Establishing Primary Airflow in WBCS Establishing Primary Airflow in - - PowerPoint PPT Presentation

▶
establishing primary airflow in wbcs establishing primary
SMART_READER_LITE
LIVE PREVIEW

Establishing Primary Airflow in WBCS Establishing Primary Airflow in - - PowerPoint PPT Presentation

Oct 10, 2022 320 likes •816 views

Establishing Primary Airflow in WBCS Establishing Primary Airflow in WBCS Systems Systems Chilled Beam Design Principles More information: How is capacity measured? Tested & reported as an assembly Is not simply a sum of component

slide-1
SLIDE 1

Establishing Primary Airflow in WBCS Systems Establishing Primary Airflow in WBCS Systems

slide-2
SLIDE 2

Chilled Beam Design Principles

How is capacity measured?

  • Tested & reported as an assembly
  • Is not simply a sum of component capacity
  • ASHRAE Standard 200

How is capacity certified? AHRI Standard 1240/1241 certification program

More information:

slide-3
SLIDE 3

3

Chilled Beam Design Principles

slide-4
SLIDE 4

Agenda

  • WBCS Concept
  • Occupant Comfort
  • Establishing Primary Airflow Rate
  • Energy Impact
  • Demand Control Ventilation
  • WBCS Concept
  • Occupant Comfort
  • Establishing Primary Airflow Rate
  • Energy Impact
  • Demand Control Ventilation

4 2015-12-15 Establishing Primary Airflow

slide-5
SLIDE 5

Focusing on what our customers care about

5 2015-12-15 Establishing Primary Airflow

  • Comfort vs. Capacity
  • System Design vs. Product Features

VS.

slide-6
SLIDE 6

Water Borne Climate System Concept

6 2015-12-15

slide-7
SLIDE 7

Transportation Costs

7 2015-12-15 Company Presentation

Air

10” duct Capacity 9900 Btuh (20 ft/s Δt 14F)

Water

3/4” pipe Capacity 9900 Btuh (110 ft/m Δt 7F)

slide-8
SLIDE 8
  • How a chilled beam works
slide-9
SLIDE 9

WBCS Basics

9

slide-10
SLIDE 10
  • 1-Way

2-Way 4-Way 1-Way 1-Way

slide-11
SLIDE 11

Chilled Beams and Occupant Comfort

11 2015-12-15

slide-12
SLIDE 12

Heating/Cooling Capacity & Air Distribution

  • A chilled beam is a combination energy source

and air distribution system so the selection is doubly important.

  • The space air distribution is equally important

to capacity in determining the comfort level. Poor air distribution will result in poor comfort no matter how much capacity is available.

  • A chilled beam is a combination energy source

and air distribution system so the selection is doubly important.

  • The space air distribution is equally important

to capacity in determining the comfort level. Poor air distribution will result in poor comfort no matter how much capacity is available.

slide-13
SLIDE 13

Chilled Beam – Energy source + air diffuser

slide-14
SLIDE 14

14

Controllable by chilled beam Metabolic rate x Clothing insulation x Air temperature

  • Radiant temperature

x Air speed

  • Air direction / throw
  • Humidity

x User adjustability

  • ASHRAE Standard 55 Comfort Considerations
slide-15
SLIDE 15

Air Distribution

Mixed Systems Mixed Systems

  • All the air in the space is

mixed to same the same temperature

  • Overhead mixed air

systems use Coanda effect

  • Most beams are based
  • n mixed air approach

(overhead)

  • All the air in the space is

mixed to same the same temperature

  • Overhead mixed air

systems use Coanda effect

  • Most beams are based
  • n mixed air approach

(overhead) Displacement Systems Displacement Systems

  • Air is introduced at floor

level at very low velocities

  • Space is deliberately

stratified

  • Only the occupant zone is

conditioned

  • Air is introduced at floor

level at very low velocities

  • Space is deliberately

stratified

  • Only the occupant zone is

conditioned

15 2015-12-15 Company Presentation

slide-16
SLIDE 16

!

