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Zhifeng Wang - One of the best experts on this subject based on the ideXlab platform.

  • Modeling and parametric study of molten salt receiver of concentrating solar Power Tower plant
    Energy, 2020
    Co-Authors: Yang Yihui, Zhifeng Wang, Jiafei Qiao, Qiangqiang Zhang
    Abstract:

    Abstract Central receiver is a key part of concentrating solar Power Tower plants, as it is not only responsible for the highly effective absorption of incident energy from the heliostat field, but also for efficient energy conversion from light to heat. Its performance will directly affect the system efficiency and generating capacity of the whole plant. In this paper, a comprehensive model of molten salt receiver, which uses the mult-section lumped parameter method, is clearly developed based on a molten salt solar Power Tower plant. In order to improve the reliability as well as the prediction accuracy of the developed model, the dynamic characteristics of the molten salt receiver are fully investigated by a step disturbance of external parameters. Besides, in order to improve the design level of molten salt receiver, the influence of key parameters on the performance of receiver system is also extensively studied. The results show that the incident solar flux, wind speed and absorptivity of heat-absorbing tube can greatly affect the performance of molten salt receiver system. In order to verify the validity of proposed model, the simulation results are compared with the published experimental data, and the results show the model has a high accuracy. Conclusions of this paper are good references for the design, control and commissioning of molten salt receiver systems.

  • dynamic simulation of thermal energy storage system of badaling 1 mw solar Power Tower plant
    Renewable Energy, 2012
    Co-Authors: Ershu Xu, Gao Wei, Zhifeng Wang, Jiayan Zhuang
    Abstract:

    In this paper, the thermal energy storage system of Badaling 1 MW solar Power Tower plant is modelled from mathematical models for whole of the working conditions using the modular modelling method. This model can accurately simulate the recharge and discharge processes of thermal energy storage system. The dynamic and static characteristics of the thermal energy storage system are analyzed based on the model response curves of the system state parameters that are obtained from different steam flow disturbances. Conclusions of this paper are good references for the design, operating, and control strategy of solar thermal Power plant.

  • energy and exergy analysis of solar Power Tower plants
    Applied Thermal Engineering, 2011
    Co-Authors: Chao Xu, Zhifeng Wang, Xin Li
    Abstract:

    Establishing the renewable electricity contribution from solar thermal Power systems based on energy analysis alone cannot legitimately be complete unless the exergy concept becomes a part of that analysis. This paper presents a theoretical framework for the energy analysis and exergy analysis of the solar Power Tower system using molten salt as the heat transfer fluid. Both the energy losses and exergy losses in each component and in the overall system are evaluated to identify the causes and locations of the thermodynamic imperfection. Several design parameters including the direct normal irradiation (DNI), the concentration ratio, and the type of Power cycle are also tested to evaluate their effects on the energy and exergy performance. The results show that the maximum exergy loss occurs in the receiver system, followed by the heliostat field system, although main energy loss occurs in the Power cycle system. The energy and exergy efficiencies of the receiver and the overall system can be increased by increasing the DNI and the concentration ratio, but that increment in the efficiencies varies with the values of DNI and the concentration ratio. It is also found that the overall energy and exergy efficiencies of the solar Tower system can be increased to some extent by integrating advanced Power cycles including reheat Rankine cycles and supercritical Rankine cycles.

  • energy and exergy analysis of solar Power Tower plants
    Applied Thermal Engineering, 2011
    Co-Authors: Chao Xu, Zhifeng Wang, Xin Li
    Abstract:

    Establishing the renewable electricity contribution from solar thermal Power systems based on energy analysis alone cannot legitimately be complete unless the exergy concept becomes a part of that analysis. This paper presents a theoretical framework for the energy analysis and exergy analysis of the solar Power Tower system using molten salt as the heat transfer fluid. Both the energy losses and exergy losses in each component and in the overall system are evaluated to identify the causes and locations of the thermodynamic imperfection. Several design parameters including the direct normal irradiation (DNI), the concentration ratio, and the type of Power cycle are also tested to evaluate their effects on the energy and exergy performance. The results show that the maximum exergy loss occurs in the receiver system, followed by the heliostat field system, although main energy loss occurs in the Power cycle system. The energy and exergy efficiencies of the receiver and the overall system can be increased by increasing the DNI and the concentration ratio, but that increment in the efficiencies varies with the values of DNI and the concentration ratio. It is also found that the overall energy and exergy efficiencies of the solar Tower system can be increased to some extent by integrating advanced Power cycles including reheat Rankine cycles and supercritical Rankine cycles.

  • modeling and simulation of 1 mw dahan solar thermal Power Tower plant
    Renewable Energy, 2011
    Co-Authors: Ershu Xu, Zhifeng Wang, Qiang Yu, Chenyao Yang
    Abstract:

    1 MW Dahan solar thermal Power Tower plant is modeled from mathematical models for all of the working conditions using the modular modeling method. The dynamic and static characteristics of the Power plant are analyzed based on these models. Response curves of the system state parameters are given for different solar irradiance disturbances. Conclusions in this paper are good references for the design of solar thermal Power Tower plant.

