Objectives
• Differentiate fans
• Select fan
appropriate for
system
• Calculate system
curve for multi-
terminal duct system
Fans
• Driving force to move air in buildings
• Raise pressure and produce flow
• Two main types:
• Centrifugal
• Axial
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Guidelines and tips
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Differentiate Fans - Building Environmental Systems - Slides | ARE 346N, Study notes of Architecture
Material Type: Notes; Professor: Siegel; Class: BUILDING ENVIRONMENTAL SYSTEMS; Subject: Architectural Engineering; University: University of Texas - Austin; Term: Spring 2009;
Typology: Study notes
Pre 2010
1 / 13
This page cannot be seen from the preview
Don't miss anything!
Related documents
Partial preview of the text
Download Differentiate Fans - Building Environmental Systems - Slides | ARE 346N and more Study notes Architecture in PDF only on Docsity!
Objectives
- Differentiate fans
- Select fan appropriate for system
- Calculate system curve for multi- terminal duct system
Fans
- Driving force to move air in buildings
- Raise pressure and produce flow
- Two main types:
- Centrifugal
- Axial
Relevant Fan Parameters
- Total pressure rise
- Static pressure rise
- Power requirement
- Efficiency
- Note^ ηtot does not account for motor efficiency D = blade diameter m = mass flow rate (of air) ρ = gas (air) density P = total pressure Wtot = total power Wshaft = shaft power
Balance Point
Axial Fans
Controlling Air Flow
Effect on Fan Curve
Dampers
VAV Operation
Duct Layout (cont.)
- Find pressure drop data for all components and duct fittings
- Complete rough sizing using either
- Equal friction
- Static regain method
- Complete second sizing
- Check sound levels
- Accessibility for maintenance
Equal Friction method
- Small to medium size buildings
- Low pressure and low velocity
- Shaded area on friction loss diagram
Example 18.
- Modifications: Cooling coil at Pt. 1, real diffusers (NC<35)
Static Regain Method
- Large buildings (high velocity, high pressure, high noise)
- Use terminal boxes and flexible ducts
- Design system so that total pressure drop and velocity pressure drop are the same - Reduce velocity as you move towards terminal boxes
Other Issues
- Other equipment
- Duct leakage
- Noise
- Material costs
- IAQ impacts
- Cleaning and maintenance