Heat transfer and resistance characteristics of conical spiral tube bundle based on field synergy principle

Abstract

Conical spiral tube bundle are universally used in heat transfer enhancement in heat exchangers. The heat transfer and resistance of the tube bundle are affected greatly by the conical structure, so the analysis of it is necessary. In order to a further evaluation, the heat transfer and resistance characteristics of conical spiral tube bundle are investigated with regression analysis based on numerical simulation data. The correlations of heat transfer and pressure drop of conical spiral tube bundle are proposed both in laminar and turbulent fluid flow. On the based of the field synergy principle, the synergy of four vectors, the velocity, the velocity gradient, the temperature gradient and the pressure gradient, are calculated and discussed via the user defined function (UDF) program. The synergy angles β and θ, which respectively denote the performance of heat transfer enhancement and pressure drop of the conical spiral tube bundle, are analyzed. Finally, the comprehensive performance of the conical spiral tube is evaluated by the synergy angle γ and all of the three synergy angles of conical spiral tube bundle are compared to both bare tube and thin cylinder-interpolated tube. The analysis of the synergy angles shows that the heat transfer enhancement and pressure drop of conical spiral tube bundle are smaller than that of the thin cylinder-interpolated tube, while the comprehensive performance of conical spiral tube bundle is greater. The analysis of the heat transfer and pressure drop of conical spiral tube is valuable and instructional on the design and optimum of conical spiral tube bundle heat exchangers.