Solar Updraft Tower Research Articles

Experimental study on the effects of integrating phase change material with a solar updraft tower

AbstractThe solar updraft tower power plant presents a promising renewable energy solution but faces limitations in thermal efficiency and energy production during nonsunny hours. This study addresses a critical gap in the literature by investigating the integration of latent heat storage systems utilizing paraffin wax as phase change materials (PCMs) to enhance solar updraft tower (SUT) performance. Two identical small‐scale SUTs were constructed, both using the same tank configuration; however, the PCM device was filled with paraffin wax as a PCM, while the non‐PCM device contained only atmospheric air. Three scenarios were explored, featuring varying PCM tank heights of 2, 4, and 6 cm (the full capacity of the PCM tank). Results indicated that, from 3 p.m. until sunset, the PCM‐integrated SUT in Case 3 (with 6 cm of PCM) achieved the best performance, with an average absorber temperature rise of 25°C, compared with 12°C for the non‐PCM device. During the same period, the average air velocity at the tower neck, where a wind turbine could be installed, was 1.21 m/s for the PCM device, versus 0.82 m/s for the non‐PCM device. Notably, the nocturnal operating time extended significantly with PCM use, rising from 90 min for the 2 cm case to 125 min for the 6 cm case. In contrast, the non‐PCM device exhibited no operational time after sunset. This research not only demonstrates the effectiveness of PCM in improving the thermal performance and operational longevity of SUTs but also introduces a novel tank configuration that allows for flexible PCM integration, representing a significant advancement in the development of more efficient SUT systems.

Thermo-fluid dynamic numerical analysis of vestibule functions in a solar updraft tower

Solar updraft towers (SUTs) represent a promising avenue for renewable energy generation, leveraging solar energy to drive their operation. Although the collector of SUTs is generally vacant, ongoing research have focused on auxiliary structures inside the collector aimed at enhancing the overall efficiency. This study delved into the computational fluid dynamics (CFD) analysis of a SUT model featuring a 5 m radius collector and a 12 m height chimney. Specifically, we investigated the vestibule functions which created by implementing baffle inside the SUT collector with various radial locations. Through rigorous examination, the thermo-fluid dynamic effects of both roof-mounted and bottom-mounted baffles on SUT performance were explored, aiming to ascertain the optimal vestibule parameters. The vestibule was found to mitigate the backward flow leakage, isolate the inner room from the outside air, and enhance the heat exchange efficiency of the main flow. Notably, when the roof-mounted baffle was positioned at a radial location of 4.5 m, a remarkable 11.4 % and 28.1 % increase in the mass flow rate at the chimney outlet and kinetic power were achieved, respectively. These findings highlight the significant performance improvements achievable through the incorporation of a vestibule within SUTs of a given scale.

Influence of different flow models on numerical simulation of solar updraft tower

Solar updraft tower is a new kind of solar heat utilization technology. In the numerical simulation of solar updraft towers, selecting different flow models will affect the accuracy of prediction results. To improve the reliability of the numerical simulation results of the solar updraft tower, this paper uses the solar load model is used to simulate the local conditions of Hohhot, Inner Mongolia Autonomous Region, China at different times, and adds the ambient crosswind air domain to simulate the operation of the device under the actual environmental conditions. Laminar flow, Re-Normalisation Group (RNG), transition, and k-omega shear stress transport (SST) models were selected according to the Reynolds number corresponding to the characteristic length of the system at different positions to simulate and predict the flow field in the solar updraft tower heat collection system, and the results were compared with the test data. The results show that in the simulation of Hohhot at 13:00 and 17:00 on July 19, compared with the RNG model, the relative errors of the calculated data and experimental data of the transition model are reduced by 1.04% and 0.1%, respectively. The surface temperature distribution of the absorber is more consistent with the actual physical law. The superiority of the transition model in the numerical simulation of solar updraft tower is verified.

