<p>The present study investigates the heat transfer and fluid flow performance of a tubular heat exchanger with backward facing flat metallic cone inserts under laminar flow conditions (Re = 1000–1600). Numerical simulations were performed and validated against experimental measurements for inserts with 2, 3 and 4 strips, installed in three axial positions and kept at a constant attack angle of 22°. Water served as the working fluid, and the 4-strip insert delivered the highest thermal enhancement performance. However, the 3-strip insert shows a relatively lower thermal effectiveness with the increase of Reynolds number. The 2-strip insert, although showing the minimum Nusselt number, shows the minimum friction factor, leading to favourably overall thermal performance. For the 4-strip insert, the maximum thermal performance factor of 1.26 was obtained at Re = 1600. The good agreement between the numerical and experimental results confirms the reliability of the adopted approach and the suitability of these inserts for laminar flow heat transfer enhancement. The findings help build energy-efficient heat exchanger systems, supporting SDGs 7 (Affordable and Clean Energy) and 9 (Industry, Innovation, and Infrastructure).</p> Graphical abstract <p></p>