ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2013

An Iron rod and a Copper rod lies side by side, as the temperature is changed, the difference in the length of the rods remains constant value of 10 cm. The lengths of Iron and Copper rods at zero degree centigrade shall be ---------- . (coefficient of Linear expansion of lron = $$1.1 \times 10^{-5}$$ per degree centigrade and coefficient of Linear expansion of
$$Cu = 1.7 \times 10^{-5}$$ per degree centigrade)

The specific speed of a turbine is given by the equation:

A furnace is made of a red brick wall of thickness 0.6 m and conductivity 0.8 W/m K. For the same heat loss and temperature drop, this can be replaced by diatomite earth of
conductivity 0.16 W/m K_ and thickness of --------

An elevator weighing 500 kgis to be lifted up at a constant velocity of 0.20 m/s. The minimum horse power of the motor is: (assume $$g = 9.8 m/sec^2$$)

An electric cable of aluminium conductor (k = 230 W/mk) is to be insulated with rubber (k = 0.18W/m K).The cable is to be located in air (h = 6 W/m$$^2$$ ).The critical thickness of insulation will be:

A hotfluid enters the counter flow heat exchanger at $$120^\circ C$$ and leaves at $$80^\circ C$$. A cold fluid enters the heat exchanger at $$60^\circ C$$. The mean temperature difference between the two fluids is (Assume the values of fluid flow rates and specific heats in such a manner that the heat capacities of the two fluids are equal)

In a psychrometric process, the sensible heat added is 40 kJ/s and the latent heat added is 30 kJ/s. The sensible heat factor for the process will be:

When two refrigerants are mixed in the proper proportions, the mixture forms a third refrigerant called:

A fixed gear having 300 teeth is in mesh with another gear having 60 teeth. The two gears are connected by an arm. The numbersof turns made by the smaller gear for one )
revolution of arm about the centre of bigger gear is:

Nusselt numberis the ratio of