Power Tower Research Articles

Performance investigation of the solar power tower driven combined cascade supercritical CO2 cycle and organic Rankine cycle using HFO fluids

ABSTRACT Current study examined the effect of solar power tower (SPT) design parameters (solar emittance, concentration ratio and heat transfer fluid velocity, solar irradiation) on SPT-integrated combined cascade sCO2 (CSCO2) cycle and organic Rankine cycle (ORC) using ultra-low global warming potential (GWP) hydro fluoro olefins (HFO) fluids. Exergy efficiency, thermal efficiency and net output power were considered as performance parameters. A computational technique was used for the analysis. It was investigated that thermal and exergy efficiencies of the standalone (SPT+ CSCO2) cycle improved by 2.36% and 2.41%, respectively, by the incorporation of the ORC as bottoming cycle. Highest exergy efficiency, thermal efficiency and net output power were increased with solar irradiation, concentration ratio, heat transfer fluid velocity while decreased with solar emittance. Highest performance were found with R1224yd(E) while lowest with R1234yf among other considered low GWP fluids at current input conditions.

Monitoring the blades of a wind turbine by using videogrammetry

Wind power is a reliable source of clean energy that is extensively used around the world. The blades of wind turbines are subject to a variety of mechanical stresses while they rotate and it is important to monitor their condition and diagnose problems to ensure their safe operation. Prevalent methods to this end are designed to be applied when the turbines are not operating. Moreover, current techniques to examine turbines are limited in that they can be used only to inspect defects on the surfaces of their blades. However, many faults in the blades of wind turbines are apparent only when they are operating, which makes it important to closely monitor the state of the blades as the turbine bears loads of varying magnitudes. Based on advanced videogrammetry, this study proposes a series of techniques to detect structural defects in the blades of turbines during their normal operation. Measurements of the global movement and local deformation in their operation, combined with inspections of the surface of the blades through an unmanned aerial vehicle, enable a complete inspection of the blades of the turbine as well as its systems of transmission, gear box, and wind power tower. The proposed method represents an important technical advancement that can help repair defects in wind turbines in a timely manner to reduce the cost of maintenance of wind power systems.

Heliostat field aiming strategy optimization with post-installation calibration

Heliostat field aiming strategy significantly affects the safety and operational efficiency of the Solar Power Tower (SPT) system. Heliostats installed in fields are likely to show deviations of optical properties from design specification to some extent. Such deviations generally reflect in the surface curvatures and normal directions of heliostat facets. These differences can give rise to the inevitable degradation of optical performance, impacting the execution effect of the pre-designed aiming strategy. Focusing spot distortion with an inappropriate aiming strategy possibly leads to overheated local areas or component damages. To cope with this error and to improve the light concentration performance, an aiming strategy optimization approach with post-installation calibration was proposed in this paper. An equivalent parameter model was developed based on heliostat parameters, producing a more accurate description of optical performance. The adopted heliostat parameters were obtained by the parameter identification method. The parameter identification was formulated by photographed solar flux images and simulated flux distributions. The aiming strategy optimization model of heliostat field was built with obtained identification parameters, and the optimization goal considers utilized solar power absorbed by the heat transfer fluid and flux distribution uniformity. The simulation results showed substantial improvement from the proposed aiming strategy. • A novel approach to heliostat field aiming strategy optimization is developed. • Effective heliostat optical parameters are obtained by parameter identification. • Identified parameters calibrate heliostat deviations in aiming strategy optimization. • Flux distribution uniformity and heat loss are considered in the optimization goal.

A review on integrated design and off-design operation of solar power tower system with S–CO2 Brayton cycle

The solar power tower (SPT) system integrated with supercritical CO2 (S–CO2) Brayton cycle is a potential flexible power output station to balance supply and demand in the future power system with high renewable energy penetration, so as to maintain the reliability of power supply. Reasonable design and accurate parameter adjustment are crucial to the efficient, low-cost, and reliable operation of the SPT system with S–CO2 Brayton cycle. Many works have studied the design optimization and operation control strategy of the system. But the research focuses and conclusions are various, and there is a lack of important summary in this field. This paper provides a review on the integrated design and off-design operation of SPT system with S–CO2 Brayton cycle. In terms of system integrated design, the performance criteria, subsystem selections, and key parameter optimizations are summarized. Furthermore, an improved system design method based on off-design operating performance is introduced and recommended. In terms of system off-design operation, the fluctuating factors, parameter control strategies, and the actual operation results are introduced. The conclusions and study prospects for this promising technology in the aspects of design and operation are presented.

