1. HW4 Problem 18.13 (Use TITUS Square Ceiling MCD diffuser
Problem 18.16
(The building size is 100 ft x 60 ft; use proportion to determine room sizes)
Problem 18.19
Problem 18.20
Problem (design problem)

2. Objectives
Finish with Duct Design
Learn about Fans

3. Example A C B Size the ducts and calculate pressure drop from - A to C
- B to C A a c C b B
Tabulated calculation:
……..

4. Local Dynamic losses Losses associated with Two methods
Changes in velocity
Obstructions
Bends
Fittings and transitions
Two methods
Equivalent length and loss coefficients

5. Conversion Between Methods

6. Duct design concepts Equal friction method
Static pressure regain method

7. Equal friction method (the example)

8. Static pressure regain method

9. Fans Driving force to move air in buildings
Raise pressure and produce flow
Two main types:
Centrifugal
Axial

10. Relevant Fan Parameters
Total pressure rise
Static pressure rise
Power requirement
Efficiency
Note ηtot does not account for motor efficiency

11. Balance Point

12. Fan Performance

13. Centrifugal fans

16. Axial Fans

19. Fan Laws “Approximate relationships”
Given two aerodynamically similar fans, can extrapolate performance data
Be very careful