Photothermal conversion characteristics of gold nanoparticle dispersions

Abstract

This work proposes and validates a novel idea of using plasmonic nanoparticles (PNP) to improve the solar thermal conversion efficiency. Gold nanoparticle (GNP) is synthesized from an improved citrate-reduction method, and used as an example to illustrate the photothermal conversion characteristics of PNPs under a solar simulator. The experimental results show that GNP has the best photo-thermal conversion capability comparing to other reported materials. At the lowest particle concentration examined (i.e., 0.15 ppm), GNP increases the photo-thermal conversion efficiency of the base fluid by 20% and reaches a specific absorption rate (SAR) of ~10 kW/g. The photo-thermal conversion efficiency increases with increasing particle concentrations, but the SAR shows a reverse trend, which is unexpected as all GNPs should be still in the independent scattering regime.

Volumetric solar heating and steam generation via gold nanofluids

“…The Also the rate of rise in surface temperature in case of DI water is also much slower very far low than that of 0.040 wt% gold nanofluid (Fig. 5a) The energy absorbed by the nanofluid sample in the sensible heating was calculated using the following relation in their studies done by Zhang et al [32,53] and Neumann [44], where only one temperature sensor was used to represent the bulk fluid temperature; (1) where , and are the specific heat capacity, mass of the sample taken and temperature change of the fluid volume over the specified time. The change in temperature was replaced by , the average change in temperature in the study done by Jin et al [41,48] in which more than one thermocouple were used for the measurement of fluid temperature.…”

“…The energy absorbed by the nanofluid during the sensible heating period was calculated using the following relation by Zhang et al [32,53] and Neumann [44], where only one temperature sensor was used to represent the bulk fluid temperature; (1) where , and are the specific heat capacity, mass of the sample taken and temperature change of the fluid volume over the specified time. The change in temperature was replaced 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 10 by , i.e., the average temperature difference by Jin et al [41,48], in which more than one thermocouple were used.…”

“…[32] and Chen et al [54]. In the synthesis process, 100 ml of 5mM HuACl 4 solution was mixed with 100 ml of 10 mM trisodium citrate solution.…”

“…Beside the problem of varying solar flux and spot heating mentioned above, most of the experiments were performed by a single-point temperature measurement, ignoring the temperature distribution in the bulk fluid [32,44,53]. Though Jin et al [41] and Ni et al [43] used multipoint temperature measurement, only the average temperature was used for the evaluation of the photothermal efficiency.…”

“…A variety of direct absorption nanoparticles materials had have been analyzed in terms of the enhancement in the photothermal performance, including Ag [27][28][29], Au [30][31][32], CNT (carbon nanotubes) [33][34][35], Cu [36], Al 2 O 3 [37,38], graphite [17], graphene [22], and TiO 2 [39]. In addition to the volumetric heating, direct vapor generation due to localized heating of the As far as the steam generation mechanism is concerned, for nanobubbles to be produced around heated nanoparticles, it has been shown analytically that a minimum radiation flux of 3×10 8 W/m 2 is required to produce nanobubbles on heated nanoparticles [46,49,50], which can may only be reached developed by powerful laser beams.…”