Current Issue : July - September Volume : 2017 Issue Number : 3 Articles : 5 Articles
The thermal performance of three novel solar air collectors with perforating corrugated\nplate, slit-perforated plate, and corrugated packing were experimentally studied in this paper.\nExperiments were conducted in Tianjin to study the thermal and dynamic performance of the\ncollectors in cold and severe cold regions. A chamber with a PID (Proportion Integration\nDifferentiation) temperature controller was designed to control the inlet air temperature of the\nthree collectors. Effects of radiation intensity, inlet air temperature, and flow rate on the thermal\nefficiency and outlet air temperature were experimentally studied. The results indicated that the\nthermal efficiency of the three collectors in severe cold regions could be much higher than 50% and\nthe collector with perforating corrugated plate had the highest thermal efficiency. The inlet air flow\nrate had significant effects on the thermal comfort of buildings in cold and severe cold regions and\nit should be lower than 45 m3/h. The results indicated that the pressure drops of collectors with\nperforating corrugated plate were a little larger than the collectors with slit-perforated plate, but the\nthermal efficiency and outlet air temperature was higher. Therefore, the collector with perforating\ncorrugated plate was more suitable to use in cold and severe cold regions....
Cube satellites have a limitation for generating power because of their cubic structure and extremely small size. In addition, the\nincidence angle between the sun and the solar panels continuously varies owing to the revolution and rotation of the satellite\naccording to the attitude control strategy. This angle is an important parameter for determining the power generation performance\nof the cube satellite. In this study, we performed an experimental feasibility study that uses a Fresnel lens as a solar-energy collection\nsystem for cube satellite applications, so that the power generation efficiency can be enhanced under the worst incidence angle\ncondition between the sun and solar panels by concentrating and redirecting solar energy onto the solar panels with a commercial\nFresnel lens. To verify the effectiveness of the proposed system, we conducted a power-measurement test using a solar simulator and\nFresnel lenses at various angles to the light source. In addition, we predicted the on-orbit power-generation enhancement achieved\nby employing the solar-energy collection system with various attitude control strategies....
For efficient application of solar energy, a pebble bed energy storage heating system\nin a solar attic is optimally designed and operated. To study the characteristics of the heating\nsystem, a numerical model for the system is presented and is validated with the experiment data\nin the literature. Based on the model, the influence of the envelopes of the solar house and the\nmeteorological condition on the system performance is investigated. The results show that the\nenvelopes, except those on the north face, with more glazed exterior surfaces can be beneficial to raise\nthe temperature of the solar house. It is also found that outdoor temperature may have less impact\non the energy storage in the system compared with solar radiation. Furthermore, through optimizing\nthe system design and operation, solar energy can account for 56% of the energy requirement in\nthe heating season in Xiââ?¬â?¢an (about 34ââ??¦ N, 108ââ??¦ E), which has an average altitude of 397.5 m and\nmoderate solar irradiation. Also, the suitability of the system in northwest China is investigated, and\nthe outcome demonstrates that the external comprehensive temperature should be more than 269 K if\na 50% energy saving rate is expected....
Modeling and simulation of photovoltaic (PV) systems represents an essential\ntask for the integration of PV panels in current power applications. At the\npresent time, there are sizing tools of photovoltaic systems available on the\nmarket, taking into account the proposed energy consumption, site localization\nand system cost. An advanced specialized program (PVSyst) was considered.\nThe sizing and simulations of two PV important applications were developed\nusing PV modules based on three different technologies: monocrystalline\nand polycrystalline silicon, as well as CIS. Our results showed how different\ntypes of solar cell technologies influenced the final power output and\nperformances for a PV LED lighting, as well as for a PV water pumping system,\nin terms of overall yield, efficiency and system availability....
There are numerous theoretical approaches to estimating the power conversion efficiency\n(PCE) of organic solar cells (OSCs), ranging from the empirical approach to calculations based\non general considerations of thermodynamics. Depending on the level of abstraction and model\nassumptions, the accuracy of PCE estimation and complexity of the calculation can change\ndramatically. In particular, PCE estimation with a drift-diffusion approach (widely investigated in\nthe literature), strongly depends on the assumptions made for the physical models and optoelectrical\nproperties of semiconducting materials. This has led to a huge deviation as well as complications\nin the analysis of simulated results aiming to understand the factors limiting the performance of\nOSCs. In this work, we intend to highlight the complex relation between mobility, exciton dynamics,\nnanoscale dimension, and loss mechanisms in one framework. Our systematic analysis represents key\ninformation on the sensitivity of the drift-diffusion approach, to estimate how physical parameters\nand physical processes bind the PCE of the device under the influence of structure, contact, and\nmaterial layer properties. The obtained results ultimately led to recommendations for putting effort\ninto certain properties to get the most out of avoidable losses, presented the impact and importance\nof modification of material properties, and in particular, recommended to what degree the design of\nnew material could improve OSC performance....
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