Investigation of the effects of using hexagonal boron nitride-water nanofluid on thermal performance in solar collectors

Abstract

In this study, the effects of adding a rectangular spiral fin inside a collector pipe used in a parabolic solar collector and the use of nanofluids on thermal performance were numerically investigated. Four model geometries were created by changing the number of spiral turns along the tube length of the fin. It is assumed that Hexagonal Boron Nitride-Water (hBN-water) nanofluid passes through the collector pipe. The volumetric mixing ratios of the nanofluid were changed between 0% and 4%. The flow is laminar and the Reynolds number is taken at a constant 1500. Analyzes were made with the help of Computational Fluid Dynamics for different parameters. As a result of the study, it was observed that the heat transfer increased as the volumetric mixing ratio of the hBN particle in the nanofluid was increased. In addition, increasing the number of turns of the fin added in the collector pipe also increased the heat transfer. With the addition of fins to the collector tube and the use of hBN nanofluid, the value of the heat transfer coefficient increased by approximately 284% and the value of the Nusselt number increased by approximately 256% compared to a collector tube without fins and only water flowing through it.

Keywords

• Nanofluid
• Hexagonal Boron Nitride
• hBN
• Thermal performance

Güneş kolektörlerinde hegzagonal bor nitrür-su nanoakışkanının kullanımının ısıl performans üzerindeki etkilerinin incelenmesi

Abstract

Bu çalışmada parabolik güneş kolektöründe kullanılan toplayıcı bir borunun içine dikdörtgen spiral bir kanatçık eklenilmesi ve nanoakışkan kullanımının ısıl performansa olan etkileri sayısal olarak incelenmiştir. Kanatçığın boru uzunluğu boyunca spiral sarım sayısı değiştirilerek dört adet model geometri oluşturulmuştur. Toplayıcı borunun içinden Hegzagonal Bor Nitrür-Su (hBN-su) nanoakışkanının geçtiği kabul edilmiştir. Nano akışkanın hacimsel karışım oranları %0 ile %4 aralığında değiştirilmiştir. Akış laminer bir akıştır ve Reynolds sayısı sabit 1500 değerinde alınmıştır. Farklı parametreler için Hesaplamalı akışkanlar Dinamiği yardımı ile analizler yapılmıştır. Çalışmanın sonucunda, nanoakışkan içindeki hBN partikülünün hacimsel karışım oranı artırıldıkça ısı transferinin arttığı gözlemlenmiştir. Ayrıca toplayıcı boru içerisine eklenen kanatçığın sarım sayısının artırılması da ısı transferini artırmıştır. Toplayıcı boruya kanatçık eklenmesi ve hBN nanoakışkanının kullanımı ile, kanatçıksız ve içinden sadece su akan bir toplayıcı boruya göre, ısı taşınım katsayısının değeri yaklaşık %284 Nusselt sayısının değeri ise yaklaşık %256 artış göstermiştir.

Keywords

• Nanoakışkan
• Hegzagonal Bor Nitrür
• hBN
• Isıl performans

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