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Varmevekslere
Dansk Gasteknisk Center, Hørsholm
Onsdag den 12. maj 2004, kl. 13:00 - 16:30
Som noget nyt er DANSIS vært for et par sandwich samt øl eller vand før mødet fra kl. 12.00 på Dansk Gasteknisk Center a/s. Muligheden er skabt for dels at give 'tilrejsende' mulighed for at få noget at spise før mødet, og dels at give alle andre mulighed for at netværke. Hvis du er interesseret i denne mulighed, så kræver det en speciel tilmelding direkte til Sekretær Hanne Møller-Andersen hos DGC via E-mail: hma@dgc.dk
Vigtige kendetal og relationer ved design af varmevekslere
Ph.D. Knud Erik Meyer, Lektor, MEK, DTU
Udformningen af varmevekslere er styret af den række grundlæggende relationer og fysiske begrænsninger. Forskellige krav til virkningsgrad, trykfald, materialeforbrug og fysisk størrelse kan medføre helt forskellige udformninger. Det er som regel nødvendigt at inddrage økonomiske overvejelser for at kunne vælge en optimal løsning. Der findes flere muligheder for at optimere varmevekslere ved f.eks. at skabe højere varmeovergang.
CFD in design and development of heat exchangers
Professor Bengt Sundén, Lund Institute of Technology/Lund University, Sweden
The rapid development of numerical solution methods for non-linear differential equations and advances in computers during recent years have gradually enabled predictions of flow and temperature fields as well as associated heat fluxes and stresses in engineering applications. However, turbulence modeling still presents a problem as accurate and reliable predictions of flow separation, reattaching, impinging and recirculating flow regions are required. In addition, experimental investigations are needed to verify the computations. Nevertheless in several circumstances numerical investigations might be useful supplements to experimental testing methods, e.g., in providing details of local phenomena and fundamental mechanisms. For heat exchangers both laminar and turbulent flows are of importance and in addition the geometry is commonly more or less complex and sometimes of small dimensions. This lecture considers current CFD methods including turbulence modeling, associated problems and limitations as well as providing examples of applications of CFD in a variety of heat exchanger problems. Narrow ducts of complex geometries will be of main concern. These will include wavy ducts, cross-corrugated surfaces, finned surfaces, louvered fin geometries and ducts with bumps.
Application of CFD in design of high performance compact heat exchangers
Mr. Frederik Strömer, CFD-Engineer, SWEP International AB, Sweden
The Compact Brazed Plate Heat Exchanger (CBE) have been used in industry for several decades. The most common pattern design in the plate heat exchangers is the so called herring bone pattern. This pattern is very cost efficient due to its high heat transfer performance, strength and its possibility for automatic manufacturing. Comparing CFD results with laboratory tests has given us confidence in the CFD accuracy regarding hydraulic performance. CFD simulations on heat transfer performance is now ongoing. The goal is to find methods with same accuracy and robustness as the hydraulic simulations.
Udfordringer i dimensionering af roterende regenerative varmevekslere
Mr. Niels Elmo Andersen, Udviklingsingeniør, B&W Energi A/S, Gentofte
Det grundlæggende princip bag de roterende regenerative varmevekslere (Ljungström-type varmevekslere) er meget simpelt med en roterende matrix, hvor den ene halvdel befinder sig i den gasstrøm der skal afkøles og den anden i den gasstrøm der skal opvarmes, og hvor varmen flyttes af den roterende matrix. I dag udføres disse varmevekslere med en rotordiameter på over 20 meter og med en matrixvægt på over 1000 tons. For at kunne designe disse varmevekslere har BWE udviklet et designprogram der løser de sammenhængende ulineære partielle differentialligninger. I indlægget gennemgås de forskellige typer der er udviklet for anvendelse i dampkedler og i røggasrensningsanlæg samt den måde de dimensioneres på.
DANSIS - The Danish Society for Industrial Fluid Dynamics     Email: dansis@dansis.dk