Physical quantity synergy analysis and efficiency evaluation criterion of heat transfer enhancement

On the basis of the core-flow heat transfer enhancement and field synergy principle, the difference between fluid-oriented and surface-oriented heat transfer enhancement methods is performed. The physical nature of heat transfer enhancement and friction reduction is illustrated through revealing the synergy principle of heat transfer and friction characteristics of physical quantity and describing the internal relations of velocity and temperature fields as well as velocity and pressure fields. The efficiency evaluation criterion (EEC) and the efficiency evaluation plot are proposed to analyze and evaluate heat transfer enhancement techniques corresponding to the different regions in the efficiency evaluation plot. Region I represents the heat transfer enhancement ratio is larger than the pumping power increase ratio and region II represents the heat transfer enhancement ratio is less than the pumping power increase ratio in comparison with a bare tube. 3-D numerical simulations of several inserts in tube are provided to verify multi-fields synergy principle of convective heat transfer and efficiency evaluation plot is carried out to demonstrate the characteristics of enhancement tubes.