Experimental Study On Field Synergy Principle And Fouling Characteristic In Rectangular Channel

Field synergy principle is put forward in the research on strengthening heattransfer. The theory reveals the essence of strengthen the convective heat transfer, andprovides a direction for the design of the heat exchanger. Although this study alsostay in the aspect of strengthening heat transfer, the study of fouling characteristic forheat exchanger according to field synergy principle is also little. In this paper, therectangular wing vortex generator is selected as the research object, with nanometermagnesia particles as the fouling working medium. For analyzing the relationshipbetween the field synergy theory and fouling characteristics, the experimental sectionwith different arrangement of vortex generator do a study in the clean and foulingcondition.Firstly, four kinds of layout are researched in the clean and fouling condition,including tabula rasa, front thick and rear sparse, front sparse and rear thick and fullinstall. In the clean condition, the pressure drop curve under different Reynoldsnumber of the experimental section’s entry and exit is gained by changing thevelocity, and in a certain velocity the experimental section’s total heat transfercoefficient is also got. Then a certain concentration of nanometer magnesia particlessolution is prepared as the fouling working medium doing the fouling characteristicexperiment for the four arrangements. The results show that: the wing-type vortexgenerator installed on the heat transfer surface can not only enhance heat transfer butalso stop form the particulate fouling. Arrange vortex generator in downstream isbetter than in upstream both in enhance heat transfer and reduce flow resistance,moreover it can bring about less particulate fouling under the condition of dirt. Theamount of fouling is reflected on the differential pressure of entry and exit of theexperimental section to same extent.Secondly, to explore the effects of transverse vortex and longitudinal vortex onparticulate fouling, in-line, staggered and insert-row were studied, with the abovethree forms respectively adopting the ways of45°and90°Angle of attack. In the clean condition, flow resistance experiment of different arrangement is did. Then acertain concentration of nanometer magnesia particles solution is prepared as thefouling working medium for the fouling characteristic experiment. The results showthat: no matter whether the vortex generator is installed, nanometer MgO particle hasno obvious induction period in the rectangular channel; installing rectangular wingvortex generator on the heat transfer surface can inhibit form the particulate fouling,but in the same time it increase the flow resistance; staggered arrangement is betterthan in-line in the matter of restrain particle fouling when the angle of attack is90°;changing the angle of attack to45°, staggered arrangement and in-line with the sameability in restrain particle fouling, and both of them are better than90°angle ofattack; on the condition of same angle of attack, insert-row has the best ability inrestrain particle fouling, but it`s flow resistance is biggest, when the angle is different,45°angle of attack is better than90°.