Coanda effect

"# $% "% $

Thanks to the negative pressure, the air follows the ceiling instead of falling straight down when it leaves the module When the air reaches the occupied zone, it has attained a temperature and speed that reduces the risk of draft

slide-17
SLIDE 17

17

Induction and Coanda Effect

slide-18
SLIDE 18

Creating Coanda Effect

18

Diffuser nozzle design

  • Beams have built in “Diffuser” technology
  • Beam selection and placement to ensure comfort is

an important as when selecting diffusers

  • “One big beam in a space may meet cooling load but

may not deliver the comfort that two smaller beams would deliver”

slide-19
SLIDE 19

Airflow Pattern

19 2015-12-15 Company Presentation

  • Beams can offer wide range of airflow patterns to

suit space

slide-20
SLIDE 20

20 2015-12-15 Indoor Climate Systems - Water based or Air?

2-way discharge strategy

  • Uses only small area of the ceiling
  • Air volume distributed into narrow region

4-way discharge strategy

  • Maximizes use of available ceiling area
  • Air volume distributed diffusely, more slowly
  • Flexible discharge patterns / field adjustable

Beam Selection For Comfort

slide-21
SLIDE 21

WBCS Primary Airflow Analysis

21 12/15/2015 Intro to ComVent - Establish loads and Primary Airflow

slide-22
SLIDE 22

Compare Office Vs. School

2015-12-15 Company Presentation 22

slide-23
SLIDE 23

Cooling Load Summary

23 2015-12-15 Company Presentation

Sensible Load Latent Load Total Load SHR Btu/h Btu/h-ft² Btu/h Btu/h-ft² Btu/h Btu/h-ft² Classroom 24756 24.8 7795 7.8 32551 32.6 0.76 Office 23116 23.1 2573 2.6 25688 25.7 0.9

slide-24
SLIDE 24

Cooling Load Calculations

  • Loads same regardless of

HVAC system

  • Fancoil, WSHP, GSHP and

VRF need zone latent and sensible loads separate from outdoor air load

  • WBCS need zone sensible

load separate from zone latent load and outdoor air latent and sensible load

  • Loads same regardless of

HVAC system

  • Fancoil, WSHP, GSHP and

VRF need zone latent and sensible loads separate from outdoor air load

  • WBCS need zone sensible

load separate from zone latent load and outdoor air latent and sensible load

24 12/15/2015 Intro to ComVent - Establish loads and Primary Airflow

slide-25
SLIDE 25

WBCS Primary Airflow Design

  • The primary airflow rate must be the larger of;
  • The air flow rate to meet the ventilation rate required

to deliver acceptable indoor air quality.

  • The airflow rate to provide latent cooling in the zone.
  • The airflow rate required to assist in meeting the zone

sensible cooling rate.

  • The primary airflow rate must be the larger of;
  • The air flow rate to meet the ventilation rate required

to deliver acceptable indoor air quality.

  • The airflow rate to provide latent cooling in the zone.
  • The airflow rate required to assist in meeting the zone

sensible cooling rate.

25 12/15/2015 Intro to ComVent - Establish loads and Primary Airflow

slide-26
SLIDE 26

Ventilation Rate

  • Office
  • Ventilation rate = 10 x 5 cfm

+ 0.06 x 1000 ft² = 110 cfm

  • = 0.11 cfm/ft²
  • Classroom
  • Ventilation rate = 30 x 10 cfm

+ 0.12 x 1000 ft² = 423 cfm

  • = 0.42 cfm/ft²
  • Office
  • Ventilation rate = 10 x 5 cfm

+ 0.06 x 1000 ft² = 110 cfm

  • = 0.11 cfm/ft²
  • Classroom
  • Ventilation rate = 30 x 10 cfm

+ 0.12 x 1000 ft² = 423 cfm

  • = 0.42 cfm/ft²

26 2015-12-15 Company Presentation

slide-27
SLIDE 27

Latent Rate

27 2015-12-15 Company Presentation 75 °F DB 50% RH 64.6 gr/lb HR

Qp = Platent/(0.68 x (Wr- Wprimary air))

slide-28
SLIDE 28

Sensible Rate

28 2015-12-15 Company Presentation 75 °F DB 50% RH 64.6 gr/lb HR

Qp = Psensible /(1.085 x ((Tr – Tp) + IR x (Tr – Ta))

slide-29
SLIDE 29

Primary Airflow Summary

  • Can’t go below ventilation rate
  • Latent load usually dominates
  • Offices 0.4 to 0.6 cfm/ft², 53 °F off coil
  • Classroom 0.6 to 0.8 cfm/ft², 49 °F off coil (reheat

required)

