HEAT AND MASS TRANSFER QUIZ

Conduction and convection

Convection

Conduction

Radiation

kcal/m hr °C

kcal/hr °C

kcal/m² hr °C

kcal/m²

U/A.Cmin

U.Cmin

Cmin/U

U/Cmin

0.3

1.7

0.7

0.1

I.C. engine

None of these

Air preheaters

Heating of building in winter

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

All of these

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

In radiation, increasing the temperature and reducing the emissivity.

Directly proportional to the difference of temperatures between the two bodies

Both (A) and (B)

Directly proportional to the surface area

Either (A) or (B)

40 mm

25 mm

800 mm

160 mm

None of these

Radiation

Conduction

Convection

1/h₁ + 1/h₂ + 1/h₃

None of these

h₁ + h₂ + h₃

(h₁.h₂.h₃)1/3