Performance Of Solar Chimney Research Articles

A Review of Comprehensive Guidelines for Computational Fluid Dynamics (CFD) Validation in Solar Chimney Power Plants: Methodology and Manzanares Prototype Case Study

This review provides a comprehensive examination of CFD modeling procedures for SCPP, with an emphasis on the detailed methodologies and a case study of the Manzanares prototype in Spain. The introduction delineates the historical context and physical modeling principles of solar chimneys, while highlighting their potential in industrial applications. The governing equations are meticulously discussed, covering assumptions in both 2D and 3D CFD modeling, the continuity and momentum equations, and the selection and accuracy of turbulence models, particularly the k-ε equations. The review also delves into heat transfer modeling, encompassing the energy equation and radiation modeling. Analytical evaluations of turbine pressure drop ratios and performance metrics for power generation efficiency are critically analyzed. The establishment of boundary conditions in solar chimney applications, including sky temperature assessments and distinctions between 2D and 3D boundary conditions, is extensively explored. Mesh generation techniques for both 2D and 3D CFD models are presented, supported by case studies. Parametric studies and experimental investigations are scrutinized to elucidate their impact on the performance of solar chimneys. The temperature–entropy diagram for an idealized Brayton cycle is introduced as a conceptual framework for efficiency analysis. Validation of the CFD codes, both 2D and 3D, against experimental data is performed to ensure model accuracy. The review further examines energy balance approaches in modeling solar chimneys, presenting state-of-the-art CFD results and discussing their implications in both 2D and 3D contexts. The synthesis of these findings culminates in a comprehensive conclusion, offering insights into the future directions and potential advancements in the CFD modeling of solar chimneys. This work aims to serve as a definitive reference for researchers and practitioners in the field, providing a robust foundation for the development and optimization of SCPP technology.

The effects of geometric factors on power generation performance in solar chimney power plants

This research aims to create an admissible source for specifying the relation between the plant's output power and specified geometrical parameters unique to each simulated chimney dimension. In the current study, the solar chimney output power has been studied considering 49 solar chimneys, including different collector diameters, chimney heights, and chimney diameters. The study employs the Ansys-CFX to simulate the numerical model for the unsteady k-ε turbulent flow for a vast number of geometries. The obtained results indicate that the velocity as the main factor in generating the output power has significantly improved by elevating the collector radius. The output power increased up to 50 % by elevating the collector radius and around 30 % by enhancing the chimney heights which cause an increase in airflow, temperature differentials. Moreover, increasing the chimney height has generally ascended the power plant system. Among all geometrical parameters, chimney radius had the least impact on solar chimney performance. The results indicate that the best ratio between collector radius and chimney height is 6 %–10 % to achieve the optimized output power. Our findings were verified with the available experimental setups.

Comparison assessment for the effect of porous media and phase change material on the performance of photovoltaic solar chimney

In the research, an experimental model of a hybrid PV solar chimney was manufactured and installed, and it was combined with different materials. The effect of these materials on the PV/solar chimney performance was studied. Asphalt was used as a phase-change- material (PCM), and the gravel bed as a porous media. Results were taken for PV chimneys integrated and not integrated with PCM and the porous media.The results found that these materials have a good effect on the performance of solar chimneys. The experimental results were as follows: The highest values of electrical efficiency were for the chimneys combined with porous media and PCM, reaching 13.16 % and 13.12 %, respectively, at 8: 00 a.m. The temperature of the PV panels of the chimney combined with these materials was lower than that of other chimneys. The air velocity exiting the collector for systems not combined with these materials was higher than for systems combined with PCM and porous media from the beginning of the test until the afternoon, which reached 1.60 m/s and 1.45 m/s, respectively, at noon. The total efficiency values of the SC that did not contain porous media and PCM were higher than the chimneys combined with these materials, reaching 70.62 % for the system that did not contain PCM and 68.95 % for system that did not contain porous media at noon.

Research on the new passive optimization strategies for improving the performance of combined solar chimney

Focusing on the Combined Solar Chimney (CSC), this study introduces two innovative passive optimization measures: deflectors and segmented heat-absorbing walls. Using numerical simulations, the impact of five control parameters—the angle and length of the straight deflector, the central angle of the curved deflector, the number of heat-absorbing wall segments, and the Rayleigh number (Ra)—on CSC performance is analyzed. Results indicate that air changes per hour (ACH) can be significantly improved with the implementation of deflectors and segmented walls. Optimal deflector configurations are identified as a 25° angle, a 0.375 length-to-width ratio (l/W), and a 60° central angle. The study recommends using two heat-absorbing wall segments for practical applications. When both measures are applied, ventilation performance can be enhanced by up to 25.71%. Additionally, this research establishes quantitative relationships between the control parameters, ACH, and heat exchange efficiencies, providing a theoretical foundation for practical engineering designs.

