Till date, different active and passive techniques for increasing heat transfer in compact heat exchangers for air-conditioning and refrigerant applications etc. have been used. In the present research work, fluid flow and heat transfer characteristics in the laminar flow in a channel in the presence of three triangular prisms is numerically investigated. The computations are performed for Reynolds number of 50, 100,150,200 and 250 and blockage ratio (b) of 0.25, where blockage ratio is the ratio of prism base to channel height. The Navier Stokes equations and the energy equation are solved by using SIMPLE Technique. For the computational domain, the unstructured quadrilateral mesh is used. The results show that in the presence of three triangular prisms, the average nusselt number is 6.69% (at Reynolds number 100) and 11.1% (at Reynolds number 250) more as compared to plane channel flow. The increase is due to the vortices formation which travels a long way in the downstream direction. It is further observed that the heat transfer and the nusselt number increases by increasing the Reynolds number (Re). The average nusselt number and heat transfer enhancement for Reynolds number 50,150 and 200 for three triangular prisms are also investigated. It is also found out that increase in heat transfer is related with a greater pressure drop.