HEAT AND MASS TRANSFER QUIZ

The thermal diffusivities for gases are generally

Dependent on the viscosity

More than those for liquids

More than those for solids

Less than those for liquids

TRUE ANSWER : ?
YOUR ANSWER : ?

Upto the critical radius of insulation,

Added insulation will decrease heat loss

Heat flux will decrease

Added insulation will increase heat loss

Convective heat loss will be less than conductive heat loss

TRUE ANSWER : ?
YOUR ANSWER : ?

A designer chooses the values of fluid flow rates and specific heats in such a manner that the heat capacities of the two fluids are equal. A hot fluid enters the counter flow heat exchanger at 100°C and leaves at 60°C. A cold fluid enters the heat exchanger at 40°C. The mean temperature difference between the two fluids is

20°C

66.7°C

60°C

40°C

TRUE ANSWER : ?
YOUR ANSWER : ?

Stefan Boltzmann law is applicable for heat transfer by

Radiation

Conduction and radiation combined

Convection

Conduction

TRUE ANSWER : ?
YOUR ANSWER : ?

Depending on the radiating properties, a body will be black when(Where a = absorptivity, p = reflectivity, X = transmissivity.)

P = 0, x = 0 and a = 1

X = 0, a + p = 0

P = 0, x = 1 and a = 0

P= 1, T = 0 and a = 0

TRUE ANSWER : ?
YOUR ANSWER : ?

Depending on the radiating properties, a body will be opaque when

P = 0, x = 1 and a = 0

X = 0, a + p = 1

P = 0, x = 0 and a = 1

P=1, x = 0 and a = 0

TRUE ANSWER : ?
YOUR ANSWER : ?

Wien’s law states that the wave length corresponding to ________ is proportional to the absolute temperature.

None of these

Minimum energy

Maximum energy

Both (A) and (B)

TRUE ANSWER : ?
YOUR ANSWER : ?

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

Brilliant white polished body

Grey body

Black body

Red hot body

TRUE ANSWER : ?
YOUR ANSWER : ?

The use of heat exchangers is made in

Condensers and boilers in steam plants

Condensers and evaporators in refrigeration and air conditioning units

Radiators in automobile

All of these

TRUE ANSWER : ?
YOUR ANSWER : ?

According to Dalton's law of partial pressures, (where pb = Barometric pressure, pa = Partial pressure of dry air, and pv = Partial pressure of water vapour)

Pb = pa + pv

Pb = pa - pv

Pb = pa/pv

Pb = pa × pv

TRUE ANSWER : ?
YOUR ANSWER : ?

↑