Ershu Xu - One of the best experts on this subject based on the ideXlab platform.

  • Analysis and Optimization of the Start-up Process based on Badaling Solar Power Tower Plant
    Energy Procedia, 2015
    Co-Authors: Yanhong Yang, Ershu Xu, Guanghui Ma, Z. Wang, Q. An
    Abstract:

    Abstract As the mutual movement of the sun and the earth cause alternating night and day, solar Power Tower plants face frequently start and stop operations for solar radiation being its energy source. Besides, in the start and stop process of solar Tower Power plants, key components such as receivers, drum and turbine face rapid changes in temperature and pressure. Therefore, how to select and set reasonable start-up parameters, reducing start-up time was crucial to improve operating efficiency and ensure the operational life of the solar Tower Power plants. In this paper, how to determine the temperature rising curve of water in the drum during the start-up process was studied. The range of thermal stress and cyclic stress of the drum during start-up were calculated. Genetic algorithms were used to optimize the start-up operation. According to the design parameters of Badaling solar Power Tower plant, after optimization, the start-up time of the drum was 55 min while the origin time was 120 min. Moreover, it is obvious that the higher rated parameters are, such as rated temperature of the drum, the better is the effect of the optimization methods.

  • dynamic simulation of thermal energy storage system of badaling 1 mw solar Power Tower plant
    Renewable Energy, 2012
    Co-Authors: Ershu Xu, Gao Wei, Zhifeng Wang, Jiayan Zhuang
    Abstract:

    In this paper, the thermal energy storage system of Badaling 1 MW solar Power Tower plant is modelled from mathematical models for whole of the working conditions using the modular modelling method. This model can accurately simulate the recharge and discharge processes of thermal energy storage system. The dynamic and static characteristics of the thermal energy storage system are analyzed based on the model response curves of the system state parameters that are obtained from different steam flow disturbances. Conclusions of this paper are good references for the design, operating, and control strategy of solar thermal Power plant.

  • modeling and simulation of 1 mw dahan solar thermal Power Tower plant
    Renewable Energy, 2011
    Co-Authors: Ershu Xu, Zhifeng Wang, Qiang Yu, Chenyao Yang
    Abstract:

    1 MW Dahan solar thermal Power Tower plant is modeled from mathematical models for all of the working conditions using the modular modeling method. The dynamic and static characteristics of the Power plant are analyzed based on these models. Response curves of the system state parameters are given for different solar irradiance disturbances. Conclusions in this paper are good references for the design of solar thermal Power Tower plant.

Khaled A. Alnefaie - One of the best experts on this subject based on the ideXlab platform.

  • Techno-economic comparison of solar Power Tower system/photovoltaic system/wind turbine/diesel generator in supplying electrical energy to small loads
    Journal of Taibah University for Science, 2018
    Co-Authors: Nidal Abu-hamdeh, Khaled A. Alnefaie
    Abstract:

    ABSTRACTThis study presents a techno-economic comparison of four alternatives (experimental prototype of concentrating solar Power Tower system, photovoltaic (PV) system, collapsible vertical axis ...

  • design considerations and construction of an experimental prototype of concentrating solar Power Tower system in saudi arabia
    Energy Conversion and Management, 2016
    Co-Authors: Nidal Abuhamdeh, Khaled A. Alnefaie
    Abstract:

    Abstract A prototype of a solar Power Tower system was designed and constructed to produce electricity from solar energy. This prototype of a solar Power Tower system was constructed and installed at King Abdulaziz University in Saudi Arabia where solar intensity is excessive. Heliostats were implemented to capture the solar rays during daylight. These mirrors are used to direct the solar energy to a solar receiver that is made of alloy steel so that thermal energy is conveyed to a thermal fluid inside the receiver. Based on a detailed selection procedure presented in this article, a final number of ten heliostats were chosen to direct the solar energy to the solar receiver. In addition; two motors were used to control the heliostat rotational and elevation movements. The thermal fluid is a molten salt mixture (which consists of 60% NaNO3 and 40% KNO3). Cold and hot storage tanks were manufactured from steel and they were insulated with calcium silicate from all sides. A one-meter high and one and a half-meter cylindrical vessel was adopted for each of the cold and hot tanks. In this article, a detailed design analysis of each component is presented. The thermal Power transferred to the water in the heat exchanger as it is heated by the molten salt was measured and found to be 11.26 kW. The thermal Power given by the molten salt in the heat exchanger was also measured and found to be 12.31 kW. The design thermal Power was 13 kW. The percentage error in the thermal Power obtained is about 5.3%.

  • Construction and Building of an Experimental Prototype of Solar Power Tower Plant
    Applied Mechanics and Materials, 2016
    Co-Authors: Nidal Abu-hamdeh, Khaled A. Alnefaie
    Abstract:

    In this paper it is aimed to present the detailed design procedure of the first solar Power system in Jeddah. A prototype of solar Power Tower system was built at King Abdulaziz University in Jeddah, Saudi Arabia where direct irradiation is very high. Heliostats were used to track the incident sun rays and focus the energy flow towards a solar receiver. The system consists of 10 heliostats directing incident solar rays to a Tower of height about 7 meters. Two motors were used to control the heliostat rotational and elevation movements. A solar receiver made of alloy steel is installed at the top of the Tower to collect solar energy reflected from the heliostats. A molten salt fluid consists of sodium and potassium nitrates (60/40) re-circulated in the receiver transfers the collected heat in the receiver to a storage tank. A cylindrical vessel with height of 1 m and diameter of 1.5 m was adopted for each of the cold and hot tanks. The design thermal Power was 13 kW. The percentage error in the thermal Power obtained is about 5.3%.

