Size Effect of Graphene Nanoparticles on the Thermal Properties of the Doped Phase Change Materials

Öz

In this study, the size effects of the Graphene nanoparticles (GNP) doped into a paraffin type organic phase change material (PCM) on thermal properties were examined. The thermal conductivities, melting/solidification temperatures and melting/solidification latent heats of the GNP/PCM composites, which were obtained by incorporating GNP nanoparticles with three different sizes into an organic PCM in mass fractions of 1%, 3% and 5%, were measured. The changes obtained in thermal properties were determined by referring to the non-doped PCM data. The results obtained showed that in low PCM mass fractions, thermal conductivity enhancement was a function of both surface area and thickness of the GNP nanoparticles. In addition, it was determined that thicker nanoparticles formed a more efficient conduction network at high PCM fractions. The reflections of the enhancements obtained in thermal conductivity on thermal performance were also determined in the study.  Enhancements in thermal conductivity depending on the increase in thickness of GNP were obtained as 6.3%, 107.5% and 113.7% for 5% GNP(1-5nm)/ PCM, 5% GNP(6-8nm)/PCM and 5% GNP(11-15nm)/PCM composites, respectively. These thermal conductivity enhancements resulted performance increase in the energy storage unit around 5.5%, 18.3% and 20% respectively.

Anahtar Kelimeler

• PCM,Thermal conductivity,Size effect,Graphene,Nanoparticles

Grafen Nanoparçacık Boyutunun Katkılı Faz Değişken Malzemelerin Termal Özelliklerine Etkisi

Öz

Bu çalışmada, parafin tipi bir organik Faz Değişken Malzeme (FDM) içerisine katkılanan Grafen nanoparçacık boyutunun termal özellikler üzerindeki etkileri incelenmiştir. Üç farklı boyuta sahip GNP nanoparçacıkların organik bir FDM içerisine %1, %3 ve %5 kütle bölüntülerinde katkılanması suretiyle elde edilen GNP/FDM kompozitlerinin ısıl iletkenlik, erime/katılaşma sıcaklıkları ve erime/katılaşma gizli ısıları ölçülmüştür. Termal özelliklerde elde edilen değişimler katkılanmamış FDM verileri referans alınarak belirlenmiştir. Elde edilen sonuçlar, düşük GNP kütle bölüntülerinde ısıl iletkenlik iyileştirmesinin hem GNP nanoparçacık yüzey alanının hem de kalınlığının bir fonksiyonu olduğunu göstermiştir. Buna ilave olarak, daha kalın nanoparçacıkların yüksek FDM kütle bölüntülerinde daha etkin bir iletim ağı oluşturdukları belirlenmiştir. Çalışmada ayrıca ısıl iletkenlikte elde edilen iyileştirmelerin termal performansa yansımaları da belirlenmiştir. GNP nanoparçacık kalınlığındaki artışa bağlı olarak ısıl iletkenlikteki iyileşmeler; 5% GNP(1-5nm)/ FDM, 5% GNP(6-8nm)/FDM ve 5% GNP(11-15nm)/FDM kompozitleri için sırasıyla %6.3, %107.5 ve  %113.7 olarak elde edilmiştir. Bu ısıl iletkenlik iyileştirmeleri, bir enerji depolama biriminde sırasıyla %5.5,% 18.3 ve % 20 civarında performans artışı sağlamıştır.

Anahtar Kelimeler

• FDM,Isıl İletkenlik,Boyut Etkisi,Grafen Nanoparçacık

Kaynakça

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