Heat Transfer Operations Practice Test 3

1. In the calculation of Reynold’s Number for the Friction factor of the shell, which is the correct formula for equivalent diameter De?

Depends on the pitch

\(\frac{4×(D_{io}^2 - D_{oi}^2)×\frac{π}{4}}{π(D_{io}+D_{oi})}\)

\(\frac{4×(D_{io}^2 - D_{oi}^2)×\frac{π}{4}}{π(D_{io})}\)

\(\frac{4×(D_{oi}^2 - D_{io}^2)×\frac{π}{4}}{π(D_{io})}\)

2. If we desire to have 5 shell passes for a shell of length 40cm, what is the baffle spacing in the shell side?

7cm

6cm

5cm

8cm

3. Recognize the following fin.

Cut on Helix

Serrated

Double helix

Partially cut on helix

4. In assumption for using fins, the heat flow and temperature distribution throughout the fins is _______ time.

Directly Proportional to

Square proportional to

Inversely Proportional to

Independent of

5. The Heat Transfer Coefficient remains constant throughout the surface of the fin.

True

False

6. For the calculation of Friction Factor on the Shell side, which one of the following is the correct formula?

F = 0.0035+ \(\frac{0.264}{Re^{0.42}} \)

F = 0.0035+ \(\frac{0.42}{Re^{0.264}} \)

F = 0.0027+ \(\frac{0.264}{Re^{0.42}} \)

F = 0.0027+ \(\frac{0.42}{Re^{0.264}} \)

7. Fins are not usually attached to the main body of the heat exchanger by ______

Glue

Welding

Brazing

Groove fitting

8. Consider we have a 2-4 Shell and Tube Heat Exchanger, with the inner tube of Outer diameter 20mm (thickness 2mm) and shell of inner diameter 100mm. We have two fluids A & B, both of density 990 Kg/m³, we desire to have their flow rates as 15m/s(tube) and 21 m/s(shell) respectively, friction factor of 0.00096 and length of the tube as 1m. What is the value of Frictional Head Loss for the inner tube?

2.46 m

2.76 m

24.6 m

27.6 m

9. Which one of the following is correct about the temperature of the fluid in contact with the fins?

Depends on flow pattern

Is at a constant temperature

Temperature increases along the fin length

Temperature decreases along the fin length

10. If U_D = Overall Dirt Heat Transfer coefficient and U_c = Overall Clean Heat Transfer coefficient, then which of the following relation is correct?

U_D < U_c

U_D = U_c

U_D >> U_c

U_D > U_c