Empirical Pressure Drop Behavior of Oil-based Al₂O₃–MWCNT Hybrid and Al₂O₃ Nanofluids in Double-Pipe Heat Exchanger

The use of nanofluids for enhancing heat transfer has attracted significant attention in recent years; however, the increase in pressure drop remains one of the major challenges in their application. In this study, the pressure drop variations of a hybrid nanofluid Al₂O₃–MWCNT–thermal oil and a single nanofluid component Al₂O₃–thermal oil was experimentally investigated and compared. The nanofluids were prepared by dispersing MWCNT and Al₂O₃ nanoparticles in the base oil and stabilizing them using an ultrasonic device. Experiments were conducted at weight concentrations of ۰.۱%, ۰.۳%, ۰.۵%, ۱%, and ۱.۵% inside a tube with an inner diameter of ۱۱.۲۳ mm, under laminar and transitional flow conditions at three volumetric flow rates of ۷.۶, ۱۱.۳, and ۲۴.۶ L/min. The results indicated that for the hybrid nanofluid, the ۰.۱% weight concentration exhibited the smallest pressure drop at both low and high flow rates, while no significant change was observed at the intermediate flow rate. Conversely, the highest pressure drop occurred at a concentration of ۱.۵%, due to increased viscosity. Furthermore, the single nanofluid demonstrated better performance compared to the hybrid nanofluid, as a reduction in pressure drop was observed at all concentrations and at both low and high flow rates, attributed to the rolling and anti-friction effects of the nanoparticles. The maximum recorded pressure drop corresponded to the hybrid nanofluid with a ۱.۵% weight concentration at the intermediate flow rate, amounting to a ۲۶% increase.

کلیدواژه ها:

Experimental analysis ، Pressure drop ، Hybrid nanofluids ، Aluminum oxide ، MWCNT ، Thermal oil