Displacement Ventilation

Transcription

1 Displacement Ventilation

2 Displacement Ventilation Displacement Ventilation vs. Dilution Ventilation Characteristics Design Considerations Layout and Selection Product Overview Casino Case Study

3 Dilution Air Distribution Induce as much as possible Ensure maximum 50 fpm within Occupied Zone High velocity jets at diffusers Diffuser Performance aerodynamic dependant Supply air used to dilute pollution in space Diffuser located Outside OZ

4 Dilution Air Distribution Complete Mixing in Entire Space 9 FT Minimal Temperature Stratification Uniformity is Sought Supply of 55 F - < 0 > + Temperature

5 Displacement Air Pattern Low Velocity Supply Low Induction Uniform Distribution Often Located in the Occupied Zone Supply between 65 F and 75 F

6 Body s Thermal Plume

7 Air Distribution Characteristics 5-10 deg F Cooling Differential Supply Air Flows Along Floor Rises When Heat Source is Contacted Displaces Room Air Upward

8 Air Pattern Cooling 2-10 o F Cooling Differential 0-5 o F Heating Differential 5 o F+ Heating Differential Morning Warm-up

9 Perimeter Radiation Radiant Ceiling Panels Fan Coil Units Heating Options

10 Air Distribution Characteristics Stratified Room Temperature Maximum 5 deg F in Occupied Zone* deg F Return Air *Based on ASHRAE 55. Current research is showing that occupants may be comfortable with a larger temperature gradient

11 Air Distribution Characteristics Warm Air at Top Pollutants at Top High Level Return

12 Ventilation Effectiveness How effectively airborne contaminants are removed from a room. E = c C C Exhaust Occupant Mix air Systems DV Systems E c = E c =

13 Limitations Pollutants Need to be Buoyant in Air Warmer/lighter Ceiling Height of at least 9 ft Recommended Large Drafts Cause Unwanted Mixing Limit in Cooling of 38 BTU/Hr/ft^2 Radiant cooling systems Chilled Beams/Sails Radiant Panels/Floors Limit Loads into Space Higher R walls Low E windows

14 Humidity Control Side-Stream Bypass EXHAUST AIR RETURN AIR COOLING COIL SUPPLY AIR 65 F OUTSIDE AIR PRIMARY AIR 55 F

15 Layout and Selection

16 Performance Data Sound - NC Level Pressure Drop - Inches W.G. ASHRAE Test Standard Throw Not Applicable

17 Performance Data

18 Displacement Ventilation and Comfort Supply air is injected directly into occupied zone Designers must be cautious to limit the velocities near occupants The aspect ratio or the diffusers is important Taller diffusers have higher velocities in the near zone

19 Effect of Air Motion on Comfort Ankle Region Neck Region Feeling Of Coolness AIR VELOCITY, FPM Feeling of Coolness Feeling of Warmth AIR VELOCITY, FPM Feeling of Warmth TEMPERATURE DIFFERENCE, F TEMPERATURE DIFFERENCE, F Percentage of Occupants Objecting to Drafts in Air- Conditioned Spaces

20 Comfort Criteria Maximum 40 FPM Face Velocity* per ASHRAE Research Project RP-949 Based on Commercial Applications Velocity can be increased for Transient Spaces Higher airflow rates are acceptable for Industrial Applications.

21 Selection Outlet Type Determined by Room Layout and Architecture Outlet Quantity Determined by Air Volume and Room Layout Outlet Size Based on Performance Maximum 40 FPM Face Velocity Sound and Pressure Drop not Significant

22 Layout Considerations Heat sources pull supply air to region Easily moves along walls to source entire room

23 Layout Considerations

24 Layout Considerations For large open spaces, diffuser can be located in the space Areas of high load should have more diffusers

25 Layout Considerations Diffusers should be located at least 2 ft from occupants Diffusers should not be located behind large objects that might restrict air flow to the zone