  • Can’t go below ventilation rate
  • Latent load usually dominates
  • Offices 0.4 to 0.6 cfm/ft², 53 °F off coil
  • Classroom 0.6 to 0.8 cfm/ft², 49 °F off coil (reheat

required)

Ventilation Rate Latent Rate Sensible Rate Btu/h cfm/ft² Btu/h cfm/ft² Btu/h cfm/ft² Classroom 423 0.43 740 0.75 761 0.76 Office 110 0.11 461 0.46 333 0.33

29 12/15/2015 Intro to ComVent - Establish loads and Primary Airflow

slide-30
SLIDE 30

Primary Airflow Summary

  • The zone sensible cooling load should be

between 20 to 40 Btu/h·ft².

  • The primary airflow will be most likely set by

the zone latent load. A good range is 0.4 to 0.6 cfm/ft².

  • A good office system has 1/3 of the load met

by the primary air and 2/3 of the load met by the chilled beam coil.

  • Assume an induction ratio between 2.5 to 3.5.

Start with 3.

  • The zone sensible cooling load should be

between 20 to 40 Btu/h·ft².

  • The primary airflow will be most likely set by

the zone latent load. A good range is 0.4 to 0.6 cfm/ft².

  • A good office system has 1/3 of the load met

by the primary air and 2/3 of the load met by the chilled beam coil.

  • Assume an induction ratio between 2.5 to 3.5.

Start with 3.

30 2015-12-15 Company Presentation

slide-31
SLIDE 31

Primary Airflow Summary

  • The chilled water supply temperature should

be 2-3 °F above space dew point. 57 °F is a common supply water temperature.

  • The chilled water temperature range will be 4

to 6 °F. Consider putting the primary air system in series with the chilled beams.

  • The chilled water supply temperature should

be 2-3 °F above space dew point. 57 °F is a common supply water temperature.

  • The chilled water temperature range will be 4

to 6 °F. Consider putting the primary air system in series with the chilled beams.

31 2015-12-15 Company Presentation

slide-32
SLIDE 32

WBCS Energy Considerations

32 12/15/2015 Intro to ComVent - Establish loads and Primary Airflow

slide-33
SLIDE 33

Design vs. Annual Energy Usage

33 2015-12-15 Company Presentation Fans 25% Chiller 56% Pumps 14% Tower 5%

Design Day

Fans 44% Chiller 32% Pumps 21% Tower 3%

Annual

slide-34
SLIDE 34

Annual Cooling Load Profile

34 2015-12-15 Company Presentation

50 100 150 200 250 300 350 400 450 500 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 Hours Percent Cooling Load

slide-35
SLIDE 35

Standard DOAS Unit

35 12/15/2015 Intro to ComVent - Establish loads and Primary Airflow

slide-36
SLIDE 36

Primary Airflow vs. Delta Humidity Ratio

12/15/2015 36

  • All points of curve deliver same amount latent cooling to space

Platent = 0.68*Qp* (Wr – Wprimary air )

10 20 30 40 50 60 70 80 90 100 3.8 6.1 8.3 10.5 12.6 14.6 16.5

Primary Airflow (cfm) Delta Humidity Ratio (gr/lb)

slide-37
SLIDE 37

Cooling Capacity of Primary Airflow

37 12/15/2015

10 20 30 40 50 60 70 80 90 100 2062 1352 1043 864 753 678 625

Primary Airflow (cfm) Primary Air Sensible Capacity (Btu/h)

  • Primary cooling capacity drops off as airflow is reduced
  • Shifts load to beam
slide-38
SLIDE 38

Primary Airflow vs. Induction Ratio

38 12/15/2015 Intro to ComVent - Establish loads and Primary Airflow

10 20 30 40 50 60 70 80 90 100 1.1 2.8 4.4 5.9 7.4 8.9 10.2

Priamry Airflow (cfm) Induction Ratio

  • Higher beam load requires higher induction rate
  • APD and noise become issue
slide-39
SLIDE 39

