Numerical Research On Heat Transfer And Flow Resistance Performance Of A New Novel Type Plate Heat Exchanger With Dimples/Protrusions

Plate heat exchanger plays a very important role in industrial production andPeople’s Daily life，As the main factor influencing the heat exchanger’s heat flowand heat transfer, the shape of the plate becomes a focus in the study of domesticand foreign experts. Despite the study of plate with dimples/protrusions is so much,there are still some problems. The research on the influence of plate with sphericaldimples/protrusions is not systematic and comprehensive enough. The research onother shapes of plate with dimples/protrusions is a little. So the influence ofstructural parameters of plate with spherical dimples/protrusions is researchedsystematic and comprehensive enough in this paper. Against disadvantages of platewith spherical dimples/protrusions, this paper puts forward the plate with shuttledimples/protrusions and plate with overlapping dimples/protrusions, and analysesthe influence of different geometry size to the flow and heat transfer. Finally thispaper chose the representative structure of three to analyze, the conclusions are asfollows:1. The existence of dimples and protrusions increases the heat exchange area,destroyed the boundary layer which leads to the boundary layer has been in adiscontinuous growth status and produces the vortex and secondary flow. In general,plate with dimples/protrusions reinforced heat exchange, also increases theresistance to flow, integrated heat exchange factor η is between1.2~2.4andsuperior to the tablet.2. In the condition of3000＜Re＜15000, the height and diameter of dimples/protrusions have an optimal proportion, namely Hd/De=0.25.In the range of W/De=1.25~1.75, if Re＜5000, the smaller W is, the larger η is, if Re＞5000,η is the largest,when W/De=1.5. In the range of S/W=1~3, if Re＜7000, the smaller S is, the largerη is, if Re＞7000,η is largest when S/W=2. In the range of H/De=1~2,if Re＜5000,the smaller H is, the larger η is, if Re＞5000, the larger H is, the larger η is. In therange of L/S=0~0.5, if Re＜13000, the larger L is, the larger η is; if Re＞13000, η is the largest when L/S=0.3. When3000＜Re＜5000, the comprehensive heat transfer performance of theplate with Hd/De=0.25、W/De=1.25、S/W=1、H/De=1、L/S=0.5is optimal, η=2.0~2.4.When5000＜Re＜7000, the comprehensive heat transfer performance of the platewith Hd/De=0.25、W/De=1.5、S/W=1、H/De=2、L/S=0.5is optimal, η=1.8~2.0. When7000＜Re＜13000, the comprehensive heat transfer performance of the plate withHd/De=0.25、W/De=1.5、S/W=2、H/De=2、L/S=0.5is optimal, η=1.6~1.8. When13000＜Re＜15000, the comprehensive heat transfer performance of the plate withHd/De=0.25、W/De=1.5、S/W=2、H/De=2、L/S=0is optimal, η=1.5~1.6. The heightof dimples/protrusions Hdhas the greatest impact on the flow and heat transfer.4. The plate with shuttle dimples/protrusions makes the flow more quietly andproduces large and sparse swirl. It’s heat transfer and resistance are smaller than theplate’s with spherical and overlapping dimples/protrusions. It’s comprehensive heattransfer performance is poorer than the others. Overlapping dimples/protrusionsmakes small and dense swirl, enhances heat transfer, At the same time it alsoreduces the height of the dimples/protrusions, weakens the heat transfer. When3000＜Re＜5000, the comprehensive heat transfer performance of plate with sphericaland shuttle dimples/protrusions is better; when5000＜Re＜7000, the threecomprehensive heat transfer performance is basically the same; when Re＞7000，thecomprehensive heat transfer performance of plate with overlapping dimples/protrusions is the best. Small and dense swirl effects the comprehensive heattransfer performance better than big and sparse swirl. In heat exchanger design, wecan avoid large and sparse swirl and add small and dense swirl by optimizing thestructure, thus improve the comprehensive heat transfer performance of the heatexchanger.