March 2019

A. Rate of heat transfer
B. Flow velocity
C. Turbulence of shell side fluid
D. All A., B. and C.

A. A red hot steel slab (having outside surface temperature as 1300°C) exposed to the
atmospheric air at 35°C
B. 10 kg of dry saturated steam at 8 kgf/cm2 flowing through a short length of stainless steel pipe
exposed to atmospheric air at 35°C
C. Boiling brine kept in open vessel when the bottom surface temperature of the vessel is
maintained constant at 180°C
D. A sub-cooled refrigerant liquid at 8°C flowing at the rate of 6 Kg/minute through a copper
pipe exposed to atmospheric air at 35°C

A. Conduction
B. Natural convection
C. Forced convection
D. Radiation

A. Temperature gradient of the wall to that across the entire pipe
B. Temperature difference to the temperature gradient at the wall
C. Heat flux at the wall to that across the entire pipe
D. None of these

A. Thermal diffusivity/Momentum diffusivity
B. Thermal diffusivity × Momentum
C. Thermal diffusivity × Mass diffusivity
D. Mass diffusivity × Momentum diffusivity

A. 1
B. > 1
C. < 1
D. Between 1 & 2

A. Decreases
B. Increases
C. Remains unchanged
D. May increase or decrease; depends on the gas

A. εx + εy
B. εx . εy
C. 1/εx + 1/εy
D. (εx + εy)/( εx + εy – εx . εy)

A. Increases
B. Decreases
C. Remain same
D. May increase or decrease depending on the type of gas

A. Logarithmic mean area
B. Arithmetic mean area
C. Geometric mean area
D. None of these