Theoretical models for predicting ventilation performance of vertical solar chimneys in tunnels

Solar chimney as a reliable renewable energy system has been primarily utilized for building ventilation, but its application in the tunnel is rarely explored. This study develops theoretical models to predict the ventilation performance of vertical solar chimney in urban tunnel. Five temperature distribution types within the chimney cavity are analyzed, including uniform, vertically linear, horizontally semi-parabolic, two piecewise semi-parabolic in the depth direction, and three-dimensional parabolic profiles. The theoretical models consider the effect of chimney configuration, tunnel geometry, glazing materials, and solar radiation intensity on airflow rate through solar chimney. Validation against experimental data and numerical simulation shows that considering three-dimensional temperature distributions results in an average 11 % deviation from validation data, outperforming assumptions of uniform (29.3 % deviation) or lower-dimensional profiles. The volumetric flow rate through solar chimney exponentially decreased with h/w and h/d that the optimum ratio of h/d is 10. The airflow rate linearly increased with 0.14 power of glazing absorptivity. This analysis provides technical guidance for optimizing solar chimney design in tunnels, enhancing natural ventilation, and reducing energy consumption for mechanical ventilation systems.

Annual performance of solar chimney for a multi-story building based on Modelica multizone model

Integration of solar chimney is an effective passive strategy for facilitating fresh air flow and offering significant potential for building energy conservation. This research evaluates the optimal design and control strategy for a six-story office building that includes a solar chimney, focusing on stack effect ventilation and energy performance throughout the year. The ventilation rates in different configurations of solar chimney are compared to meet fresh air requirements. The results indicate that the separated solar chimney ensures uniform airflow across each floor, with ventilation standard-reaching rates ranging from 79.5 % to 88.6 %. Furthermore, maximums of air flow rate occur at each floor, with critical cavity width values of 0.5 m, 0.4 m, 0.4 m, 0.3 m, 0.3 m, and 0.2 m on the 1st to 6th floor, respectively. Under the condition of equal cavity inlet area, air flow rates rise with the increasing length/width ratios. Finally, when the outdoor temperatures fall beyond the design range, controlling excessive ventilation generated by solar chimney leads to a 19.6 % reduction in total energy consumption over the year, with 71.5 % of the savings during winter.

Theoretical analysis and numerical study of natural convection inside combined solar chimney

AbstractSolar chimneys may induce natural ventilation through solar radiation. However, sufficient theoretical studies are needed as a basis to fully exploit passive design in practical green building design. In this work, we investigate the heat transfer properties of turbulent natural convective flows in a combined solar chimney with a thermal flux at the absorption wall by means of theoretical analysis and numerical simulations. Two different flow patterns have been found, one with a clear thermal boundary layer flow pattern and the other without, based on high Rayleigh numbers. For flow development in these two flow regimes, the transient scaling analysis is performed separately and the control mechanism for each phase is presented. Some new scale relationships are established to characterize the ventilation performance of solar chimneys, including thermal boundary layer thickness δT, velocity vT, mass flow m, and so on. For the distinct thermal boundary layers, δT,s ~ HΓ2/5/Bo1/5κ2/5, vT,s ~ Bo2/5κ4/5Γ1/5/H, m ~ ρBo1/5κ2/5Γ3/5. For nonobvious thermal boundary layers, vT,f ~ Bo1/3κ/H2/3W1/3, m ~ ρBo1/3κ/A2/3. The important scale relationships are validated using corresponding numerical simulation data, such as the mass flow rate scale M ~ (Γ/κ)3/5Bo1/5 in the distinct thermal boundary layer flow state, and so on. The air changes per hour and heat exchange efficiencies are calculated for a solar chimney with a fixed height‐to‐width ratio to provide a basis for the design of a solar chimney.

Enhancement of the performance of solar chimneys using associated petroleum gas

ABSTRACT In this article, an idea has been presented that utilizes the heat produced from the petroleum gas burning accompanying the process of oil extraction to enhance the solar chimney performance. The simulation software tool ANSYS Fluent 2020R1 was used to know the possibility of exploiting this waste energy of gas and combining it with a solar chimney. Seven gas channel configurations were tested on the solar chimney to determine which can produce the most electricity. The simulation results showed that this idea could be exploited to produce higher electric energy, and the efficiency of the solar chimney was increased so that the electric energy production process continues for 24 hours instead of production during the sunshine period only. Different designs were considered for the channels inside the solar collector. Case1 and Case2 were meant for validation purposes only. Good agreement was achieved with the previous research with a maximum error of 2%. The results showed that the circular design of the two-ring burner was the best choice which gave the optimum electric power from the system of about 121.1 kW. It was noted that the circular design of the two-ring burner achieved the highest thermal efficiency, which amounted to 0.523%.

