Chamfered circular ring (CCR) innovated from conventional circular ring by introducing chamfered surface on its periphery at 30o attack angle is numerical investigated to study its effect on fluid flow characteristics, heat transfer enhancement and friction factor in a heat exchanger pipe. In order to study flow blockage effect on overall performance of device, three diameter ratios (DR = Di / Do = 0.6, 0.7 & 0.8) with three spacing ratios (SR = s / D = 1, 2 & 3) are used. Turbulent model k - ϵ, RNG with enhanced wall treatment is used to solve governing equations. Results shown that CCR chamfered surface produced nozzle jet effect on pipe wall surface through clearance of 1mm, which further induced turbulent and recirculating flow effect near pipe wall area. This resulted in to higher heat transfer rate. All the diameter ratios with SR =1 shown thermal performance factor value more than unity at most of the lower Reynolds number. The range of TPF shown by DR = 0.6, 0.7 & 0.8 with SR =1 is 1.21 – 0.93, 1.23 – 0.97 and 1.19 – 0.99 respectively. Compromised results of TPF are shown by DR = 0.7 and DR = 0.8 at SR = 1. CCR has shown better results over circular ring, perforated conical ring, short length twisted tape, twin co-twisted tape, wire rod bundles and perforated twisted tape. Numerical results shown better agreement with predicted results within the range of 10%. Highest TPF of 1.23 is shown by DR = 0.7 & SR = 1 at Re 6000.

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