scholarly journals Thermal Efficiency of a New Prototype of Evacuated Tube Collector using Sn-Al2O3 as a Selective Solar Absorber

2018 ◽  
Vol 15 (11) ◽  
pp. 793-802
Author(s):  
Warisa WAMAE ◽  
Tawat SURIWONG ◽  
Thotsaphon THRERUJIRAPAPONG
Keyword(s):  
Thermal Efficiency ◽  
Al2o3 Layer ◽  
Solar Absorptance ◽  
Solar Absorber ◽  
Solar Absorbers ◽  
Evacuated Tube Collector ◽  
Distribution Of Elements ◽  
Solar Receiver ◽  
Tin Content ◽  
Evacuated Tube

Three tin pigmented aluminium oxide (Sn-Al2O3)films were prepared with different tin content using an anodization process, which is applied as a selective solar absorber in a new prototype of evacuated tube collector (ETC). The morphology and distribution of elements on the coatings were characterized using a Scanning Electron Microscope (SEM) equipped with an Energy Dispersive X-ray (EDX) analyzer. The spectrally selective properties, defined as the ratio of solar absorptance (αsol) to thermal emittance (εtherm) were examined. In order to investigate the thermal performance of ETC using Sn-Al2O3 on an Al fin as a solar receiver, thermal efficiency (η) of the ETC was collected under steady-state conditions, as prescribed by ISO 9806-1 standard. The results, of the Sn-Al2O3 coatings reached a darker black colour with an increase in the colouring time. The samples were composed of different contents of Sn in the Al2O3 layer. The solar selectivity (αsol/εtherm) significantly increased with the increases in Sn content. The maximum thermal efficiency (ηmax) of the ETC under the nearly constant heat loss coefficient (UL), was obviously increased with the increasing Sn content. Therefore, the Sn-Al2O3 with different Sn contents is a good candidate for selective solar absorbers in a new prototype of ETC.

scholarly journals An Ultra-High Temperature Stable Solar Absorber Using the ZrC-Based Cermets

2021 ◽  
Vol 9 ◽  
Author(s):  
Jian Wang ◽  
Zuoxu Wu ◽  
Yijie Liu ◽  
Shuaihang Hou ◽  
Zhikun Ren ◽  
...  
Keyword(s):  
High Temperature ◽  
Conversion Efficiency ◽  
Steel Substrate ◽  
Selective Absorption ◽  
Solar Absorptance ◽  
Excellent Thermal Stability ◽  
Solar Absorber ◽  
Solar Absorbers ◽  
Stable Operating ◽  
Ultra High Temperature

Exploring the spectrally selective absorbers with high optical performance and excellent thermal stability is crucial to improve the conversion efficiency of solar energy to electricity in concentrated solar power (CSP) systems. However, there are limited reports on the selective solar absorbers utilized at 900oC or above. Herein, we developed a selective absorption coating based on the ultra-high temperature ceramic ZrC and the quasi-optical microcavity (QOM) optical structure, and experimentally achieved the absorber via depositing an all-ceramic multilayer films on a stainless steel substrate by magnetron sputtering. The prepared multi-layer selective absorber demonstrates an excellent high solar absorptance of ∼0.964 due to the multi absorptance mechanisms in the QOM, and a relatively low thermal emittance of ∼0.16 (82°C). Moreover, the coating can survive at 900oC in vacuum for 100 h with a superior spectral selectivity of 0.96/0.143 (82°C) upon annealing, resulting from the introduction of ultra-high temperature ceramic ZrC in the QOM structure. Under the conditions of a stable operating temperature of 900°C and a concentration ratio of 1,000 suns, the calculated ideal conversion efficiency using this absorber can reach around 68%, exceeding most solar selective absorbers in previous reports.

Effect of Etchant Concentration on the Optical Properties and Surface Topography of MoO3 Selective Solar Absorber Thin Films

MRS Advances ◽  
2020 ◽  
Vol 5 (21-22) ◽  
pp. 1133-1143 ◽  
Author(s):  
R. Akoba ◽  
G. G. Welegergs ◽  
M. Luleka ◽  
J Sackey ◽  
N Nauman ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Cost Effective ◽  
Solar Absorptance ◽  
Solar Absorber ◽  
Solar Absorbers ◽  
Metal Oxide Nanostructures ◽  
Xrd Patterns ◽  
Solar Thermal Applications ◽  
Chemical Etchant

ABSTRACTA novel technique providing a cost effective sustainable wet chemical etching method of synthesizing black Moly thin films rapidly has been presented. A top- down method for fabricating MoO3 has been investigated to understand the effect of chemical etchant concentration on the structural, morphological and optical properties of the thin films on Mo substrates. The XRD patterns demonstrated the formation of Tugarinovite MoO2 films on Mo substrate after annealing at 500°C in a vacuum. In this work, we developed nanostructured MoO3 on Mo substrate solar absorber, with a high solar absorptance of over 89%. These results suggest that solar absorbers made from refractory metal oxide nanostructures can be used for solar thermal applications.