Solar Chimney Performance Driven Air Ventilation Promotion: An Investigation of Various Configuration Parameters

Climate change represents a vital public health challenge, resulting in serious impacts that require passive strategies in the built environment sector to mitigate such impacts. Such strategies are associated with the Sustainable Development Goals (SDGs), which present a vital need. Consequently, the solar chimney (SC) can be considered as an effective passive strategy to provide energy, thermal comfort, and air ventilation performance. Therefore, this study focused on SC performance and its related significance on air ventilation. This study aimed to bridge the gap in previous studies and indicates the hotspot topics to conduct a conceptual framework with three phases that can integrate various configurations of a SC with various buildings by considering the recent tools of numerical analysis. Thus, a bibliometric analysis based on the Biblioshiny and VOSviewer tools within the scope of the SC and air ventilation promotion was accomplished. Then, various configuration parameters related to SC performance-driven air ventilation are provided. The results indicate that further studies are required to develop themes like the “building design” of SC and its associated effects such as air quality and ventilation, in addition to “numerical analysis” and “optimization” in terms of hotspot topics and the potential for future consequences. Additionally, limited configurations of previous studies provide promising investigations resulting in several applications including many zones and floors that can be achieved by the proposed conceptual framework. Various insights and possibilities can promote numerous configuration parameters related to SC performance-driven air ventilation promotion, which serves as research guidance for designers and specialists toward the mitigation of climate change impacts and attaining the SDGs.

Enhancing the Performance of a Rooftop Solar Chimney Through Flow Disturbers

Abstract Enhancing the performance of passive solar chimneys constitutes a key point for successful applications in bioclimatic architecture. Present work assesses applications of several kinds of flow disturbers in a rooftop solar chimney, under isoflux heating and windless conditions, and including surface radiative effects. Systematic numerical calculations are conducted aiming a comprehensive analysis, by means of a low-Reynolds turbulence model, being the range of Rayleigh number considered 2.170 × 1012 − 2.170 × 1013. Effect of different geometrical parameters is analyzed, although main attention is posed on the influence of disturbers elements on the thermohydraulic behavior of the established airflow, for obtaining best performance conditions. Some obstacles cause a clear decrease in the efficiency of the system, but given disturbers appropriately located produce valuable enhancements in the thermal or dynamic efficiency. Insertion of intermediate plates proves to be the best option, achieving maximum increases of even approximately 50% in the ventilation capacity.

Investigation of various absorber surface shapes for performance improvement of solar chimney power plant

Solar chimney power plants are important for the development of renewable energy. The absorber surface shape can play a critical role in the solar chimney’s performance. In the relevant literature, there is no comprehensive study on the effect of various absorber surface shapes on the performance of solar chimney. The present study aims to numerically investigate the effect of absorber surface shapes on the power generated by a solar chimney. The investigated absorber shapes include a right triangle, an equilateral triangle, a rectangle, and a semi-circle. In addition, the effect of the absorber surface height is studied. The modelling of heat transfer and fluid flow in the chimney is based on conservation equations. The finite volume method is used to solve the set of equations using ANSYS Fluent software. The model is verified by comparison with experimental data from the literature, and good agreement is obtained. The outcomes of this study show that the maximum effect is found in the case of a rectangular-shaped absorber surface. Furthermore, increasing the height of the modified absorber surface increases the generated power. The output power improves by up to 67.4% in the case of a rectangular absorber with a height of 7.5 cm when compared to the baseline flat-chimney. These findings are useful for designing efficient solar chimney.

Computational investigation of combined solar chimney power plant with gas power plant in different working conditions

Numerous studies have recently focused on enhancing the efficiency of solar chimney power plants (SCPP) and increasing their output power during periods of limited solar radiation. One such study proposes a novel solution: combining an SCPP with a gas power plant to create a hybrid power plant that generates power consistently, day and night. The system involves burying pipes underground and channeling the hot gas from the gas power plant through them, rather than releasing it into the atmosphere. This process increases the temperature of the soil beneath the canopy, which in turn raises the air temperature and the velocity of the air. The resulting decrease in air density leads to an increase in output power. Our results show that the performance of solar chimney of soil ground with buried pipe is about 30% higher than sand domain.

