Review of Parametric Studies for Optimizing Laboratory ... · 7 ANSI/ASHRAE Standard 110-2016...

Review of Parametric Studies for Optimizing Laboratory Ventilation

HE Yueyang (Dr.), Department of Building, [email protected]

Daniel HII Jun Chung (Dr.), School of Design & Environment, [email protected]

WONG Nyuk Hien (Prof.), Department of Building, [email protected]

PECK Thian Guan (Dr.), Office of Safety Health and Environment, [email protected]

22 October 2019

mailto:[email protected]:[email protected]:[email protected]:[email protected]

2

◼ Introduce the background of our lab ventilation research project in NUS

◼ Review existing standards/parametric studies of air flow rates

◼ Review existing standards/parametric studies of air distributions

◼ Discuss lab design parameters to be tested in CFD simulations

◼ Objectives

Section 1

Background: Lab Energy Performance

0

100

200

300

400

500A

vera

ge E

ner

gy U

se In

ten

sity

(kW

h/m

2yr

)2013 2016 2017

◼ University energy consumptions in Singapore

4Source: Building Construction Authority (BCA), 2018

◼ BCA Green Mark for laboratories (GM Lab: 2017)

5

◼ Background• Official launch: 13 June 2017

• World’s 1st green certification scheme for laboratories design and

operation

◼ Lab 2-1 Energy efficiency• Use more efficient air distribution system (baseline: 0.35 kW/ton)

• Design for air recirculation within laboratory while meeting safety

requirement

• Adopt VAV lab air flow and variable flow exhaust controls

◼ Lab 2-2 energy effectiveness• Use occupancy sensor or sash position monitoring for fume hood/

biosafety cabinet to reduce exhaust air ventilation

• Use VAV fume hood/ biosafety cabinet with lower face velocity (Platinum:

≤ 0.5 m/s & Gold: ≤ 0.6 m/s for biological and chemical lab)

• Link sash position/exhaust rate/face velocity monitoring to BMS

Source: Building Construction Authority (BCA), 2017

◼ Inaugural Platinum awards

6

◼ Lab ACH Control Band:

• Cornell’s Laboratory Ventilation Management Program: never go down to 2ACH, 3ACH is bare

minimum (Source: https://sp.ehs.cornell.edu)

• OSHA’s Lab Standard: 4-12 ACH: adequate general ventilation

◼ Inaugural Platinum awards

• NUS Chemistry Lab – Tahir Foundation

• Cambridge Centre for Advanced Research and Education (Cares)

• Agency for Science, Technology and Research's (A*Star) Institute of Bioengineering and

Nanotechnology - IBN Chemistry Lab

7

Tahir Foundation Building (MD1)

Floor plan at level 17

Single laboratoryequipped with 8 fume hoods

(Area = 48.2 m2/ 518.8 ft2)

