Duct design .ppt
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This document discusses duct design considerations for a mechanical engineering project. It covers various duct shapes and sizes, materials, air distribution systems, diffusers and other components. Rectangular ducts are generally more energy efficient than round ducts. Distribution systems discussed include above ceiling, displacement and underfloor. Displacement systems aim to deliver conditioned air directly to the occupied zone without mixing. The document provides information on duct aspects, velocities, pressures and various design tradeoffs to consider for ductwork.
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Duct design .ppt
- 1. Duct Design Submitted in partial fulfillment of requiredment for the award of the degree of BACHELOR OF TECHNOLOGY IN MECHANICAL ENGINNEERING Submitted by MD ZEESHAN 13X01A0366 SANDEEP SINGH 13X01A0392 ZAFARYAB HAIDER 13X01A03C2 MD RIZWAN 13X01A0367
- 2. Ductwork Considerations • Shape • Size • Aspect ratio • Velocity • Static Pressure of the system • Space conflicts
- 3. Terms • Aspect ratio • Flexible ductwork • Overhead system • Underfloor air distribution (UFAD) system • Displacement system • Dumping • Diffuser • Grille • Register • Slot diffuser • Shift Zone • Plenum
- 4. Materials • Sheet metal (by gauge) • Galvanized • Iron • Aluminum • Stainless steel • Flexible • Insulated • Tube (socks) • Other • PVC • Fiberglass
- 7. Rectangular • Lower aspect ratios • More energy efficient • Use less ductwork • Velocity and Area have an inverse relationship to the CFM (CFM = V x A) • Velocity and Pressure Drop have a direct relationship W D Aspect ratio = W / D 1 to 1
- 8. Air Distribution Systems • Three Types • Above Ceiling • Displacement • Underfloor • Services • Supply air • Return air • Ventilation air • Relief air • Exhaust air
- 9. Above Ceiling Distribution System horizontal heat pump suppl y duct return duct diffuse r return air grille American Standard © 1999
- 10. Dilute the Air + pressure 1600 CFM 200 CFM 1400 CFM OA SA RA MA 1600 CFM
- 11. Outside Air (OA) v. “Fresh Air” • Source of outside air must be carefully considered. • May have to pre- filter or condition
- 12. Other Design Considerations • Thermal mass • Prevailing winds • Natural light • Solar shading • Control strategies • Life safety issues • Infiltration • Bioterrorism • Mixed Air (MA) conditions • Energy in the air • Comfort level of the air • The amount of water in the air
- 14. Short Circuiting
- 15. DISPLACEMENT PRINCIPLES •Conditioned air moves upward past the persons breathing zone. •This invisible plume continues an upward movement toward the ceiling. •A person will breathe lower contaminant levels vs. a mixing design. DISPLACEMENT DIFFUSERS RECESSED IN WALL
- 16. UNOCCUPED ZONE SHIFT ZONE OCCUPIED ZONE: TEMPERATURE GRADIANT H E I G H T Thermal Displacement Ventilation Temperature Stratification By only cooling the occupied zone, tonnage requirements may be reduced
- 17. DISPLACEMENT: Delivering fresh air where it is needed •Better IAQ, lower particulate concentrations than mixing systems. •Increase use of outdoor air without energy penalty. •Quiet diffusers, draftless conditions for the occupants.
- 18. Displacement Advantages/Disadvantages • Advantages • Moderate supply air temperature • Low velocity • Air delivered to the comfort zone without mixing • Aesthetics • Better IAQ • Can accommodate more outside air for same energy cost • Very quiet • Disadvantages • Higher initial cost • Less well understood • Aesthetics • Too quiet
- 19. Underfloor System • Reduces floor to floor height
- 21. ▪ Passive swirl diffusers; pressurized plenum; displacement theory ▪ Occupant may control airflow volume; 3’ clear zone around diffuser Air Delivery: UF-HVAC Diffuser Types Tate Building Technology Platform®
- 22. Rooftop Chiller HVAC Solution Equipment room (chiller, pumps, controls) Chilled water supply & return Cooling tower Supply air outlet Stub duct Indoor air handler VAV MIT terminals Supply air loop Tate Building Technology Platform®
- 23. Take-Aways (The Ah Hahs) • Eliminate the contaminant is always the first step • Capture it if you can’t eliminate it • Healthy buildings are well ventilated • Watch your outside air sources! • Operating cost and usually first cost go up as your ventilation goes up
- 24. Access Floors… Advancements in Building Systems
- 25. ...they’re not just for Computer Rooms anymore!! Advancements in Building Systems