Grashoff number

Biot number

Stanton number

Prandtl number

B. Biot number

Conduction

Convection

Radiation

None of these

Conduction

Convection

Radiation

None of these

In heat exchanger design as a safety factor

In case of Newtonian fluids

When a liquid exchanges heat with a gas

None of the above

Varies with temperature

Varies with wavelength of the incident ray

Is equal to its emissivity

Does not vary with temperature and. wavelength of the incident ray

Steam

Solid ice

Melting ice

Water

Conduction

Convection

Radiation

Conduction and convection

1 : 1

2 : 1

1 : 2

4 : 1

Added insulation will increase heat loss

Added insulation will decrease heat loss

Convective heat loss will be less than conductive heat loss

Heat flux will decrease

Same

More

Less

Depends on other factors

Different heat contents

Different specific heat

Different atomic structure

Different temperatures

Iron

Lead

Concrete

Wood

Velocity reduction method

Equal friction method

Static regains method

Dual or double method

Wien's law

Stefan's law

Kirchhoff's law

Planck's law

m²/hr

m²/hr °C

kcal/m² hr

kcal/m. hr °C

Convection

Radiation

Conduction

Both convection and conduction

kcal/m²

kcal/hr °C

kcal/m² hr °C

kcal/m hr °C

The time taken to attain the final temperature to be measured

The time taken to attain 50% of the value of initial temperature difference

The time taken to attain 63.2% of the value of initial temperature difference

Determined by the time taken to reach 100°C from 0°C

Its temperature

Nature of the body

Kind and extent of its surface

All of the above

In conduction, reduction in the thickness of the material and an increase in thermal conductivity.

In convection, stirring of the fluid and cleaning the heating surface.

In radiation, increasing the temperature and reducing the emissivity.

All of the above

P = 0, x = 0 and a = 1

P=1, x = 0 and a = 0

P = 0, x = 1 and a = 0

X = 0, a + p = 1 Where a = absorptivity, p = reflectivity, X = transmissivity.

Pb = pa - pv

Pb = pa + pv

Pb = pa × pv

Pb = pa/pv

0.002

0.02

0.01

0.1

Grashoff number

Nusselt number

Weber number

Prandtl number

J/m² sec

J/m °K sec

W/m °K

Option (B) and (C) above

Thermal coefficient

Thermal resistance

Thermal conductivity

None of these

20°C

40°C

60°C

66.7°C

Zeroth law of thermodynamics

First law of thermodynamic

Second law of the thermodynamics

Kirchoff's law

Higher

Lower

Same

Depends on the area of heat exchanger

More than those for liquids

Less than those for liquids

More than those for solids

Dependent on the viscosity

Irregular surfaces

Nonuniform temperature surfaces

One dimensional cases only

Two dimensional cases only