Title

Enhancement of Thermal Conductivity and Local Heat Transfer Coefficients using Fe₂O₃/water Nanofluid for Improved Thermal Desalination Processes

Abstract

The enhancement of thermal conductivity and local convective heat transfer coefficient by nanofluid of Fe2O3/water has been studied experimentally for the improvement of the thermal desalination processes using a newly developed sophisticated noninvasive heat transfer coefficient probe that is flush mounted on the inner wall surface of the test section. Fe2O3 nanoparticles have been selected due to their magnetic characteristic for improving the thermal efficiency of desalination since they can be collected by magnet and reused. The volume fraction of 0.01-0.09% using different nanoparticle sizes of 3 nm, 10 nm, and 20 nm has been used at varying experimental temperatures of 25, 45, and 65 ºC in laminar and turbulent flow regimes. The thermal conductivity and local heat transfer coefficient increased with the increase of the Fe2O3/water nanofluids volume fraction and temperature. Also, decreasing the nanoparticle size enhanced the thermal conductivity as well as the local heat transfer coefficient. In the laminar flow regime, the change in the thermal boundary layer film thickness is small compared with that of the turbulent flow regime. Therefore, the enhancement of the local heat transfer coefficient in the turbulent flow regime is larger than that of the laminar flow regime for all the experimental conditions.The maximum enhancement in the thermal conductivity was 32%, whereas the enhancement in the local heat transfer coefficient was 70% for 3 nm at 0.09 volume fraction and 65 ºC. The improvement in the local heat transfer coefficient was larger than that in the thermal conductivity due to a decrease in the thermal boundary layer film thickness. The correlation of Y. M. Xuan and Q. Li, ASME J. Heat Transfer 125, 151 (2003) which accounts for the nanoparticles, presence in terms of volume fraction, predicts our results well and their trends for the conditions studied at 65 ºC with the variation in nanoparticles volume fraction and size. The improvement we obtained in the thermal conductivity and local heat transfer coefficient will enable thermal improvement of desalination processes.

Department(s)

Chemical and Biochemical Engineering

Keywords and Phrases

Fe2O3 nanoparticles; Heat transfer coefficient; Nusselt number; Thermal boundary layer film thickness; Thermal conductivity; Thermal desalination processes

International Standard Serial Number (ISSN)

2169-432X; 2169-4338

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2019 American Scientific Publishers, All rights reserved.

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