Application of a multi-field synergy principle in the performance evaluation of convective heat transfer enhancement in a tube

For laminar and turbulent convective heat transfer, the synergy among vectorial physical quantities of a fluid particle is analyzed to reveal the relation between the multi-field synergy mechanism and heat transfer enhancement. Additionally, the efficiency evaluation criterion (EEC) is proposed to evaluate the overall performance of heat transfer enhancement. Meanwhile, using synergy angles alpha, beta, theta, gamma and eta, a unified evaluation system and corresponding evaluation indexes for heat transfer enhancement are suggested. A model of a heat-transfer-enhanced tube inserted with poles in a triangular configuration is built, and a corresponding numerical simulation is conducted to verify the proposed evaluation system and criterion. The calculation results show that there is correlation between synergy angles reflecting the direction of heat transfer enhancement and evaluation criterion reflecting the effect of heat transfer enhancement. In the Re number range of 300-1800, the performance evaluation criterion PEC lies in the range of 1.2-2.3, but the efficiency evaluation criterion EEC lies in the range of 0.33-0.45.