1 / 29

Objectives

Objectives. Finish duct design Discuss HW4 Learn about pumps. Frictional Losses. Non-circular Ducts. Dynamic (local) losses. Losses associated with Changes in velocity Obstructions Bends Fittings and transitions. Loss Coefficients. Δ P t = C o Δ P v,o. Duct Design Example.

jescie-hansen
Télécharger la présentation

Objectives

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Objectives • Finish duct design • Discuss HW4 • Learn about pumps

  2. Frictional Losses

  3. Non-circular Ducts

  4. Dynamic (local) losses • Losses associated with • Changes in velocity • Obstructions • Bends • Fittings and transitions

  5. Loss Coefficients ΔPt = Co ΔPv,o

  6. Duct Design Example • Determine total pressure drop from in this duct system F l1=150ft l3=100ft l2=50ft B A VA = 2000 CFM pdiffuserB = 15Pa VA = 1000 CFM pdiffuserA = 10Pa VA = 1000 CFM

  7. Solution Equal friction method:

  8. Two design methods Equal friction method (Example 18.9): Static regain method (Example 18.10):

  9. Fan Performance

  10. Controlling Air Flow

  11. VAV Operation

  12. How to use multiple pumps

  13. Dampers

  14. Summary of Air Distribution Systems • Select diffuser based on ADPI • Given a layout of duct system • Calculate total pressure drop • Deal with non-circular ducts and fitting losses • Select the fan based on fan and duct curve

  15. HW4 • Design: • Air handling unit (AHU) with components (cooling coil and fan) • Duct system • Diffusers • Chiller • Pump • Power requirement

  16. Pumps and Plumbing • Very similar to fans and ducts • Same principles based on fluid dynamics • With some specifics

  17. Hydronic Terms • Head loss • Open-loop vs. closed loop

  18. Head Loss

  19. Fittings

  20. Pumps • Driving force to move air water in buildings • Raise pressure and produce flow • One main type • Centrifugal

  21. Pump curves • NPSHR = Net Positive Suction Head Required

  22. Use Multiple Pumps

  23. Plumbing Arrangements

  24. Example 19.7 • Similar to equal friction method • Calculate head loss for common pieces of system • Size pipes to have equal head loss between points 2 and 3

More Related