| Popis: |
In the present study, numerical method is used to investigate the exergy and energy characteristics of the air flow through tube banks which their arrangements are common inline or staggered. Furthermore, new arrangement called “twisted tube bank” is introduced and perused. Realizable K-ε model is selected for the investigation of the turbulence impact. The influence of dimensionless transverse and longitudinal pitches, Reynolds number, twist angle and dimensionless duct diameter on three objective parameters, COP, CEP and second law efficiency are analyzed. Equations are suggested for prediction of these three objectives parameters. Furthermore, a multi-objective method will be introduced and used to obtain the optimum cases of the geometrical and operational variables. Results indicate, if the Reynolds number is doubled, the CEP increases by 39.5% while, the second law efficiency and the COP reduce by 75.7% and 10.2%, respectively. Furthermore, it was realized, the application of the twisted tube bank is superior when the CEP and the second law efficiency are the objective parameters simultaneously while, for other multi-objects the inline arrangement is more appropriate. The optimum cases will be achieved at twist angle equal to 43° and 84°. |
