Designing equipment by using Designing equipment by using CFDCFD

Benefits and pitfallsBenefits and pitfalls

Geert JanssenAdvanced Thermal Transfer Equipment

A2TE

CFD - PhoenicsCFD - Phoenics

CORA2 – graduate studiesPhoenics user since 1985

– Analysis• Flow in intake manifolds of IC engines• Flow & heat transfer process industry

– Design from 1990• Heat transfer equipment

– Ovens and furnaces

Applied CFDApplied CFD

Better understanding– Flow– Heat transfer– Mass transfer– Chemics

Sensitivity analysisPriceworthyfast

Why limited CFD usageWhy limited CFD usage

Long learning curveSpecialists required

– Jargon– physics insight and knowledge ?– Standard rules from handbooks?

Design <-> modelling – Communication skills

Example - 1Example - 1

OvenPerforated plates

– Flow distributors

Example - 2Example - 2

Molten metal in tundishTarget

– Continuous casting– No slag inclusions– No bubbles

TundishTundish

Symmetric inflowSteady state ?No match with

experimental dataBlame on CFD?

Designing equipment & Designing equipment & CFDCFDRules of thumbStandard textbooksSome understanding of physicsCFD ‘tricks’Designers skills or strong

interaction with designer

Example 3 - ageing ovenExample 3 - ageing oven

Continuous belt ovenBase of lamp (automotive)3 lanes: 3 x 800 pcs/hrHeating to 200°C and holding for 4

hrsCooling to 50°CFloorspace approx. 5 m2

Temperature differences < 5°C

Ageing oven - 2Ageing oven - 2

Heat transfer and pressure drop from packed bed relations

Required velocities through belt– Heating section– Cooling section

Fan in holding section identical to those of other sections

Ageing oven - 3Ageing oven - 3

Ageing oven - 4Ageing oven - 4

Ageing oven - 5Ageing oven - 5

Ageing oven - 6Ageing oven - 6

CFD model took 3 daysConceptual design 2 weeks

Ageing oven - Ageing oven - 77

Ageing oven - Ageing oven - 88

Example 4 curing ovenExample 4 curing oven

Contact lensesAutomated processPolypropylene: 95°C ± 3°CAt least 15 minutes at 92°C

(minimum)Heating up in 10 – 12 minutesAluminium trays, 1300 grams

– 1 tray in 40 seconds

Curing oven - trayCuring oven - tray

Curing oven - analyticalCuring oven - analytical

Calculation of required heat transfer coefficient (mass – time)

High value needed (75 Wm-2K-1)Multiple jets

One heat-up zone– Costs (fan, controller, cabinet)

Curing oven - trayCuring oven - tray

Curing oven - trayCuring oven - tray

Curing oven - trayCuring oven - tray

Curing ovenCuring oven

Conclusions from tray calculations– Required air-inlet temperature >

105°C

Curing oven – cross Curing oven – cross sectionsection

Curing oven - power Curing oven - power changechange

Curing oven - belt levelCuring oven - belt level

Curing oven – CFD modelCuring oven – CFD model

CFD models: 2 weeksConceptual design 4 weeks

ConclusionsConclusions

Use of CFD can be very profitableOften CFD alone does not ‘do the

trick’– Handbooks– Rules– Experience