Study of a Novel Updraft Tower Power Plant Combined with Wind and Solar Energy

This study presents a novel solar updraft tower power plant (SUTPP) system, which has been designed to achieve the simultaneous utilization of solar and wind energy resources in desert regions, in response to the pressing demand for sustainable and efficient renewable energy solutions. The aim of this research was to develop an integrated system that is capable of harnessing and converting these abundant energy sources into electrical power, thereby enhancing the renewable energy portfolio in arid environments. The methodology of this study involved the design and construction of a prototype SUTPP, comprising a 53 m high tower, a 6170 m2 collector, five horizontal-axis wind turbines, and a thermal energy storage layer made up of pebbles and sand. The experimental setup was meticulously detailed, and experiments were conducted to collect data on the system’s performance under various environmental conditions. Subsequently, three-dimensional numerical simulations were performed to explore the effects of ambient wind speed and solar radiation on the output power of the SUTPP. The results indicate that the output power of the system increases with the increase in ambient wind speed and solar radiation. The impact of solar irradiation on output power was observed to diminish as ambient wind speeds increased. Notably, as the inlet wind speed rose from 4 m/s to 12 m/s, the output power showed a substantial increase of 727%. The numerical simulations revealed that ambient wind speed has a more pronounced effect on power output compared to solar radiation. Furthermore, it was found that the influence of solar radiation is significant at low wind speeds, with its impact decreasing as wind speed increases. This research provides essential guidance for the design and engineering of highly efficient solar thermal energy utilization projects, representing a significant advancement in the field of renewable energy technology deployment in desert environments.

Energy Generation Intensity (EGI) of Solar Updraft Tower (SUT) Power Plants Relative to CSP Plants and PV Power Plants Using the New Energy Simulator “Aladdin”

The current investigation provides information about solar updraft tower power plants, SUTPPs (also called solar chimney power plants, SCPPs), which form a unique method of solar-powered electricity production through a ducted wind turbine driven by induced airflow as a result of solar heating. The investigation is conducted using numerical modeling via the system-level simulation tool Aladdin (developed and released freely by the Institute for Future Intelligence, IFI) for solar energy systems, wind energy systems, or the built environment. The Aladdin energy simulator is first evaluated here by comparison with published experimental and numerical results corresponding to the historical 50 kW prototype SUTPP that was successfully tested in Manzanares (Spain) between 1982 and 1989. This prototype has a height of about 195 m for the chimney (the updraft tower) and a radius of about 122 m for the solar heat absorber (the solar air collector or the greenhouse). Next, various climate and performance characteristics are investigated and contrasted for nine different locations around the world with a similar latitude of 24°, which is within the sunbelt, assuming that the same Manzanares SUTPP prototype geometry is employed in these locations. These nine locations are Muscat (Oman), Al Jawf (Libya), Riyadh (Saudi Arabia), Karachi (Pakistan), Ahmedabad (India), Havana (Cuba), Culiacán (Mexico), Dhaka (Bangladesh), and Baise (China). The energy generation intensity (EGI) for the Manzanares-type solar updraft tower power plant in these nine examined locations was between 0.93 kWh/m2 per year (in Baise) and 2.28 kWh/m2 per year (in Muscat). Also, Muscat had the smallest seasonality index (maximum-to-minimum monthly electric output) of 1.90, while Baise had the largest seasonality index of 4.48. It was found that the main limitation of the overall SUTPP energy conversion efficiency is the chimney efficiency (the process of accelerating the air after entering the chimney). This study concludes that solar updraft towers (SUTs) cannot compete with existing mature and modular renewable energy alternatives, particularly photovoltaic (PV) panels, if the aimed use is commercial utility-scale electricity generation. Instead, SUTs may become attractive and achievable if viewed as hybrid-use projects by serving primarily as a large-scale greenhouse area for agricultural applications while secondarily allowing energy harvesting by generating clean (emissions-free) electricity from the incoming solar radiation heat.

