A non-dimensional number generally associated with natural convection heat transfer is________________?

A. Grashoff number
B. Nusselt number
C. Weber number
D. Prandtl number

In heat exchangers, degree of approach is defined as the difference between temperatures of________________?

A. Cold water inlet and outlet
B. Hot medium inlet and outlet
C. Hot medium outlet and cold water inlet
D. Hot medium outlet and cold water outlet

A steam pipe is to be insulated by two insulating materials put over each other . For best results__________________?

A. Better insulation should be put over pipe and better one over it
B. Inferior insulation should be put over pipe and better one over it
C. Both may be put in any order
D. Whether to put inferior oil over pipe or the better one would depend on steam temperature

According of Kirchhoff’s law______________________?

A. radiant heat is proportional to fourth power of absolute temperature
B. emissive power depends on temperature
C. emissive power and absorptivity are constant for all bodies
D. ratio of emissive power to absorptive power is maximum for perfectly black body

LMTD in case of counter flow heat exchanger as compared-to parallel flow heat exchanger is _________________?

A. Higher
B. Lower
C. Same
D. Depends on the area of heat exchanger

Fourier’s law of heat conduction is valid for_________________?

A. One dimensional cases only
B. Two dimensional cases only
C. Three dimensional cases only
D. Regular surfaces having non-uniform temperature gradients

In counter flow heat exchangers_________________?

A. Both the fluids at inlet (of heat ex¬changer where hot fluid enters) are in their coldest state
B. Both the fluids at inlet are in their hot¬test state
C. Both the fluids .at exit are in their hottest state
D. One fluid is in hottest state and other in coldest state at inlet

The concept of overall coefficient of heat transfer is used in case of heat transfer by________________?

A. Conduction
B. Convection
C. Radiation
D. Conduction and convection

Joule sec is the unit of_________________?

A. Universal gas constant
B. Kinematic viscosity
C. Thermal conductivity
D. Planck’s constant

According to Kirchoff’s law, the ratio of emissive power to absorptivity for all bodies is equal to the emissive power of a _________________?

A. Grey body
B. Brilliant white polished body
C. Red hot body
D. Black body