Solar Chimney System Research Articles

Techno-Economic evaluation and multi-objective optimization of a filter equipped solar chimney system

Urban air pollution has recently become a pressing challenge, and innovative solutions are needed to reduce it. The current study proposes and investigates the performance of integrating a solar chimney system with an air filtration unit to mitigate urban air pollution and generate electricity simultaneously. A comprehensive computational fluid dynamics model coupled with optimization techniques is proposed to analyze and optimize the design parameters from system performance and cost perspectives. A multi-objective optimization is performed to determine the optimal placements of the air filter and geometric parameters of the hybrid solar chimney to maximize power output and filtration efficiency while minimizing the capital cost. Results indicated that placing the filter in the middle of the chimney resulted in optimal configuration with a power output of 18.83 kW, and filter efficiency of 53.73 % at a cost of $ 4.83 million, whereas placing the filter close to the inlet of the collector achieved the highest output power of 100.4 kW, a filter efficiency of 89.67 % at a capital cost of $ 7.35 million. It is concluded that placing the filter on the collector side is more beneficial in terms of performance and cost per unit of power produced.

A novel hybrid passive cooling system for providing thermal comfort conditions and reducing energy consumption in buildings in hot climates

In the present study, the performance of a novel hybrid passive cooling system was studied analytically and numerically in terms of its ability to achieve thermal comfort conditions, produce electricity, and reduce energy consumption. The new hybrid system that has been proposed in this study consists of a photovoltaic solar chimney (SC-PV) system, which in turn consists of a solar chimney (SC) combined with photovoltaic panels (PV). An underground space (UGS) system connects to the photovoltaic solar chimney (SC-PV) system through a residential room. This novel hybrid system is a completely new passive cooling system that is called SC-PV-UGS in the present study. The present system's performance has been studied in hot and moderate climates. The results indicated that the SC-PV-UGS system can provide thermal comfort conditions for the room's residents. The total electricity produced during the hours of solar radiation for the three test days in the hot climate was 310 kWh, while it was 329 kWh in the moderate climate. The total annual electricity produced by the SC-PV-UGS system for the hot climate was 2024 kWh, and for the moderate climate, it was 2318 kWh. The total cooling demand in a hot climate was reduced to 339 kWh, which is 55.9 % of the total cooling demand of the conventional non-passive system.

Passive ventilation for building not subjected to solar radiation

Some small-height buildings are not exposed to direct solar radiation due to shading from neighboring buildings. Therefore, for these buildings to be ventilated naturally, it was necessary to develop a method using a thermal chimney. This is done by using hot water resulting from the solar heater at the top of the building to heat the base of the chimney instead of direct solar radiation. In this paper, the solar chimney system used to generate power, using some modifications, to be used in ventilation operations is investigated. The effect of different variables on the airflow rate inside the chimney ventilation air drawn was studied. From the experimental result, the ventilation air flow rate increase with the chimney height and diameter. Also, the increase of heated plate area and the heater capacity increases the ventilation air flow rate. Increasing the inlet air gap thickness decreases the ventilation air. For the divergent chimney, the ventilation air increases with the increase of the conical angle.

An experimental investigation of a solar chimney integrated with a bladeless wind turbine for sustainable energy harvesting

The current study explores the potential of combining small-scale solar chimney systems with blade-less wind turbines for sustainable energy solutions in Egypt through mathematical modelling, numerical simulation, and experimental work. The integration of a vortex bladeless turbine and a conventional horizontal axis wind turbine in a hybrid energy harvester solar chimney system (VBSCS) was evaluated, as well as the effect of changing the absorber material on improving the system's performance. Shredded rubber improves heat absorption in solar chimney collectors, optimizing energy conversion and providing a sustainable, eco-friendly solution while addressing challenges and cost-effectiveness in implementing this hybrid solution. The mathematical model predicted the highest power at 0.38 W, while the CFD model yielded 0.298 W. Experimental results showed power outputs of 0.18 and 0.25 W for the SCS with concrete and shredded rubber absorbers, respectively. In addition, the VBSCS with a concrete absorber produced 0.29 W. The determined percentage improvement over the SCS with a concrete absorber was 61.1 % for the VBSCS and 38.9 % for the SCS with a black rubber absorber. These findings demonstrate the delicate interplay of design aspects and material choices that influence the performance of both bladeless wind turbines and solar collector systems.

