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Summary: This work evaluates the impact of integrating a hybrid solar chimney power plant (HSCPPS) into a medium voltage distribution grid in the Safawi area, Jordan. The HSCPPS can operate as a traditional solar chimney power plant system during the day and as a cooling tower during the night, achieving continuous system utilization. Real data from the distribution grid and CYME software are used to monitor the impact of integrating the HSCPPS to the grid over a 24‐hour duration. The impact of the integration step on the performance parameters of the grid corresponding to voltage profile, losses, power factor (PF), and voltage step are investigated. For each of these parameters, a comparison between the grid performance with and without the HSCPPS is carried out and demonstrated. The results show a maximum reduction of voltage deviation from the nominal value by around 0.9%, a maximum reduction in the losses by approximately 0.33%, and a reduction in the PF from 0.83 to 0.74 as the HSCPPS is set to supply only active power (unity PF). In addition, the voltage step test is carried out according to International Electrotechnical Commission 61000‐3. The results show that there is a safe margin, and the voltage step limits did not exceed 3% of the nominal voltage. [ABSTRACT FROM AUTHOR]

Summary: This article presents a comparative experimental study of three different cooling systems used with thermoelectric generators mounted on a chimney for waste heat recovery. The studied systems are heat pipes, closed‐circuit liquid cooling, and open‐circuit liquid cooling. The study considers the variation of the performance of each system at different operating conditions and their impact on the output thermoelectric generator power. The auxiliary power consumed by the cooling system itself is included. The heat pipes' system is studied at different fan speeds, while the liquid‐cooling systems are studied at different water flow rates and fan speeds for the radiator (closed‐circuit only). Also, the required surface area for each system is considered. The results show that for the heat pipes' system, the optimum system net power is achieved at medium fan speed at an operating voltage of 5.5 to 6.0V. The closed‐circuit liquid‐cooling system can generate up to 8% more power compared to the heat pipes' system, while the open circuit can generate up to 45% more power. When considering the occupied area, these numbers become 111% and 184% more power per unit area, respectively. The liquid‐cooling system is a better option compared to the heat pipes' system, especially when considering the required surface area. [ABSTRACT FROM AUTHOR]

Summary: The foreseeable growth of photovoltaic (PV) systems highlights the prominence of improving its efficiency. The performance of PV module deteriorates as a major part of irradiance is converted to heat. Amongst several PV thermal management techniques, passive air cooling is gaining importance due to its self‐sustained nature. In the present experimental study, the performance of conventional solar air heater is enhanced by incorporating chimney. Further, by placing the PV module in the airflow path, its performance is improved compared to an identical module kept open to ambient. During testing, a maximum system efficiency of 35% was observed as air heater contributes to the maximum thermal efficiency of 25%. Further, due to better airflow over the PV module rear surface, a 13% reduction in surface temperature was observed compared to the outer module, which gave a 6% rise in power output. In such a combi system, the working of both PV and air heater complements the advantage to each other. Hence, the total efficiency of the air heater and PV module as two separate entities is always less than the system efficiency of the combi system. [ABSTRACT FROM AUTHOR]

Summary: A mathematical model based on one‐dimensional energy and mass balance across the solar chimney has been developed. The air flow characteristics such as exit velocity and temperature are evaluated with respect to the collector inclination angle, hourly solar radiation, ambient temperature, and wind speed. The model is validated by comparing the performance parameters obtained, with the experimental results and also with the experimental data of different geometrical range and environmental conditions from the literature. An average deviation of 8% for exit air velocity and 1.35% for exit air temperature is obtained for the solar chimney with absorber inclination angle 30°, collector area 0.41 m2, and chimney height 0.24 m. The experimental daily average and maximum exit air velocity during the month of April are 0.5 and 0.88 m/s, respectively. The predicted optimum operating conditions are 75° inclination angle, 0.63 m2 absorber area, and 0.48‐m chimney height. The maximum average exit air velocity and temperature numerically obtained are 0.64 m/s and 331 K, respectively, when operating with optimum conditions. It is observed that the exit air velocity increases 33% by increasing the absorber area from 0.5 to 3 m2 for a solar chimney with 0.5 m height. An increase in exit air velocity of 52% was obtained by increasing the chimney height from 0.5 to 3 m for a solar chimney with 0.64 m2 absorber area. A reduction in exit air velocity of 4% was observed for the increment in wind flow over the glass cover from 1.5 to 3 m/s. These results confirm that the solar chimney could be designed based on the predicted monthly performance by the present model. [ABSTRACT FROM AUTHOR]

SUMMARY A large number of researchers have paid great attention to solar chimney (SC) power generating technology, but only a few have studied the chimney configuration. Taking a 10 MW SC system as an example, the physical and mathematical models illustrating the fluid flow, heat transfer and output power features of the system are established. Based on constraints such as equal chimney bottom section area or equal chimney surface area, the impact of several sizes of three different chimney configurations upon the chimney outlet air temperature and velocity, system output power and efficiency is analyzed and the influence of the height-to-diameter ratio (H/D) of the cylindrical chimney on system performance is studied as well. After a comprehensive analysis of system output power and efficiency, it is proved by the numerical simulation that the cylindrical chimney would be the best choice among the three basic configurations, whose optimum H/D value ranges from 6 to 8. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Theoretical investigations were conducted of pollutants dispersion, NOx, SO2 and Particulate Matter (PM), from stacks of arbitrary four power plants in Libya, e.g. North Benghazi, South Tripoli, Zweitina, Khoms. The first four stations are gas power plants, while the last one is gas and steam station. Gaussian plume model has been used to identify ground-level NOx concentrations profile downwind and crosswind of the chimneys through urban regions and also the location of maximum pollutant concentrations. The study is based on the worst-case emission conditions of Pasquill stability categories (class D). Results indicate that maximum ground-level NOx impacts for all plants locate at a distance of approximately 1.0–2.5 km from stacks. The site most critical to ambient air NOx impact is Zweitina, where the plant site is in direct vicinity to residential areas. Khoms electric station exhibits the maximum emitted NOx, SO2, and PM intensity, about 305, 48, and 0.7 µg/m3, respectively, that is lower than allowable concentrations recommended by World Health Organization. Copyright © 2006 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A set of differential equations is developed to analyze a solar chimney. The equations are integrated by making a few simplifying assumptions, and expressions for the power generated, as well as, the efficiency are obtained in closed form algebraic formulas. The analytical model is shown to consistently under predict the performance by 4–6% vis-a-vis the differential model. Copyright © 1999 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]