Investigation On Flow And Heat Transfer Enhancement In Spiral Wound Tube Heat Exchanger

As a kind of shell and tube heat exchanger,spiral-wound heat exchanger is widely used in electric power,chemical industry,petroleum and other fields because of it has advantages of compact structure,high heat transfer performance,small thermal stress and so on.In this paper,the three-dimensional geometric model of the spiral wound tube heat exchanger with different tube structures was designed by studied the influence of different special tube structures on the flow and heat transfer characteristics of the spiral-wound heat exchanger by used the numerical simulation;Based on the semicircular groovs along the traditional circular tube,the influence of performance optimization of traditional circular tube heat exchanger are compared by the different grooving methods and grooving depth.the rules of flow and heat transfer enhancement in spiral wound tube heat exchanger are obtained.(1)Study on the heat transfer performance of traditional spiral wound tube heat exchanger.The three-dimensional model is built and simulated through the test parameters.The results show that the data calculated by RNG K-ε model is consistent to the experimental dates and the average error is 7.2%;The increase of the tube inlet flow has a great influence on the temperature in the tube,but has a little influence in the shell side.The PEC of tube side increases with the increase of tube inlet flow,and the heat transfer performance is improved.(2)Numerical study on heat transfer performance of spiral-wound tube heat exchanger with Special-shaped tube.Through the simulation of heat transfer performance of spiral-wound tube heat exchanger with tirfol-shaped tube and water drop-shaped tube,the results show that: When the tube side velocity and temperature are fixed,the fluid temperature in the tube and in the shell are decreases with the increase of inlet velocity at the shell side,the low temperature section at the shell side of the heat exchanger moves down,and the fluid pressure loss increases;Under the same working condition,the shell side outlet temperature of the heat exchanger with water drop-shaped tube is higher than that the heat exchanger with trifol-shaped tube,the maximum difference is 3%,and the minimum difference is 1.6%.The overall velocity and temperature distribution of the heat exchanger with water drop-shaped tube are more uniform,the flow and heat exchange enter can into stability faster;Under the same condition,the shell side friction coefficient of the heat exchanger with trifol-shaped tube is 4.3% higher than that of the heat exchanger with water drop-shaped tube;The PEC value of heat exchanger with wate drop-shaped tube is higher than that of heat exchanger with trifol-shaped tube.The heat transfer performance of heat exchanger with wate drop-shaped tube is better than that of heat exchanger with water drop-shaped tube.(3)Numerical simulation of heat transfer performance of spiral-wound heat exchanger based on grooved tube.The influence of horizontal grooving and spiral grooving on the flow and heat transfer of spiral-wound heat exchanger is analyzed.And for the heat exchanger with spiral grooving tube,the optimization degree of grooving depth on the overall heat transfer performance of the heat exchanger is analyzed,the result show that:Grooving along the circular tube can destroy the boundary layer on the tube wall.enhance the disturbance of the fluid and heat transfer on the tube wall,but it will increase the pressure losses.Grooving the tube can effectively improve the comprehensive heat transfer capacity of heat exchanger;Compared with the heat exchanger with horizontal grooving tube,the heat exchanger with spiral grooving tube has a higer outlet temperature and Nu,and the resistance coefficient is smaller.The PEC value of heat exchanger with spiral grooving tube is 25% better than that of heat exchanger with circular tube,while that of parallel groove heat exchanger is 20% better than that of heat exchanger with circular tube;the heat transfer performance is better in heat exchanger with spiral grooving tube;With the increase of the groove depth,the Nu and resistance coefficient are first increases and then decreases.Under the same condition,the PEC value of heat exchanger with spiral grooving tube with 0.5mm groove depth is the maximum.