NUMERICAL STUDY OF TURBULENT HEAT TRANSFER PROCESS IN DIFFERENT WAVY CHANNELS WITH SOLID AND PERFORATED BAFFLES

This study numerically investigated the effects of different baffle arrangements on heat transfer enhancement and flow in channels with different wave profiles. Four different wave profiles - rectangular, trapezoidal, triangular, and circular - were considered for the wavy channels. Analyses were made on the solid and perforated baffles that were installed vertically in the channel's central area to determine their hydrodynamic performance and convective heat transfer. Pressure-velocity coupling in discretized equations was handled with the SIMPLE algorithm, and analyses were carried out using the ANSYS Fluent solver. The standard <i>k-&epsilon;</i> turbulence model was used to solve the simulations. In this study, the channel geometry, the baffle arrangement, and the Reynolds number (4000 &le; Re &le; 12,000) were changed. The wavy surfaces were preserved at <i>T_&omega;</i> &#61; 360 K. The results were presented with different dimensionless parameters such as Nusselt number (Nu), friction factor (<i>f</i>), and thermal performance factor (TPF). Analyses indicated that the Nu number increased with increasing Re in all channel flows. In all wave profiles, the highest heat transfer was obtained in the solid baffle arrangement. The heat transfer increased by 2.12 times in the rectangular channel with solid baffle at Re &#61; 4000 compared to the channel without a baffle. The highest average Nusselt number and relative friction factor were obtained about 143.34 and 1.24, respectively, in rectangular profile with solid baffle at Re &#61; 12,000. The variation of the friction factor differed according to the wave profile and the baffle arrangement. The triangular profile with two-perforation baffles had the lowest TPF value, 1.09, and the rectangle profile with a solid baffle had the highest TPF value, 2.02. The results of the present study showed that the flow and heat transfer behaviors were similar in trapezoidal and circular channels.