A NUMERICAL INVESTIGATION OF FLOW STRUCTURE AND HEAT TRANSFER ENHANCEMENT IN SQUARE RIBBED CHANNELS WITH DIFFERENTLY POSITIONED DEFLECTORS

Square cross-section ribbed channels with deflectors are computationally simulated to determine their optimal configuration for enhancing heat transfer with minimized pressure drop penalties. In this study, the channel inlet Reynolds number ranges from 8,000 to 24,000. The influence of deflector arrangement on the overall performance characteristics of ribbed channels is investigated with six different cases; i.e., one case of an array of seven continuous ribs mounted on one wall with a pitch ratio of P/e = 10 and the other five cases with deflectors installed on side walls that are designed to determine the most optimal performance. The details of turbulent flow structure, temperature fields, local heat transfer, pressure drop, normalized heat transfer, and normalized friction factor are obtained using the v(2)f turbulence model, and the thermal boundary conditions are appropriately set on all surfaces. The conjugate heat transfer methodology is also used to simulate the ribbed channels with deflectors. The overall performances of the six tested ribbed channels are evaluated and compared. Numerical results show that the usage of deflectors can modify or improve the local flow structure and thereby the local heat transfer. The heat transfer and friction characteristics are affected by the deflector location. Compared with the ribbed channel without deflectors, the reasonable configurations of the ribbed channel with deflectors yield better heat transfer. In all cases, Case D, in which the deflectors are positioned above and close to the ribs and the distance from the bottom wall is 20 mm, presents the most prominent effect on the heat transfer enhancement and thermal enhancement factor.