Steam generation under one sun enabled by a floating structure with thermal concentration

Abstract

Abstract:Harvesting solar energy as heat has many applications, such as power generation, residential water heating, desalination, distillation and wastewater treatment. However, the solar flux is diffuse, and often requires optical concentration, a costly component, to generate high temperatures needed for some of these applications. Here we demonstrate a floating solar receiver capable of generating 100°C steam under ambient air conditions without optical concentration. The high temperatures are achieved by using thermal concentration and heat localization, which reduce the convective, conductive, and radiative heat losses. This demonstration of a low-cost and scalable solar vapor generator holds the promise of significantly expanding the application domain and reducing the cost of solar thermal systems. Keywords: solar thermal, steam generation, thermal concentration, water treatmentThe sun is a promising and abundant source of renewable energy that can potentially solve many of society's challenges. Solar thermal technologies, i.e., the conversion of the sunlight to thermal energy, are being developed for many applications such as power generation, domestic water heating, desalination, and other industrial processes. [1][2][3][4][5][6][7] Steam and vapor generation is often desired in these applications, but the dilute solar flux (1000 W/m 2 ) does not provide enough power per unit area of the absorber to reach the required high temperatures and to compensate for the large latent heat of water vaporization. Optical

High‐Performance Large‐Scale Solar Steam Generation with Nanolayers of Reusable Biomimetic Nanoparticles

“…Compared to the recent structure studied in ref. [21], whose theoretical performance at 1 sun and 1 thermal concentration shows an ideal efficiency of 72% and a temperature lower than 20 °C, our nanoparticles present remarkable improved performances by showing experimentally retrieved efficiencies of 76% and temperatures of 35 °C. These results are also quite significant considering also the extremely little amount of nanomaterial used, equivalent to only 200 nm of gold.…”

“…[11,13,17,[19][20][21][22] By using graphite membranes, the highest solar thermal efficiency (see Equation (4)) of 85% has been reported under an equivalent solar intensity of 10 suns. [13] One of the main drawback of this approach, besides the large light intensity requirement, lies in the fact that carbon-based systems (both graphite and graphene) are vulnerable to the contamination of pollutants or salt in the water, thus limiting the recyclability of the membrane after prolonged use.…”

Novel Receiver-Enhanced Solar Vapor Generation: Review and Perspectives

“…Recently, Ni et al [127] demonstrated a floating solar receiver capable of generating 100°C steam under ambient air conditions without optical concentration. The high temperatures are achieved by using thermal concentration and heat localization while reducing the convective, conductive and radiative heat losses.…”

“…These figures show the receiver reached steady-state operation in roughly 5 min, clearly demonstrating continuous steam generation under 1 sun irradiance. [127]. Reprinted from [127].…”

“…Similarly, the liquid propagation using hydrophilic wick and the associated fouling and salt accumulation problems are also not quantified as it would also affect the overall performance. Thus, we proposed an improved design of scalable semi spectrally selective absorber The evaporation slots were varied in size to control the operating temperature [127]. Reprinted from [127].…”