The Design Method Research Of Pre-stressed Heat Exchanger Tube

The shell and tube heat exchanger is widely used in petroleum chemical industry becauseof its advantages such as simple manufacture, mature production technology, long-termexperience of usage, and large quantity, strong adaptability,safety and reliability. Thedifference of tube wall temperature deeply affected the traditional fixed tube plate heatexchanger, which limits its widespread application, and the pre-stress technology caneffectively reduce the temperature stress of fixed tube plate heat exchanger, improve thesafety performance, therefore, the research of pre-stress heat exchanger on heat transfer andstress state has important significance. In this paper, the main work includes:1. Numerical calculation for performance of flow and heat transfer was conducted underthe operation condition of heat exchanger with segmented simulation and overall simulation;The same size with different number of the segment models were adopted for simulation toexplore the applicable scope of the segmented simulation and overall simulation under thesame discrete precision; At the same time, different length of models and discrete precision ofgrids were calculated respectively to explain the advantages and development prospect ofsegmented modeling and simulation technology.2. Due to the factors influencing thermal deformation of the heat exchanger was verycomplex, this paper fit the relation formula of various factors on the deformation, andanalyzed influence of various factors on the deformation of heat exchanger using the methodof dimensional analysis in order to better explain the relationship of deformation and theinfluence factors. Another new model at the same time was created, the deformation ofsimulation and the deformation calculated by formula were compared to verify the correctnessof formula.3. The tube plate stress of the heat exchanger under different optimal degree ofpre-deformation was acquired by applying the best degree of pre-deformation got bysimulation to heat exchanger model, and the stress status of tube plate was analyzed beforeand after exerting pre-deformation, fit formula of tube plate stress containing pre-deformationeffect coefficient and verified the accuracy of the formula.4. Designed testing experiment of the tube plate stress of pre-stress heat exchanger, analysis of the simulation results was compared with the experimental data to verify theaccuracy of simulation results.On the basis of previous studies, this paper considered the factors influencingtemperature deformation of heat exchanger, fit multifactor relation formula of temperaturedeformation of pre-stress heat exchanger, the deformation increases with the increasing ofheat pipe length, baffle spacing, the fluid velocity ratio in the tube shell and temperature ratio,and has the opposite relationship with shell diameter and tube plate thickness, due to thesimulation results; Conducted simulation by loading deformation to the model, fit the designformula of tube plate of pre-stress heat exchanger with simulated results, analysis of thesimulation results was compared with the experimental data to verify the accuracy ofsimulation results. And then verify the accuracy of deformation formula with fitting thenumerical simulation results and design formula of tube plate of pre-stress heat exchanger,adaptability of segmented simulation is better than the overall simulation under the samediscrete precision, showing from the experiment results, segmented numerical simulationmethod has certain reliability. Through the research of this paper, enriched the existingresearch theory and technology of pre-stress, lay a solid foundation for promoting pre-stress.