26 Ceiling Diffusers Ceiling mounted diffusers Supply air will gain some heat during fall Reduced if along a surface Reduced Ventilation Effectiveness Recommend to mount near walls to limit heat gain Ensure that space below diffuser is a transient space

27 Air Volume Calculations ASHRAE Design Guide Calculation Method Supply Air Volume Supply Air Temperature Exhaust Air Temperature Only suitable for zones with ~9ft ceiling height Need another calculation method for large volumes

28 Loads Two Components to loads Convection Radiation ASHRAE handbook lists portions attributable to each

29 Room Load Calculations Room Load Coefficients Occupants, Lamps, Equipment (a oe ) = 0.295* Overhead Lighting (a l ) = 0.132* Conduction and Radiation (a ex ) = 0.185* Remember: Building Loads are same as OH *From ASHRAE Design Guide based on RP-949 This methodology should only be used for typical office spaces

30 Energy / Airflow Modeling CFD Analysis Useful for Validation of Design Can Predict Airflow in Building

31 Why Use DV? IAQ Efficient removal of smoke, odors Pollutants lighter than supply air VE of (typically) Can be > 3 Thermally comfortable environment Meet ASHRAE 55 Higher SAT No Drafts

32 Why Use DV? Energy Efficiency Reduced Room Cooling Load Extended Economizer Cycle Efficient System Load Flexibility Cool supply air will find the heat load. As loads are reconfigured or move, the system will automatically compensate.

33 Why Use DV? Architectural Flexibility DV is a robust system Diffusers can be mounted in various locations Ceiling In walls In furniture In the floor In architectural elements

34 Displacement Outlet Types Flat 1 Way Diffuser Flat 3 Way Diffuser Flat Wall Diffuser Flat Corner Diffuser Flat Riser Diffuser Linear Enclosures Round Full Circular Diffuser Round Half Circular Diffuser Round Corner Diffuser Floor Diffusers Flat multi-way Industrial Diffusers Special Applications

35 Displacement Diffuser Low Velocity Supply Low Induction Uniform Distribution Dual Perforated face

36 Flat 1-way 1 way discharge Side wall application where one way discharge required Square or rectangular Mounted against wall inside of occupied space 3.6 to 14.2 ft 2 face area CFM Top, left, right, and rear ducted options Accessories Duct Cover Base

37 1-Way Pattern

38 Flat 3- Way Square or Rectangular Side wall application where three way pattern is required 3-way Air Pattern 7.7 to 27.2 ft 2 face area CFM Top and rear ducted available Accessories Duct cover Bases

39 3-Way Pattern

40 Flat Corner Unit Square or Rectangular Mounted in Corner 90 Degree Air Pattern 3.8 to 17.6 ft 2 face area CFM Accessories Duct cover Base

41 Corner Pattern

42 Square or Rectangular Mounted in Wall Provided with plenum Square inlet 1-way Air Pattern 3.6 to 7.4 ft 2 face area CFM Wall Unit

43 Rectangular Mounted in Wall / Stair Riser / Integrated into baseboards 1-way Air Pattern CFM.19 to 17.5 ft 2 face area Snaps into mounting flange flush with wall Can be used in any wall mounted application where a pressurized plenum can be provided Ideal for concealed look Recessed Unit

44 Linear Enclosure Displacement Linear Enclosure Attractive Linear Grille Rigid Steel Construction Heavy Duty Ducted from below, behind or from the side Ideal for: Offices Boardrooms Classrooms Available 2 nd QTR 2006

45 Round Face Mounted Free Standing in Interior Space Can be ducted from above or below 360 Degree Air Pattern 1.5 to 62.5 ft 2 face area CFM Designed for large capacities Accessories Bases Expansion Collars Circular Unit

46 Circular Pattern

47 Elevated Circular Unit Round Face Fastened directly to elevated ductwork 360 Degree Air Pattern 1.5 to 62.5 ft 2 face area CFM Designed for large capacities

