Sains Malaysiana 46(7)(2017): 1017–1024

http://dx.doi.org/10.17576/jsm-2017-4607-02

Thermal Stability and Conductivity of Carbon Nanotube Nanofluid using Xanthan Gum as Surfactant

(Kestabilan Termal dan Kekonduksian Bendalir Nano Karbon Tiub Nano menggunakan Gam Xantan sebagai Surfaktan)

SABA RASHID1^I*, RASHMI, W²., LUQMAN CHUAH ABDULLAH³, KHALID, M⁴., FAKHRUL-RAZI AHMADUN⁵ & M.Y. FAIZAH⁶

¹Institute of Tropical Forestry and Forest Product, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan, Malaysia

²Department of Chemical Engineering, Taylor's University, 47500 Subang Jaya, Selangor

Darul Ehsan, Malaysia

³Materials Processing & Technology Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan, Malaysia

⁴Research Centre for Nano-Materials and Energy Technology, Sunway University, No. 5, Jalan Universiti, Bandar Sunway, 47500 Subang Jaya, Selangor Darul Ehsan, Malaysia

⁵Humanitarian Assistance and Disaster Relief Research Centre, National Defense University, Sungai Besi Camp, 57000 Kuala Lumpur, Federal Territory, Malaysia

⁶Institute of Advanced Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan, Malaysia

Diserahkan: 17 Oktober 2016/Diterima: 17 Februari 2017

ABSTRACT

A nanofluid is a suspension of nano-sized particles dispersed in a base fluid. It is very much obligatory to know more about stability and thermal characteristics of such a nanofluid for their further use in practical applications. In this research, multiwalled carbon nanotubes (CNT) is dispersed in water. CNT dispersed in water is highly unstable and it sediments rapidly due to the Vander Waals force of attraction. Therefore, to overcome this limitation, xanthan gum (XG) was added which behave as a promising dispersant followed by 4 h water bath sonication. Experimental work includes stability studies using UV Vis spectroscopy with respect to CNT concentration (0.01 and 0.1 wt. %) and XG concentration (0.04 and 0.2 wt. %). The thermal conductivity of the most stable suspensions was measured using KD 2 Pro as a function of temperature (25-70°C) and CNT concentration. The optimum XG concentration was found for each CNT concentration studied. Thermal conductivity was observed to be strongly dependent on temperature and CNT concentration. The dispersion state of the CNT-water nanofluid is further examined using scanning electron microscope (SEM). In short, CNT nanofluids are found to be more suitable for heat transfer applications in many industries due to their enhanced thermal conductivity property. This work provides useful insight on the behavior of CNT nanofluids.

Keywords: Carbon nanotubes; nanofluid; stability; thermal conductivity; xanthan gum

ABSTRAK

Bendalir nano ialah penggantungan zarah bersaiz nano dalam bendalir asas. Adalah sangat penting untuk mengetahui lebih lanjut tentang kestabilan dan pencirian termal daripada bendalir nano tersebut bagi tujuan kegunaan praktik selanjutnya. Dalam kajian ini, pelbagai lapisan karbon tiub nano (CNT) terserak di dalam air. Penyerakan CNT ini tidak stabil dan endapan berlaku dengan pantas kerana adanya daya tarikan Vander Waals. Oleh itu, bahan sampingan gam xantan (XG) telah digunakan dalam kajian ini sebagai agen serakan. Penyelidikan bagi mengkaji kesan kepekatan CNT (0.01 dan 0.1 wt. %), kepekatan XG (0.04 dan 0.2 wt. %) dan masa sonikasi (4 jam) ke atas kestabilan bendalir nano telah dijalankan. Bacaan kestabilan diambil dengan menggunakan spektrofotometer UV-Vis. Termal konduktiviti yang paling stabil telah diukur sebagai fungsi suhu (25-70°C) dan kepekatan CNT. Bendalir nano didapati tidak stabil pada sonikasi selama 4 jam dan kepekatan optimum XG didapati antara 0.04,0.2 % bt. dan 0.01,0.1 % bt. bagi julat kepekatan CNT yang dikaji. Pemerhatian menunjukkan bahawa, konduktiviti termal amat bergantung kepada suhu dan kepekatan CNT. Keputusan mendapati CNT bendalir nano adalah lebih sesuai untuk aplikasi pemindahan haba dalam pelbagai industri kerana adanya peningkatan sifat konduktiviti termal. Kajian ini menyediakan maklumat mengenai sifat CNT nano bendalir.

Kata kunci: Bendalir nano; karbon tiub nano; kestabilan; konduktiviti termal; gam xantan

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*Pengarang untuk surat-menyurat; email: Saba.rashidi604@gmail.com