Details

Autor(en) / Beteiligte

• Unger, Sebastian
• Beyer, Matthias
• Szalinski, Lutz
• Hampel, Uwe

Titel

Thermal and flow performance of tilted oval tubes with novel fin designs

Ist Teil von

• International journal of heat and mass transfer, 2020-06, Vol.153, p.119621, Article 119621

Ort / Verlag

Oxford: Elsevier Ltd

Erscheinungsjahr

2020

Link zum Volltext

Quelle

Elsevier ScienceDirect Journals Complete

Beschreibungen/Notizen

• •Heat exchangers with novel additive manufactured fins were devised, fabricated and experimentally studied for different tube tilt angle.•Nusselt number is higher for both novel heat exchanger designs compared to the conventional heat exchanger and increases with tube tilt angle.•The serrated integrated pin fin design gives the best.•Highest volumetric heat flux density was achieved for the circular integrated pin fin design with highest tube tilt angle.•The global performance of the finned oval tubes depends on the fin design, the Reynolds number and the tube tilt angle.•Correlations for the heat transfer from the novel heat exchangers were proposed for different tube tilt angle. We studied the thermal and flow performance of tube heat exchangers with novel fin designs for tube tilt angles of 0°, 20°, 30° and 40° to the horizontal. The novel fin designs target to enhance the conduction heat transfer within the fin and the convective heat transfer along the fin surface simultaneously. Tubes with three different fin designs, the circular plain fin (CPF), the circular integrated pin fin (CIPF) and the serrated integrated pin fin (SIPF), were additively manufactured by selective laser melting and experimentally investigated in an air flow channel for Reynolds number between 1800 and 7800. We analysed the performance evaluation criterion, the volumetric heat flux density and the global performance criterion. It was found, that the SIPF achieves highest performance evaluation criterion and the CPF performs worst. Thus, the SIPF is recommended, when the required surface area, the material cost and the weight of the finned tube heat exchanger are relevant. Highest heat transfer per volume heat exchanger and temperature difference was achieved for the CIPF at highest tube tilt angle. The value of the global performance criterion strongly depends on the fin design and the tube tilt angle. For the horizontal orientation the CPF reaches highest global performance and for the 40∘ tube tilt angle the CIPF gives best performance. From the experimental data we derived appropriate heat transfer correlations for Reynolds number, Prandtl number, tube tilt angle and fin designs.