Applied Mechanics and Materials Vols. 291-294

Abstract: In order to improve the accumulating efficiency of solar energy, we designed a trolley with a 2-DOF attitude regulation structure of solar panels. In it, a solar orientation sensor was used to detect the solar orientation and the solar light intensity. A trolley’s differential wheels and a steering engine were used to keep the solar panels of the trolley vertically facing the Sun. At a certain interval, the steering engine adjusted the elevation angle of the solar panels and the trolley’s differential wheels adjusted the solar panels’ azimuth angle. Test experiment results show that the trolley can improve the accumulating efficiency of solar energy.

Abstract: In this paper, a two-dimensional mathematical model of simultaneous heat and mass transfer of vapor absorption process in a counter-flow dehumidifier is conducted. The governing equations with different boundary and interfacial conditions describing the dehumidifying process are established. The calcium chloride solution is applied as the desiccant. The dehumidifying process between falling liquid desiccant film and process air with first, second and third boundary conditions is analyzed and calculated, respectively. Temperature distribution of the process air and desiccant solution is presented. Outlet parameters of the dehumidifier for both the process air and the desiccant solution are obtained.

Abstract: By using a solar air collector module with independent design as the object of study, obtained the temperature distribution of collector module in various conditions through experimental studying of its structure and operating parameters. The experimental results show that adding bulkhead in collector module and increasing the collector plate openings of collector module can enhance the heat-transfer by convection between air and collector plate. At the same time, the outlet air temperature of collector module is significantly higher than the temperature of the collector plate; On the other hand, the maximum temperature difference between import and export can reach to 333 K when the collector plate is 90° corrugated table-flap. And this condition has the maximum temperature difference between import and export in all conditions at some point.

Abstract: The model and simulation of three-phase Two-level Grid-connected Photovoltaic System are established. According to the equivalent circuit and mathematical model of the PV cell, the general simulation model of photovoltaic array is established. Regulating duty ratio in Boost circuit to realize the maximum power point tracing with method of high-precision incremental conductance. Model of photovoltaic inverter is established based on power decoupling vector control strategy. SVPWM modulation improves the utilization ratio of voltage in DC side. Finally, the simulation of three-phase two-level grid-connected photovoltaic system is conducted in MATLAB. The result shows that the system can rapidly and accurately track maximum power point and the output of current keep in the same frequency and phase, which can be connected to power grid flexibly.

Abstract: In order to meet the needs of experiments, teaching and training on output characteristics of PV solar panel, this paper designed and produced a real-time training experimental box to test the output characteristics of the PV module, basing on the principle and characteristics of the PV generation .The partial function of the experimental box is designed according to the operational principle of the PV streetlight. So it may be used combining with PV module or PV streetlight. It is a teaching and training tool to carry out appropriate experiments. The photovoltaic output characteristics have been verified by the test results on the equipment.

Abstract: There’s a sufficient solar energy resource in our country, but the shortcomings of its discontinuity and instability makes it hard for a further development. The research on multiple applications of the solar collector and phase-change material cannot only reduce the building energy consumption, but also improves the thermal environment. This method can make the solar energy into a continuous, stable and available state which has a very important meaning to alleviate the increasingly serious energy status. This article mainly introduced two united systems of solar energy collector with phase change energy storage wall and phase change composite floor, theoretical basis and actual operation effect for these two systems are introduced summarily in the article.

Abstract: Influenced by partial shade, there are power losses induced by irradiation reduction, photovoltaic (PV) modules mismatch and maximum power point tracking (MPPT) failure. In order to raise power generation efficiency of building integrated PV (BIPV) power station, typical series-parallel PV array controlled with centralized MPPT is taken into consideration. Simulation model is constructed to describe the output characteristic of PV array under complex partial shade conditions. Due to bypass/blocking diodes, there are multiple peaks on P-V characteristic curve under partial shade. Potential power losses under partial shade are analyzed and divided into three parts respectively. Simulation results demonstrate that there are considerable power losses induced by PV module mismatch under determined tangible partial shade lasting for long time. Optimal configuration of BIPV array are brought forward to minimize PV module mismatch power loss for moving shade conditions, and it is also suitable to large desert or hillside PV power stations.

Abstract: The acid value of jatropha curcas oil is 9.41mgKOH/g. The most of fatty acids should be removed if base catalysts are adopted to catalyze the transesterification reaction for biodiesel production in case of soap formation. In this study, methanol and ethanol were adopted to extract the fatty acids in jatropha curcas oil. Then, it was catalyzed by calcium methoxide for biodiesel production. The extracted fatty acids can be used to produce biodiesel at supercritical or sulfuric acid conditions. The results indicated that the acid value of jatropha curcas oil decrease to 0.31 mgKOH/g from 9.41 mgKOH/g using ethanol extraction for 3 times at 25°C. The biodiesel yield exceeded 96% using solid base catalyst. The advantages of methanol and ethanol extractions are low oil loss and high biodiesel yield.

Abstract: In this paper, multiplier decomposition is adopted to examine the effects of expanding grain-based fuel ethanol and cassava-based fuel ethanol on agriculture in China. The results show that, reasonable development of grain-based fuel ethanol has a greater role than cassava-based fuel ethanol in accelerating China’s economy, improve rural household’s income, and mitigate gap between rich and poor

Abstract: The low-carbon economy is attention increasingly all over the world, and which has become the best economic mode to cope with global warming. And it is the important way to achieve the low carbon economy, optimize the energy structure through developing the biomass power generation and other new energy. In recent years, the development of biomass power generation in China is rapid, there are also some problems. Therefore, it is necessary to predict the biomass power generation industry development, especially the installed capacity of biomass power generation. In this paper, the authors used the GM (1, 1) model to predict the installed capacity of biomass power generation, which can reveal the evolution of things under the circumstances of less data and less information. The installed capacity prediction from 2011 to 2020 showed that the results given by this model were reliable, and it is feasible to predict the installed capacity of biomass power generation.