3.2 The influence of rib configurations

Seven configurations of rib trapezoidal corrugated channels are denoted (B1, B2, C1, C2, C3, D1, and D2) which are presented in Figure 4a. Also, the smooth channel is indicated by A. The variation of the Nusselt number for all channels is depicted in Figure 4b. The increase in Re and flow velocity causes enhancement in mixing the

Figure 4.

(a) Different configurations of corrugated channels and the influence of rib configuration on Nu, f, and PEC as depicted in (a), (b), and (c), respectively, for the different values of Re.

### Thermal-Hydrodynamic Characteristics of Turbulent Flow in Corrugated Channels DOI: http://dx.doi.org/10.5772/intechopen.84736

rate between the core flow and recirculating flow. Thus, the heat exchange between the heating wall and the flow is enhanced. On the other hand, f is higher for corrugated channels than the smooth one as revealed in Figure 4c. In one side, the results revealed that the heat is transferred more effectively in the corrugated channel than the smooth one due to the additional surface area, suppressing the boundary layer thickness associated with corrugated channels. On the other side, the corrugation results in a substantial flow recirculation and separation and an extra surface area, and thus it creates higher pressure drop. The corrugated channel C1 registers the highest Nu, while the minimum Nu is achieved for corrugated channel B1. Conversely, the results exhibit that the minimum pressure drop is registered for B1 configuration channel among other corrugated channels. Moreover, the influence of rib configuration of corrugated channels on the PEC is presented in Figure 4d. The results reveal that there is a monotonic decrease of PEC with the Re. The optimum performance is accomplished at the lower Re. As Re increases the conflict between the augmentation in thermal performance and degradation in pressure drop is initiated. The higher values of PEC are obtained for C3 and B1 corrugated channels, whereas D1 and D2 configurations have the minimum values of PEC.

Figure 5. Nu, f, and PEC for different (a) rib heights, (b) rib pitches, and (c) rib widths.

minimum friction factor, while the ICC owns a maximum pressure loss. Moreover,

Seven configurations of rib trapezoidal corrugated channels are denoted (B1, B2, C1, C2, C3, D1, and D2) which are presented in Figure 4a. Also, the smooth channel is indicated by A. The variation of the Nusselt number for all channels is depicted in Figure 4b. The increase in Re and flow velocity causes enhancement in mixing the

(a) Different configurations of corrugated channels and the influence of rib configuration on Nu, f, and PEC as

depicted in (a), (b), and (c), respectively, for the different values of Re.

the performance evaluation criterion (PEC) varies inversely with the Re as exhibited in Figure 3c. The increase in pressure loss exceeds the enhancement in the heat transfer for all corrugated channel layouts. Also, OCC has higher PEC than both IOCC and ICC channels. This is due to the increase in f of OCC is lower than that of ICC and IOCC. Even though, both ICC and IOCC have higher Nu than IOCC.

Boundary Layer Flows - Theory, Applications and Numerical Methods

3.2 The influence of rib configurations

Figure 4.

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