A Simplified Approach to Design Transverse Ribs Which Array Alternately in Rectangular Channel

Abstract

To identify optimum configuration of ribbed cooling channel, an experimental investigation is performed at the Reynolds number from 10300 to 26250, based on the hydraulic diameter of the rectangular passage with cross section 12 × 29 mm2. Despite the fact that the extended surface through rib array can enhance the heat exchange between the passage wall and the coolant flow, the rib array could also result in a large pressure loss due to the friction and obstruction of the ribs. This paper presents a simplified approach to optimize the ribbed passage configuration. Through the optimization, a ribbed channel with higher synthetical performance, a relatively higher heat transfer coefficient and lower pressure loss, can be obtained. In the experiments, the transverse ribs studied have 0.5mm rounded edges both at the root and end of the ribs, the ratio of the rib height to the hydraulic diameter of the passage ranges from 0.118 to 0.353, and the ratio of the rib pitch to the height ranges from 5 to 10. The experiments are carried out by two steps. At first, the ratio of the rib height to the hydraulic diameter of the passage is fixed, and the pitch of two neighboring ribs is changed. Through comparing the experimental results, an optimal pitch to height ratio is confirmed. In the second step, the optimal pitch to height ratio is fixed, while the rib height is changed. After integrally analyzing the experimental results obtained from the two steps, an optimal ribbed channel with higher synthetical performance is obtained. The result shows that the configuration with the ratios of p/e = 7.5 and e/Dh = 0.235 has the best synthetical performance. The experimental data of Rallabandi et al. (2009) are used to compare and validate the optimization approach, and the results are coincident. This approach can be used to simplify the design process of the ribbed passage, not only to experimental investigations but also to numerical analyses.