1. Objectives
Air Distribution Systems
Duct design
HW4

2. HW4
DUE: April 10, 2013
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)

3. Relationship Between Static and Total Pressure

4. Duct Design
Total and static pressure drops are proportional to square of velocity
Plot of pressure drop vs. volumetric flow rate (or velocity) is called system characteristic

5. System Characteristic

6. Electrical Resistance Analogy

7. Frictional Losses

8. Non-circular Ducts
Parallel concept to wetted perimeter

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

10. Loss Coefficients
ΔPt = CoPv,0

12. Example 18.7
Determine total pressure drop from 0 to 4

13. Conversion Between Methods

14. Reading asignement
Chapter 18
(including 18.4)