scholarly journals Design a New Receiver for the Central Tower of Solar Energy

2018 ◽  
Vol 225 ◽  
pp. 02009
Author(s):  
Ayad K. Khlief ◽  
Syed I.U. Gilani ◽  
Hussain H. Al-Kayiem ◽  
Sanan T. Mohammad
Keyword(s):  
Thermal Efficiency ◽  
Energy Input ◽  
Radiative Heat ◽  
Heat Losses ◽  
Solar Irradiation ◽  
Solar Systems ◽  
Proposed Model ◽  
Simulation Results ◽  
Solar Receiver ◽  
Evacuated Tube

Heat loss is an important factor in the performance of the solar receiver for concentrated solar systems (CSP). This study presents a proposed model for a new design for the receiver using an evacuated tube that has been performed to reduce convection loss and radiative heat losses with a zigzag distribution to minimize spillage losses. In this study, simulation results showed that the energy input increases with increased solar irradiation; the increase ranges from 3429 to 5584 W and 1879 to 3875 W at 9 AM and 13 PM for preheater and superheater respectively. The thermal efficiency of the receiver was around 72%.

Application of Ni-Al 2 O 3 cermet coating on aluminium fin as the solar absorber in evacuated tube collector (ETC)

2018 ◽  
Vol 5 (7) ◽  
pp. 14793-14798 ◽  
Author(s):  
Sathit Banthuek ◽  
Tawat Suriwong ◽  
Pornnipa Nunocha ◽  
Amanuel Andemeskel
Keyword(s):  
Cermet Coating ◽  
Solar Absorber ◽  
Evacuated Tube Collector ◽  
Evacuated Tube

Characterization and Spectral Selectivity of Sn-Al2O3 Solar Absorber

2016 ◽  
Vol 675-676 ◽  
pp. 467-472 ◽  
Author(s):  
Titiporn Chorchong ◽  
Tawat Suriwong ◽  
Sukruedee Sukchai ◽  
Thotsaphon Threrujirapapong
Keyword(s):  
Near Infrared ◽  
Spectral Irradiance ◽  
X Ray Diffraction ◽  
Solar Absorptance ◽  
Aluminium Substrate ◽  
X Ray ◽  
Solar Absorber ◽  
Solar Absorbers ◽  
Infrared Spectrophotometer ◽  
Relationship Of

In present work, tin-pigmented alumina (Sn-Al2O3) solar absorber on the aluminium substrate was successfully prepared by anodic anodization and further characterized by different methods. The phase, morphology, reflectance (R) and thermal conductivity of the Sn-Al2O3 solar absorber were measured by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) equipped with energy dispersive X-ray (EDX) analyzer, and Ultraviolet-visible-near infrared spectrophotometer in the wavelength of 300-2500 nm. The solar absorptance (α) was calculated based on the relationship of the spectral reflectance, R(λ), and the solar spectral irradiance of AM 1.5, Is(λ), in the wavelength interval of 300-2500 nm. As the results, the surface color of the Sn-Al2O3 film was dark-black color. The XRD pattern of Sn-Al2O3 films was indexed as aluminium and tin phases. The chemical composition of the Sn-Al2O3 films composed of tin (Sn), aluminum (Al) and oxygen (O) elements. The average thickness of the produced films was 18.9 μm. It was found that Sn-Al2O3 films showed the low R (0.09) and high α (0.93) values for the whole wavelength 300-2500 nm, corresponding to theoretical properties of the solar absorber. Therefore, it can be concluded that the Sn-Al2O3 film on aluminium substrate can be applied to be the solar absorber in solar collector due to high α, which is similar to the commercial solar absorbers.

PERFORMANCE OF AN ACTIVE SOLAR STILL COUPLED TO EVACUATED TUBE COLLECTOR

2014 ◽  
Vol 13 (2) ◽  
pp. 333-344
Author(s):  
Karuppusamy Sampathkumar ◽  
Palanisamy Senthilkumar
Keyword(s):  
Solar Still ◽  
Evacuated Tube Collector ◽  
Evacuated Tube

Thermomechanical Modeling of Laser Spot Welded Solar Absorbers

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
L. A. Spyrou ◽  
N. Aravas
Keyword(s):  
Spot Welding ◽  
Laser Spot ◽  
Structural Failure ◽  
Absorber Plate ◽  
Solar Absorber ◽  
Solar Absorbers ◽  
Laser Spot Welding ◽  
Thermomechanical Modeling ◽  
Different Levels ◽  
Flattening Process

A finite element (FE) approach is developed to investigate the laser spot welding (LSW) of flat-plate solar absorbers and the stress and distortion fields that develop after fabrication and during operation. Numerical calculations at two different levels are carried out. At a microscopic scale, the details of a spot weld are analyzed. At a macroscopic level, a global approach is used to simulate the joining of the pipeline to the absorber plate and the “restoration” (flattening) process of the absorber. The simulated welding-induced distortion is compared with experimental measurements. The thermomechanical behavior of a solar absorber under working conditions is also studied and operational stresses and the critical locations for structural failure are reported.

