Shell And Tube Heat Exchangers Computer Aided Design

Shell and tube heat exchanger is widely used in industrial heat transfer processes. With its advantages such as large range of operating temperature and pressure, lower cost, easy to clean, larger capacity, reliability, etc., it is the preference of the designers. The traditional design of shell and tube heat exchanger is generally non-standardlised. Moveover, there are a lot of repeated tentative calculations and checks of parameters of material property and structure, which results in plenty of calculating work and lower design quality. However, the application of computer-aided design (CAD) will greatly improve the design efficiency, as well as the design quality.In this paper, the characteristics and research progress of shell and tube heat exchanger were outlined. Its thermodynamic calculation theory was also discussed in details. The design process was summed up. Then the intergal structure of CAD system for shell and tube heat exchanger was constructed. The system consisted of material calculation module, type selection calculation module and checking calculation module. In the material calculation module, the four known temperatures, a flow rate, and three temperatures, two flow rates were considered respectively, therefore the density, specific heat capacity, kinematic viscosity and thermal conductivity of the single-component or multi-component gas-liquid mixture in the tube or shell could be calculated. The inputs of physical properties of material and calculations could be carried out simultaneously. In the type selection calculation module, the forms of heat exchanger include fixed tube plate type, U tube type and floating head type. Bundle support structures included segmental baffle, rod baffle, and ring baffle plate. Tube types included light tube, spiral shape tube, and bellow shape tube. According to the ratio range of 0.8～1.2, which was the ratio of influx area in the windows and influx area of cross flow between two baffle plates, the baffle spacing and round vacancy rates of segmental baffle were optimized, with the flow velocity in the shell being the controll index. In checking calculation module, the tube and shell flow area, heat transfer coefficient, heat transfer area, pressure drop were checked, considering different types of bundle support structure and tube type, using corresponding method of thermal calculation. The caculation results were output in the form of EXCEL report, which helps the designers to make comparisons conveniently. Finally, the CAD system of design, check procedure and operating interface of shell and tube heat exchanger was discussed in details. In the final,the software system was proved to be usdful, by using a design example of a shell and tube heat exchanger.In the system, the human-friendly interface of Visual Studio.NET, and the data saving and managing functions of SQL Sever were fully used. The structure and type diversity of shell and tube heat exchanger, and the complexity of factors which affect the heat exchanging were considered, so the system has a comprehensive function of physical properties calculation, design, and check in shell and tube heat exchanger, moreover, physical properties of more than 500 common chemical materials can be also calculated. The software developed in this paper can sucessfully solve many factual problems of the design of shell and tube heat exchanger, which greatly lightens designer's work. The system can increase design efficiency of shell and tube heat exchanger, and it is of certain reference of the computer aided design system for other type of heat exchanger.