The effect of twisted tape inserts on the heat transfer in pipes of two types of cross-sections (circular and square) has been investigated numerically. The improvement in the heat transfer coefficient by incorporating the insert has been quantified using a parameter \(\Delta h\) . While a modest improvement has been observed in the case of airflow, a significant improvement in \(\Delta h\) has been obtained for water flow. For a given mass flow rate and area of flow, the insertion of a twisted tape results in greater improvement in heat transfer in the square pipe as compared to the circular pipe. Moreover, the pressure drop is smaller in the square pipe as compared to the circular one for the same insert. Therefore, the insertion of twisted tapes in square pipes will provide better performance compared to insertion of the same in circular pipes in connection with the design of heat exchangers.