Thermo-hydraulic performance of nanofluids flow in various internally corrugated tubes

This study examines the impact of corrugation configuration on the thermal, hydraulic, and overall energy performances of nanofluid flows in corrugated tubes. Different fluids (distilled water "DW", GNP-SDBS/DW, Al2O3/DW, and SiO2/DW) and tube geometries (rectangular, triangular, trapezoidal, and curved ribs) are investigated using a carefully validated computational fluids dynamics (CFD) model. Compared to DW flow in a smooth tube, the maximum overall performance improvement (similar to 37 %) was found in the case of GNP-SDBS/DW nanofluid flow in a curvedly ribbed tube at Re of 10,000. For all fluids and tube geometries, the overall performance enhancement was found to decrease at Reynolds numbers higher than 10,000. Curvedly ribbed tubes have better performances at medium and high flow rates, regardless of the fluid type. However, at low flow rates or when the pumping power consumption is not a major concern, trapezoidal ribs can be used to achieve higher heat transfer rates. Overall, using corrugated tubes (maximum performance improvement of similar to 20 %) was found a more energy-efficient technique than using nanofluids (up to similar to 11 %). Combining both techniques achieves enhances the performance by up to similar to 37 %. These findings can be used as a guide for determining the most suitable technique based on an overall techno-economic evaluation.