Source: NUS

◼ Compact laboratory design in NUS

◼ Diagram for optimizing lab ventilation

8

Air Flow Rates (ACH) Air Distributions

CFD Parametric Studies

Review of Existing Standards and Researches

Chemical Spill Experiments

Potential ACH ReductionSafety Requirements

Validation

Evaluation

Future Lab Designs

Section 2

Review: Air Flow Rates

◼ Reviewed lab ventilation standards and criteria

10

NO Standard Region

1 OSHA Federal register 29 CFR part 1910 US

2 ANSI/ASHRAE Standard 62.1-2016 Ventilation for acceptable indoor air quality US

3 NFPA 45-2015 Standard on fire protection for laboratories using chemicals US

4 ANSI/AIHA/ASSE Z9.5-2012 Laboratory ventilation US

5 ASHRAE Handbook 2015 - HVAC Applications, Chapter 16: Laboratories US

6 ACGIH 2016 Industrial ventilation: a manual of recommended practice for design US

7 ANSI/ASHRAE Standard 110-2016 Method of testing performance of laboratory fume hoods US

8 SEFA 1-2010 Laboratory fume hoods recommended practices US

9 Cornell University’s laboratory ventilation management program (LVMP) US

10 International Building Code 2012 ICC

11 BS 7258-1994 Laboratory fume cupboards / BS EN 14175 -7 fume cupboards British

12 DD 191-1990 Method for determination of the containment value of a laboratory fume cupboard British

13 DIN 1946-7 Ventilation and air conditioning Germany

14 VDI 2051 Air-conditioning - Laboratories Germany

15 SS 553-2016 Code of practice for air-conditioning and mechanical ventilation in buildings Singapore

16 SS 554-2016 Code of practice for indoor air quality for air-conditioned buildings Singapore

17 SS 641-2019 Code of practice for fire safety for laboratories Singapore

18 GM Lab: 2017 BCA Green Mark for laboratories Singapore

19 SCDF Fire Code 2018 chapter 7 Air-conditioning and mechanical ventilation systems Singapore

20 WSH guidelines – Laboratories handling chemicals 2014 Singapore

21 WSH guidelines – Management of indoor air quality in air-conditioned workplaces 2016 Singapore

22 Workplace safety and health act Singapore

◼ Standards for fume hood

11

Document Standard Year

Laboratory fume cupboards BS 7258-2 1994 U ≥ 0.3 m/s 1994

SEFA1-2010 U = 0.3 – 0.5 m/s 2010

ANSI/AIHA Z9.5

U = 0.3 – 0.4 m/s (excellent containment characteristics)U = 0.4 – 0.5 m/s (most hoods)

U = 0.5 – 0.6 m/s (most hoods with higher operating costs)U = 0.6 – 0.7 m/s (performance is not significantly better)

2012

BCA Green Mark for laboratories GM Lab: 2017

U ≤ 0.5 m/s (Platinum)U ≤ 0.6 m/s (Gold)

2017

◼ Standards for air flow rates (ACH)

12

Document Standard Highlight Year

OSHA 29 CFR, Part 1910 ACH = 4 – 12 1990

NFPA 45-2004ACH ≥ 4 (unoccupied)

ACH > 8 (occupied)2004

NFPA 45-2015 N/A 2015

ANSI/AIHA Z9.5 ACH = 4 – 10⚫ ACH cannot meet all conditions. Furthermore, ACH is not the

appropriate concept for designing contaminant control systems.2012

ASHRAE 62.1-2016 ACH ≥ 1.2 (9-foot ceiling) 2016

ASHRAE handbook HVAC

2007ACH = 6 – 10 (occupied) 2007

ASHRAE handbook HVAC

2015N/A

⚫Minimum ventilation rates should be established on a room-by-room basis …

2015

ACGIH 2016 N/A⚫ ‘ACH’ is a poor basis for ventilation criteria where environmental

control of hazards, heat, and/or odors is required …2016

◼ Standards for air flow rates (ACH)

13

Document Standard Highlight Year

Cornell University LVMPACH = 4 – 8 (normal)

ACH = 3 – 6 (moderate)

⚫ Low ventilation: less than “moderate” rates, determined by review of operations in lab.

⚫ Lab-specific ventilation: determined by specific review of non-chemical hazards in lab.

2013

International Mechanical

Code (IMC) 2009ACH ≥ 1.2 (9-foot ceiling) 2009

DIN 1946-7:2009-7 ACH ≥ 9.1 (9-foot ceiling supply) 2009

VDI 2051 Air-conditioning

- LaboratoriesACH ≥ 9.1 (9-foot ceiling supply) 2018

Singapore Civil Defence

Force (SCDF) fire code

2018

ACH = 4 – 8 (Chemical/hazardous materials warehouses)

ACH ≥ 20 (rooms involving use of flammable and explosive substances)

2018

SS 641-2019 Code of

practice for fire safety for

laboratories using

chemicals

ACH = 8 – 12 (prescribed value)ACH = 4 – 8 (further reduction based

on risk assessment)

⚫ For energy conservation purposes, the air change rate for occupied laboratories can be reduced via the Risk Assessment Flow Chart

2019

◼ Parametric study of ACH

14

ACH (-) Floor area (m2)

Method References2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

55.0 CFD Liu et al., 2017

22.5 CFD Barbosa & Brum, 2017

21.0 CFD Morcos et al., 2014

70.0 Measurement Stuart et al., 2014

N/A Measurement Sweet & Stuart, 2013

21.0 Measurement Jin et al., 2012

65.0 Measurement Klein et al., 2010

65.0 Measurement Klein et al., 2009

73.0 Measurement Smith & Smith, 2009

N/A CFD Schuyler, 2009

60.0 CFD Memarzadeh, 2009

60.0 CFD Memarzadeh, 2007

N/A N/A Sandru & Ouyang, 2005

◼ Summary of ACH as a design parameter

15

◼ Existing standards prefer a case-by-case criteria to a common criteria of ACH

◼ Existing studies mainly focus on the ACH ranged from 6 to 12

◼ ACH is not a appropriate basis for ventilation criteria

◼ Minimum ventilation rates should be established on a room-by-room basis considering the hazard level

16

◼ SS 641-2019 Code of practice for fire safety for laboratories using chemicals

Section 3

Review: Air Distributions

◼ Standards for air flow distribution

18

Document Category Highlight Year

ANSI/AIHA Z9.5

Supply location,Exhaust location

⚫ Supply air diffusers close to the personnel corridor and entry door to the lab

and far from the major exhaust devices.