Investigating the impact of the diameter of the solar collector on the output power of the solar chimney system

The aim of this of paper is to study the effects of the collector radius of a solar chimney power plant (SCPP) on the power output of a solar chimney system. The data was collected from a small prototype solar chimney which was conducted at the College of Engineering, Sabratha. Geometric measurements were taken from the first model used in Manzanares, Spain. In this research, the height of the chimney was fixed at 194.6 m, the geometric dimensions of the solar chimney station were fixed and, the value of the collector radius was varied for energy production .The power output value was calculated for each radius. MATLAB software was used as numerical solution tool to assess the thermal behavior and performance of a solar chimney power plant . The maximum value obtained for the output power was 192.19 kilowatts with a diameter of 544 meters whereas the lowest value was 55 kilowatts with a diameter of 244 meters. Both values were obtained at the same time at 3 p.m. which shows the effect of the collector radius on the amount power produced. Also, it was concluded that the theoretical power output of SCPP is directly proportional to the radius of the collector.

A genetic programming approach for the prediction of solar chimney power plant power

This study empirically examines the effectiveness of the solar chimney power plants (SCPP), which is an innovative method for the use of solar energy, in the middle latitude region (37.88° N) in the northern hemisphere. Experimental measurement parameters of temperature, velocity, and radiation obtained from four cardinal directions (north, south, east, and west) and from 26 different locations were recorded throughout the day (08:00 am-07:30 pm). These measurements were used to calculate and estimate the power values used to measure the energy efficiency of the solar chimney. In the study, the genetic programming method was used to estimate the power value. In the five different forecast models developed, 15 different parameters were used diagonally. The obtained power estimation equations were cross-checked using statistical methods. Determination coefficient value is higher than >0.90 in all equations and is close to the ideal. In the comparison of all statistical models, the Global Performance Indicator (GPI) was used, with the best result obtained from Model 2. The results of this model are MAPE:6.5233, MBE: −0.0124, RMSE:1.1036 ve t-stat:0.0374, which is quite close to zero. In addition, the power values obtained from both the calculated and developed models were dimensioned and compared over the power-time factor of eight different studies in the literature. The mean relative error value nof the values calculated as a result of this comparison varies between 2.3% and 21.3%. This study provides a model for the different geometries of solar chimney prototypes and provides an example for measuring the design and performance of solar chimney systems to be installed in the middle latitudes and in regions with “Csa” climate characteristics, and is recommended for academic and industrial users. The mathematical models developed can be considered as a step to increase the efficiency of the solar chimney power plants.

Experimental and Numerical Study on the Integrated Solar Chimney System with Solar Still for Water Desalination

The integrated solar chimney and solar still system offers a promising approach for simultaneous water and electricity production. However, there have been only few experimental studies conducted on this combined design. In this regard, a solar chimney with 12 m height and 3.4 m collector diameter is constructed and accompanied with solar stills, installed inside the collector. The maximum velocity at the chimney's inlet for the combined system reaches near 2 m s−1, while it is 0.3 m s−1 smaller than the conventional arrangement. The maximum water production is 861 g h−1 which is attained in the evening hours. In the normal solar chimney without solar stills, air temperature inside the collector reaches its peak at 64 °C when solar radiation is maximum. While in the integrated system, this value is 59 °C which reaches with 2 h delay due to water heat storage. In addition, it is found that the effect of height of vapor space inside the basin can be negligible while the lower water depth in the basin provides higher water production.

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 simulation and performance evaluation of filter-equipped solar chimney power plants

