This paper presents computational fluid dynamics (CFD) simulation of the Solar Chimney power plant to analyze to analyze buoyancy-nature of heated air by har-nessing Solar energy. ANSYS Fluent a fi nite volume code has been used for axisym-metric model of the Solar Chimney power plant (SCPP) prototype in Manzanares, Spain considering updraft tower. A standard k- turbulence model and Boussinesq approximation for buoyancy driven flow is considered. Small pressure difference because of natural draft inside the Chimney during day time has been observed due to Solar radiation. The numerical results obtained for average velocity and temper-ature at Chimney inlet are validated with the experimental results of the prototype. It has been observed that both the velocity and temperature of air inside the SCPP increases signifi cantly with the increment in Solar radiation. Increase in the Chimney height and collector radius also increases the power output of the plant. The effect of Chimney convergence with different area ratio on the power output of SCCPs have been analyzed.

Solar Chimney power plants are Solar thermal power based plants, including three parts of collector, Chimney, and turbine, which are able to produce electrical energy. One of the effective parameters in increasing the power production is the collector angles versus horizon. In the present study, a numerical analysis of a Solar Chimney power plant for different angles of the collector (divergent, convergent and horizontal type collector) is proposed. The introduced numerical model uses mathematical models of heat transfer. In this regard, the effect of various angles of the three considered collectors on temperature distribution and power production of the Solar Chimney is evaluated. Divergent type collectors produce more power than convergent and horizontal collectors, as they produce more velocity and mass flow rates. It is shown that increasing the angle of a divergent-type collector (keeping the inlet height constant) increases the power production and decreases the output temperature. The angle variation of 0. 8 to 1 increases the divergent type collector output power by 11 % and decreases the output temperature by 0. 78%. In the other case, when the output height is kept constant and the collector angle changes, the performance of the divergent type collector is better than the other two collectors. Power production in a constant mean height is shown to be 3 times and 1. 5 times more than the convergent and horizontal collectors, respectively.

In this research, the effect of using the exhausted smoke of a cogeneration power plant as the working fluid of a Solar Chimney to increase power generation is studied by numerical methods. First, the cogeneration power plant is modeled using ASPEN HYSYS; then, the properties of the exhausted smoke including temperature, mass flow rate and etc. are entered to the model of Solar Chimney power plant, developed in ANSYS FLUENT. Using this hybrid model, the effect of Solar radiation on power generation is compared for both air and smoke as working fluids. Furthermore, the effect of inlet temperature on power generation is also studied. The results showed that the power generation increases on average 4 times using smoke instead of air. It is also found that the optimum Chimney height is 500 m using air and 600 m using the exhausted smoke of cogeneration power plant.

The environmental pollution crisis caused by the excessive use of fossil fuels and the risk of the destruction of natural resources and reserves, as well as the excessive production of greenhouse gases and, consequently, global warming, led many energy researchers to use renewable energy As a fossil fuel alternative. Solar Chimneys are one of the types of renewable energies that have been taken into consideration by researchers over the past decade. Solar Chimney power plants are such plants which include Solar collectors, Chimney and turbines that are placed at the entrance of the Chimney. The aim of this study is numerical modeling of a Solar Chimney power plant prototype model built in Tehran University and investigation of the affecting parameters on enhancement the air velocity within it. The two dimensional numerical modeling based on finite volume method is conducted using standard wall function turbulence modeling through an optimum mesh. The numerical results show good agreement with experimental data with maximum 6 percent difference in magnitude. Comparing with similar studies, modeling the power plant without using the energy storage properties of the earth by using constant heat flux on the collector regardless of the environmental radiation conditions has been conducted in the present research. The results show that increasing the Chimney height, collector radius and collector height and decreasing the radius of the Chimney would result in increasing 76 percent in air velocity through the Chimney (from 1. 7 m/s in the experimental model to 3m/s) and consequently improving the model efficiency. Furthermore, among the effective parameters, collector and Chimney radius play greater roll on increasing the air velocity through the Chimney. The results of this research may play significant role on optimizing the constructed Solar Chimney power plant model.

Building industry is one of the most energy consuming parts of the developed and developing countries. Cooling, heating and ventilating systems devote a great amount of this consumption so studying natural ventilation systems have become more important in order to improve their performance. In this paper, air flow has modeled by a computational fluid dynamic model with finite volume method in Solar Chimney as a new kind of natural ventilation system and in a combined system with Baadgir. For this reason, different turbulent models have been compared by a valid statistical test in order to find a suitable turbulent model in these systems and at the end a ke-RNG model has been selected. Also the effect of increasing height, span width and thermal gradient of the walls on improvement of Solar Chimney's performance have been studied by computing parameters like mass flow rate and mean velocity.

In this paper, by using a mathematical model, potential for power generation of a Solar Chimney Power Plant (SCPP), has been studied in Semnan city conditions. Conceptual model of Solar Chimney power plant was developed. Governing equations were developed for a Solar Chimney power plant based on the conceptual model. The iteration technique (try and error) are applied for solving the mathematical model.Mathematical model was validated by experimental data from Manzanares plant and also data from literature. Then model was run for different weather conditions in Semnan city. Given results showed that generated power in Semnan city conditions is lower than in Manzanares plant at the different selected times.In April this power plant produces power of 49 kW. When inlet temperature at collector inlet is increased 5 oC, generated power of plants is decreased approximately 3%. Among the geometric dimensions of the plant, Chimney height has the most influence on generated power. Also it was found that radiation has the most influence on power plants performance.

