Effect of twisted turbulator perforated ratio on thermal and hydraulic performance of magnetic nanofluids in a novel thermal exchanger system

A novel evaluation criterion (exergy efficiency plot) for the comprehensive performance is developed and applied in a novel heat exchanger system with built-in perforated twisted turbulator. Effect of twisted turbulator with different perforated ratios on the exergy efficiency was explored and optimized experimentally. The results exhibited that with the increase of the perforated ratio, the thermo-hydraulic performance of the system will be improved slightly at first, and then the performance begins to decline after reaching the peak, until the perforated ratio reaches 100%, which is equivalent to no twisted turbulator. Further, the influence factors such as Reynolds number and magnetic field form were introduced to regulate the thermo-hydraulic performance of the system. It was indicated that the rising Reynolds number and vertical magnetic field play a positive role in improving the performance of the system, and the change of Reynolds number will also lead to the migration of the perforated ratio corresponding to the best performance. Moreover, in this study, the exergy efficiency method was adopted to analyze the comprehensive characteristics of each experimental case, and it was found that the heat transfer efficiency of the system has been significantly improved.