| The full utilization of non-renewable energy has laid the foundation for the development of industrialization today.However,the exploitation of fossil energy has led to a series of problems,such as global environmental changes that threaten human development.Therefore,improving the utilization of fossil energy and reducing atmospheric pollution is a problem we cannot ignore today.Shell-and-tube heat exchangers are widely used in many heavy industrial fields.However,the traditional single-segment baffle heat exchanger has high energy consumption despite high heat exchange.Improving it and increasing the energy consumption ratio of the equipment is of great significance.The fluid in the shell side of the single segment baffle heat exchanger is transverse,resulting in the formation of a low speed area on the backside of the baffle,which affects the overall temperature distribution of the shell side and causes tube bundle vibration.Additionally,the fluid and the vertical baffle create greater resistance,increasing energy consumption.Based on the aforementioned issues,this thesis proposes a new type of heat exchanger with an annular orifice support structure.The structure and performance of its shell path are studied and optimized.In this thesis,key parameters of the shell and tube heat exchanger and the shell flow field,pressure,and temperature field are compared through numerical simulations of the new annular orifice heat exchanger and the single segment baffle heat exchanger.The advantages and reliability of the annular orifice heat exchanger are established.Then,using the rule of factors affecting the annular orifice plate,a single-factor analysis method is used for quantitative and qualitative analysis.The factors analyzed include the opening height of the ring hole,the number of baffles,and the cutting rate of baffles.These factors are analyzed at different flow rates.Finally,the thesis adopts the orthogonal experimental design,and the test content uses the range and variance analysis method to study the parameters that influence the heat exchanger’s performance.A correlation formula is fitted regarding pressure drop and heat transfer coefficient.The conclusions are as follows:(1)The shell pass fluid flow of the single segment baffle is optimized by changing the transverse flow into a mixed form of transverse flow and longitudinal flow.The experimental results show that the low-speed zone formed on the backside of the traditional single-segment baffle is reduced,the pressure drop of the shell pass is reduced,and the temperature distribution is uniform.The comprehensive performance of the annular orifice plate heat exchanger is better than that of the single-segment baffle heat exchanger.(2)Through the single-factor test of the annular orifice plate,it is found that the opening height,baffle number,and baffle cutting rate significantly affect the performance of the heat exchanger.When the parameters change,the pressure drop and heat transfer coefficient increase or decrease simultaneously.With an increase in opening height,the shell side pressure drop and heat transfer coefficient of the heat exchanger decrease.When the number of baffles increases,the pressure drop and heat transfer coefficient increase simultaneously.The best opening height is 11 mm,the number of baffles is 4,and the cutting rate of the baffle is 40.(3)Three factors and levels of shell and tube heat exchangers are analyzed through orthogonal test design,and weight analysis is carried out on the pressure drop,heat transfer coefficient,and comprehensive efficiency that affect the performance of the heat exchangers.The results of variance are verified by experiments and comparisons of the heat exchangers with the best parameter combination.Finally,a correlation formula between the shell pressure drop and heat transfer coefficient is obtained through multiple linear regression and verified. |
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