A solar-assisted large-scale cleaning system (SALSCS) is a solar thermal system that utilizes the concept of a solar chimney power plant (SCPP) to improve outdoor air quality. In an SALSCS, air purification is facilitated by passing the buoyancy-induced airflow through an air filter installed in the system. In the current study, a new solar chimney system called a filter-equipped SCPP (FSCPP), which is a hybrid of SCPP and SALSCS, is proposed and investigated to identify the possibility of generating electrical power and purifying outdoor air simultaneously. A three-dimensional numerical model is developed to study the heat transfer and fluid flow inside the solar chimney. The simulation method is implemented and validated with experimental data from the literature. The simulation results reveal that the pressure drop is higher across the filter than at the turbine in the FSCPP, indicating a higher energy consumption at the filter. Numerical simulations are also carried out to compare the performance of the SCPP, SALSCS and FSCPP. The results show that the FSCPP has the lowest volume flow rate and the highest temperature rise. The electrical power generated by the FSCPP is only about 20 ∼ 40% of the SCPP’s power generation, but its air purification capabilities approximate those of the SALSCS, with only a 2 to 4 % reduction. The influence of the system’s dimensions on overall system performance is also analyzed. The FSCPP shows an enhancement in primary capabilities (i.e., power generation and air purification) with an increase in the width and height of the solar chimney system of up to 200 meters. • A filter-equipped solar chimney power plant (FSCPP) system is proposed. • Numerical simulations are conducted to evaluate the performance of FSCPPs. • The electrical power generation of FSCPP decreased by 20 to 40% compared to SCPP’s capability. • The air purification capability of FSCPP is almost similar (about 96 to 98%) to that of SALSCS.

Analysis for hybrid photovoltaic/solar chimney seawater desalination plant: A CFD simulation in Sharjah, United Arab Emirates

Solar chimney power plant (SCPP) technology is considered among the most viable ways to exploit solar energy on a large scale. This technology possesses several advantages, including low operation and maintenance costs, high reliability, low environmental impact, and a long lifetime. A novel configuration of the solar chimney system is proposed in this work by the integration of transparent PV cells coupled with water desalination. Transparent PV cells were incorporated within this configuration to enhance total electricity production. ANSYS Fluent software was used as a simulation tool for the steady flow and the natural convection problem within the solar chimney. A complete parametric study was also performed for conventional SCPP integrated with transparent PV to evaluate the effect of different parameters on air velocity, static pressure, mass flow rate, air temperature inside the chimney, and turbine power output under 850 W/m2 solar radiation. The effect of radiation on the turbine and PV power output was investigated. The results of the present model showed that the net output power and the freshwater production for the hybrid system could reach up to 261 kW and 8.867 kg/s, respectively.

Thermofluid effects of solar chimney geometry on performance parameters

The solar chimney system (SCS) is a novel application that has recently become the focus of researchers in this field. The current study included a numerical simulation of changing all the variables defining the system's shape construction, in addition to the influence of curvatures on performance assessment. The approach confirms the SCS output power, velocity, and temperature based on studying more than 40 cases in various assemblages. These sets are grouped into diverse forms by changing variable parameters, including collector angle, chimney angle, collector height, turbine location, fillet radius, and shape. The findings indicated that increasing the chimney angle up to 3° increases both velocity and efficiency, while the increment in maximum velocity reaches 200% which radically improves the system power output. The change of the chimney inlet height influences the average velocity substantially from 2.04 to 2.41. The effect of collector angle efficiently improves the SCS performance for the positive angles, where the maximum increment in average velocity equals 6.25%. The greater the collector height up to 70% of turbine radius, the increase in the mass flow. The concaved shape of chimney reduces flow separation and the energy loss resulting from eddies inside it.

Impact of non-uniform heat flux on ventilation performance of solar chimney

Solar chimney (SC) is an effectively practical way to enhance building natural ventilation through thermal buoyancy force, which is induced due to the temperature difference between indoor and outdoor air temperatures. The ventilation performance of solar chimney directly depends on the heat flux distributions and values in the absorbed plate. Recently, many researches have been done on the thermal performance of solar chimneys under uniform heat flux. However, the uniform heat flow distribution cannot reflect the uneven characteristics of the solar radiation. There are few studies focused on the flow characteristic and thermal performance of solar chimneys under non-uniform heat flux distributions. In this paper, a two-dimensional numerical model of solar chimney integrated building is firstly established to explore the natural ventilation performance under non-uniform heat flux distributions. The numerical simulation is conducted to predict the flow and heat transfer characteristics in the room as well as in solar chimney. Subsequently, the effects of the location of the vent are analyzed to evaluate the performance of the solar chimney system. Finally, a comparison between the ventilation performance of solar chimney under the uniform heat flux and the non-uniform heat flux distributions is presented, and the thermal and flow structures of the solar chimney integrated building are further illustrated simultaneously. Research results show that the ventilation performance of solar chimney is closely related to its heat flux distribution, and the inhomogeneity of the heat flux of solar chimney will decrease the ventilation performance of the building. In addition, the position of the vent have highly influence on the flow structure and thermal performance for the solar chimney as well as the building. This paper will provide theoretical basis and technical approach for the improvement of the performance of the solar chimney, especially for the nonuniform heat flux distribution.

