Performance characteristics of heat exchanger with internal turbulence generators under various blade configurations and operating conditions

In this study, turbulence generators with rectangular geometry were designed to be fixed inside the tube of an oil cooler for the hydraulic steering of automobiles and their performance characteristics in the heat exchanger were investigated. The heat transfer rates, heat transfer coefficients, the coefficient of the pressure drop values, and friction factors were measured in accordance to the flow rates and inlet temperature of the oil. The resulting Nusselt numbers (Nu) increased when the angle of the turbulence generator wings was increased up to 45–65° but decreased when the angle was increased further up to 75°. On the hand, the friction factor (f) continued to increase as the angle configuration was increased. The highest value of the thermal performance enhancement factor (TEF), which was 6.46, was obtained from the turbulence generator angle of 45°, which could be considered as the optimum angle configuration. Lastly, the empirical correlations that were developed for the Nu and the f had good agreement with the experimental values and both had conservative error range of ±20%.