Thermal and energy analysis of a novel solar updraft tower design with divergent chimney and convergent collector concept: CFD analysis with experimental validation

Abstract The fact that energy sources are heavily dependent on fossil fuels increases the need for alternative energy day by day. Solar energy is the most popular alternative energy source with massive potential. Solar chimney power plants (SCPP) are one of the systems of interest based on solar energy. SCPP systems are rare systems that can provide 24-hour power output. Their performance has been the subject of constant research since the first pilot plant in Manzanares. Design is crucial for performance figures of SCPPs, and the limitation of climatic parameters causes the system to be approached with different designs. This study makes a 3D CFD model by combining the divergent chimney and convergent collector structure based on the first pilot plant. The solar ray tracing algorithm and the RNG k-e turbulence model are applied and the model equations are solved under dynamic conditions with the reliable software ANSYS FLUENT. After the mesh-independent solution of the model is complete, it is validated with experimental data. The two cases are compared for solar radiation of 1000 W/m2 and environmental temperature of 293 K. A power output of 50.51 kW is achieved for standard pilot sizing. With the new model, the power output rises to 146.34 kW. It is seen that the divergent chimney and convergent collector affect the airflow in the system, increasing the maximum air velocity to 19.363 m/s. In parallel with the experimental data, it is seen that the temperature on the ground exceeds 360 K in the CFD results.

Potential need for vestibule structures in solar updraft tower

A solar updraft tower (SUT) is a power-generating structure that transforms solar energy into electricity through the kinetic energy of air rising due to solar-radiation-induced buoyancy. In traditional architecture, a vestibule is a small room that leads to the main room, and it separates the indoor and outdoor atmospheres, thereby reducing heat loss and improving the thermal performance of the main room. Herein, we propose a canopy-attached divider structure that can create a vestibule-like space and increase the overall thermo-fluid dynamic efficiency of SUTs. A computer simulation study was conducted for various divider geometries in terms of their locations and shapes to create diverse vestibules. The control parameters were the gap between the divider tip and the ground and the length along the radial direction, which determines the vestibule volume. SUT efficiency was analyzed using the velocity, temperature, and turbulence kinetic energy (TKE) contours obtained herein. The vestibule created by installing a divider with a gap of 0.06 m and a length of 4.6 m can increase the outlet velocity by up to 6.97%. The results of this study indicate the possibility of applying this thermo-fluid dynamic engineering technology used in other fields to SUTs.

Crosswind and Vortex Usages for Electricity Production Enhancement of Solar Updraft Tower

This research presents an improvement to the traditional solar updraft tower, which relies solely on solar energy and cannot operate continuously throughout the day. The enhancement involves a hybrid energy approach by installing a vortex generator at the top of the tower to convert crosswinds into a vortex flow at the chimney’s top. This modification induces an updraft within the tower, enabling it to generate electricity continuously, even at night when there is no sunlight. The aim is to enable the solar updraft tower to harness crosswind energy without altering the tower’s main structure. This involves developing a vortex generator from a unidirectional wind intake design to a three‐directional intake, enhancing the feasibility of commercial installation. Additionally, various designs and heights of vortex generators were developed, considering different crosswind speeds (2, 4, 6, and 8 m/s). The research utilizes the finite element method, along with real model construction, to validate the reliability of the study’s findings. The results indicate that the updraft speed is directly proportional to the crosswind speed. From a physical standpoint, the vortex generator with a height equal to D produced the best results in all experiments. The square, cylindrical, and diffuser shapes increased the wind speed inside the chimney by 60%, 41%, and 48%, respectively. These results from various shapes provide effective design and development guidelines for the future commercial use of vortex generators.

Square solar updraft tower coupled phase change material: An experiment

Solar updraft tower is a low-cost heat collection ventilation power generation technology in solar heat utilization technology, which has high research potential and application value. However, the traditional circular solar updraft tower has some problems, such as low thermal efficiency, short working time, and unstable heat collection performance, which are caused by ambient crosswind disturbance and low heat capacity of the absorber. Therefore, this study designed a new square one-sided inlet solar updraft tower to prevent most of the heat from being lost through the ambient crosswind. At the same time, a phase change paraffin thermal storage unit was coupled in the absorber, which could reduce the temperature field fluctuation of the device and extend the working time by releasing latent heat when the solar irradiance decreased. Control experiments were conducted on the two processes. The test results show that the working time of the coupled new device is at least one hour longer than that of the square solar updraft tower without phase change material. The average temperature difference between the inlet and the external environment after the solar radiation drops at 17:00 is 79.12% higher than that of the traditional circular solar updraft tower of the same size, and the average instantaneous heat collection efficiency is 99.98% higher. While the effectiveness of the improved solar updraft tower is proved, the economic analysis of the integrated application of the single-side inlet solar updraft tower on the agricultural solar greenhouse is made. The carbon emission reduction of at least 2.144 tons in the year of using this system, and the construction cost is saved about 1330USD. The use of the system will reduce carbon emissions by at least 2.144 tons per year, save at least 2.30 tons of standard coal, and save construction costs of about 1330 US dollars. The research can provide theoretical and technical support for the efficient commercial application of solar updraft towers.