Numerical analysis of the performance of a hybrid solar chimney system with an integrated external thermal source

In this study, a three-dimensional hybrid solar chimney with an integrated external thermal source is developed to complements the solar energy for uninterruptible power generation using flue gas channels as a supply source in the collector. The hybrid system is examined numerically using ANSYS Fluent software including a solar air collector with a diameter of 6 m, a 6.65-meter-long chimney, and four thermal channels. The timetable is set for different hours, namely for two modes, i.e. without flue gas during daytime (1st Case), with flue gas during daytime (Case 2-A), and with flue gas during night (Case 2-B). Moreover, the turbine effect in different day hours and with different heat sources during night are applied. The numerical method is validated by comparing its results with previous works based on different chimney heights. The present results show that the hybrid approach increases system performance significantly. Simulation is done in thermal channel with 0.0015 kg/s in chimney temperature of 116 °C. The results indicate that mass flow rate and power increased by 7.63% and 11.48%, respectively, compared to the mode with no flue gas. This study proved that the proposed method can eliminate the night defect and allow the operation of solar chimney power plants at night.

Environmental and Economic Impact of Employing Solar Chimney and Photovoltaic Cells in Buildings with Various Climates

In this research, Solar Chimney (SC) as a passive system in the building, is used to provide thermal comfort and reduction of energy consumption. The operation of SC will have different effects in different climates. Investigating this issue can make it possible to use this system in places where its operation is more efficient in terms of thermal comfort and economic issues. EnergyPlus was applied to model a house with SC. Potential of cooling and heating generated by SC was investigated in Humid (Babol) and Semi-arid (Tehran) climates. The result shows that in Babol, SC saves approximately 21% in cooling load and 16% in heating load consumption. On the other hand, in Tehran, using SC can save 35% in cooling load and 20% in heating load consumption. For both humid and semi-humid climates, Summer-SC (ventilation mode) performs better than Winter-SC (heating mode). In continue, for each city, the cost of saving electricity consumption by SC was spent on the purchase and installation of photovoltaic cells (PV). According to calculations, SC and PV systems annually produce 4717 kWh of clean energy in Babol and 6965 kWh in Tehran. In addition to producing clean energy, despite the low cost of grid electricity in Iran, employing these systems in each house, annually reduces the cost of electricity consumption by $ 8 and $ 14, respectively, in the cities of Babol and Tehran. Of course, this amount would be considerable for all the houses in a city.

Solar Chimney Applications in Buildings

A solar chimney is a renewable energy system used to enhance the natural ventilation in a building based on solar and wind energy. It is one of the most representative solar-assisted passive ventilation systems attached to the building envelope. It performs exceptionally in enhancing natural ventilation and improving thermal comfort under certain climate conditions. The ventilation enhancement of solar chimneys has been widely studied numerically and experimentally. The assessment of solar chimney systems based on buoyancy ventilation relies heavily on the natural environment, experimental environment, and performance prediction methods, bringing great difficulties to quantitative analysis and parameterization research. With the increase in volume and complexity of modern building structures, current studies of solar chimneys have not yet obtained a unified design strategy and corresponding guidance. Meanwhile, combining a solar chimney with other passive ventilation systems has attracted much attention. The solar chimney-based integrated passive-assisted ventilation systems prolong the service life of an independent system and strengthen the ventilation ability for indoor cooling and heating. However, the progress is still slow regarding expanded applications and related research of solar chimneys in large volume and multi-layer buildings, and contradictory conclusions appear due to the inherent complexity of the system.

Performance analysis of a solar chimney power plant system in two Algeria regions

In this paper, we have investigated the possibility of implementation of three solar chimney systems in the two Algeria regions (Constantine, Tamanrasset). Numerical simulations were performed for the prototype geometry in Manzanares, Spain. Usage of CFD techniques (Computational Fluid Dynamics); we have simulated a two-dimensional axisymmetric model of an SCPP with the RNG k–ε turbulence. Using a band radiation model to solve the equation of radiation transfer by implementing the model of discrete ordinate radiation. Our results show that the secondary and tertiary collector roof system is able to achieve the highest electricity generation. The obtained results show the solar chimney power plant systems can be produced from 51 to 79 kW of electricity over the year and the highest hourly electricity produced in June is around 47 to –80 kW. The highest electricity generation has been recorded in the Tamanrasset region.

