A thorough performance assessment of solar chimney power plants: Case study for Manzanares

Solar chimney power plants (SCPPs) are promising systems for clean energy generation. SCPPs are ideal for the large-scale harnessing of solar energy. They operate efficiently without auxiliary energy and do not cause any environmental pollution. There are several theoretical, numerical and experimental attempts to date for performance assessment of SCPPs, however, there are still contradictions in the findings, and a thorough performance evaluation is still missing. Therefore, in this study, a novel three-dimensional axisymmetric computational fluid dynamics (CFD) approach is proposed by considering the pioneer plant in Manzanares region. For a realistic approach, actual geometric parameters of the pilot plant are utilised in the CFD model, and the performance assessments are done regardless of time. Pressure, temperature and velocity distributions within the SCPP from collector inlet to chimney outlet are numerically modelled with respect to changes in solar radiation and atmospheric temperature. For model validation, the numerical findings are compared with the typical experimental findings performed in pilot plant, and a good agreement is obtained. For a certain value of solar radiation (1000 ​W/m2), maximum air velocity in the pilot plant is found to be 14.24 ​m/s, which is compatible with the experimental data of 15.00 ​m/s. Static pressure is found to sharply decrease from chimney ground to turbine inlet, and then steadily rises to the chimney outlet. Minimum static pressure is observed to be −100.18 ​Pa ​at 21.92 ​m from the ground. Output power of SCPP linearly increases with the solar intensity whereas it steadily reduces with ambient temperature. Available power is determined to be 49059 ​W for the case of 1000 ​W/m2, and the atmospheric temperature of 293 ​K

Numerical performance modelling of solar chimney power plants: Influence of chimney height for a pilot plant in Manzanares, Spain

3D axisymmetric CFD model is developed for a solar chimney power plant (SCPP) in Manzanares, Spain, and potential impacts of chimney height (H) on main performance parameters are comprehensively analysed. Mesh-independent solutions are achieved, and accuracy justification is done over the previous numerical and experimental attempts prior to parametric research. Discrete ordinate (DO) non-grey radiation model with solar ray tracing approach is adopted in the research. A very good accordance is achieved between the numerical findings and in-situ data. For five different H values, temperature, pressure and velocity distributions within the pilot plant are achieved as well as maximum air velocity, mass flow rate of air, temperature rise in collector, dynamic pressure difference at the turbine position, overall system efficiency and potential electrical power. It is found that maximum air velocity thus mass flow rate shows an exponential growth in H. On the contrary, temperature rise in collector notably reduces with the increasing H. Overall system efficiency is determined to be 0.67% whenH = 500 m. Power output (P) linearly rises with H. The system is capable of generating 55 and 134 kW electrical power, for H = 200 and 500 m, respectively

Collector factor in a solar chimney power plant: CFD analysis for the pilot plant in Manzanares SAULĖS KAMINO ELEKTRINĖS KOLEKTORIAUS KOEFICIENTAS: MANSANARESO BANDOMOSIOS JĖGAINĖS SKAIČIUOJAMOSIOS SKYSČIŲ DINAMIKOS (CFD) ANALIZĖ

Solar chimneys are popular systems for their simple structures and clean energy generation. Thanks to its semi-permeable structure, the collector, one of the system’s basic elements, transfers solar radiation to the system. As a result of the heating of the system air under the collector by the solar radiation passing through the collector, it is directed to the high chimney in the collector centre. During the upward movement of the system air, it converts its energy into electricity via a tur-bine. Due to its large structure, estimating the amount of energy entering the collector system creates a great cost. The ideal size for the collector is therefore important. This study offers a recommendation for the ideal collector size for the pilot plant in Manzanares in terms of collector size and power output. While 59 kW power output is obtained with the system with a collector radius of 122 m in the reference case, it is observed that the power output increases by 78% when the collector radius is increased to 170 m and the collector area is doubled. The ratio of the ideal collector radius to the reference size for the pilot plant should be in the range of 1–1.5

Performance assessment of solar chimney power plants with the impacts of divergent and convergent chimney geometry

Influence of area ratio (AR) on main performance parameters of solar chimney power plants (SCPPs) is investigated through a justified 3D axisymmetric CFD model. Geometric characteristics of Manzanares pilot plant (MPP) are taken into consideration for the numerical model. AR is varied from 0.5 to 10 to cover both concave and convex (convergent and divergent) solar chimney designs. Following the accuracy verification of the CFD results and proving mesh-independent solution, main performance oriented parameters are assessed as a function of AR such as velocity, temperature and pressure distribution within MPP, temperature rise of air in collector, mass flow rate of air around the turbine area, dynamic pressure difference across the turbine, minimum static pressure in the entire plant, power output and system efficiency. The results reveal that AR plays a vital role in performance figures of MPP. Mass flow rate of air () is found to be 1122.1 kg/s for the reference geometry (AR = 1), whereas it is 1629.1 kg/s for the optimum AR value of 4. System efficiency (eta) is determined to be 0.29% for the reference case; however, it is enhanced to 0.83% for the AR of 4.1. MPP can generate 54.3 kW electrical power in its current design while it is possible to improve this figure to 168.5 kW with the optimal AR value