⚫ Hoods and exhaust devices away from entry doors and exit corridors2012

CFD solutions ⚫ Additional design information can be obtained using CFD

ASHRAE handbook

HVAC 2015

ACH,Supply-exhaust location,

supply type, pollutant source location, pollutant release rate, heat source

position, room layout

⚫ Airflow patterns, temperature, and particle distribution … depend on several

interrelated factors

⚫ The success of a mixed air distribution system depends primarily on supply

diffuser location.

2015

CFD solutions

⚫ Physical testing and measurements … are time consuming and labor

intensive, … analysis of various realistic scenarios through CFD simulations

becomes an attractive alternative.

◼ Standards for air flow distribution

19

Document Category Highlight Year

DIN 1946-7:2009-7 Supply-exhaust location

⚫ The flow of air within the lab is primarily determined by the position and construction of supply air openings.

⚫ Supply air openings shall be constructed and arranged in such a way that they will not interfere with the extract air equipment.

2009

VDI 2051 Air-

conditioning -

Laboratories

ACH, room space, room layout

⚫ Air flow patterns in lab areas depend on the intended use and the associated air volume flow rates and cooling loads. Further items to consider include the space required for the ventilation equipment and the arrangement of the components and devices.

2018

Workplace safety

and health

guidelines–

laboratories

handling chemicals

Pollutant-exhaust location,Local exhaust location

⚫ Air exhaust points should be located as near as possible to expected contaminant sources

⚫ Fume cupboards should be located away from doors and high traffic areas2014

◼ Parametric studies at lab scales

20

Authors Supply positionSupply

propertyExhaust/return

positionExhaust/ return

property Spill position

Chemical property

Methods

Liu et al., 2017

• Wall-mount supply 1• Wall-mount supply 2• Wall-mount supply 3• Ceiling supply 1• Ceiling supply 2• Ceiling supply 3• Ceiling supply 4

• 360 × 360 • 420 × 420

• Wall return 1• Wall return 2• Wall return 3• Wall return 4• Ceiling return 1• Ceiling return 2

• X 1

• Bench-top 1• Bench-top 2• Bench-top 3• Bench-top 4

• Benzene CFD

Jin et al., 2012 • Ceiling supply • Square• Bench exhaust• Wall exhaust 1• Wall exhaust 2

• X 1

• On the desk • On the floor near

an occupant • On the floor away

from occupants

• SF6 measurement

Klein et al., 2009

• Ceiling supply• 3 grilles • 6 grilles

• Overhead exhaust grill

• X 6• Floor level• Bench-top

• Diethylether

measurement

Klein et al., 2010

• Ceiling supply • 6 grilles• Overhead

exhaust grill• X 6

• Floor level• Bench-top

• Ether• Acetone• Ethanol

measurement

Memarzadeh, 2009

• Door gap and ceiling• Linear and

square

• Ceiling exhaust • Bench hood

exhaust

• X 1• X 2• X 4

• Bench-top N/A CFD

Morcos et al., 2014

• Ceiling supply • Square• Bench exhaust• Wall exhaust 1• Wall exhaust 2

• X 1

• On the desk • On the floor near

an occupant • On the floor away

from occupants

• SF6 CFD

◼ Summary of the design parameters affecting lab ventilation

21

◼ Existing standards provide some general recommendations for laboratory layouts

◼ Existing studies mainly focus on supply/exhaust/return/chemical emission positions and their properties

◼ CFD solution is recommended for additional design information

Section 4

Parametric Studies

23

ScenarioRoom exhaust

operationHood exhaust

operationPollutant position Measuring variable

1 OnOn

(100% open sash)N/A

Air/face velocity (U), air temperature (Tair) and surface temperature (Tsurface)

2 On Off Bench-top

VOC concentration (VOC)

3 On Off Ground

◼ Spill experiments for CFD validation

◼ Baseline laboratory configuration

ScenarioP1: Fume hood

operationP2: Supply response

P3: Fume hood position

P4: Supplyposition

P5: Room exhaustposition

Baseline Single Synchronous Aside Above-corridor Ceiling

Pollutant source

24

◼ Testing design parameters

BaselineP1: Fume hood operation

MultipleP2: Supply response

Asynchronous

P4: Supply positionAbove-bench

P5: Room exhaust position

FloorP3: Fume hood position

Central25


BaselineSingle

P1: Fume hood operationMultiple

P2: Supply response

Asynchronous


P3: Fume hood positionCentral


Floor26


BaselineSynchronous


P2: Supply response

Asynchronous




Floor27


BaselineAside


P2: Supply response

Asynchronous




Floor28

BaselineAbove-corridor


P2: Supply response

Asynchronous



FloorP3: Fume hood position

Central


29


BaselineCeiling


P2: Supply response

Asynchronous




Floor (*dense gas)30

◼ Matrix of testing design parameters (pending)

