KANATÇIKLI DİKDÖRTGEN KESİTLİ MİKROKANALDA NANOAKIŞKAN AKIŞININ SAYISAL İNCELENMESİ

Kanatçıklı bir mikrokanalın ısı transferi ve basınç düşüşü özellikleri üzerindeki geometrik parametrelerin ve nanoakışkan konsantrasyonunun etkilerini bulmak için sayısal bir çalışma gerçekleştirilmiştir. Dikdörtgen kesite sahip tek bir mikrokanala farklı yerleşimlere sahip altı adet ikili dikdörtgen kanat yerleştirildi. Mikrokanalın hidrolik çapı sabit tutularak yatay eksenler arasındaki kanat uzunluğu, genişliği ve açısı parametre olarak belirlendi. Baz akışkan olarak su seçilmiş ve hacimsel nanoakışkan konsantrasyonunun (Al2O3 (% 0 -% 0.4)) akış ve ısı transferi üzerindeki etkisi araştırılmıştır. Nanoakışkanların hacimsel konsantrasyonu ve kanatçık geometrisi, farklı parametrelerin seviyeleri için Yanıt Yüzey Optimizasyon (Response Surface Optimization) yöntemi ile optimize edilmiş ve farklı akış hızlarında Hesaplamalı Akışkanlar Dinamiği (CFD) analizleri (ANSYS Fluent 18) gerçekleştirilmiştir. Optimum kanatlı mikrokanal için hesaplanan CFD sonuçları, düz (kanatsız) mikrokanalınkilerle karşılaştırıldı. Çalışma sonucunda nanoakışkan konsantrasyon artışı ve kanatçıklar ısı transferini iyileştirmiş ve basınç düşüşünü artırmıştır.

Anahtar Kelimeler:

Mikrokanal, Nanoakışkan, kanatçık, CFD analizi, Optimizasyon

A NUMERICAL INVESTIGATION OF NANOFLUID FLOW IN RECTANGULAR FINNED MICROCHANNEL

A numerical study and parameter optimization was carried out to find the effects of geometric parameters and nanofluid concentration on heat transfer and pressure drop characteristics of a finned microchannel. Six dual rectangular fins with different layouts were placed in a single microchannel having rectangular cross section. The hydraulic diameter of the microchannel was kept constant and the length, width and angle of fin between the horizontal axes were determined as parameters. The water was selected as base fluid and the effect of volumetric concentration of nanofluids (Al2O3 (0% to 0.4%)) on fluid flow and heat transfer were investigated. Volumetric concentration of nanofluids and fin geometry was optimized with Response Surface Optimization method for the levels of different parameters and Computational Fluid Dynamics (CFD) analyses (ANSYS Fluent 18) was performed at different flow rates. CFD results calculated for the optimum finned microchannel were compared to those of the straight (finless) microchannel. As a result of the study, nanofluid concentration increment and fins improved the heat transfer and increased the pressure drop.

Keywords:

Microchannel, Nanofluid, Fin, CFD Analysis, Optimization,

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