Numerical simulation of flow and heat transfer characteristics of nanofluids in built-in porous twisted tape tube

For enhancing the heat transfer efficiency of heat exchanger, silica-water (SiO2-H2O) nanofluids were used as a working medium in this study. Further, the effects of tube structure, twisted tape hole spacing, and hole shape on the flow and heat exchange characteristics of nanofluids in the tube were systematically researched by numerical simulation. The results displayed that a triangular tube exhibited larger flow resistance, better heat transfer effect and more comprehensive performance compared to the round tube. The conclusion also showed that the highest comprehensive evaluation index (PEC) was obtained by producing open circular holes on the twisted tape. The usage of porous twisted tape, nanofluids, and triangular tube could significantly improve the system economy and enhance the heat exchange ability. At the same time, the flow in the tube was disordered and accompanied with the increase in entropy. The maximum improvement of heat exchange efficiency of nanofluids in round tube and triangular tube with porous twisted tape was 74.80 and 55.97%, respectively.