NUMERICAL AND EXPERIMENTAL INVESTIGATION OF SEMICIRCULAR SOLAR UPDRAFT TOWER SYSTEM EMPLOYING POROUS COPPER METAL FOAM

The numerical and experimental study was carried out under Iraqi weather conditions to verify the improvement of the performance of the solar updraft tower system SUTS by introducing porous metal foam as a heat-absorbent plate. a semicircular basin of the solar collector was divided into two equal identical quarters. A porous foam material was fixed on one of the basins while the other basin was fixed on a traditional copper plate. The positions of the metal foam absorber plate are changed with two inclination angles (0֯ and 18֯) and the optimum position is achieved when it gives the highest thermal performance. A finite volume modeling technique is used to solve the governing equations and radiation heat transfer equations by using ANSYS Fluent. The experimental part was conducted in Baghdad / Iraq at latitude 33.3°. The presence of the metal foam absorber plate caused a significant decrease in the average temperatures of the heat-absorbent plate. The maximum airflow temperature was recorded with an inclined angle of 18◦. The metal foam as a heat-absorbent plate enhanced the efficiency and the output power of the SUTS to about 51.9% and 47.2% respectively compared to the traditional plate.

Vertical limit reduction of chimney in solar power plant

The practical feasibility to install solar updraft tower (SUT) for power production require huge capital investment and difficulties in installing tall giant chimney structure. The chimney is the most expensive element of SUT and typically covers one-fourth of the total SUT cost. Previous finding has shown that a divergent chimney shows significant increase in power output than a conventional design for the same height. This paper deals with the unexplored scientific question: for how much height of divergent chimney can be dispensed with for the same or higher performance of a conventional design? Using an experimentally validated numerical model, we systematically investigated height reduction of chimney (and hence substantial cost) of a high performing divergent chimney whose power output is identical with a long unstable costly conventional cylindrical chimney. The conventional cylindrical design was chosen as the conventional SUT prototype installed at Manzanares, Spain in the year 1980. Results show that it is possible to reduce the vertical limit by about 80% of the height of conventional cylindrical chimney. Further, the cost analysis estimated for each SUT designs and the optimum divergent chimney SUT holds payback period 40% less than the conventional SUT. The proposed designs would be useful for floating chimney as well made of fabric material with light density air filled to keep short chimney height upright vertically to resolve the instability issues with the conventional tall chimney structure during high wind speed environmental conditions The present investigation would assist scientific community to develop more advance clean energy-based power generation systems to achieve net-zero carbon emissions targets.

Computational fluid dynamics simulation and optimization of the fluid flow behaviour in a multi‐stage solar updraft tower using a new chimney design

AbstractThis work proposes a new chimney design that allows for the development of a multi‐stage solar updraft tower (SUT). The new design consists of two successive divergent chimneys. A 3D model was established to inspect the air flow behaviour within the SUT in six configurations: four multi‐stage systems with four divergence angles of the second stage were compared to the simple conventional SUT and the simple SUT with a divergent chimney. The new SUT performs better than the conventional one, while the two‐stage solar tower multiplied the system efficiency. Two high‐velocity zones appeared for the two‐stage SUT, whereas one zone occurred for the conventional system. The velocity in the two zones achieved a significant value, like that of the conventional system. In addition, the second stage's divergence angle directly impacts the velocity value inside the two stages. The static pressure distribution varies with the change in chimney design. The depression area occurs twice for the multi‐stage SUT in the inlet of each stage.