Nowadays, the arising problems of fossil petroleum oils have been widely raised. As a type of traditional energy resource solution, the scientists have recently looked for a new concept in order to face the problems involved in the traditional power sources. In this investigation, the solution depends up on the approaches to produce power from a clean and new source of renewable energy. Furthermore, the solution for the crude and traditional power source problems should focus on using the Solar energy to generate electricity, either directly or indirectly. One of the most appropriate solutions for this problem is the Solar Chimney, which is one of the promising concepts in the renewable energy technology. Solar Chimney is one of the Solar energy methods that can be considered as the best option for electricity generation. In this review article, Solar Chimney is reviewed in order to find out the remarkable advances in understanding the Solar Chimney power plant (SCPP) performance investigation through extensive studies with different focuses on several aspects of the SCPP technology. In the present review article, Solar Chimneys are studied based on the historical viewpoint, design enhancements, basic working principles, components and effective electricity production factors, and advantages and disadvantages.

all over the world, the growing trend in depletion of energy resource and fuel costs make a large scale-effort to reduce energy consumption; Moreover, a major portion of energy use, about 40% belongs to building sector in heating, cooling and ventilation. Designed various methodologies to reduce total energy use in buildings can help to implement energy-efficiency conservation programmer to gain the highest saving results in construction part. Air ventilation is necessary for removing or depleting pollution. This ventilation can be supplied through Solar Chimney as a passive strategy. Solar Chimney works as a simple and practical idea to enhance natural ventilation in adjacent space. Heat transferring in Solar Chimney is through convection and the driving force is buoyancy force. The Solar energy absorbed by Chimney causes the air larger between two parallel planes of Chimney to be heated so that the air of space in which the Chimney entrance is located is sucked in. Therefore, the breeze inside the space lets the fresh air enter the space through window. Solar Chimney is employed in vertical or angled position. But the commonest design of Solar Chimney for ventilation is in vertical form. Applications of Solar Chimney have attracted many researchers to the issue to discover the most influential parameters. Many researchers have analyzed the application of Solar Chimneys in different configuration, in natural ventilation improvement. The following paper intends to study on impact of applying Solar Chimney in air ventilation of adjacent compartments in hot and dry climate on Isfahan. Since Solar Chimney is not a common element in building design, there is no access to a practical model to study on, so computer simulation method is selected as an alternative method to reach on. The final result is concluded from the simulation models of various Solar Chimney applied to an office building through energy plus software ver.5 was used for simulation which is an independent simulation engine used to model energy values without any graphic medium so the models are simulated in Ecotect software as graphic medium and then the model geometry is transferred to energy plus software to be calculated. Different models compared together based on different Solar Chimney by different dimensions. Data recorded included air flow rate and air outlet temperature. The results show the optimum width by the relationship H/11 where H is the Chimney height (2m width for 22m height of Solar Chimney). Two design configurations were considered: the first is a tall Solar Chimney attached to each floor and the second, Solar Chimney is attached to only one floor witch air flow rate in second model is more than the first one. Furthermore, the other models with a number of different floors were compared while the area of the Solar Chimney with optimal dimension spaces (on each floor and with a number of different distance from top of Solar Chimney) providing required air change is expressed. The maximum air changes occur in seventh floor which is in minimum distance from Solar Chimney air outlet.

Solar Chimney power plant (SCPP) is among the potential technologies in all over the world. In this study, a comprehensive energy and exergy analysis has been performed for SCPP. Exergy balance of the SCPP is conducted to calculate the irreversibility and exergetic efficiency of the SCPP. Influence of the effective parameters e. g. tower height, Solar radiation, tower and collector radius is examined on the performance of the SCPP through the parametric study. The results show that by increasing all the effective parameters, irreversibility would increase except for tower radius. The results further indicate by increasing the collector radius, there is a maximum point from exergetic efficiency viewpoint. Eventually, increment of the effective parameters would increase the power output.

The design of air conditioning systems is one of the effective factors in optimizing energy consumption in residential and commercial buildings. In this study, the performance of a Solar Chimney with different Solar thermal flux on it and the use of an absorbent wall in the Chimney have been investigated. Increasing the air temperature adjacent to the absorbing wall has the effect of thermosyphon in the Chimney that ultimately leads to continuous air movement inside the Chimney. In most of the proposed designs for these Chimneys, the absorbing wall is one of the sidewalls. With sunlight warming up the wall, the air flows into the Chimney. By heating the absorbing wall and increasing the temperature gradient, some heat in this wall will be lost through the conduction phenomenon in the wall thickness to the outside or inside the building. In the proposed scheme, the absorbing wall is located in the middle of the Chimney and since the optimum width for the Chimney is between 0. 2m and 0. 3m, in the proposed scheme, the distance between each wall and the intermediate absorbing wall is equal to 0. 25m. In order to simulate the flow field, the equations of mass, momentum, and energy conservation are solved in the two-dimensional form with constant, incompressible, and turbulent flow assumptions simultaneously. To solve the equations, an academic code based on Fortran's language and SIMPLE algorithm is used. Due to the nature of the turbulent flow of air within the solution field, the $k-varepsilon$ turbulent model is used because of the good performance of this model in simulating boundary layer flows with high reciprocating gradients. The intensity and concentration of heat transfer and geometric parameters related to the Solar Chimney, such as the entrance area, the thickness and length of the absorbing wall, and the location of the absorbing wall in the amount of discharged air flow have been investigated and the optimal values for maximum air discharge have been extracted. Moreover the absorbent wall partitioning is presented as a novel solution to increase the thermosyphon phenomenon in the Solar Chimney.