ScenarioP1: Fume hood

operationP2: Supply response

P3: Fume hood position

P4: Supplyposition

P5: Room exhaustposition

1 Single Synchronous Aside Above-corridor Ceiling2 Single Synchronous Aside Above-corridor Floor3 Single Synchronous Aside Above-bench Ceiling4 Single Synchronous Aside Above-bench Floor5 Single Synchronous Central Above-corridor Ceiling6 Single Synchronous Central Above-corridor Floor7 Single Synchronous Central Above-bench Ceiling8 Single Synchronous Central Above-bench Floor9 Single Asynchronous Aside Above-corridor Ceiling

10 Single Asynchronous Aside Above-corridor Floor11 Single Asynchronous Aside Above-bench Ceiling12 Single Asynchronous Aside Above-bench Floor13 Single Asynchronous Central Above-corridor Ceiling14 Single Asynchronous Central Above-corridor Floor15 Single Asynchronous Central Above-bench Ceiling16 Single Asynchronous Central Above-bench Floor17 Multiple Asynchronous Aside Above-corridor Ceiling18 Multiple Asynchronous Aside Above-corridor Floor19 Multiple Asynchronous Aside Above-bench Ceiling20 Multiple Asynchronous Aside Above-bench Floor21 Multiple Asynchronous Central Above-corridor Ceiling22 Multiple Asynchronous Central Above-corridor Floor23 Multiple Asynchronous Central Above-bench Ceiling24 Multiple Asynchronous Central Above-bench Floor

31

◼ Evaluation of the design scenarios

◼ Pollutant source positions (focus on fugitive emission)

◼ Gas species

• Acetone

• Dimethyl Ether

◼ Minimum safety level

• PEL?

◼ Evaluation zone (focus on breathing zone)

Bench-topNear door

Bench-topAway from door

Evaluation zone

32

◼ Balance of ACH reductions and pollutant concentration

◼ ACH reductions (energy saving)

Level 1 – Current ACH level

Level 2 – Slight ACH reduction

Level 3 – Moderate ACH reduction

◼ Pollutant concentration control (user safety)

Steady simulations – Normalized mass fraction of pollutants (Cnormalized) and Local mean age of air (τzone)

Transient simulations (selected scenarios) – Dilution time of pollutants (Tdilution)

𝐶𝑛𝑜𝑟𝑚𝑎𝑙𝑖𝑧𝑒𝑑 =𝐶 − 𝐶𝑠𝑢𝑝𝑝𝑙𝑦

𝐶𝑒𝑥ℎ𝑎𝑢𝑠𝑡 − 𝐶𝑠𝑢𝑝𝑝𝑙𝑦=

𝐶

𝐶𝑒𝑥ℎ𝑎𝑢𝑠𝑡

𝑇𝑑𝑖𝑙𝑢𝑡𝑖𝑜𝑛 = 𝑇𝑖𝑛𝑖𝑡𝑖𝑎𝑙 - 𝑇𝑡ℎ𝑟𝑒sℎ𝑜𝑙𝑑

τ𝑧𝑜𝑛𝑒 =𝑀

𝑄

(1)

(2)

(3)

Source: Etheridge & Sandberg, 1996 33

Section 5

Conclusion

◼ Challenges and concerns in the future study

◼ Safety threshold:

• Irregular risks associated with airborne chemicals in the laboratory

• Safety versus energy saving

◼ Laboratory design:

• Simplified models versus complicated lab environments

• Selection/filter of key design parameters

◼ CFD simulations limitations:

• Huge number of scenarios - super computer (HPC) required

• Limitations of opportunities to validate CFD model with measurements

• LES simulation method to capture the unsteady nature of flow – computationally expensive

Source: Sweet & Stuart, 2013 35

HE Yueyang (Dr.), Department of Building, [email protected]

Daniel HII Jun Chung (Dr.), School of Design & Environment, [email protected]

WONG Nyuk Hien (Prof.), Department of Building, [email protected]

PECK Thian Guan (Dr.), Office of Safety Health and Environment, [email protected]

Thank you!

Questions
mailto:[email protected]:[email protected]:[email protected]:[email protected]

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