 kg while coal fired per hour is 25 kg. The net enthalpy rise per kg of water is 150 kJ. lf the calorific value of the coal is 2050 kJ/kg, then the boiler efficiency will be

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Question 28

The metacentric height of a ship is 0.5 m and the radius of gyration is 6 m. The time of rolling of a ship is:

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Question 29

For an irrotational flow the equation $$\frac{\partial^2 \phi}{\partial x^2} + \frac{\partial^2 \phi}{\partial y^2}$$ is known as,

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Question 30

A Pelton Wheel develops 2500 kW under a head of 150 metres while running at 200 r.p.m. and discharging 200litres of water per second. The unit power of the wheel is:

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