Determination of absorption coefficient of nanofluids with unknown refractive index from reflection and transmission spectra. (July 2018)

• Record Type: Journal Article
• Authors: Kim, Joong Bae; Lee, Seungyoon; Lee, Kyungeun; Lee, Ikjin; Lee, Bong Jae
• Is Part Of: Journal of quantitative spectroscopy & radiative transfer. Volume 213(2018)
• Page Start: 107
• Page End: 112
• Publication Date: 2018-07
• Subjects: Absorption coefficient -- Nanofluids -- Reflection/transmission spectra; Spectrum analysis -- Periodicals; Radiation -- Periodicals; Analyse spectrale -- Périodiques; Rayonnement -- Périodiques; Radiation; Spectrum analysis; Periodicals; 543.0858
• DOI: 10.1016/j.jqsrt.2018.04.018
• Languages: English
• ISSNs: 0022-4073

Abstract

Highlights: Analytical method of determining the absorption coefficient of nanofluids with unknown refractive index is proposed. Measurable range of the absorption coefficient of nanofluids is identified by considering the measurement uncertainty. Absorption coefficients of Therminol VP-1 and the Therminol VP-1 - graphite nanofluids are retrieved. Abstract: It has been shown that the absorption coefficient of a nanofluid can be actively tuned by changing material, size, shape, and concentration of the nanoparticle suspension. In applications of engineered nanofluids for the direct absorption of solar radiation, it is important to experimentally characterize the absorption coefficient of nanofluids in the solar spectrum. If the refractive index of the base fluid (i.e., the solution without nanoparticles) is known a priori, the absorption coefficient of nanofluids can be easily determined from the transmission spectrum. However, if the refractive index of the base fluid is not known, it is not straightforward to extract the absorption coefficient solely from the transmission spectrum. The present work aims to develop an analytical method of determining the absorption coefficient of nanofluids with unknown refractive index by measuring both reflection and transmission spectra. The proposed method will be validated with deionized water, and the effect of measurement uncertainty will be carefully examined. Finally, the general applicability of the proposed method will also be demonstrated for Therminol VP-1 as well as the Therminol VP-1 - graphite nanofluid.