The Comparative Study And Numerical Simulation Of Shell-and-Tube Heat Exchangers

Heat exchangers are widely used in many industrial fields such as chemical industry,oil industry,power industry, food industry, light industry, atomic energy industry, pharmaceutical industry, aviation industry. Because the energy prices are soaring, the research about enhancing heat transfer of heat exchangers receives the widespread recognition. Shell-and-tube heat exchanger has many advantages such as reliable structure,mature technology and good adaptability, so it is the mostly used structure at home and abroad. Shell-and-tube heat exchangers often use segmental-baffled support structures and smooth tube bundles, which have simple manufacturing processes, strong adaptability, and large throughput. However, segmental-baffled heat exchangers have high resistance in shell side, whose practical values of heat transfer coefficients are lower than theoretical values.In order to improve the comprehensive performance of heat exchangers, shell-side support structures with low resistance and high efficiency and enhanced heat transfer tubes are combined, and research on performance of heat exchangers by experiments and numerical simulation are made in this paper. The main contents of this study are as follows:⑴The enhanced heat transfer surfaces are routinely employed in the process industry to improve the overall performance of the heat transfer equipments. Heat transfer enhancement performances of smooth-tube heat exchangers , corrugated tube heat exchanger and spiral corrugated heat exchanger are investigated for comparison. The experimental results indicate that corrugated tubes are particularly effective in enhancing convective heat transfer when Reynolds number ranges from about 5000 to 30000. Compared with smooth tube, tube-side heat transfer coefficient of corrugated tube has an increment which is about 167.8%, while spiral corrugated tube 60.2%.⑵Based on the research of structure characteristics of shell side of heat exchanger, rod-baffle heat exchangers have low pressure loss and high heat transfer coefficient than segmental heat exchanger,which also has good performance of anti-vibration, anti-fouling. The shell-side pressure drop of Rod-baffle heat exchanger decreases 20%~60% than Segmental-baffle heat exchanger. Instead, heat transfer coefficient increases 18%~55%.⑶The interval size of the rod-baffle and segmental-baffle has effect on the overall coefficient of heat transfer. By comparing 14.2cm, 19.4cm, and 24.2cm spacing of support elements, heat transfer is facilitated by smaller spacing.⑷By use of VC++ programming and curve fitting to get correlation equations under conditions of different support elements and tubes.⑸Using the FLUENT software to analyze temperature fields and velocity fields of simplified element model and 3-D model. By comparing numerical results and experimental data, it can be found that numerical simulation to heat exchanger is valid and reliable.