Integerated optimization and advanced thermal assesment of nanofluid-assisted and dimple-enhanced shell-and-tube heat exchangers

This study investigates the combined impact of CuO-water nanofluids and teardrop-shaped dimples on the hydrodynamic and thermal performance of shell-and-tube heat exchangers (STHEs). Three STHE configurations, differing mainly in their length and number of baffles, are analyzed using a segment-by-segment approach within the P-NTU framework. Water is used as the base fluid on both tube and shell sides to accommodate nanoparticle suspensions of 0% mass fraction, 1% mass fraction, and 2% mass fraction CuO. The results highlight that a 1 wt% concentration strikes an optimal balance, enhancing thermal conductivity up to 24% while minimizing pumping-power penalties. Incorporating teardrop dimples on the tube surface significantly increases heat transfer, about 116%, but also results in higher tube-side pressure loss. However, combining dimples with nanoparticles yields only marginal additional improvements beyond those provided by dimples alone. Performance evaluation criteria ( PEC ) are employed to weigh thermal gains against aerodynamic losses. Moreover, while enlarging the heat exchanger by increasing its length and number of baffles may improve the thermal performance, it leads to a considerable rise in weight and size, which is often a critical feature in aerospace and other weight-sensitive applications. Overall, the study provides practical insights for optimizing STHE design by implementing an enhanced balance between heat transfer improvement and fluid flow penalties.