Failure mechanism and vibration control for tower tube of wind generator under extreme climate

The wind power tower is sensitive to wind loads with high aspect ratio. The failure characteristics and failure mechanism of the wind turbine tower structure are analyzed under the extreme climate conditions. Based on the principle of tuned mass damper theory, the suspension damper application in wind turbine tower structure is designed. The appropriate typhoon wind speed spectrum is selected. With the finite element software, the 3D model for tower structure is established and the control effect of the damper structure is analyzed. The maximum displacement and acceleration of the structure under extreme climatic conditions are greatly reduced after the suspension tuned mass damper being given. The efficiency of vibration reduction is 80.26% and 54% respectively. The results show that the response of displacement and acceleration for the damper are obviously decreased, which is beneficial to the safety of the tower structure under the extreme climate condition.

A comparison between lumped parameter method and computational fluid dynamics method for steady and transient optical-thermal characteristics of the molten salt receiver in solar power tower

Lumped parameter method (LPM), which neglects the change of the temperature within the cross-section of the molten salt, is widely used to predict solar receiver's steady and transient optical-thermal characteristics. To consider the influences of the temperature variation inside molten salts on the performance of solar receivers, the receiver's steady and transient thermal performance are comparatively studied by computational fluid dynamics method (CFD) and LPM. The results show that the rise time of the outlet temperature predicted by the CFD model under the start process, the change of mass flow rate, and the change of direct normal irradiance are more than two times those of the LPM model. Take the start process on spring equinox as an example, the rise time predicted by the CFD and LPM model are 52s and 22s, respectively. Therefore, the temperature distribution within the molten salt should be considered for predicting a more precise transient thermal performance of the receiver. The predicted outlet temperatures in the steady state by the two models are nearly the same, with an absolute difference less than 2.0 °C, which indicates that whether considering the temperature distribution within the molten salt does not influence receiver's steady thermal characteristics.

Surface Wind Pressure Distribution of Molten-Salt Power Tower by CFD Analysis

Surface Wind Pressure Distribution of Molten-Salt Power Tower by CFD Analysis

Mitigating avian collisions with power lines through illumination with ultraviolet light

Collisions with anthropogenic structures by long-distance migrants and threatened and endangered species are a growing global conservation concern. Increasing the visibility of these structures may reduce collisions but may only be accepted by local residents if it does not create a visual disturbance. Recent research has shown the potential for ultraviolet (UV) light, which is nearly imperceptible to humans, to mitigate avian collisions with anthropogenic structures. We tested the effectiveness of two UV (390–400 nm) Avian Collision Avoidance Systems (ACASs) at reducing collisions at two 260-m spans of marked power lines at the Iain Nicolson Audubon Center at Rowe Sanctuary, an important migratory bird stopover location in Nebraska. We used a randomized design and a tiered model selection approach employing generalized linear models and the Akaike Information Criterion to assess the effectiveness of ACASs considering environmental (e.g., precipitation) and detection probability (e.g., migration chronology) variables. We found focal (assessed power line) and distal (neighboring power line) ACAS status and environmental variables were important predictors of avian collisions. Our top model suggests that the focal ACAS illumination reduced collisions by 88%, collisions were more likely at moderate (10–16 km/h) compared to lower or higher wind speeds, and collision frequency decreased with precipitation occurrence. Our top model also indicates that the distal ACAS illumination reduced collisions by 39.4% at the focal power line when that ACAS was off, suggesting a positive “neighbor effect” of power line illumination. Although future applications of ACASs would benefit from additional study to check for potential negative effects (for example, collisions involving nocturnal foragers such as bats or caprimulgiform birds drawn to insects), we suggest that illuminating power lines, guy wires, towers, wind turbines, and other anthropogenic structures with UV illumination will likely lower collision risks for birds while increasing human acceptance of mitigation measures in urban areas.