Heat Transfer Analysis of a Novel Pressurized Air Receiver for Concentrated Solar Power via Combined Cycles

2009 ◽  
Vol 1 (4) ◽  
Author(s):  
I. Hischier ◽  
D. Hess ◽  
W. Lipiński ◽  
M. Modest ◽  
A. Steinfeld
Keyword(s):  
Heat Transfer ◽  
Thermal Efficiency ◽  
Porous Ceramic ◽  
Conservation Equation ◽  
Heat Transfer Analysis ◽  
Operational Parameters ◽  
Small Aperture ◽  
Solar Absorber ◽  
Energy Conservation Equation ◽  
Combined Cycles

A novel design of a high-temperature pressurized solar air receiver for power generation via combined Brayton–Rankine cycles is proposed. It consists of an annular reticulate porous ceramic (RPC) bounded by two concentric cylinders. The inner cylinder, which serves as the solar absorber, has a cavity-type configuration and a small aperture for the access of concentrated solar radiation. Absorbed heat is transferred by conduction, radiation, and convection to the pressurized air flowing across the RPC. A 2D steady-state energy conservation equation coupling the three modes of heat transfer is formulated and solved by the finite volume technique and by applying the Rosseland diffusion, P1, and Monte Carlo radiation methods. Key results include the temperature distribution and thermal efficiency as a function of the geometrical and operational parameters. For a solar concentration ratio of 3000 suns, the outlet air temperature reaches 1000°C at 10 bars, yielding a thermal efficiency of 78%.

scholarly journals Calorimetric Evaluation of Novel Concentrating Solar Receiver Geometries With Enhanced Effective Solar Absorptance

2016 ◽  
Author(s):  
Jesus D. Ortega ◽  
Julius E. Yellowhair ◽  
Clifford K. Ho ◽  
Joshua M. Christian ◽  
Charles E. Andraka
Keyword(s):  
Thermal Efficiency ◽  
Solar Power ◽  
Solar Furnace ◽  
Heat Transfer Fluid ◽  
Discrete Ordinates ◽  
Base Case ◽  
Outlet Temperature ◽  
Black Paint ◽  
Solar Absorptance ◽  
Flow Rates

Direct solar power receivers consist of tubular arrays, or panels, which are typically tubes arranged side by side and connected to an inlet and outlet manifold. The tubes absorb the heat incident on the surface and transfer it to the fluid contained inside them. To increase the solar absorptance, high temperature black paint or a solar selective coating is applied to the surface of the tubes. However, current solar selective coatings degrade over the lifetime of the receiver and must be reapplied, which reduces the receiver thermal efficiency and increases the maintenance costs. This work presents an evaluation of several novel receiver shapes which have been denominated as fractal like geometries (FLGs). The FLGs are geometries that create a light-trapping effect, thus, increasing the effective solar absorptance and potentially increasing the thermal efficiency of the receiver. Five FLG prototypes were fabricated out of Inconel 718 and tested in Sandia’s solar furnace at two irradiance levels of ∼15 and 30 W/cm2 and two fluid flow rates. Photographic methods were used to capture the irradiance distribution on the receiver surfaces and compared to results from ray-tracing models. This methods provided the irradiance distribution and the thermal input on the FLGs. Air at nearly atmospheric pressure was used as heat transfer fluid. The air inlet and outlet temperatures were recorded, using a data acquisition system, until steady state was achieved. Computational fluid dynamics (CFD) models, using the Discrete Ordinates (DO) radiation and the k-ω Shear Stress Transport (SST) equations, were developed and calibrated, using the test data, to predict the performance of the five FLGs at different air flow rates and irradiance levels. The results showed that relative to a flat plate (base case), the new FLGs exhibited an increase in the effective solar absorptance from 0.86 to 0.92 for an intrinsic material absorptance of 0.86. Peak surface temperatures of ∼1000°C and maximum air temperature increases of ∼200°C were observed. Compared to the base case, the new FLGs showed a clear air outlet temperature increase. Thermal efficiency increases of ∼15%, with respect to the base case, were observed. Several tests, in different days, were performed to assess the repeatability of the results. The results obtained, so far, are very encouraging and display a very strong potential for incorporation in future solar power receivers.

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