The effect of helix angle and pitch ratio of helical surface disc turbulators on the thermal performance of double pipe heat exchanger are discussed in this study. Tests are performed with air as working fluid for different pitch ratios, numerous helix angles, and various Reynolds number. Water and air are allowed to flow along inner tube and through annulus, respectively. In each case, the thermal enhancement factor is observed to be higher than unit value. Smallest pitch ratio and highest helix angle yield highest thermo-hydraulic performance of 1.39 at Re = 3,500. Correlations are developed for various parameters.