climate control and hvac simulation for occupied...

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Climate control and HVAC simulation for occupied spaces Implementation and validation

Eugene de Villiers

22.06.2010

5th OpenFOAM Workshop, Chalmers, Gothenburg, Sweden, June 21-24, 2010

Copyright © 2010 Engys Ltd. All rights reserved.

Contributors

• Engys Ltd., London, UK

Dr. Eugene de Villiers, [email protected]

Dr. Andrew P. Jackson, [email protected]

Francisco Campos, [email protected]

• Engys UG, Rostock, Germany

Thomas Schumacher, [email protected]

• Beuth Hochschule für Technik Berlin, Germany

Thomas Tian, [email protected]


mailto:[email protected]







Content

• Introduction to Engys

• CFD for HVAC

• HVAC with OPENFOAM®

Basic approach

Validation cases

Examples

• Future Work


OPENFOAM® is registered trade mark of OpenCFD Ltd.

Company Details

• Offices: UK and Germany

• Open Source software for industrial application

• Offering OPENFOAM related services

Consultancy

Training

Support

Custom development


CFD for HVAC


Turbulent flowConvective heat transfer

BuoyancyThermal radiation

Solar radiationHumidity / CondensationContaminant transport

Comfort predictionPhysiological modellingConjugate heat transfer

Built environment

Transportation

Component cooling

Manufacturing

HVAC in FOAM | Basic Approach

• Incompressible flow solver

RANS, URANS, LES

• Integrated properties for incompressible

• r, a, Prt, Cp,

Temperature transport

• Thermal wall functions

• Kader, Jayatilleke

Boussinesq approximation for buoyancy


xgpPp

TTTgS

mref

mmmmb

r

rrrr

HVAC in FOAM | Basic Approach (cont.)

• Radiation

Customised non-participating grey FVDOM

• Implemented as function object

• Reduced memory consumption by ~30%

• 1st order explicit marching-front solver

• 5 -10x faster

Solar radiation function object

Temperature coupled boundaries

• Iterative solution of Tw ,Tw

Qconv + Qrad-e = Qsolid + Qrad-a + Qlatent + Qsolar


HVAC in FOAM | Basic Approach (cont.)

• Passive scalar transport

Humidity, smoke, contaminants

Surface condensation/evaporation

• Droplet area model

• Latent heat thermal coupling

• Comfort assessment

ISO 7730 → PMV, PPD, DR, PD

Age of air

ISO 14505-2 → Equivalent temperature

16 zones human model


Validation | Natural Convection

• Experiments by Betts and Bokhari (2000)

• 2D closed vertical cavity

• Ra = 8.6 ∙ 105


x

yW=0.076m

H=

2.1

8m

HOT WALL

T = 34.7ºC

COLD WALL

T = 15.1ºC

Vertical velocity: Uy

Validation | Natural Convection (cont.)

• Experiments by Betts and Bokhari (2000)

• 2D closed vertical cavity

• Ra = 8.6 ∙ 105


x

yW=0.076m

H=

2.1

8m

HOT WALL

T = 34.7ºC

COLD WALL

T = 15.1ºC

Temperature: T

• Experiments by Restivo(1979)

• 2D rectangular cavity

• Reh = 5000

Validation | Forced Convection


INLET→ U0 = 0.455m/s

h = 0.168m

OUTLET

t = 0.48m

L=9m

H=3m

x

y

Ux/U0 @ X=3m



• Reh = 5000

Validation | Forced Convection (cont.)



h = 0.168m

OUTLET

t = 0.48m

L=9m

H=3m

x

y

Ux/U0 @ X=6m



• Reh = 5000

Validation | Forced Convection (cont.)


Y = 0.084m

Y = 2.916m


h = 0.168m

OUTLET

t = 0.48m

L=9m

H=3m

x

y

• Experiments by Blayet.al (1992)

• 2D square cavity

Validation | Mixed Convection


INLET

U = 0.57m/s

T = 15ºC

h = 0.018m

OUTLET

t = 0.024m

H = L = 1.04m

x

y

FLOOR

T = 35.5ºC

WALLS

T = 15ºC

Temperature @ X=L/2

• Experiments by Blayet.al (1992)

• 2D square cavity

Validation | Mixed Convection (cont.)


Y = H/2

INLET

U = 0.57m/s

T = 15ºC

h = 0.018m

OUTLET

t = 0.024m

H = L = 1.04m

x

y

FLOOR

T = 35.5ºC

WALLS

T = 15ºC

Temperature @ Y=H/2

Validation | Standing Manikin

• Experiments by Nielsen, Kato, Yang et.al (2003)

• Displacement ventilation

• Supply → U = 0.182m/sT = 21.8 °C

• Manikin → Q = 76W


Validation | Standing Manikin (cont.)

• Air temperature profiles


Validation | Standing Manikin (cont.)

• Thermal radiation effects


Radiation OFFRadiation ON

Example | Aircraft Cabin and Cockpit

• Mixed ventilation

• Buoyancy

• Thermal Radiation

• Solar radiation


Example | Generic Aircraft Cockpit

• Windshield defogging

Initial liquid water content on windshield evaporated by dry, hot air from windshield air inlet


Example | Generic Aircraft Cockpit (cont.)

• Smoke evacuation

Transient flow, passive scalar for smoke


Example | Classroom Ventilation

• Comfort assessment → PMV, PPD


Future

• Transient conjugate heat transfer

Face based 1D solid modelling

Automatic 3D thin-solid modelling

• Self-scaling surface-to-surface radiation

• Human physiological models

Coupled multi-node, sweating/shivering

• Smoke

Source modelling

Visibility index


Acknowledgements

• Thanks to Dr. J-H Yang (Yeungnam University) for providing the standing manikin geometry

• Thanks to Dr. A Musser and Dr. K McGrattan for providing experimental results for Blay’s 2D cavity


Disclosure


The contents of this document may not be copied, reproduced,translated, transferred, or reduced to any form, in whole or in part,including electronic medium or machine-readable form, ortransmitted or publicly performed by any means, electronic orotherwise, without written authorisation issued by Engys.Unauthorised distribution or use may give rise to a claim fordamages and/or be a criminal offence as subjected to the laws ofEngland, Scotland and Wales.

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