Partially metal foam wrapped tube bundle as a novel generation of air cooled heat exchangers

• Published in: International journal of heat and mass transfer 2018-03, Vol.118, p.171-181
• Main Authors: Alvandifar, N., Saffar-Avval, M., Amani, E.
• Format: Article
• Language: English
• Subjects: Aerodynamics; Extreme values; Fluid flow; Heat exchangers; Heat transfer; Heat transfer enhancement; Metal foams; Partially wrapped; Porous metal foam; Pressure; Pressure drop; Tube bank; Tubes
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2017.10.104

•Covering tubes of tube banks with a thin metal foam layer results in considerable enhancement in heat transfer in comparison to bare tube banks.•New arrangement leads to approximately the same Nusselt number compared to the fully wrapped tubes but the pressure drop reduces by 60%.•This arrangement of partially metal foam wrapped tubes bank has 50% foam usage reduction with respect to the fully wrapped foam tubes. Heat transfer and pressure drop for a tube bank with 5 rows of tubes wrapped by metal foam layers has been numerically studied. The results show that covering the tubes with a thin metal foam layer could result in substantial heat transfer enhancement in comparison to the bare tube bank. Moreover, it is indicated that metal foam wrapped tube banks could be considered as an effective alternative to finned tube banks because of their better performance. Pressure drop could be regarded as the main drawback of the metal foam wrapped tube banks. Therefore, introducing some new arrangements in which the tubes are partially covered by the foam layer is the most interesting results of the present study. By means of a new arrangement, approximately the same Nusselt number can be achieved compared to the fully wrapped tubes and at the same time the pressure drop reduces by 60%, area goodness factor increases by 33% and the amount of the foam usage decreases by 50% with respect to the fully wrapped foam tubes. This result would be extremely important for designing industrial heat exchangers with higher effectiveness and lower costs. It seems that these new arrangements can lead to the design of a new generation of air cooled heat exchangers.