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Abstract Thermal performance of three naturally ventilated public buildings in which the wind tower is an important architectural freature is studied. One of the three builidings as well as it's wind tower is instrumented for temperature, relative humidity and airflow velocity measurements, and the other two are instrumented for temperature measurement. The results have led to a discussion concerning the degree of wind tower effectiveness in achieving thermal comfort.

Abstract Molten nitrate salts are widely used as heat transfer and energy storage medium in Concentrated Solar Power (CSP) systems. Solar Salt (60 wt% NaNO3-40 wt% KNO3) is the commercial binary molten nitrate salt, which is the preferred energy storage material with high density, high specific heat, low melting point, high thermal stability, and low vapor pressure. This paper explored the effects of impurity Cl− on the thermophysical properties of Solar Salt, including liquidus temperature, density, viscosity, and thermal stability. The results showed that Cl− can significantly reduce the liquidus temperature, and when Cl− was less than 0.5 wt%, the liquidus temperature of molten salt system decreased within 1 °C. On the other hand, Cl− had little effect on the density, viscosity and thermal stability of the mixed molten salt system at 400 °C, but at high temperature Cl− will promote the volatilization of components. By analyzing the thermostatic stability at 565 °C, it was found that the total mass loss changes less than 0.3% when Cl− was less than 0.01 wt%. After comprehensive analysis, the conclusion is that the upper limit of Cl− is preferably less than 0.1 wt% for keeping good thermal performances of Solar Salt.

Abstract Solar water evaporation has been a topic of interest in recent years due to its applications in desalination, power generation, and heating. As water is not a good absorber of light, seeding it with light-absorbing particles can enhance evaporation efficiency. Activated carbon (AC) is one such material with desirable absorption properties for this application. However, particle sizes in granular and powder activated carbon can vary significantly. In this work, AC particles of different sizes are analyzed and their effect on evaporation rate is studied. It is found that particle sizes less than or comparable to solar wavelength spectrum produce higher evaporation efficiencies under independent scattering conditions ( f v 0.6 % ). It is also found that the solar absorption coefficient reaches between 0.98 and 0.9 for a volume fraction as low as 0.01%. The evaporation efficiency is 57.3% and 38.2% higher than for pure water evaporation for size of 80 nm and 8 μm, respectively, for a volume fraction of 0.01%. A parametric analysis is performed to identify the respective effect on evaporation rate.

Abstract The vacuum solar receiver is the key component of a parabolic trough solar plant, which plays a prominent role in the gross system efficiency. Recently, China’s first high temperature vacuum receiver, Sanle-3 HCE, has been developed and produced by Southeast University and Sanle Electronic Group. Before being utilized in China’s first parabolic trough solar plant, accurately estimating the thermal properties of this new receiver is important. This paper first establishes and optimizes a 1-D theoretical model at Matlab program to compute the receiver’s major heat loss through glass envelope, and then systematically analyzes the major influence factors of heat loss. With the laboratorial steady state test stand, the heat losses of both good vacuum and non-vacuum Sanle-3 receivers were surveyed. Comparison shows the original 1-D model agrees with the ends covered test while remarkably deviating from end exposed test. For the purpose of identifying the influence of receiver’s end to total heat loss, an additional 3-D model is built by CFD software to further investigate the different heat transfer processes of receiver’s end components. The 3-D end model is verified by heating power and IR temperature distribution images in the test. Combining the optimized 1-D model with the new 3-D end model, the comparison with test data shows a good accordance. At the same time the heat loss curve and emittance curve of this new receiver are given and compared with those of several other existing receivers as references.

Abstract Cu2BaSn(S,Se)4 (CBTSSe) solar cells are emerging photovoltaic devices due to their high theoretical efficiencies of ~31%, environment-friendly and earth-abundant composition, low density of non-recombination defects, and so on. However, the record efficiency of CBTSSe solar cell is only 5.2%, showing the importance of studying their performance via numerical analysis to further enhance their practical efficiencies. In this paper, the effect of absorber and buffer layers on performances of Cu2BaSnS4 (CBTS) solar cells are firstly systematically studied via the SCAPS-1D software to provide a platform for the study of the effect of MoS2 interlayer on the performances of CBTS solar cells. The highest PCE of CBTS solar cell with a 30 nm CdS buffer layer is 11.87%. The PCE of CBTS solar cell with a 0.8 μm CBTS absorb layer is 12.51%, indicating that the CBTS solar cell is a potential low-cost solar cell due to its large optical absorption coefficient (α > 104 cm−1). The efficiency of CBTS solar cell is improved to 16.47% when the carrier concentration of CBTS is 1016 cm−3. The relationship between the performance of solar cell and the band gap, thickness, donor concentration, acceptor concentration of MoS2 interlayer is systematically investigated on the basis of the optimized efficiency. It is found that MoS2 interlayer plays an important role in the performance of CBTS solar cell. The p-type MoS2 has a beneficial effect on the efficiency improvement while the n-type MoS2 has a negative effect on the efficiency enhancement. The highest PCE of CBTS solar cell is as high as 18.28% when the thickness and the acceptor concentration of MoS2 are 4 nm and 1019 cm−3, respectively. Our simulation result provides a promising research direction to further improve the actual efficiency of the CBTS solar cell.

Abstract The ground-level spectral distribution of direct solar irradiance at Reunion Island was measured for six bands covering the spectrum of solar radiation. The measurements, distributed over one year, were made under clear sky conditions with a pyrheliometer (Eppley, NIP) and six large pass-band flat filters. Good stability of spectral irradiances as a function of Solar height allows us to propose approximate relationships which significantly characterize the irradiance into each spectral band. Measurements at Reunion vary significantly from data obtained with the same apparatus in a northern hemisphere continental area (Lyon). The determination of aerosol attenuation coefficients, for different spectral bands, allows the establishment of a mean curve, for these coefficients as a function of wavelength, characteristic of marine aerosols.