Advanced Materials Research Vols. 512-515

Abstract: This paper presents the thermal performance of a multi-effect distillation (MED) solar desalination unit located in southern China. The system was designed and installed in April 2011, and has been in operation since that time till now. The seawater desalination system is driven by 60 m² all-glass vacuum tubes solar collector with an additional rainwater utilization system to produce fresh water on both sunny and rainy days. The preliminary experimental results show that the water production of the system for per unit of solar collector area could reach up to more than 12.5kg/m²·day under the fine weather conditions. Water production of the system was stable in long period and the annual production could reach to 387.5 m³ in southern China. The economic performance of the system is also discussed. The cost of water production is estimated approximately 4.15 $/m³ for the 15-year service life.

Abstract: The present work described the atomized aqueous solution such as seawater and dense water suddenly encounter the high-temperature hot air heated by solar energy, Heat and mass transfer process between the two fluids, a saline solution was pressured between 0.4Mpa and 0.6Mpa, then to force the solution through one non-pneumatic nozzle to produce solution mesoscopic droplets，blowing a heated air stream through first evaporation chamber, dispersing the droplets into the heated air stream，permitting water in the droplets to evaporate hereby separating water vapor from aqueous solution in the heated air stream，then the outlet hot saturated air was condensed to fresh water .The water vapor from dense brine in the heated air stream was evaporated, and so the salt crystals therefrom could be obtained in the second evaporation chamber. Compared with the conventional Humidification-dehumidification desalination (HDD) process method, the heat efficiency is high, when heated air stream temperature is between 100°C and 150°C ,fresh water production can be increased by 50% or more. There is no general problem of scale desalination, can handle high concentrations of salt water without any chemical additives.

Abstract: The output of photovoltaic generation system is influenced by the factors such as solar radiation, temperature and so on. So the change of photovoltaic generation power is a non-stationary random process that will impact on the grid. In order to promote large-scale photovoltaic generation connected to the grid, we need to configure energy storage devices for photovoltaic power station and in order to coordinate the allocation of photovoltaic system with energy storage system, we requires a thorough understanding of output characteristics of the photovoltaic system. This paper firstly analyzes the influence brought by the large-scale photovoltaic generation system connected to the grid and then introduces the effect factors of photovoltaic output. Based on the history data of the 100 kWp photovoltaic power station and the statistical method, the paper qualitatively and quantitatively analyzes the photovoltaic output performance; finally puts forward the PV output power evaluation index. The conclusions of this study will provide powerful data references for follow-up studies and have practical value.

Abstract: Based on density functional theory (DFT) within the framework of the generalized gradient approximation method, we have studied the Cd_1-xZn_xS sphalerite crystal structure and optical properties. We calculated electronic and optical properties of Cd_1-xZn_xS at the doping concentration x = 0, 0.25, 0.50, 0.75, 1.0. Optical properties (reflectivity, absorption coefficient, refractive index, dielectric function) and the electrical properties (band structure, electron density, etc.) are obtained including Zn-doing effects on the crystal structure, optical properties and electrical properties. With the increase of doping concentration x, the lattice parameter reduces from 0.5910 nm to 0.5409 nm; as a direct wide band gap semiconductor, its band gap increased from 1.15 to 2.22. Optical absorption coefficient increases with the increase of doping concentration, but the rate of increase is relatively small.

Abstract: The main function of junction box on a solar photovoltaic module is to transmit the electricity from solar photovoltaic panel to the load. The invented smart junction box is designed for the following purposes: (1) to optimize efficiency through auto control, (2) to reduce the vicious effect of the cloud and dust on electricity output, and (3) to prevent the battery from overcharging. When actuated, the temperature of inner transistor is raised up to 158 °C because it consumes more solar electric power than a conventional junction box. Thus, a more effective thermal diffusion system is invented to cool down inner transistor to avoid failure. It is found that the presented heat plate diffusion system modified from heat pipe is capable of satisfying all required thermal diffusion conditions of the smart junction box.

Abstract: The solar thermal collector performance evaluation system is designed for the actual needs of tests for industrial production and scientific research, which is adequate for stable efficiency, time constant, incident angle modifier and pressure drop measurement on either end of the thermal collector.

Abstract: Cu(In_0.8Al_0.2)(SSe)₂ (CIASSe) absorber layers of thin film solar cell were prepared by selenization of Cu(In_0.8Al_0.2)S₂(CIAS) nanocrystals. The CIAS nanocrystals were synthesized by a new solution-based technique and successfully deposited on Mo-coated glass substrates in a one-step process. The phase structure, optical and electrical properties of CIASSe thin films were characterized by power X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectrophotometer and the Hall Effect Measurement system. The results showed that single-phase CIASSe solid solution was successfully obtained for a selenization temperature of above 400oC. And the diffraction peaks shifted to the lower angle with an increase in selenization time and selenization temperature. The films selenized at 500oC were found to be p-type and the resistivity was only 0.9484×10^-4Ω cm. The optical band gap of the films is 1.508eV and the optical absorption coefficient is over 10⁴cm^-1.

Abstract: The Ag-assisted electroless etching of p-type silicon substrate in HF/H₂O₂ solution at room temperature was investigated. The porous silicon layer was formed in a mixed solution of H₂O₂ and HF by using screen-printed Ag front electrodes as the catalyst. And influence of the different concentration etching solution (HF and AgNO₃) on the porous silicon layer was study by scanning electron microscopy (SEM). Through investigation of the track of catalyst particles, it was shown that Ag really catalyses the etching of silicon underneath Ag particle.

Abstract: Abstract. Solar radiation is the most important energy source in the Earth. And its spatial distribution has critical effects on the life and environmental process on the Earth. The characteristics of spatial distribution of total solar radiation in the complicated topography in the mountain area of east Tibetan Plateau was simulated in the present study. The three kinds of radiation, i.e. direct solar radiation, diffusive solar radiation and total solar radiation were calculated based on the existing astronomical parameters and experiential formula. The calculation of topographical shading was modified by using the 30m-resolution DEM data. The results revealed in general that the total solar radiation tended to decrease northwest-southeastwardly. At regional scale, the latitudinal zonality of the spatial distribution of annual total solar radiation differed insignificantly. Local topography affected profoundly the spatial distribution of annual total solar radiation. The annual total solar radiation in complicated topography was relatively less, whereas there was significant inner difference.