Experimental study of heat transfer un turbulent flow thorugh a tube with perforated rectangular strip insert

Abstract

An experimental investigation was carried out for turbulent flow heat transfer in a circular tube with perforated rectangular strip inserts. Mild steel perforated rectangular strips with holes of different diameters were used as inserts in this experiment. Heat transfer and pressure drop characteristics were obtained in the tube for the turbulent flow. The flow of air through the tube was varied by using the flow control valve. Heat transfer and pressure drop data were taken for Reynolds numbers ranging from 1.5 x 10 4 to 4.7 x 10 4. Air velocity, temperatures, tube wall temperatures, pressure drops were measured for the plain tube as well as for the tube with perforated rectangular strip inserts. Heat transfer coefficients, heat transfer rate, Nusselt numbers, friction factor, blower power and heat transfer effectiveness were calculated using measured variables for the plain tube as well as for the tube with inserts. Heat transfer rate was found to be increased up to 1.85 times with corresponding increase in friction factor and blower power for the tube with perforated rectangular strip inserts. For the comparable Reynolds number, the heat transfer coefficient for the tube with perforated rectangular strip inserts was found to be increased up to 2.80 times than that of the plain tube. The friction fator for the tube with perforated rectangular strip inserts was found to be increased up to 1.8 times compared to that of the plain tube.Whereas, the required blower power for the tube with perforated rectangular strip inserts was found to be increased up to 1.45 times than that of the plain tube. It was also found that the heat transfer effectiveness for the tube with perforated rectangular strip inserts was increased up to 2.45 times compared to that of the plain tube. With the experimental data, a correlation was developed for prediction of the heat transfer in the turbulent flow for the tube with . perforated rectangular strip inserts.