Impacts of Ground Slope on Main Performance Figures of Solar Chimney Power Plants: A Comprehensive CFD Research with Experimental Validation

Geometric parameters in solar chimney power plants are numerically optimised for the purpose of better power output figures. Several parameters have been investigated in the pilot plant such as chimney height and diameter, collector diameter and slope, and slenderness. However, ground slope has not been studied to date despite its perspicuous impact on turbulent flow. In this study, the impacts of the different slope angles of the ground, where the solar radiation is absorbed through the collector, on the main performance parameters of the system are numerically analysed through a reliable CFD software ANSYS FLUENT. By considering the actual geometric figures of the pilot plant, a 3D model is constructed through DO (discrete ordinates) solar ray tracing algorithm and RNG k-epsilon turbulence model. For the solar intensity of 1000 W/m(2), the maximum velocity inside the system is found to be 14.2 m/s, which is in good accordance with the experimental data of 15.0 m/s. Starting from 5 m inside the collector, the chimney inlet heights are reconfigured 0.209, 0.419, 0.625, 0.838, and 1.04 m, respectively, and when the ground slope is 0.1, 0.2, 0.3, 0.4, and 0.5 degrees, the changes in the performance output of the system are investigated. For the reference case which refers to the horizontal ground, the maximum air velocity is determined to be 14.2 m/s and the power output is 54.3 kW. However, when the ground slope is made 0.5 degrees, it is observed that the maximum velocity increases by 37% to 19.51 m/s, and the power output is enhanced to 63.95 kW with a rise of 17.7%. Sloping ground is found a key solution to improve the turbulent effects inside the plant, thus to enhance the electrical power output

Solar Chimney Power Plants: A Review of the Concepts, Designs and Performances

This research presents a comprehensive review of solar chimney power plants (SCPP) as a reliable source of renewable electricity generation. Solar chimney power plants differ from other renewable energy technologies because thermal and momentum effects result in 24-h electricity generation. However, they are influenced by a wide range of design, geometrical and operational parameters, and environmental conditions. This review evaluates the design aspects and the theoretical, numerical, experimental, and performance findings in previous works holistically and concisely. The study also extensively discusses the various optimization strategies, advantages, disadvantages, and limitations of solar chimney power plants. Energy storage aspects and hybrid system designs are also addressed in the present review in order to overcome the known handicaps and limitations of solar chimney power plants. The performance figures of the technology are clearly demonstrated as a function of the design and operational conditions, and future prospects are discussed in detail. It is hoped that designers and policymakers will gain valuable insight into the technological features and advancements of solar chimney power plants, assisting them in making a better-informed decision

Performance Evaluation of Solar Chimney Power Plants with Bayburt Stone and Basalt on the Ground as Natural Energy Storage Material

This research examines the effect of using Bayburt stone or basalt as an energy storage unit in SCPPs. The effect of using low-cost materials on the system performance is evaluated. Based on the Manzanares pilot plant (MPP), a 3D CFD model was created. Geometric parameters were kept constant in simulations performed with ANSYS FLUENT engineering commercial software. In addition to DO (discrete coordinates) for the radiation model, the solar ray-tracing algorithm (SRTA) and the RNG k-e turbulence model (RNGTM) were solved, coupled, and the outputs of the system were evaluated at outdoor temperatures of 290 and 300 K. The temperature and velocity distributions, as well as power outputs (PO) of the system by using Bayburt stone and basalt as ground material, are compared for different outdoor temperatures and solar radiation conditions. It is understood that the use of both materials contributes to the performance of the system at a similar rate and can be used economically. It is noticed that the plant gives a PO of approximately 41,636 kW with both storage materials at a radiation intensity of 800 W/m(2) and an outdoor temperature of 300 K. It is seen that the outdoor temperature affects the temperature rise in the plant, which is higher at 290 K

Performance assessment of solar chimney power plants with natural thermal energy storage materials on ground: CFD analysis with experimental validation

This study interprets the effect of using sand or gravel as energy storage unit in solar chimney power plants. The effect of using low-cost materials is evaluated. Based on the Manzanares pilot plant, a 3D CFD model is created. Geometric parameters are kept constant in simulations performed with ANSYS FLUENT engineering commercial software. By simultaneously solving DO (discrete ordinates) solar ray tracing algorithm and RNG k-epsilon turbulence model, the outputs of the system are examined at 290 and 300 K temperatures. The temperature distribution and power outputs of the use of sand and gravel as soil material at different temperatures and solar radiation are compared. It is understood that the use of both materials does not significantly affect the performance of the system and can be used economically instead of each other. It is seen that the system will give a power output of approximately 41.636 kW with both storage materials at a radiation intensity of 800 W/m(2) and an ambient temperature of 300 K. It is seen that the ambient temperature affects the temperature increase in the system, and the temperature increase is higher at 290 K