Objectives Air Distribution Systems Duct design HW4

HW4 DUE: April 10, 2013   Problem 18.13 (Use TITUS Square Ceiling MCD diffuser http://www.titus-hvac.com/ecatalog/subcategory.aspx?refid=186) 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 18.27 (design problem)

Relationship Between Static and Total Pressure

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

System Characteristic

Electrical Resistance Analogy

Frictional Losses

Non-circular Ducts Parallel concept to wetted perimeter

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

Loss Coefficients ΔPt = CoPv,0

Example 18.7 Determine total pressure drop from 0 to 4

Conversion Between Methods

Reading asignement Chapter 18 18.1-18.4 (including 18.4)