FdSC 405 Engineering Exam 2

Question 1

Types of Heat Transfer

Answer 1

• Blanching/Pasteurization/Sterilization
• Freezing
• Drying

Question 2

Principles of Heat Transfer

Answer 2

Conduction: Heat transfer by within solids by molecular movement

Convection: Heat transfer in liquids by movement of molecules due to density difference.

Radiation: Transfer of heat by electromagnetic waves (e.g. solar heating)

Answer 3

• A measure of energy needed to raise the product temperature
• Q = m cp (T2 – T1) = m cp ΔT
• Cp = Q/(m ΔT)
• Units = kJ/kg K
• It is the quantity of heat gained or lost by a unit mass to accomplish a degree change in temperature without change in state.

Question 4

Specific Heat Predicition model

Answer 4

cp = 1.424Xh + 1.549Xp + 1.675Xf + 0.837Xa + 4.187Xw

Where X is the mass fraction

Subscripts on the right-hand side are

Question 5

Thermal Conductivity

Question 6

Thermal Conductivity

Answer 6

• It is the rate of heat conducted through an unit thickness of material with an unit cross sectional area for an unit temperature difference across the surface

Question 7

Thermal Diffusivity

Answer 7

α = k / (ρ cp)

Question 8

Steady State Heat Transfer in a Rectangular Slab

Fouriers Law

Answer 8



Question 9

Steady State Heat Transfer in Rectangular Slab/wall


Q

Question 10

Heat Transfer in Radial Geometry

Answer 10

(2 pie L k) (T_i - T_o)

q_r =

            ln (r<sub>o</sub>/r<sub>i</sub>)

Question 11

Steady State Heat Transfer in Cylindrical Pipe

Question 12

Steady State Heat Transfer in Cylindrical Pipe