Jiayan Zhuang - One of the best experts on this subject based on the ideXlab platform.

Jesus Guallar - One of the best experts on this subject based on the ideXlab platform.

  • A two-parameter aiming strategy to reduce and flatten the flux map in solar Power Tower plants
    Solar Energy, 2019
    Co-Authors: Francisco J. Collado, Jesus Guallar
    Abstract:

    Abstract In surrounding solar Power Tower plants, the collector field is designed with all the heliostats pointing to the cylindrical receiver equator to obtain maximum intercept. However, in commercial plants, the addition of thousands of energy spots at the same receiver level causes an excessively high peak heat flux of about 2 MW/m2. Therefore, this peak flux should be almost halved to avoid receiver problems due to creep and fatigue effects. The single-parameter aiming strategy (Vant-Hull, 2002) has already shown its ability to divide this high peak flux into two lower peaks; it consists in moving the hot spots up and down from the equator, in alternative heliostat rows, to create symmetric flux maps although they are clearly not very homogeneously distributed along the receiver height. In this work, a slight variation of the single-parameter aim strategy, simply proposing two aim parameters, has been successfully tested for a commercial solar Power Tower plant with a regular layout. The new two-parameter aiming strategy achieves not only reasonable peak flux values, but also an acceptably flattened flux profile and a slight reduction in spillage compared with the single-parameter strategy.

  • two stages optimised design of the collector field of solar Power Tower plants
    Solar Energy, 2016
    Co-Authors: Francisco J. Collado, Jesus Guallar
    Abstract:

    Abstract In solar Power Tower (SPT) systems, selecting the optimum location of thousands of heliostats and the most profitable Tower height and receiver size remains a challenge. Given the complexity of the problem, breaking the optimisation process down into two consecutive steps is suggested here; first, a primary, or energy, optimisation, which is practically independent of the cost models, and then a main, or economic, optimisation. The primary optimisation seeks a heliostat layout supplying the maximum annual incident energy for all the explored combinations of receiver sizes and Tower heights. The annual electric output is then calculated as the combination of the incident energy and the simplified (annual averaged) receiver thermal losses and Power efficiencies. Finally, the figure of merit of the main optimisation is the levelised cost of electric energy (LCOE) where the capital cost models used for the LCOE calculation are reported by the System Advisor Model (SAM)-NREL and Sandia. This structured optimisation, splitting energy procedures from economic ones, enables the organisation of a rather complex process, and it is not limited to any particular Power Tower code. Moreover, as the heliostat field layout is already fully optimised before the economic optimisation, the profiles of the LCOE versus the receiver radius for the Tower heights explored here are sharp enough to establish optima easily. As an example of the new procedure, we present a full thermo-economic optimisation for the design of the collector field of an actual SPT system (Gemasolar, 20 MWe, radially staggered surrounding field with 2650 heliostats, 15 h of storage). The optimum design found for Gemasolar is reasonably consistent with the scarce open data. Finally, optimum designs are strongly dependent on the receiver cost, the electricity tariff and the assumed maximum receiver surface temperature.

  • a review of optimized design layouts for solar Power Tower plants with campo code
    Renewable & Sustainable Energy Reviews, 2013
    Co-Authors: Francisco J. Collado, Jesus Guallar
    Abstract:

    Solar Power Tower (SPT) systems are viewed as one of the most promising technologies for producing solar electricity, in which direct solar radiation is reflected and concentrated by a field of giant mirrors (heliostats) onto a receiver placed at the top of a Tower. However, the optimized design of a heliostat field is a rather complex problem because the annual performance of a heliostat is a function of not only the instants of time considered and its own position, but also the relative location of neighbouring heliostats, which cause shadows and blockings. A variety of procedures may be found in the open literature, although there is great lack of information on the details of an optimized layout. This review shows that these complex problems have partially led to the expansion of parabolic trough technologies in USA and Spain in spite of their lower thermodynamic efficiencies compared with solar Tower Power. As a modest support of SPT systems, the authors have presented elsewhere the abilities of a new code called campo for fast and accurate calculations of the shadowing and blocking factor for each and every heliostat. This work explores a review of the optimized heliostat field layouts yielded by campo. Campo commences the optimization search based on the densest layout, with the worst shadowing and blocking factor, but with good values for the other optical factors, and then progresses towards gradually expanded distributions. The search for maximum annual energy through campo results in a clear, steady and reproducible procedure. Finally, as an example of this new procedure, some options of optimized heliostat field layouts are reviewed using as input parameters the scarce open literature data on Gemasolar, the first solar Power Tower commercial plant with molten salt storage in the world.