Advanced Materials Research Vols. 860-863

Abstract: Solar radiation is a very important and major variable in crop simulation models. However, it is measured at a very limited number of meteorological stations worldwide. In this study, with Xining station, China, as a case study, 9 models were calibrated and evaluated using the meteorological data from 1959 to 2000 for estimating daily global solar radiation. The best results were derived from models 1-4, which used sunshine hours as the predictor. Temperature-based models (models 7-9) provided less accurate results. Therefore, we proposed a strategy to select an optimal method for calculating daily global solar radiation: (1) when sunshine hour data are available, use models 1-4; (2) when only temperature data are available, use models 7-9; and (3) when any meteorological data are not available, use models 5 and 6. Although these models were based on the metrological data of Xining station, they could be applied to other regions with similar meteorological conditions in China after calibration.

Abstract: In the comparative analysis of image characteristics of shadow-free and shaded area, an algorithm for shaded area, avoiding the area whose illumination is weak and tending to the area with strong light via looking for the strongest and weakest light area, is established, which can thereby improve the efficiency of power generation. The result demonstrates that the method can find the region with the strongest sunlight fast and accurately.

Abstract: According to the methods of focusing,the solar thermal generation can be classified to tower system,parabolic trough system and dish-stirling system. The parabolic solar thermal generation system is an important type of solar thermal utilization. Compared to tower and dish-stirling system,the parabolic trough system has many advantages such as the small concentration ratio,the simple process,the low material requirement and the simple tracking device because of many concentrator on-axis tracking. The parabolic trough system is the lowest cost, least close to commercialization,larger potential system optimization,and the most suitable to large operation in this three thermal generation systems [1,. The parabolic trough system is composed of concentrator and receiver,and the receiver is the key component that uses solar energy to heat working fluids in receiver. Therefore,the key problem is how to make the solar energy transfer to subsequent generation system efficiently and stably.

Abstract: This paper reports mainly a work of the influence of annealing on the solar cell which the active layer is made from poly (3-hexylthiophene) and [6,-phenyl C61 butyric acid methyl ester. XRD analysis of the active layer indicates that the layer annealing can improve the film crystallization. With the reducing of light reflection rate, the light transmittance rate improves due to the annealing treatment of the active layer. Comparing in various annealing temperature, it is found that a better result can be obtained when the annealing temperature is 140 °C. At this annealing temperature, the organic solar cell brings out relatively high conversion efficiency in the experiment.

Abstract: Economy is one of the main factors for the development of photovoltaic grid-connected system. From the view of economic operation in this article, four aspects of photovoltaic grid-connected system are reviewed, including the component modeling, the objective function, constraints and optimization strategies. Typical research methods used in economic operation are analyzed, and the key issues about photovoltaic grid-connected system operation are pointed out.

Abstract: In the present specification of domestic solar water heating systems (GB/T19141), regardless of the type of collectors used in the systems, Q₁₇, the daily heat gain corresponding to the daily radiation of 17MJ/m² on the collector surface, is a key indication to rate the thermal performance of a domestic solar water heaters. In this work, an attempt was made to investigate effect of the distance between two adjacent tubes in solar tube collectors of a water-in-glass evacuated tube solar water heater (ETSWH) on by theoretical calculations and experimental measurements. Results obtained by simulations and experimental test showed that the tube space had a significant effect on of the ETSWH, the shorter the tube distance, the higher the Q₁₇, thus better the ETSWH performs. However, the actual situation is the case, the shorter the tube distance, the lower the real daily solar gain of the system, thus worse it performs. This implied that Q₁₇ as the indication of thermal performance of the ETSWH is not reasonable, and specifying the tube distance in solar tube collectors of the ETSWH in the technical specification of GB/T19141 is advisable so as to eliminate effect of the tube distance on Q₁₇.

Abstract: With the highlight of less regards to insulation measures and the key factor of the flow rates, slotted-plate solar collectors possess rather lower thickness and lighter mass, higher heat production, and better matching with various buildings compared with the common plate solar collectors. Results show that a much higher instantaneous efficiency could be obtained by increasing the flow rates suitably in a low-temperature working environment. The average efficiency could reach up to 51% with the maximum instantaneous efficiency of 61%. Based on the analysis of the relation between instantaneous efficiency and flow rates or the relation between instantaneous efficiency and the temperature difference of the inlet and the outlet water, a experiential formula for the optimal flow rate is proposed to improve the heating-up rates and working efficiency. The performances investigation of slotted-plate solar collectors would pave a way for their widespread and positive applications in the near future.

Abstract: This paper constructed a new type of solar photovoltaic and solar heat coupling water source heat pump heating system, the composition of the system structure and operation mode is introduced, with the result of the experiment, parameters were analyzed, and successfully solves the solar panel and battery temperature is high, the problem of low efficiency, the system is a kind of close to zero energy consumption, pollution-free and efficient energy utilization system. Is suitable for the application of the climate condition in qinhuangdao.

Abstract: In this paper, a new kind of solar collector wall system was designed. Numerical simulation for the orifice plate solar collector wall was carried out to analyze the change of the distributions of the temperature and velocity and the heat collecting efficiency under the conditions of different air inlet velocity. The results shows that the temperature stratification decreases with the increase of the inlet velocity, and the velocity field stratification enhances with the increase of the inlet velocity, and the collection efficiency first increases then decreases with the constantly increasing inlet velocity, and the collection efficiency is the highest when the inlet velocity is 2.5 m/s, up to 81.34%.

Abstract: This paper aims to study the heat collecting efficiency of the solar air collector with ten groups of single pipe in parallel. The simulations and experimental verification are carried out to obtain the best angle and air inlet flow rate. The result is that when the angle of the collector is 45 °and the inlet flow rate is 48.6 m³/h (2.7 m/s), the heating effect is the best for the solar air collector we have studied in this article. The average collection efficiency of it during stable operation can reach 65%.The simulation results are consistent with the experimental results. In practical application the results can provide a theoretical foundation to choose the appropriate flow rate and angle of the collector.