The sloped-collector solar chimney (SCSC) is a promising and cost-effective solution for large-scale solar energy applications, though its performance in ambient crosswinds (ACW) still needs evaluation. This research employs three-dimensional computational fluid dynamics (CFD) analysis to investigate the effects of ACW, solar radiation, and collector slope angles on SCSC performance. Findings indicate that low crosswind speeds adversely affect system performance. However, a collector slope angle between 20 degrees and 30 degrees enhances updraft generation compared to conventional designs. Dimensional analysis predicts output power for large-scale applications with a 200-m chimney, similar to the Manzanares prototype. An optimal slope angle of 20 degrees can increase output power by 10 %-35 % compared to traditional systems. Furthermore, adverse crosswinds can reduce output power by 55 % at a wind speed of 12 m/s, but increasing the slope angle can recover 16 % of that power, resulting in approximately 35 kW. This research provides essential insights for optimizing large-scale SCSC design, suggesting adaptive designs that improve efficiency in various climatic conditions for solar chimney projects.

This study focuses on the thermal behavior of tunnel boring machines (TBMs) through an in-depth investigation into the temperature distribution of their disc cutters. Utilizing the differential quadrature method (DQM), the research conducts a comprehensive numerical analysis to assess the impact of excavation and geological parameters on disc cutter temperature and wear. The accuracy of the DQM model is validated against the finite difference method (FDM), demonstrating comparative results with reduced computational requirements. The findings indicate a significant correlation between disc cutter temperature and various factors, such as rotational speed, spacing, geological conditions, and material strength. Notably, increased spacing or cutter speed leads to higher temperatures and accelerated cutter wear. Moreover, geological factors, particularly rock strength, influence friction coefficients, affecting disc cutter temperatures significantly. For instance, even a slight increase in cutter spacing results in a substantial 65% rise in cutter consumption, underscoring the relevance of these findings for life cycle assessment (LCA) evaluations across diverse geological and environmental conditions in TBM operations.

Solar Chimney Power Plants (SCPP) are among the promising solar thermal electricity generation technologies. Equipped with a Thermal Energy Storage (TES) system, such technologies can overcome variations in the main driving factors such as solar radiation and ambient air temperature. This article presents a comprehensive semi -analytical model of a TES to predict the time-dependent performance of an SCPP. By introducing a Quality Factor of power generation (QF) that includes energy conversion efficiency and capacity factor, the effects of 15 TES materials have been studied on the plant performance. Results indicate no significant difference between water TES and clay or soil type, and water-filled bags or tubes are relatively ineffective in improving performance compared to them. Among the various TES materials analyzed, a type of wet soil, i.e., the specific wet mixture of clay, sand, and silt in closed and dark-colored bags, show excellent performance in both QF enhancement and having low Heat Penetration Depth (HPD) simultaneously. The QF and HPD are directly affected by thermal effusivity and thermal diffusivity, respectively. Implementing wet soil TES for the studied power plant (Manzanares) enhances the QF from 7.46 % (for limestone soil) to 10.95 %. Water-filled bags demonstrate a heat penetration depth of 0.4 m, while wet soil exhibits a slightly greater depth of 0.5 m. Furthermore, water-filled bags experience a broader temperature range of 40 degrees C, whereas wet soil undergoes a comparatively smaller temperature variation of 26 degrees C. Furthermore, the capacity factor raises from 41.18 % to 61.07 % when utilizing wet soil TES compared to water-filled bags.

Nowadays, it is necessary to develop sustainable energy suppliers according to the concerning environmental issues. Solar energy is one of the appropriate solutions. Solar Chimney Power Plant (SCPP) represents a viable form of solar thermal electricity generation technology. Temporal variations in the driving factors of the plant, especially solar radiation, cause significant fluctuations in output power. This study evaluates active and passive control strategies for achieving more stable power generation in SCPP using Fuzzy Logic Control (FLC) and Thermal Energy Storage (TES) systems. The governing equations for performance modeling have been solved by a developed MATLAB code and validated with experimental data from the Manzanares prototype. Using TES reduced output power fluctuations and showed daily electrical energy generation of 331.9, 314.3, and 308.7 kWh for sand, limestone soil, and water-filled bags, respectively. Implementing an active control strategy with the FLC system alone provided a 25 and 30-kW baseload generation in the mid-hours of the day. Finally, integrating the FLC and TES systems in a hybrid control strategy continued a base load power generation of 12 and 16 kW up to 4 h after sunset, utilizing limestone soil and water-filled bags, respectively.