Economic analysis of a large scale solar updraft tower power plant

This research article provides an economic analysis of a large-scale solar updraft tower power plant (SUTPP) having 100 MW capacity and installed in Udat, Rajasthan, India, with position coordinates of 27° 35′ and 72° 43′ for meteorological conditions. A cost model developed for optimized parametric values, received from thermal and dimensional optimization of previous study, to analyse the optimized cost of electricity generation and revenue analysis with the consideration of electricity selling, carbon credits, and the levelized electricity cost. The results of the analysis suggest that the proposed plant has a higher capital and operating cost than photovoltaic and wind energy, but it also has a lower levelized cost of electricity generation. As, for a fixed power output, the optimized cost of electricity generation is inversely proportional to Rcollector and Rtower, and obtained an optimum value between ₹9.16 to ₹10.57 for power plants ranging from 100 MW to 200 MW. The results also show that the cost of construction of such a power plant largely depends on plant configuration and can lie between ₹4.5cr. to ₹12cr. per MW, which indicates that a large-scale SUTPP can be installed economically. Although the optimum values of optimized cost of electricity generation came with larger dimensional values of the power plant, that also create challenges during the construction and operation of the power plant. Based on these findings, the authors conclude that, with proper subsidies and support, a large-scale SUTPP can be considered a promising renewable energy technology for power generation.

Performance investigation of a solar updraft tower concept with downdraft windcatcher

In this study, a novel solar updraft tower system that combines updraft and downdraft is examined, its functional principle is explained and its performance is presented. A prototype was built at Faculty of Engineering of Trakya University in Edirne Türkiye in 2017. The concept includes counter-rotating dual drag type vertical axis turbines, wind catchers, three prismatic diffuser towers and sloped transpired solar collector. The results showed that the downdraft wind catcher integration increased annual energy production by 8 times compared to a conventional solar updraft tower. In the diffuser-shaped downdraft tower, the incoming wind accelerated up to 2.5 times. The power potential, which is 160 W for the conventional system, becomes 83 kW at a wind speed of 10 m/s and a downdraft pressure coefficient of 1.0.

Technical Analysis of a Large-Scale Solar Updraft Tower Power Plant

This study investigates the possibility of applying a large-scale solar updraft tower power plant in India with local ground conditions as an environmentally friendly and economically viable energy source. A reference model Solar Updraft Tower Power Plant (SUTPP) is constructed to examine the influence of the most prominent plant dimensional parameters, including collector radius (RCollector), tower height (HTower), and tower radius (RTower) with dimensional limits and intervals on the power output of the SUTPP. Udat, Rajasthan, India, is used as a reference location for meteorological conditions to evaluate SUTPP power output equations for a ranging power output, with position coordinates of 27°35′ and 72°43′. Multiple simulations for the objective function are carried out, and the outcomes are compared to the optimized dimensions of each set of plants. The model examines the effect of variation in ambient, plant geometry, and material conditions on power output and analyzes efficiency and power output for optimizing configuration. There exists no definitive approach to determining the proper correlation between the geometrical parameters of a SUTPP with optimized power output. For a fixed power output, the tower radius (RTower) serves as the most influencing dimensional parameter in SUTPP performance. A change in tower height (HTower) has a detrimental impact on SUTPP output and performance. An initial increase in collector radius (RCollector) has a positive influence on SUTPP performance; however, this effect reduces as collector radius (RCollector) increases.

Prospect for the use of the solar updraft tower project for the generation of electrical energy in the republic of Uzbekistan

Fulfilling the decision of the Paris Agreement on Climate Change (COP-21 of the UNFCCC) dated December 12, 2015, the government of the Republic of Uzbekistan has developed and adopted an energy development plan of the Republic for 2020-2030. The plan provides for the construction of 3 GW of wind and 5 GW of solar power plants annually. RES will generate electrical energy in parallel with the generation of energy by thermal stations and transfer it to the general energy system. The main disadvantage of the joint operation of RES and thermal power plants is the need to have standby generating capacity due to the fact that the sources of solar and wind energy are fickle by nature. System costs rise with the increasing share of renewable energy sources. The Solar Updraft Tower project is a renewable energy option that does not have the main disadvantage of other types of renewable energy sources - the variability of electricity production and therefore is more acceptable for operating conditions in a single energy system. The article discusses and evaluates the Solar Updraft Tower (SUT) project for the generation of electrical energy, taking into account the conditions of Uzbekistan.

