Performance analysis of cylinder type turbulators in heat exchangers

Turbulator is used in heat exchangers to enhance heat transfer rates from the fluids by increasing the contact surfaces of the fluids by increasing the turbulence flow. More contact surfaces are necessary for effective heat transfer, particularly in applications requiring high productivity and capabilities. By using turbulators, the maximum energy gain can be achieved, leading to high efficiency rates and lower costs. In this study, different turbulators are placed in the inner tube of the heat exchanger, which consists of concentric outer and inner pipes, within the scope of increasing the heat transfer. In the heat exchanger, steam was applied to the outer pipe at a temperature of 98°C, and to the inner pipe with the help of the compressor, the air flow was applied in a parallel and same direction at different speeds. The contribution of the cylindrical turbulator to the energy efficiency of the heat exchanger was investigated. Heat transfer performance was analysed in the case of placing Type-A (rod) and Type-B (wing) cylindrical turbulators placed on a 1 m-long shaft with 15 cm steps using the experimental setup. In the experimental setup, the inlet and outlet temperatures of the heat exchanger were measured at various speeds using Type-A and Type-B cylindrical turbulator and without turbulator (empty) conditions by using thermocouples via data logger. It has been observed that the highest temperature difference occurs when turbulator Type-B is used. Compared to the empty (without turbulator) condition, it was observed that maximum temperature differences were reached with a %28 increase at 2,5 m/s speed in the case of using Turbulator Type-A, and %118 increase at 3 m/s speed in the case of using Turbulator Type-B. It has been observed that the average temperatures are close to each other in case of Type-A turbulator is used and without turbulator, while the average temperature is higher at 1 m/s and above air flow rates when Type-B turbulator is used. It was observed that the highest Nusselt number were reached with a %32 increase at 2,5 m/s speed in the case of using Turbulator Type-A, and %157,9 increase at 3 m/s speed in the case of using Turbulator Type-B, compared to the empty (without turbulator) condition. The highest hm heat transfer coefficient increase rate was reached at Reynolds 11423 for Turbulator Type-A as %32,5 and at Reynolds 13899 for Turbulator Type-B as %157,9, compared to the empty inner pipe condition. In the case of using Type-A and Type-B turbulators, it was observed that the heat transfer amount and effectiveness rate were higher than the case without a turbulator in all of the determined Reynolds values. In the case of using Turbulator Type-B in all Reynolds values, the highest heat transfer amount and effectiveness rate were reached with a significant increase. It has been observed that the use of turbulators increases the heat transfer and the Type-B turbulator has a significantly better heat transfer performance than the Type-A turbulator, in all conditions.