Numerical Analysis of Passive, Compound, and Active Augmented Heat Transfer Methods for Concentric Tube Heat Exchanger

Passive, compound, and active augmented heat transfer (AHT) methods in a countercurrent flow concentric tube heat exchanger (CCTHE) were explored and examined in this work. The finite volume method using ANSYS Fluent 2021 R2 was applied to evaluate the fluid flow and heat transfer characteristics of a CCTHE in each AHT study. The influence of the circular perforated insert at varied quantities (N) was analyzed in a passive AHT study. A comparable heat transfer improvement of 41.8% was recorded at an insert quantity of N = 7; however, a notable decreasing trend in the thermal performance factor (α) indicated that pressure drop increases as the number of inserts increases. In the active AHT study, the inner pipe rotation at 300 rad/s resulted in a heat transfer rate enhancement of 428%. The compound AHT method employed rotating perforated inserts at various rotational speeds, which resulted in a heat transfer rate increase of 47.5% at 300 rad/s and N = 7. This work demonstrated how each type of flow disturbance affected the heat transfer rate inside a CCTHE and investigated the effectiveness of each method through the evaluation of α.