ES410 Air Quality: smoke control

Development of an intelligent, real-time smoke control system

1

Project Goal

“To develop an intelligent, real-time sensor control framework that will detect, monitor

and control the development of smoke propagation throughout an office

environment”

2

Project Objectives

• Create a physical test rig to perform testing on

• Simulate propagation of flow using CFD

• Draw Conclusions from CFD

• Use to develop responsive sensor control system

Experimental Data

Fluid Theory

Simulations

Control System

3

Management Structure

• Project Manager throughout the project for stability.

• Project Leader changing every few weeks to give everyone experience.

• Specific dynamics of individuals within the team allowed it to work.

4

Work Breakdown Structure

5

Network Diagram

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Gantt Chart

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SMOKE

SmokeRegulationsExisting Systems

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Smoke

• Hot Gases and Particulates

• Variable Toxicities and Density

• Transmits Heat via Convection

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Smoke Effects

• Deaths

• Non Fatal Casualties

• Reduced Visibility

Inhibit ability to escape

Increases difficulty for firefighting

• Generate Flashover Conditions

• Property Damage

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Regulations• Building Regulations

Part B

• British Standards• Design Guidance

e.g. CIBSE Guide E• Continuing Research

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Smoke & Heat Extraction Ventilation - SHEV

Morgan H P, Smoke control methods in enclosed shopping complexes of one or more storeys: a design summary, BRE, 1979 12

Pressure Differential Systems

• Stairwell kept at higher pressure than floors

• Prevents smoke spreading into stairwell

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Smoke Containment

Morgan H P, Smoke control methods in enclosed shopping complexes of one or more storeys: a design summary, BRE, 1979

Example of a Smoke Curtain

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TEST RIG DESIGN

DesignScaling

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Reason for use of Test Rig

Simulation models needed to be validated by experimental data.

“For many phenomena [such as turbulence] the exact equations are either not available or [a] numerical solution is not feasible.” Ferziger and Perić , Computational Methods for Fluid Dynamics

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Test Rig Specification•Modular to allow various configurations of floors, walls, partitions, and inlets.

4 Outlets

6 Inlets17

Test Rig Specification1. Heating Box2. Hot Plate3. Perspex Box4. Laser Sheet5. Inlet & Outlet Fans6. Fan Power Supply7. Laser Lenses

Inlet & Outlet Fans 18

Scaling Equations

Dynamic SimilarityReynold’s Number, Re

Heat Transfer SimilarityGrashof Number, Gr

LUmRe

3

2

( )Sg T T LGr

Um = Mean VelocityL = Characteristic Lengthν = Kinematic Viscosityg = Acceleration due to Gravityβ = Volumetric Thermal Expansion CoefficientTS = Source TemperatureTinf = Quiescent Temperature 19

Scaling Results

Reynold’s NumberOffice value 20x larger than test rig value1 Order of Magnitude

Grashof NumberOffice value 100x larger than test rig value2 Orders of Magnitude

Re

Gr

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SENSOR SYSTEM

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Measurement: Sensory data used for analysis.

Control: Sensory data used to provide feedback to control system tocontrol smoke behaviour.

Sensors

Control PCControl Laws Smoke Behaviour

Closed Loop Control

Ventilation+ -

Feedback leads to a dynamic system which reacts to the smoke in real time

Control & Measurement System

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Temperature Sensors

MCP9701A±2°C Absolute Accuracy±1°C Relative Accuracy (25°C)Can drive large capacitive loadsLinear response – direct ADC connection

Smoke Sensors

Custom madeOptical attenuation880nm wavelengthMeasures relative smoke density

1) Phototransistor (Receiver)2) IR LED (Emitter)3) Transparent windows4) Smoke slot5) Casing

Sensory Array

Smoke Sensor

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40mm Brushless DC fansComplimentary pairs

Fan Control Circuitry

Low Pass Filtered PWM2 Pole FilterDC onlyDiode protected MOSFETLow side control

Ventilation

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I2C Bus

Control PC

RS232

Microcontroller(I2C Master)

InletFan

OutletFan

TempSensor

SmokeSensor

Microcontroller(I2C Slave)

InletFan

OutletFan

TempSensor

SmokeSensor

System Block Diagram

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Packet Formatted Communications Protocol

SmokeTalk

$ Destination{1 Byte}

Destination Port

{1 Byte}

Source{1 Byte}

Source Port{1 Byte}

Type{1 Byte}

Control{1 Byte}

Data{2 Bytes} \r\n

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CONTROL SYSTEM

PurposeDesignGeneral Operation

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The Control System

• Purpose

– What

– Why

– How

• Design

– What

– Why

– How28

Purpose

• What – A PC client that sends and receives data through a serial port

• Why – To more effectively control smoke

• How – By taking measurements and following a set of control laws

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Design

• What – A Java application interfacing with the Master micro-controller via SmokeTalk

• Why – Fast development, great flexibility

• How – A scalable, modular, responsive Java application

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General Operation

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EXPERIMENTAL RESULTS

PIV Results & AnalysisSensor Results & Analysis

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Particle Image Velocimetry

Figure 1: PIV setup. Source: Dr P Dunkley, University of Warwick.33

Figure 4 - Inlet PIV Vector Plot

• Inlet and wall positions

• Velocities

• Wall interactions

• Vortex shedding (video)

