Numerical Simulation And Field Synergy Analysis Of Air Across Polished Ribs

Heat exchangers are indispensable devices for energy conversion and heat recovery,whose heat transfer performance directly affects energy efficiency.The effects of five kinds of ribs on air side heat transfer performance are studied respectively in this paper,they are circle,the hexagonal at 60°,90°,120° and rhombus.The entrance wind speed is set from 1 to 10m/s,and the air flow and heat transfer characteristics of five different sizes of ribs are numerically simulated and data processed respectivelyin this paper.And then the results are analyzed as follows:?1?The heat transfer,pressure drop,frictional resistance,and comprehensive evaluation analysis factor PEC of the air flow in five kinds of ribs are compared by the use of direct contrast.The heat transfer of the diamond-shaped ribs is the largest,the heat transfer of circular ribs is minimal and the former increased by 9.4% to 23% than the latter in the comparison of heat transfer species;the pressure drop increases the highest when the angle towards the fluid was 120°,the circular ribs are followed,and the drop pressure of the diamond-shaped ribs is the least,diamond-shaped ribs pressure drop increases 33.5% to 51% than the circle as a benchmark of circular ribs in the pressure drop contrast;Friction resistance coefficient is inversely proportional to Re,and the frictional resistance coefficient of the diamond-shaped ribs is the smallest in the friction coefficient comparison.So the comprehensive heat transfer performance of the diamond is greater than that of other ribs,the air-side flow and heat transfer performance of diamond-shaped ribs are the best.?2?The criteria for the study of air flow and heat transfer for diamond-shaped ribs was deduced through field synergy analysis combined with Zukauskas empirical correlation at last.The least square method is used to fit the unknown factors such as different flow angle,the number of liquid properties Pr and the flow factor Re number in the software ORIGIN,and then the flow heat transfer criterion of the diamond-shaped ribbed group is obtained as Nu_f=0.76Re_<sup>0.51Pr_f^0.36??/90?^0.95,the error ofthe solution is proved at last.