Heat Transfer Improvement Using Three Types Novel Turbulators Inserts with Two Pitch Ratios in Double Pipe Heat Exchanger

The present work experimentally investigates the effect of novel turbulators on improving heat exchanger (HE) performance.Tests are conducted by insertion of three types of turbulators, 3PS, 4PS, and 5PS, including two pitch ratio PR (5-3.76).The results showed that the enhancement in heat transfer (HT) when using 5PS was more than the remaining two types.The greatest worth was at the lowest pitch ratio.The outcomes of experiments showed that the enhancement in the Nusselt number for each type of 5PS, 4PS and 3PS for small pitch ratio was 194%, 177% and 164% more than that of the plain tube, correspondingly.Also, the thermal performance factor, friction factor, and Nusselt number are all increased as the pitch ratio decreases.As a result, the small pitch ratio delivers a more considerable rate of HT and lower loss in friction.In addition, the results showed that the factor of thermal performance was more significant compared to unity for each type studied, and the maximum value of thermal performance factor acquired at η=1.54 is accomplished for the 5PS turbulators.The Correlations between the friction factor and Nusselt number were evolved for the range of Reynolds number (Re) of 12385 to 24766.The most relevant results of the evaluated study were presented to aid researchers in understanding the advances in HT enhancement in double pipe HE using novel turbulators inserts.