Research On Fluid Flow And Heat Transfer Characteristics Of Twisty Flow Heat Exchanger

It is great significance to study heat transfer enhancement technology of shell-and-tube heat exchanger,which can promote the maximization of energy utilization and achieve the goal of energy conservation and emission reduction.In this paper,based on the research of heat transfer enhancement and the new type of oblique flow heat exchanger,the twisty flow heat exchanger was innovatively proposed.Comparing the fluid flow and heat transfer characteristics of the oblique flow heat exchanger and the twisty flow heat exchanger though numerical simulation method.The support structure of trapezoidal-like tilted baffles in twisty flow heat exchanger was optimized.The research contents and achievements of the twisty flow heat exchanger in this paper are as follows:According to the definition of the periodic whole cross-section computation models,an periodic whole cross-section model of the twisty flow heat exchanger was established.The pressure gradients,speeds,and dimensionless temperatures at different cross-sectional positions under different Re were studied,and the flow and temperature fields of the twisty flow heat exchanger has periodic characteristics,The periodic whole cross-section development period is 300-1300 mm,that is,from the fourth group of trapezoidal-like tilted baffles to the end of the twelfth group of trapezoidal baffles,the pressure drop and the periodic velocity of the geometric sections increase with the increase of Re in the shell.Periodic whole cross-section computation models of shutter baffle heat exchanger and twisty flow heat exchanger are established respectively.The heat transfer coefficient,flow resistance and thermal performance are studied with CFD simulation.Compared to shutter baffle heat exchanger,the results showed that the heat transfer coefficient of twisty flow heat exchanger is improved by 7.3-10.2%,pressure drop decrease by 18.5-21%,the thermal performance factor improved by 14.9-19.2%.In addition,the influence of inclination angle of trapezoidal baffles,baffles width,baffles pitch and number of baffles on the heat transfer performance in the twist-flow heat exchanger was studied.And the inclination angle of trapezoidal-like tilted baffles and baffles pitch have a significant effect on heat transfer performance,the effect of baffles width is secondary,and the number of baffles have no significant effect.The results of this paper provides a new scheme for the structural improvement of the shell and tube heat exchanger,and provides the references for further performance optimization of twisty flow heat exchanger.The main parameters affecting the heat transfer and flow are inclination angle of trapezoidal-like tilted baffles,baffles width,baffles pitch and number of baffles.The influence ofparameter on the heat transfer coefficient,pressure drop and overall performance is determined by the orthogonal experimental design.Through SPSS software,using the principle of least squares to perform multiple linear regression analysis on the results of the twisty flow heat exchanger,the correlation between heat transfer coefficient and pressure drop was fitted,which provided a reference for heat exchanger design and application.