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[en] Highlights: • A solar thermoelectric with micro-channel heat pipe system was presented. • Mathematical model of the system was built. • Experiment and the simulation were compared to verify the model. • Performance of the system with different factors was analyzed. - Abstract: Micro-channel heat pipe can convert the low heat flux to the high heat flux by changing the ratio of the evaporator area to the condenser area and has a higher heat transfer performance than the common heat pipe. Combining the solar concentrating thermoelectric generation with micro-channel heat pipe can save the quantity of thermoelectric generation and reduce the cost significantly. In this paper, a solar concentrating thermoelectric generator using the micro-channel heat pipe array was designed, and the mathematical model was built. Furthermore, the comparison of the experiment and the simulation between the solar concentrating thermoelectric generator using the micro-channel heat pipe array and the thermoelectric generations in series was made. In addition, the performance on the different areas of selective absorbing coating, different concentration ratios, different ambient temperatures, different wind speed all were analyzed. The outcomes showed the overall performance of the solar concentrating thermoelectric generator using the micro-channel heat pipe array system.
[en] A model has been solved in order to determine the thermal losses of a storage tank, where thermal energy is stored as sensible heat of a diathermic fluid at medium temperatures. A parametric analysis has been performed in order to evaluate the influence of various design parameters on the thermal discharge of the accumulator
[en] The development of microsatellites requires the development of engines to modify their orbit. It is natural to use solar energy to drive such engines. For an unlimited energy source the optimal thruster must use a minimal amount of expendable material to minimize launch costs. This requires the ejected material to have the maximal velocity and, hence, the ejected atoms must be as light as possible and be ejected by as high an energy density source as possible. Such a propulsion can be induced by pulses from an ultra-short laser. The ultra-short laser provides the high-energy concentration and high-ejected velocity. We suggest a microthruster system comprised of an inflatable solar concentrator, a solar panel, and a diode-pumped fiber laser. We will describe the system design and give weight estimates.
[en] The current study focuses on the consistent analysis of heat transfer in multichannel volumetric solar receivers used for concentrating solar power. Changes in the properties of the absorbing material and channel dimensions are considered in an optical model based on the Monte Carlo ray-tracing method and in a one-dimensional heat transfer model that includes conduction, convection, and radiation. The optical model results show that most of the solar radiation energy is absorbed within a very small channel length of around 15 mm because of the large length-to-radius ratio. Classification of radiation losses reveals that at low absorptivity, increased reflection losses cause reduction of the receiver efficiency, notwithstanding the decrease in the emission loss. As the average temperature increases because of the large channel radius or small mass flow rate, both emission and reflection losses increase but the effect of emission losses prevails
[en] Province Balochistan is largest province of Pakistan with smallest density of population with little or no development. In Balochistan bulk is rural located and devoid of lives basic ingredients. In remote rural areas of Balochistan because of high cost and problems associated with grid extension or diesel power generation, solar electricity is viable alternate. Energy generated from the sun is world's most abundant and in-exhaustible source of energy PV cells sun light is converted directly in to electricity called solar PV energy. Solar energy through photovoltaic cells can be tapped to supply electricity to remote rural areas of Balochistan. In this paper author has examined the problems in more detail, showing by simple calculation of cost economics that solar PV systems are viable. (author)
[en] Highlights: • A new method for design of segmented TEG is proposed. • Optimal length ratios for output power and efficiency are different. • Material properties, geometry and heat transfer all need to be considered. • This method is approved to be accurate and time-efficient. - Abstract: A comprehensive method for indicating the length ratio of segmented thermoelectric generator (TEG) is proposed to increase the output power and thermoelectric conversion efficiency. It is found that for a segmented TEG, there is an optimal length ratio corresponding to the highest maximum output power or thermoelectric conversion efficiency, which is not only dependent on the material properties but also the heat transfer conditions and geometry structure. The optimal length ratios corresponding to the output power and thermoelectric conversion efficiency are different. This method is also validated, and the error is within a reasonable range, indicating that this method can be used accurately and time-efficiently for the design of segmented TEGs.
