Numerical Simulation And Optimization Of Shell And Tube Heat Exchanger

The spacing and cut of baffle in shell-and-tube heat exchangers have significant impacts on the performance of heat exchangers. As the awareness and demands of saving energy arise, enhancement of the performance of heat exchangers is becoming more and more urgent.This article studies the fluid flow and heat transfer in the heat exchanger in a heat supply system using numerical simulation method, some visual pictures of flow and temperature distributions are illustritated, which help us for better analysis.To optimise the baffle in a heat exchanger, we should get a Performance Evaluation Critera(PEC) first. In the analysis of Entropy Generation Minimization,this article find that the irreversibilities caused by finite temperature difference and friction flow in heat exchanger unbalance severely. A new confine to the use of entropy generation is proposed by studying its physical meaning. The Field Synergy Principle is also analised in this article, the reasons why it is inappropriate in the evaluation of heat exchanger are given out here. Then, from the concept of the first law of thermaldynamics, this article illustrates the rationality of the JF factor as a PEC with lots of its application by other scientists.The baffle spacing is studied first. The fluid flow in shell side, heat transfer and pressure are cauculated, when the baffle spacing varies. Pressure drops during the cross flow section and window flow section is studied specially. After that, the optimised spacing is chosen out when it changes, according to the JF factors at differents arragemnets. Then, the impact of baffle cut on the performance of heat exchangers is also studied in a similar procedure, and an optimised cut is chosen out.The spacing and cut of the baffle are then optimised simutenously, a series of optimised baffle cut are got at different spacings of the baffle. And an optimised profile of this relation is fitted, which will give some advice in our design, hopefully.At last, the impact of the mass of shell-side flow on the design of baffles is analyised, which is also performed on the impact of the fouling in heat exchangers.