A design of inserting a concentric tube with negligible thickness to divide a circular conduit into two subchannels for double-pass flow and recyclic operations, resulting in substantially improved the heat transfer, has been designed and investigated. The results are represented graphically and compared with those in a single-pass device (without an inserting concentric tube and recycle). Heat transfer improvement is considerably obtainable by employing such a double-pass recyclic device, instead of using the single-pass one. The effect of concentric tube location on the heat transfer efficiency enhancement as well as on the power consumption increment, has been also discussed.