[en] Highlights: • Thermodynamic analysis is presented for a LAES system combined with packed bed units. • The LAES system round-trip efficiency is in the range 50–62%. • Cold box inlet temperature and discharge pressure have significant influence on system performance. • LAES system has smaller air storage volume and higher ASED compared with A-CAES system. - Abstract: Energy storage is a key technology required to manage intermittent or variable renewable energy, such as wind or solar energy. In this paper a concept of an energy storage based on liquid air energy storage (LAES) with packed bed units is introduced. First, the system thermodynamic performance of a typical cycle is investigated and temperature distribution in cold boxes is discussed. Then, the effects of inlet temperature of cold boxes, charge and discharge pressures on thermal behaviors of LAES system are analyzed, as well as the system round-trip efficiency. Finally, an overall comparison between this LAES system and an adiabatic compressed air energy storage (A-CAES) system is conducted. The system could achieve a round-trip efficiency in the range 50–62% depending on the values of process conditions. The system round-trip efficiency decreases with the increase of cold box inlet temperature, and increases with the rise of charge and discharge pressures. Although the round-trip efficiency of the present LAES system is a bit lower than the A-CAES system, however, the air storage volume decreases and the air storage energy density (ASED) increases remarkably for the same operational conditions. The main conclusions draw from this work is beneficial for future LAES development in particular the combination with the packed bed units and the fit with the requirements for large-scale energy storage.
[en] Aim: Policy-makers typically track the rapidly evolving U.S. residential photovoltaic (PV) market by relying on price data reported by PV installers/integrators to incentive programs. Recent years have witnessed a shift toward third-party-owned (TPO) business models, in which the absence of a cash purchase price obscures data interpretation. Appraisals—often based on estimates of the average fair market value across a diverse fleet of systems—are one way TPO prices are reported. Scope: This study investigates residential PV system price drivers to improve the accuracy, consistency, and relevance of PV price-tracking efforts. Our econometric approach evaluates system price drivers using California Solar Initiative data, controlling for system, installer, and geographic variables. Conclusions: We find that reported prices for confirmed appraised systems are $1.13/W higher than non-appraised systems and do not respond to hypothesized price drivers. For non-appraised systems, we find preliminary evidence of market distortions based on the impact of the incentive level, module cost and household income on reported price. Further, unspecified installer heterogeneity—possibly due to differences in products, cost structure or reporting practices—is a substantial price driver. Using estimates, we develop a price model to approximate non-appraised system prices. -- Highlights: •This analysis evaluates residential PV price drivers using an econometric model. •Reported prices for appraised systems are $1.13/W higher than non-appraised. •Reported prices for appraised systems do not respond to expected price drivers. •We find some evidence of market distortions in non-appraised systems. •Installer heterogeneity is a substantial price driver for all systems
[en] More than 2000 million people, mostly in developing countries, live in rural areas without access to grid connected power. Conventional approaches to supplying power, whether through extension of existing grids or through stand-alone 'mini-grids' based on diesel generator sets, or even on renewable energy minigrids, require large investments which are unlikely to receive priority in competition with more economically and politically attractive investments in urban areas. Domestic PV lighting and broadcast reception kits (DLKs), comprising, typically, a 30-60 W panel, an automotive battery, a charge indicator, and dc fluorescent lamps can be furnished and installed for about $500. DLKs are now used in the Dominican Republic, Kenya, Sri Lanka and many other countries. DLKs provide a minimum essential service with low overheads. Given the necessary credit facilities, they can give better service at comparable costs in comparison with kerosene lamps and dry cell powered radios. They also permit a substantial degree of local manufacture, thus saving on foreign exchange. This movement is starting in many countries on a purely commercial basis. The process could be greatly accelerated if 'seed money' in the form of revolving funds could be made available. (author). 1 fig., 11 tabs