Enhancing solar chimney performance in urban tunnels: Investigating the impact factors through experimental and theoretical model analysis

Efficient and sustainable ventilation in urban tunnels is crucial for combating air pollution and safeguarding human health. This study investigates the design factors impacting solar chimney performance in urban tunnels to optimize ventilation efficiency. Experimental trials analyzed the effects of blockage ratio, chimney height, and solar radiation on temperature distribution and ventilation rate. The results demonstrate that increased chimney height and solar radiation positively influence airflow velocity at the chimney outlet, enhancing ventilation. The temperature rise near absorber is higher than that closed to glazing wall. Temperature distribution within the chimney follows a distinctive horizontal two-piecewise semi-parabolic decay pattern, enabling accurate prediction of temperature profiles along the cavity depth. Novel analytical models predict temperature distribution, airflow velocity, and ventilation rate within the solar chimney system, aiding precise design and optimization. Remarkably, the blockage ratio has limited impact on ventilation rate, allowing for disregarding vehicle blockage effects in solar chimney design for urban tunnels. Matching chimney width to tunnel width and ensuring a relatively high chimney height are emphasized for optimal functionality. The study holds substantial implications for ventilation system design in urban environments, promoting healthier and more sustainable cities.

Numerical Study of Improving Solar Chimney Performance by using Energy Storage

In this study, a simulation for two story building associated with a vertical solar chimney was made by using ANSYS 2022/R1. The study conducted under the climatic conditions of Al-kut city/ Iraq on 5/8/2016. The study involved a comparison between the ventilation performance of SC before and after adding Energy Storage. Al-dura, RT-42, and block-shaped paraffin wax were the three types of PCM that were studied in order to find the optimum ES. The numerical results showed that the best Paraffin wax was Al-dura depending on the average Air Change per Hour (ACH), average indoor temperature, and the ventilation period after sunset. Comparing with the 1st model (without ES), After adding Al-dura wax, the ACH increased by 18.3 % and 9.95 % for 1st and 2nd floor, respectively. whereas, the indoor temperature was reduced by 1.17 k and 0.68 k on the 1st and 2nd floor, respectively. As for the ventilation period, it was lasted for 5 h after sunset.

Analysis of the Ventilation Performance of a Solar Chimney Coupled to an Outdoor Wind and Indoor Heat Source

The effects of different solar radiation intensities, heat flow density of indoor heat sources, outdoor wind speed, and the relative location of indoor heat sources on the natural ventilation performance of solar chimneys are investigated through three-dimensional numerical simulations. The mechanism of the mutual coupling of the solar chimney effect with the outdoor wind and indoor heat source heat plume is explored. The results of the study show that when the structural parameters of the solar chimney are the same, the heat flow density on the surface of the indoor heat source, the outdoor wind speed and the solar radiation intensity all have a gaining effect on the ventilation performance of the solar chimney and the effects of the three on the ventilation of the solar chimney promote each other, when the solar radiation intensity is 200 W/m2, the outdoor wind speed is 1.0 m/s, and the indoor heat source heat flow density increases from 0 to 1 500 W/m2, the solar chimney ventilation volume increases from 0.393 m3/s to 0.519 m3/s, the maximum value of the increase is 32.1%. In the other two cases, the maximum increase in solar chimney ventilation is 176.7% and 33.1%, respectively. Under the same conditions, solar chimney ventilation is optimal when the heat source is in the middle of the room. The presence of outdoor wind, however, affects the optimum design parameters of the solar chimney. Compared to the case where no outdoor wind is taken into account, the optimum inlet width of 0.2–0.3 m for the solar chimney no longer applies with outdoor wind, with the optimum value rising to 0.5 m.

Analysis of Solar Chimney Application for Building Heating and Cooling in Different Climates in China

Solar chimneys have been applied widely to various buildings under different climate conditions because of their superiority in improving the indoor environment and saving energy. A series of comparative studies of the performance of solar chimneys used in 12 cities in China under different climatic conditions was carried out. A typical solar chimney in a representative building was studied using numerical simulation and analyzed using orthogonal experiment methods. Results show that the optimal structural configuration and the significance of influencing factors of the solar chimney have strong seasonal consistency. The window-to-wall ratio and wall-to-south wall ratio are the most significant influencing factors. Among the 12 cities, the highest average indoor temperature of the case room could be decreased by 5.7°C in summer and increased by 6.7°C in winter. The cooling and heating loads could be reduced by 30%–100% and 46%–56% respectively. The research results can provide practical guidance for future passive solar technology design.