DOAS Energy Model Design Parameters

Off Coil DB SA DB SA HR Delta HR SA Airflow F F gr/lb gr/lb cfm 55 56 62.6 3.8 100 54 55 60.3 6.1 62 53 54 58.1 8.3 46 52 53 55.9 10.5 36 51 52 53.8 12.6 30 50 51 51.8 14.6 26 49 50 49.9 16.5 23

39 12/15/2015 Intro to ComVent - Establish loads and Primary Airflow

slide-40
SLIDE 40

Annual Energy Usage Std DOAS Unit

40 12/15/2015 Intro to ComVent - Establish loads and Primary Airflow

0.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0 100 62 46 36 30 26 23

Annual Energy Usage (kWh) Primary Airflow (cfm)

Rotor BIN Watts kWh SA Fan BIN Watts kWh Chiller Plant BIN Watts kWh HW Plant BIN Watts kWh RA Fan BIN Watts kWh

slide-41
SLIDE 41

Energy Analysis Summary

  • Fan work is dominant
  • Generally shifting sensible load to beams from primary

is more efficient

  • Practical limitation on induction ratio (5) and primary

air temperature (53 °)

  • Reheat increases operating cost – only do it if you

have to (schools)

  • Fan work is dominant
  • Generally shifting sensible load to beams from primary

is more efficient

  • Practical limitation on induction ratio (5) and primary

air temperature (53 °)

  • Reheat increases operating cost – only do it if you

have to (schools)

41 12/15/2015 Intro to ComVent - Establish loads and Primary Airflow

slide-42
SLIDE 42

Demand Control Ventilation

slide-43
SLIDE 43

Demand Control Ventilation

  • Classrooms occupied 35%
  • Offices occupied 22-38%
  • ASHRAE Std 90.1
  • 500 ft²
  • 25 people per 1000 ft²
  • greater than 3000 cfm
  • ASHRAE Std 62
  • Minimum airflow ≥ building load

component (Ra x Az)

  • Classrooms occupied 35%
  • Offices occupied 22-38%
  • ASHRAE Std 90.1
  • 500 ft²
  • 25 people per 1000 ft²
  • greater than 3000 cfm
  • ASHRAE Std 62
  • Minimum airflow ≥ building load

component (Ra x Az)

43 2015-12-15 Company Presentation

slide-44
SLIDE 44

Demand Control Ventilation

  • Vary Primary airflow based on
  • Occupancy
  • Temperature
  • CO2
  • VOC
  • Vary Primary airflow based on
  • Occupancy
  • Temperature
  • CO2
  • VOC

44 2015-12-15 Company Presentation

06:00 07:00 08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00

  • 150

200 250

&

  • 100
slide-45
SLIDE 45

Impact of Reduced Primary Airflow on Induction

50 100 150 200 250 300 350 400 10 20 30 40 50 60 70 80 90 100 110 120 130

  • Induced

Primary Chilled Beam with Integral Damper Discharge, chilled beam with upstream VAV damper

12/15/2015 Intro to ComVent - Establish loads and Primary Airflow

45

slide-46
SLIDE 46

Demand Control Ventilation Demand Control Ventilation

' ZONE DOAS

slide-47
SLIDE 47

Demand Control Ventilation Summary

  • DCV increases chilled beam turndown from 3 to 1 to

10 to 1

  • Improves occupant comfort
  • Spaces are rarely at design occupancy
  • DCV allows significant fan power savings
  • DCV control can be based on
  • Occupancy sensor (single occupant office)
  • CO2 or VOC (modulating for multi occupant

spaces)

  • DCV increases chilled beam turndown from 3 to 1 to

10 to 1

  • Improves occupant comfort
  • Spaces are rarely at design occupancy
  • DCV allows significant fan power savings
  • DCV control can be based on
  • Occupancy sensor (single occupant office)
  • CO2 or VOC (modulating for multi occupant

spaces)

47 12/15/2015 Intro to ComVent - Establish loads and Primary Airflow

slide-48
SLIDE 48

THANK YOU FOR YOUR TIME