Effectiveness of ground heat exchanger is ruled by the prevailing thermal resistances. Using serrated surface helps in curtailing the fluid side thermal resistances. In the present study, a 3-D numerical analysis has been carried out to determine an improved design of circular tubes with longitudinal serrations for minimization of the thermal resistance caused by the pipe surfaces. As the geometry of serrations is an important design parameter, for such purpose, the thermo-hydraulic performance of various serrations is assessed. For the considered geometries of the serrations, the thermal and flow parameters viz. pipe length, pipe diameter, inlet temperature, wall temperatures, and Reynolds number are kept same for all the cases. The results indicated that the deployment of triangular or rectangular fins is a promising method for augmentation of heat transfer. The maximum percentage change in the thermal conductance is found to be 423 and 448% for triangular and rectangular fins, respectively, for minimum pitch value (1/30) and maximum height (1/15). It is also noticed that the fin height and pitch should be chosen carefully as the system becomes inefficient for lower fin height (1/30) and higher pitch (1/5) values.