The Implication of Solar Chimney for Enhanced Stack Ventilation

In this study the effect of a solar chimney in enhancing the stack ventilation in an e-Bike Prototype Assembly building is analyzed. The Study area is Birgunj, Nepal. Natural ventilation in the existing plans is studied and compared with an alternate scenario of incorporating a solar chimney. Various parameters like temperature (Air, operative and radiant), pressure and velocity distribution, and comfort parameters (PPM and PPD) are compared. The DesignBuilder software is used to analyze natural ventilation. DesignBuilder internal CFD analysis is used to study the effect of solar chimney as a part of the building on the natural ventilation. Results show that there is significant improvement in ACH and air movement inside the building with incorporation of Solar Chimney. The PPD analysis results show that the comfort aspect is not only related to a single parameter like the air flow, temperature and pressure differential but a combination of these. The design of solar chimney should not only focus to improve a single aspect but a combination of the entire parameters for overall comfort. The study also shows that internal CFD analysis can be effectively used to predict internal condition of a building. The performance of Solar Chimney can be measured either or wholly in terms of air movement/air flow, temperature and velocity distribution and also thermal comfort parameters like PPD and PMV.

Ventilation performance of solar chimney integrated into a multi-storey building

Previous studies have mainly focused on solar chimneys in single-chamber/zone or single-story buildings. Its theoretical development in multi-chamber or multi-story buildings is lagging, which hampers its practical applications in multi-storey buildings. This study investigated ventilation capacity characterized by volume flow rates numerically and theoretically for a multi-storey building with a solar chimney. Three mathematical methods based on simplified models were introduced to predict the ventilation rates for each floor. By comparing the three methods, Method 1, based on the bifurcation hypothesis, was found suitable for two-storey or single-storey cases; and Method 3, based on empirical flow equations, is practical for those cases greater than two-storey. To optimize the ventilation rate, a wider cavity gap and a higher stack height for a multi-storey solar chimney were the most effective ways compared to the single-zone/floor cases. A larger window area and air inlet size promoted the ventilation capacity, where the growth rate of volume flow was small and critical values exist. It was observed that the solar chimney dimensions show a more significant effect on the volume flow rates than the solar radiation intensity. The main contribution of this study is that it establishes the links between the single-zone and the multi-storey theoretical models and proposed practical mathematical methods to obtain acceptable prediction accuracy of ventilation rates for a solar chimney in a multi-storey building.

Experimental study and numerical analysis of radiative losses of single-channel solar chimney

Solar chimneys provide natural ventilation for buildings, reducing the energy consumption of mechanical systems. Therefore, analyzing energy losses through solar chimney components and inlet/outlet of air channel is critical to develop a suitable design for this passive ventilation system. In this study, the performance and energy losses analysis of a single-channel solar chimney (SC-SOCH) is described; a parametric study under laboratory conditions was conducted regarding the air gap (0.10, 0.15, and 0.20 m) and heat flux of absorber plate (100, 200, 300, 400, and 500 Wm−2). The energy losses were analyzed with temperature sensors, heat flow transducers, and a net radiation transfer model. The parametric study results showed that between 10% and 15% of the total energy supplied to the absorber plate was dissipated to the laboratory environment through the glass cover. Furthermore, combining the different thermal insulation layers on the backside of the absorber plate and sidewalls of the air channel permitted only energy losses below 8% of the total energy supplied. The highest energy losses occurred due to radiative exchange; the radiative losses through the inlet and outlet of the air channel were between 9.38% and 25.78% of the total energy supplied. However, the radiative energy loss rate decreased as airflow increased; the volumetric flow rate was from 34.11 to 94.92 m3h−1, which was enough to satisfy the requirements of total ventilation rate for spaces of 9, 18, and 36 m2 according to ASHRAE 62.2–2019. Therefore, solar chimney designs must be optimized to minimize energy losses and increase airflow for natural ventilation.

A novel staggered split absorber design for enhanced solar chimney performance

Solar chimney enables passive ventilation in green buildings, without drawing electricity from the grid. The factors influencing the performance of this sustainable passive ventilation device have been widely studied. However, more work needs to be done to increase the induced flow rate, which is crucial to enhance the attractiveness of this ventilation method. This study highlights the importance of high uniformity of outlet velocity distribution which can be achieved through distributed heating of the air in a solar chimney, leading to the staggered split absorber design proposed in this study. The flow rate induced by this novel solar chimney design is predicted numerically using an experimentally validated model and compared against the conventional solar chimney design. This novel absorber configuration results in higher flow uniformity at the chimney outlet and increases the ventilation rate by 57.0%, from 0.194 kg/s to 0.304 kg/s, for a solar chimney of 2.8 m in height, 1 m in width and 0.84 m in depth under 600 W/m2 solar irradiance.