Numerical Investigation And Optimal Design Of Shell Side Heat Transfer Of Shell-and-tube Heat Exchangers With Trefoil-hole Baffles

Shell-and tube heat exchanger with trefoil-hole baffles is a new type of longitudinal flow heat exchangers used in nuclear power industry. The traditional segmental support baffles replaced by the trefoil-hole baffles, the fluid in the shell side are longitudinal on the whole. Owing to the improvement of the structure, the heat exchanger with trefoil-hole baffle have the advantages of higher heat transfer efficiency, lower pressure drop and less easy scaling. In this paper, the numerical investigation and optimal design are made for the heat exchanger with trefoil-hole baffles. The main research contents are as follows:1)Taking the calculation models for longitudinal flow heat exchangers into consideration, the "unit channel" model is chosen as the numerical model, and then the influence of the baffle space and the hole height to the function of the heat exchangers are analyzed.2) Based on the dimensional analysis method, the general correlation of heat transfer and pressure drop of the shell side is obtained, and then amended using the "periodic section" model.3)The numerical investigation of the big-hole heat exchange and the small-hole heat exchanger are performed, and the function of the three types of heat exchangers is contrasted. Then the general correlations of hole-baffle heat exchangers are obtained.4) The genetic algorithm is applied on the optimal design of the trefoil-baffle heat exchangers. Through Matlab programs,the Nusselt number and pressure drop are respectively optimally designed.