Experimental study of photothermal conversion using gold/water and MWCNT/water nanofluids

Abstract

This work experimentally investigated photothermal conversion behavior of Gold/water and MWCNT/water nanofluids at different volumetric concentrations (0.0001%-0.004% and 0.0001%-0.03%, respectively). The experiments were conducted for ~10 hours outdoor on each test day, without interruptions. The results show that the tested nanofluids have excellent photothermal conversion capability even under very low concentrations. Specific absorption rate (SAR) presented an exponential decay with increasing volumetric concentration of nanoparticles in the sample while both the total energy stored by the fluid sample during the heating period and the stored energy ratio (SER) increased with the increase in nanoparticles concentration. The results indicates the existence of an "optimal" volumetric concentration, above which further nanoparticle addition becomes indifferent or infeasible. This optimal nanoparticle volumetric concentration was found to be 0.002% for the gold nanofluid and 0.001% for the MWCNT samples.

Review of the Photothermal Energy Conversion Performance of Nanofluids, Their Applications, and Recent Advances

“…Nevertheless, the use of ethylene glycol alone in the heat transfer system is not a good choice because of its high viscosity, which is why most of the studies used its mixture with DI water. [19] Au one-step DI water 25-10 mg/L - [20] Au, CNT, Fe 3 O 4 two-step DI water 10-50 ppm - [21] Fe 3 O 4 two-step Water 1-5wt% - [22] Graphite two-step DI water/Paraffin -- [23] Au, MWCNT two-step DI water 0.0001-0.004vol% - [24] rGO, Ag-rGO two-step DI water 10-100 mg/L - [25] CuO two-step Paraffin 0.01-0.1wt% SSL [26] TiN, Au/TiN two-step EG 10-100 ppm - [27] CuO-MWCNT two-step DI water 0.01-0.25wt% - In the next section, the optical properties and photothermal energy conversion performance of various nanofluids are discussed and illustrated.…”

“…To investigate the photothermal energy conversion performance of the working fluid, many researchers [23,28,37,42,48,56] utilized the photothermal energy conversion efficiency and specific absorption rate of the working fluid. For instance, the photothermal energy conversion efficiency can be calculated using Equation 4 [27]:…”

“…Numerical result of the temperature distribution in nanofluids [46]; 2014, ACS. Table 2 lists the photothermal energy conversion performance of different nanofluids by comparing their temperature rises [23,42,43,51,[57][58][59][60][61]. In addition to the nanofluid properties, the differences in temperature rise can be caused by differences in the exposure time or light source and solar irradiance intensity.…”

Investigation on influence of antimony tin oxide/silver nanofluid on direct absorption parabolic solar collector

“…Chen et al [5] studied the photothermal conversion property of Au nanofluids and found that efficiency increased with an increase in the volume fraction of nanoparticle. Experimental analysis on the photothermal conversion property of gold nanofluids was performed by Beicker et al [6]. Amjad et al [7] analyzed the photothermal conversion capability of different nanofluids to be used for direct absorption applications.…”

Performance analysis of direct absorption-based parabolic trough solar collector using hybrid nanofluids

“…Beicker et al [23] investigated the photothermal conversion using different volume concentrations of gold/water and MWCNT/water nanofluids and found that both types of nanofluids showed perfect photothermal conversion even for very low concentrations. An increase in the range of 2-25% was observed by using 0.01 wt% graphite-based nanofluids.…”