SSC JE Mechanical Engineering 1st March 2017 Shift-1

Grashoff number

Biot number

Stanton number

Prandtl number

one adiabatic, two isobaric, and one constant volume

two adiabatic and two isobaric

two adiabatic, one isobaric, and one constant volume

one adiabatic, one isobaric, and two constant volume

Prevent the stagnation of shell side fluid

Improve heat transfer

Provide support for tubes

All options are correct

$$\frac{-1}{3}$$

$$\frac{-2}{3}$$

1

-1

The temperature of the surface is greater than the saturation temperature of the liquid

Bubbles are created by expansion of entrapped gas or vapour at small cavities in the surface

The temperature is greater than that of film boiling

All options are correct

A thin layer at the surface where gradients of both velocity and temperature are small

A thin layer at the surface where velocity and velocity gradients are large

A thick layer at the surface where velocity and temperature gradients are large

A thin layer at the surface where gradients of both velocity and temperature are large

Material with higher thermal conductivity should be used for the inner layer and one with layer and one with lower thermal conductivity for the outer

Material with lower thermal conductivity should be used for the inner layer and one with higher thermal conductivity for the outer

It is immaterial in which sequence the insulating materials are used

None of these

$$\frac{k}{h}$$

$$\frac{k}{4h}$$

$$\frac{h}{2k}$$

$$\frac{2k}{h}$$

Smooth glass

Plaster

Aluminium foil

Concrete

Conduction

Convection

Radiation

All options are correct