关键词: 安全型换热器, 网纹内管, 双套管双管板, 传热特性, 当量接触面积

Abstract: In order to study the double tube and double tube sheet safety heat exchanger with the reticulated inner tube, the internal and external tube contact area equivalent method was used. The contact area of the reticulated inner tube and the outer wall of the outer tube was equivalent to the correspond contact area of a straight groove tube. CFD software was used to simulate the heat transfer performance of the heat exchanger with the straight groove tube as inner tube. The fluid of the tube and shell are both water. Air and water were filled in the safety chamber respectively to simulate the heat transfer characteristics under different inlet flow conditions. The contact correction coefficient was introduced, based on the traditional empirical formula of heat transfer coefficient, and combined with the characteristics of the reticulated tube model, the calculation formula of the heat transfer coefficient of reticulated inner tube safety heat exchanger was obtained. The heat transfer coefficients of the heat exchanger under different working conditions were calculated theoretically. The experiment for evaluation of heat transfer characteristics of the reticulated inner tube safety heat exchanger was established. Results indicated that the internal and external contact area equivalent method is feasible when dealing with the heat transfer characteristics of the reticulated inner tube safety heat exchanger. The empirical formula of heat transfer coefficient based on contact correction coefficient is reliable. The results of numerical simulation, theoretical calculation and experimental results have a good coincidence trend. The heat transfer efficiency of the reticulated inner tube is 24% and 40%, respectively, higher than that of the smooth inner tube when the safety chamber is filled with water and air.

Key words: safety heat exchanger, reticulated inner tube, double tube and double tube sheet, heat transfer characteristic, equivalent contact area