Floating Solar Chimney Power Plant (FSC) proposed by Papageorgiou is regarded as a novel type of Solar Aero-Electric Power Plants with fundamental characteristics of low cost and unaffected seismic chimney. The main disadvantage of the proposed system is the tilting of the floating chimney in windy conditions compared with a conventional reinforced concrete one. In the present research, the ambient crosswind (ACW) effect is studied on an FSC with experimental and numerical approaches. An experimental floating chimney integrated with an appropriate solar collector was designed, built, and tested under real-world conditions, and the experimental results were used for validations of the numerical analysis. Three-dimensional numerical analysis was performed to study the performance of the tilted floating solar chimney exposed to the ACW and then compared with a conventional type. Numerical results show that a tilting FSC with lower apparent height can operate more efficiently than a vertical concrete chimney in windy conditions due to eliminating adverse effects of tip vortices on updraft flow in the system. The results also show that an optimum tilting angle (OTA) exists for the specified plant and critical or prevailing wind speed, making ACW adverse effects minimum. Floating solar chimney design can be enhanced significantly based on achieving optimum tilting angle in windy conditions.

Solar Chimney Power Plant (SCPP) is known as a relatively new technology for electrical power generation from solar thermal energy in a relatively simple structure and reliable operation. SCPP would be one of the main competitors with traditional power generation technologies for the present time and near future. Considering the variable nature of solar radiation and ambient temperature during a day and different days of a year as the main plant's excitation factors, it is essential to control the power output of solar chimney power plant to meet the various demands of local and national electrical grids. The design and implementation of a Fuzzy Logic Control (FLC) system for a large-scale solar chimney power plant equipped with natural or artificial thermal storage to meet various base to peak demand patterns studied in this paper. The power error between actual power generation and the reference value and the rate of change in that error are defined as the controller inputs. A knowledge base of IF-THEN rules is generated based on expert knowledge and the dynamic behaviour of the plant. The output of the controller, the opening of the turbine inlet gate, will impose on the plant. Simulation results show that SCPPs equipped with an integrated active and passive control system, including FLC and thermal energy storage, can track daily reference profiles in various grid demand patterns and different ambient conditions.

In this study, a novel bipolar flow field design is proposed. This new design consists of placed sequentially converging and diverging channels. Numerical simulation of cathode side is used to investigate the effects of converging and diverging channels on the performance of proton exchange membrane fuel cells. Two models of constant and variable sink/source terms were implemented to consider species consumption and production. The distribution of oxygen mole fraction in gas diffusion and catalyst layers as a result of transverse over rib velocity is monitored. The results indicate that the converging channels feed two diverging neighbors. This phenomenon is a result of the over rib velocity which is caused by the pressure difference between the neighboring channels. The polarization curves show that by applying an angle of 0.3 degrees to the channels, the net electrical output power increases by 16% compared to the base case.

The purpose of this study is to optimise the dimensions of the collector in a solar chimney power plant with entropy generation minimisation (EGM) method. Projection method, based on second-order finite difference discretisation, is developed to solve the coupled equations of continuity, momentum and energy of laminar natural convection in a fully staggered grid. Numerical solution showed that the irreversibility owing to heat transfer is dominant in solar collector and the chimney has minor role in total entropy generation. On the basis of temperature field, local entropy generation and Bejan number distribution in the system, an analytical solution for total entropy generation is developed and compared with numerical results for different Rayleigh numbers and collector height to radius ratios. The study showed that total entropy generation is proportional to square of Rayleigh number and it is inversely proportional to collector height to radius ratio.