Multi-objective optimization of a solar chimney for power generation and water desalination using neural network

Given that the initial cost of constructing a solar chimney system is high, the multi-purpose use of this system for power generation and freshwater production from seawater is vital to make the system economically feasible. To achieve the best balance between the turbine power generation and freshwater production, the optimization of design parameters such as collector’s height and diameter, chimney’s height and diameter, and the curvature of the outer wall of the chimney is necessary. Also, due to the high volume of calculations required for the numerical simulation of any arrangement of parameters, a neural network for the prediction of the output quantities is advantageous. Therefore, a perceptron neural network with two hidden layers has been implemented to predict the average temperature on the collector’s surface and the average air velocity at the turbine inlet to calculate total power and condensed water. Finally, the genetic algorithm is implemented for optimization, and the Pareto frontier is obtained for this problem. The total power generation values and freshwater production corresponding to the most optimal point are 719 kW and 14.28 kg.s-1, respectively.

Experimental and Theoretical Investigation on a Solar Chimney System for Ventilation of a Living Room

The present work relates to the analysis of an energy system based on the solar chimney for passive ventilation of a living space. It consists of an experimental and theoretical study of the energy performance according to some geometrical and environmental parameters. The designed prototype was installed and followed for several days. In parallel, a numerical code was developed in FORTRAN platform to simulate the phenomena in the solar chimney and compare the theoretical results with those experimental in the transient regime. The results obtained relate to the distributions of temperature on the glazing, within the airflow and on the internal wall of the chimney. The hourly rate of air change (ACH), the air-outlet velocity and its mass flow rate have also been determined. The comparison of the results obtained in this study with those of the literature has shown a good agreement. The obtained results have shown that the incidental solar radiation plays a fundamental role in the energy performance of such systems and there is an optimum value of the ratio between the width of the chimney and the wall opening for a high rate of air renewal.

Experimental and Theoretical Investigation of Performance of a Solar Chimney Model Part II: Model Development and Validation

A mathematical model based on the momentum, continuity and energy balance equations was developed to simulate the behavior of the air flow inside the solar chimney system. The model can estimate the power output and performance of solar chimney systems. The developed mathematical model is validated by the experimental data that were collected from small pilot solar chimney; (experiment was presented in part I). Good agreement was obtained between the experimental results and that from the mathematical model. The model can be used to analyze the solar chimney systems and to determine the effect of geometrical parameters such as chimney height and collector diameter on the power output and the efficiency of the system

Experimental and Theoretical Investigation of Performance of a Solar Chimney Model, Part I: Experimental Investigation

This paper presents the experimental data that was collected from small pilot solar chimney. The experimental data together with ambient conditions are used to evaluate the performance and study the behavior of the solar chimney; this data will be used for comparison with theoretical models in another paper [part II). The solar chimney prototype was designed and constructed at the Subrata Faculty of Engineering-Libya. The data were collected over several days of June 2011. The solar chimney system contains two main components; the solar collector and the solar chimney. The solar collector root‘ has a circular area of126 m3, the solar chimney is a PVC tube with internal diameter of 0.2 m and the total height of chimney is 9.3 m. The measurements include the intensity of solar radiation inside/outside the collector, temperature and velocity of air at the entrance of the chimney, temperature and speed of wind outside the collector, temperature of the ground inside collector al1d temperature measurements of air at speci?c points at different levels throughout the collector. Solar irradiance was found to affect the chimney temperature and subsequently affects chimney air velocity. The experimental results showed that temperature differences of (30 - 45°C) were recorded between the ambient temperature and that of air inside the chimney in the middle of the day, where the highest air temperature of 73.4°C was recorded at the entrance of the solar chimney. The maximum air velocity of 3.6 m/s was recorded inside the solar chimney at noon on 9 June. Wind speed outside the collector had a small effect on the speed of the air inside the chimney and tends to change slightly, hence, can neglect influence of wind speed on the performance of the system. Also the experimental results indicate that such type of system can trap a suf?cient amount of solar radiation, which elevates the air temperature to a suf?cient value able to generate enough air ?ow to operate a wind turbine to produce electricity; this means the solar chimney system for electricity production can work in the north-western part of Libya in the summer time at least.