48 Elevated Circular Unit Used where supply cannot be within the occupied zone Large open space Far from walls Raised floor not an option Valuable floor space

49 Round Face Side wall application 180 Degree Air Pattern 4 to 31 ft 2 free area CFM Top or rear ducted option, round or rectangular inlets available Accessories Duct cover Base Half Round Unit

50 Half Round Pattern

51 Corner Round Unit Round Face Mounted In Corner 90 Degree Air Pattern 2 to 15.5 ft 2 face area CFM Accessories Duct Cover Base

52 Floor Displacement Outlet 8 Round Aluminum Face Mounted In The Floor Horizontal Air Pattern CFM Compatible with underfloor products Used with raised floors or can be installed directly in floor slab

53 Sizes Shapes Face Types Colors Material Specials

54 Displacement Diffuser Accessories Duct Covers Conceal Duct work Bases Match room features Protect diffuser while cleaning Expansion Collar

55 Application of Displacement Ventilation in a Casino Edgewater Casino, Vancouver, BC

56 Major Project Challenges Retrofit of Existing Building Must Maintain Transparency Heritage Requirement Owner Demanded High Level of Comfort & IAQ Central Atrium 24 Hour Occupancy Fast Track Project

57 CFD Modeling Temperature Contour

58 Design Solutions Double Skin System New Air Handlers on Main Floor Utilized Existing Air Handlers on Second Floor Raised Floor Added to Main Level Under Floor Air Delivery on Main Floor Displacement Delivery on Main Floor

59 Turbulent Floor Outlet Generates Twist Effect Using Linear Slots in Combination With Inclined Discharge Produces Angular Vertical Pattern High Induction Turbulent Flow for Rapid Temperature Equalization Mixing Within Occupied Zone (6 ft from floor) Projects Air Upwards 3-6 Feet

60 Displacement Floor Outlet Radial Slots With Inclined Discharge Produces Horizontal Pattern Close to Floor Low Turbulence Low Velocity Minimal Mixing Air Buoyancy Carries Heat and Pollutants to Ceiling for Exhausting.

61 Lab Mockup Attended by Design Team and Owner 6 Slot Machines Simulated Floor Outlets Located Below Each Chair Measured Velocity and Temperature at Several Flows Opportunity to Feel the System

62 Lab Mockup Various Wall Mounted Displacement Outlets Were Also Demonstrated

63 Displacement Benefits Low Velocity/High Comfort Heat Sources Pull Supply Air to Region Ideal for Variable Occupancy Minimal Impact by Furnishings Easily Moves Along Walls to Fill Entire Room

64 HVAC System Details 36,000 CFM Supply Air Capacity Constant Volume with Reheat 67 Deg F Supply Air Temperature 3 CFM per Sq Ft in General Areas Demand Control Ventilation Return Through Top of Atrium

65 Main Floor HVAC

66 Main Floor HVAC Displacement Floor Air Outlets in Gaming Area 1300 Units Displacement Wall Outlets in Lobby and Eating Area

67 Second Floor HVAC

68 Second Floor HVAC Displacement Wall Outlets Throughout

69 Displacement Wall Outlets Diffuser Face Recessed into Millwork Coordination with Architect Critical Air Delivered Through Pressurized Plenums Self Balancing System Diffuser Face Sized for Maximum 40 FPM Face Velocity Sizes up to 36 x Units

70 Results Open Since February 05 Minimal Balancing Required Passed Opening Day Test No Draft Complaints Excellent Temperature Control- Within 1 Deg F

71 Results Supply Air Drawn to Occupants for High IAQ and Comfort Flexible System Extended Hours of Free Cooling Lower Fan HP Two New BC Casino s Under Design with Displacement

72 Conclusions Casino s are a Good Application for Displacement Delivery Comfort,IAQ and Energy Efficiency are Benefits CFD is a Valuable Design Tool Lab Mock Ups are Extremely Beneficial Coordinated Effort by Entire Design Team and Owner Ensures Success

73 Questions?