World Map of Low-Layer Atmospheric Extinction Values. Overview of its Impact on Solar Power Tower Plants Projects

World Map of Low-Layer Atmospheric Extinction Values. Overview of its Impact on Solar Power Tower Plants Projects

Performance Analysis of a Solar Power Tower Plant Integrated with Trough Collectors

Performance Analysis of a Solar Power Tower Plant Integrated with Trough Collectors

Thermo-Economic Analysis of Integrated Gasification Combined Cycle Co-Generation System Hybridized with Concentrated Solar Power Tower

Thermo-Economic Analysis of Integrated Gasification Combined Cycle Co-Generation System Hybridized with Concentrated Solar Power Tower

An Innovative Computer-Aided Method for Optimizing Solar Power Tower - the Case of Syrian Desert

An Innovative Computer-Aided Method for Optimizing Solar Power Tower - the Case of Syrian Desert

Optical Efficiency Analysis of Concentrated Solar Power Tower in Australia and Chile: Introduction and Optimization of Fractal Layout

Optical Efficiency Analysis of Concentrated Solar Power Tower in Australia and Chile: Introduction and Optimization of Fractal Layout

An Analytical Study of Optimal Spectral Characters of Solar Absorbing Coating and Thermal Performance Potential of Solar Power Tower

An Analytical Study of Optimal Spectral Characters of Solar Absorbing Coating and Thermal Performance Potential of Solar Power Tower

Technical Requirement Analysis of Regulation Characteristics of CSP Station with Heat Storage System

Using solar energy to generate thermal power is often called concentrating solar power (CSP), is a grid friendly clean energy utilization mode with unique development advantages. Large capacity heat storage system with relatively mature technology and low cost can be configured to ensure stable and controllable power generation. The method can be. Solar thermal power generation has become a strategic emerging industry supported by many countries around the world. Spain, the United States, India, South Africa and other countries have carried out commercial operation of power technology with solar thermal, and installed capacity is growing steadily. China has also given key support to CSP generation technology, which has been vigorously developed. As the most promising new energy technology, CSP generation from molten salt heat storage tower is one of the main technical approaches of CSP generation. The key is to store the absorbed solar heat through thermal storage materials and release it stably for a long time, so as to achieve continuous and stable power generation independent of solar radiation changes. Through analysis, this paper puts forward the key technology research and scheme of molten salt regenerative CSP generation system, promotes the research on the bidirectional relationship between CSP station and power grid, and realizes the innovation of renewable energy technology. Relevant research results and technical schemes can be popularized and applied in demonstration power stations, and can also be used for operation control of newly-built molten salt heat exchange and storage tower power stations in the future.

Combining Ray Tracing and Cfd to Evaluate the Outlet Air Temperature of an Indirectly Irradiated Solar Receiver Equipped with a 3d-Cpc for a Solar Tower Power Plant

Combining Ray Tracing and Cfd to Evaluate the Outlet Air Temperature of an Indirectly Irradiated Solar Receiver Equipped with a 3d-Cpc for a Solar Tower Power Plant

Optical-thermal-mechanical analysis of high-temperature receiver integrated with gradually sparse biomimetic heliostat field layouts for the next-generation solar power tower

Three gradually sparse biomimetic (GSB) heliostat field layouts, which gradually extend from the inside to the outside, are proposed herein. Annual optical performance is compared with the standard biomimetic (SB) layout and the widely used staggered layout. In the end, the receiver’s optical-thermal–mechanical performance is analyzed with the above five heliostat fields for the next-generation solar power tower (SPT) with the receiver’s outlet temperature at 720 °C. The results show that the GSB layout with a linear increasing factor (Linear-GSB) has the best optical performance. Compared with the staggered layout and the SB layout, the Linear-GSB layout can increase the annual intercepted energy (Eann) by 1.5% and 1.3% under the same heliostat number, respectively. Moreover, GSB layouts can simultaneously reduce the receiver’s maximum heat flux (qmax), maximum thermal stress (σw,max) and improve its heat flux distribution homogeneity. Compared with the staggered layout, qmax, σw,max, and heat flux maldistribution index of the receiver under the Linear-GSB layout at noon of spring equinox are decreased by 4.2%, 4.3%, and 19.8%, respectively. Meanwhile, the Linear-GSB layout can achieve slightly higher receiver efficiency compared with the staggered layout.