Figure 5 - Outlet PIV Vector Plot

• Outlet and wall positions

• Lower velocities

• Recirculation (video) 34

Inlet Particles

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Inlet Velocity Vector

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Outlet Particles

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Outlet Velocity Vector

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Averaged Cell 1 Smoke Density Comparison with varying fan condition

0

20

40

60

80

100

120

140

-10 -8 -6 -4 -2 0 2 4 6 8Smoke Reading (Volts)

Tim

e S

tep

(s)

4 Calibrations (----) 4 Inlets (BBBB) 4 Outlets (SSSS)

Figure 6: Averaged cell 1 smoke density comparisons with varying fan conditions

• Calibration Condition = all fans off

• Smoke movement through individual cells through turbulence and pressure differences

• Relative positioning of fans and sensors

• Both fans and sensors work as desired39

Average Smoke Readings in rig with varying fan arrangements

0

20

40

60

80

100

120

140

160

-20 -15 -10 -5 0 5 10 15 20

Smoke Reading (Volts)

Tim

e S

tep

(s)

Av BBBB Av BBSS Av BSBB Av BSBS Av Calibration Av SBSB Av SSSS

Figure 7: Average Smoke Reading in rig with varying fan arrangements

• Pressure condition – inlets and outlets

• Relative position and arrangement to inlet 40

Average Rig Smoke Readings with Varying Setups

0

10

20

30

40

50

60

-10 -5 0 5 10 15

Smoke Reading (Volts)

Tim

e S

tep

(s)

Without Floor With Floor Floor and Partitions

Figure 8: Average Smoke Reading in rig with varying setups

• Barriers to movement

• Levels of circulation

• Smoke Screen effects

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SIMULATIONS

CCM+Simulation ResultsAnalysis

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Simulation Summary

• The need for CFD• Star CCM+• CFD Solvers• Results and Analysis:

– PIV vs CFD– Phase 1– Phase 2– Phase 3

• Further Work

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The Need For CFD

• Inconsistent environment in physical rig• Stable and versatile environment• Able to visualise the Propagation• Accurate Temperature Plots• Scalable Model

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The Simulation Testing Plan

• Systematic Approach• Broken into Phases• Create an animation

for each

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Star CCM+

• Powerful CFD software• Allows us to use exact Solid Works CAD

drawing• Use of an unsteady Solver

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CFD Solvers

• Implicit Unsteady allows us to:– Observe a time-step solution– High Accuracy over Explicit

• Spalart-Allmaras turbulence model allows us to:– Observe detailed Detached Eddy formations– Create accurate at-wall viscous effects

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Results And Analysis:PIV VS CFD

• Similar wall-effect

• Similar re-circulation

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CFD Results

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Phase 1

• Aim – choose the ideal fan configuration when a fire starts in the corner of a room.

• Method – Run simulations on possible fan configurations

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Fan 1 as an Inlet

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Best fan configurations

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Best fan configurations (cont)

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Phase 2

• A best fan configuration was not found due to incomplete simulations.

• Comparisons between phases 1 and 2 possible.

• Detailed look at the temperature changes in the room.

• More difficult problem than in phase 1.

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Phases 1 and 2 Comparison

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Scalar Temperature Animation

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Phase 3

• Shows dynamic similarity between test rig and scaled room.• Further tests need to be done on good fan configurations

from small scale simulations.

0.5m 3.0m

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Further work

• Phase 4 – Simulations on realistic room• Introduction of partitions and screens• Multiple storeys• Seeing the effects of including the ducting

system in the simulations• Run simulations for much longer

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ARCHITECTURAL INTEGRATION

Full Scale SystemBuilding Control

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Full Scale System

Standard Room

Supply Fan

Extract Fan

(SHEV)

Normal Balanced

Ventilation

Sensor Network Fire Rated Data Cable

Protected damper control and power supply cables

Protected fan control and power supply cables

SmokeControlSystem

Power Supply

Linked Systems

Fire Alarm & Notification

System

Other Fire Related Control Systems

Fire Data Output to Emergency Services

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Building ControlFailsafe Smoke and Fire Rated

Control Dampers

Standard Supply Ventilation Plant

Smoke and Fire Rated

Extraction Ventilation Ductwork

Supply Ventilation Ductwork

Smoke and Fire Rated

Control Dampers

Fire Rated Ceiling Ventilation Grilles

High Temperature Smoke Heat Extraction Ventilation Unit

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CONCLUSIONS

Continued DevelopmentConclusions

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Continued Development

• The project is useful and viable• Minimising losses to human life as well as

financial losses for companies is an important area

• Laid the Foundations• Already evidence of interest• Other Avenues

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Conclusions

• Project an overall Success• Dynamic Similarity between the test rig scale

and life size• CFD analysis provided an intelligent response• The system provides an intelligent response to

detected environmental changes

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Thank You For Your Attention

Questions Please?

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