Experimental Analysis of Air Inlet Height Variation in a Solar Tower system Using Plate and Metal Foam Absorber

The experimental analysis is conducted under the Iraqi climate conditions to investigate the performance enhancement of a solar updraft tower system (SUTS) using the porous copper foam as an absorber plate and conventional absorber plate with absorber inclination angle of 18°. In the present work, a semicircular collector is divided into two identical quarter thermal collectors to become two identical SUTS. One of the quarter circular thermal collectors contains on the metal foam as an absorber plate, while the other quarter collector on the conventional flat copper absorber plate. In this study the air inlet height is changed of (3, 5, and 8) cm. The experimental tests carried out in Baghdad city (latitude 33.3° N). Results showed that the air inlet height variation caused to enhance the solar updraft tower performance. The highest values was recorded when the air inlet height is 3 cm using porous absorber compared to flat absorber plate. Copper material foam as an endothermic surface causes a marked decrease in average surface temperature of the plate. The maximum hourly thermal efficiency of solar collector was increased to about 41.6 % and the maximum enhancement of the power output to about 45.2 % compared with flat absorber plate.

A computational approach to estimate the flow and output parameters of various solar updraft tower plants and a proposed model for the best power output

ABSTRACT Three different models were developed to examine the flow and thermodynamic characteristics of the solar updraft tower (SUT) power plant and the best model is proposed. A step is taken to find the location of the turbine to absorb maximum kinetic energy. It is found that the maximum and average air velocities inside model-I were higher (3.06 and 1.63 ms−1, respectively) compared to model–II (2.4 and 1.34 ms−1) and model-III (2.9 and 1.57 ms−1). The maximum air temperature inside the model-II was higher (322 K). Turbulent kinetic energy, power produced and overall efficiency were the best in model–II than the other two models. The present outcomes were validated with the literature data and observed a good match.

Numerical study on optimization of fillet size on the chimney base of solar updraft tower plant for enhanced performance

• The effect of fillet near chimney base of SUT plant was studied with a parametric study. • Seven cases with different fillet sizes were modeled and CFD simulations were run. • The estimated output parameters were compared and the optimized case was proposed. • Case 6 with a fillet size of 2.5 m shows a 61% increment in air velocity. • Case 6 showed 97% increment in power and 96.5% on overall efficiency. A numerical study was performed to optimize the size of the fillet at the base of the chimney of a solar updraft tower plant. A parametric study was conducted with seven different fillet size models (cases 1 to 7). Therefore, seven 3D models with different fillet sizes based on the Manzanares prototype were generated and numerical simulations were performed. Realizable k-ε model for turbulence and DO irradiation model for radiation were used. The flow properties such as temperature, pressure and velocity inside the setup of all seven models were estimated. Performance characteristics such as collector efficiency, theoretical and actual turbine powers and overall efficiency were estimated for all cases and compared. The fillet has a 45° inclination such that the height to width ratio of the fillet was unity. The setup with a fillet size of 2.5 m (case 6) showed the optimum results with an increase in velocity of 61% and an improvement of 97% and 96.5% on theoretical power and overall efficiency, respectively, compared with case 1 (no fillet case).

Modeling of Solar Updraft Tower Power Plants: A Review

Solar updraft tower power plants, or SUTPP, are thermal power plants consisting of three parts: a solar collector, a power conversion unit (turbine), and a solar chimney. Different configurations of SUTPP models were presented in the previous studies. However, the type used in the modelling of SUTPP elements with the variables used is not highlighted. Therefore, a modelling approach to improving or investigating the SUTPP is reviewed in the presentwork. Modeling can be broken down by which part of the solar chimney power plant was used. Predictive, thermal, and simulation models were used for the solar collector and chimney, while analytical and simulation models were used for the wind turbine power unit. used in the modelling have been addressed, such as airflow velocity, the temperature distribution in the collector, air temperature and pressure leaving the collector, output temperature from the collector, coefficient of heat transfer by convection, power produced, SCPP efficiency, and the thrust factor of the wind turbine. The review study is of great importance to maximize the power produced and efficiency by comparing multiple models.