Comparative exergoeconomic evaluation of integrated solar combined-cycle (ISCC) configurations

This paper provides an exergy, economic, and exergoeconomic comparative analysis for the three most promising solar thermal technologies of integrated solar combined-cycle systems: direct steam generation linear Fresnel collectors, solar power tower, and oil parabolic trough collectors. The exergetic analysis shows that configurations using Fresnel collectors result in the highest exergetic efficiencies (44.1%), while the configuration using a solar tower leads to the lowest efficiency of 33.2%. Integrating the solar field into the high-pressure part results in higher efficiencies for day operation. However, this limits the steam cycle to benefit from higher pressure levels, especially during night operation, as the cycle has to operate on the same design pressure level to avoid possible part-load losses. Findings of the economic analysis show that sharing the same power block of the combined-cycle plant results in a significantly lower incremental specific investment cost for concentrated solar power (2545 $/kW) that helps new installations at moderate investments, leading to steeper learning curves of the technology. Configurations using solar collectors with direct steam generation produce electricity at the lowest price of 36.75 $/MWh. The configuration using oil parabolic trough produces electricity at the highest price (38.62 $/MWh).

Experimental investigation on thermal characteristics of a novel mesh flat-plate heat receiver in a solar power tower system

In solar power tower systems, the heating surface of a heat receiver is prone to local overheating, thermal fatigue, and thermal ratcheting under nonstationary, nonuniform, and high-heat-flow-density loads, resulting in failure of the heat receiver. Therefore, this paper proposes a novel high-temperature, mesh, flat-plate heat receiver (FPHR) comprising multiple micro heat pipe loops. A series of tests were conducted to investigate the heat transfer characteristics and cooling start-up performance of the mesh FPHR. The results indicate that the larger cooling rates can reduce successful start-up times by more than 12%, and the FPHR has excellent isothermal performance (<35.05 °C) and heat transfer performance, which can withstand high-heat-flow-density loads and effectively prevent the harm caused by thermal stress. In addition, the nonuniform heating condition has a greater impact on the isothermal performance of FPHR, and the maximum temperature difference of the heat absorption surface with the change of the tilt angle is only reduced by 2.03 °C. The efficiency of the FPHR can exceed 83.98% and the air outlet temperature can exceed 714.5 °C. The results will contribute to the further development of heat receivers used in solar power tower systems.

A Techno-Economic Analysis of Parabolic Trough Collector (PTC) and Solar Power Tower (SPT) as Solar Energy in Malaysia

Malaysia receives an annual average of 2200 hours of solar radiation, making her abundant renewable resources to generate electricity. Thus, a good planning is required to manage the resources efficiently and to utilize the abundant resources fully. Concentrating solar power (CSP) technology is a possible approach to manage renewable resources in Malaysia. Using a techno-economic analysis, the researchers, engineers, industries, or government agencies will be able to identify contributing and discouraging factors of building the CSP technology. This paper presents a techno-economic analysis of two CSP technology: parabolic trough collector (PTC) and solar power tower (SPT), for potential implementation in Malaysia. This paper provides information on two CSP technologies to researchers and industries prior to the planning and design stages. The techno-economic analysis begins with identifying potential locations based on the direct normal irradiation (DNI). Kuah, Kuantan, Miri and Labuan are identified as the potential locations using the RETScreen Expert software. Labuan could be the most promising PTC and SPT technology project because it has the highest DNI received annually. Next, the techno-economic analysis uses two reference projects, ANDASOL-1 and PS-10 systems in Spain, as references for all locations. The techno-economic analysis consists of annual electricity generation, unit cost of electricity, net Present Value (NPV), benefit-to-cost ratio (B/C), internal rate of return (IRR), and payback period calculated in Microsoft Excel. Finally, a sensitivity analysis is conducted to measure the impact of uncertainties of one or more input variables, leading to uncertainties on the output variables. Two sensitive factors are the annual electricity generation and the initial cost, affecting the construction, installation, and implementation of PTC or SPT technology.