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Designing equipment by using CFD Benefits and pitfalls. Geert Janssen Advanced Thermal Transfer Equipment A2TE. CFD - Phoenics. CORA2 – graduate studies Phoenics user since 1985 Analysis Flow in intake manifolds of IC engines Flow & heat transfer process industry Design from 1990
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Designing equipment by using CFDBenefits and pitfalls Geert Janssen Advanced Thermal Transfer Equipment A2TE
CFD - Phoenics • CORA2 – graduate studies • Phoenics 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 CFD • Better understanding • Flow • Heat transfer • Mass transfer • Chemics • Sensitivity analysis • Priceworthy • fast
Why limited CFD usage • Long learning curve • Specialists required • Jargon • physics insight and knowledge ? • Standard rules from handbooks? • Design <-> modelling • Communication skills
Example - 1 • Oven • Perforated plates • Flow distributors
Example - 2 • Molten metal in tundish • Target • Continuous casting • No slag inclusions • No bubbles
Tundish • Symmetric inflow • Steady state ? • No match with experimental data • Blame on CFD?
Designing equipment & CFD • Rules of thumb • Standard textbooks • Some understanding of physics • CFD ‘tricks’ • Designers skills or strong interaction with designer
Example 3 - ageing oven • Continuous belt oven • Base of lamp (automotive) • 3 lanes: 3 x 800 pcs/hr • Heating to 200°C and holding for 4 hrs • Cooling to 50°C • Floorspace approx. 5 m2 • Temperature differences < 5°C
Ageing 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 - 6 • CFD model took 3 days • Conceptual design 2 weeks
Example 4 curing oven • Contact lenses • Automated process • Polypropylene: 95°C ± 3°C • At least 15 minutes at 92°C (minimum) • Heating up in 10 – 12 minutes • Aluminium trays, 1300 grams • 1 tray in 40 seconds
Curing 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 • Conclusions from tray calculations • Required air-inlet temperature > 105°C
Curing oven – CFD model • CFD models: 2 weeks • Conceptual design 4 weeks
Conclusions • Use of CFD can be very profitable • Often CFD alone does not ‘do the trick’ • Handbooks • Rules • Experience