Solar Chimney Research Articles

Improving thermal performance of a passive ventilation and cooling system by integrating a phase-change material: Dynamic characteristics and parametric examinations

The coupling of a solar chimney (SC) with an earth–air heat exchanger (EAHE) is a passive ventilation and cooling system that provides fresh air and cooling to buildings. However, inherent disadvantages of the coupled system include the mismatch of the induced airflow rate and internal cooling load and the low nighttime ventilation rate, which limit the full utilization of the coupled system. These issues can be mitigated by integrating a phase-change material (PCM) in the system of SC combined with EAHE (SCEAHE). Parametric investigations were conducted to examine the thermal performance improvement of the PCM-based SCEAHE system using a dynamic model. The numerical data revealed that solar energy was effectively extracted and reallocated by the PCM, thereby increasing the nighttime airflow rate and reducing the indoor air temperature. The phase-change temperature of the PCM not only affected the airflow rate but also the thermal environment at night and in the early morning. Therefore, a PCM with a higher phase-change temperature is recommended in this study. The latent heat of fusion had a larger impact on the induced ventilation rate than the outlet air temperature of the EAHE when the latent heat of fusion exceeded 175 kJ/kg. In addition, a PCM with a thermal conductivity <1 W/(m·K) is suggested. In practical application, a thickness range of 0.04–0.05 m is the most suitable. The specific heat of the PCM had slight influence on the thermal performance of the proposed system.

Numerical Simulation of a Efficient Solar-Powered Ventilation System

The objective of this study is to conduct a numerical analysis of a small-scale solar ventilation-air conditioning system operating under the meteorological conditions of Bisha, Saudi Arabia. The primary objective of the proposed system is to provide sustainable and comfortable thermal conditions. To achieve this objective, the system recovers the heat wasted by the solar ventilation process and reuses it to power the desiccant dehumidification process. The solar chimney features a lateral (vertical) wall design, and a comparative performance investigation of two solar chimney designs (conventional vs original) is conducted. Mathematical models of the ventilated room and solar chimney are developed, and numerical simulations are carried out to evaluate the performance of each solar chimney design. The study aims to assess the ability of each design to maintain indoor thermal comfort through the analysis of air distribution temperature and air streamlines. The results of the performance comparison revealed that the proposed solar chimney design outperformed the conventional design in terms of thermal and ventilation performance. The proposed solar chimney design, with its lateral (vertical) wall, was also found to be more effective in maintaining indoor thermal comfort than the conventional design. The simulations showed that the proposed design produced a more uniform air distribution temperature within the ventilated room, resulting in improved comfort levels. Additionally, the proposed design was found to have a more efficient airflow pattern, with fewer areas of stagnant airflow. These results suggest that the proposed solar ventilation-air conditioning system has the potential to provide sustainable and comfortable thermal conditions in small-scale buildings.

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.

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.

Numerical Simulation Analysis and Full-Scale Experimental Validation of a Lower Wall-Mounted Solar Chimney with Different Radiation Models

As a type of passive architectural structure, wall-mounted solar chimneys enhance the natural ventilation volume of a building’s interior, and maximize reductions in the building’s operational energy consumption. They are indispensable in the building’s energy conservation and emission reduction. Therefore, measuring the wall-mounted solar chimney’s flow characteristics and relevant index parameters is particularly important. This paper uses a combination of full-scale experiments and numerical simulation to conduct a detailed analysis of the wall-mounted solar chimney. Four different radiation models, namely DO (discrete ordinates), S2S (surface-to-surface), MC (Monte Carlo), and Rosseland are used for comparison, and the results of the numerical simulation are compared with the experimental data. The results show that the maximum turbulent viscosity of the fluid predicted by the S2S radiation model is higher than that of the MC and DO models by 16.87% and 8.44%, respectively. The errors of the DO radiation model in the midline and glass cover plate direction concerning the experimental results are only 0.33% and 0.15%, respectively. The mistakes of the MC radiation model in these two directions are 0.51% and 0.47%, respectively. The DO radiation model is more suitable in numerical simulation predictions related to the wall-mounted solar chimney.

Modelling and simulation of solar chimney power plants in hot and arid regions using experimental weather conditions

This paper presents a MATLAB/Simulink model to design and assess Solar Chimney Power Plants (SCPPs) in any location worldwide, offering a simple and efficient approach that saves time and costs, while maintaining the flexibility of the design process. The model evaluates the physical and engineering specifications, pressure loss, power production, and characteristics of SCPPs. The model is applied to evaluate an SCPP in Kufa, Iraq, where no previous study has been conducted to evaluate such renewable energy sources. The proposed model's reliability is demonstrated by comparing the results to those from previous literature. The study concludes that the SCPP's power production built with a glazed roof radius of 50 m, a chimney radius of 5 m, a roof height of 2 m, and the chimney height of 50 m was highest during the summer months due to high solar radiation and temperatures, with the highest average production occurring in July at 537.87 kW, 12% greater than the least productive month of January. The SCPP's annual average power production is 6,122.3 kW, indicating high efficiency for renewable energy in these regions. The study also found that ambient temperature has a greater impact on energy production than solar radiation within a certain range. Otherwise, solar radiation has the greatest impact. The paper highlights the significance of temperature in regions such as Kufa, where the temperature can reach as high as 42.3 °C, and the impact of temperature and radiation on power production. This study provides a reliable model that can aid in designing and evaluating SCPPs in various locations.

Field measurement of environmental parameters in solar greenhouses and analysis of the application of passive ventilation

Solar greenhouses are passive agricultural facilities that can realize off-season production. The growth of crops in greenhouses is affected by various environmental parameters. Therefore, it is necessary to understand the variations of environmental parameters in solar greenhouses through field testing to improve their internal environment. Through field tests, it was found that the temperature variation in solar greenhouses was positively correlated with the change in solar radiation. When the top vent was opened, the minimum temperature in the greenhouse remained higher than 30 °C. The temperature gradient in the tall-plant greenhouse was twice that in the short-plant greenhouse. The relative humidity at the bottom of the tall-plant greenhouse remained greater than 65%. Top-vent opening for greenhouse ventilation is not conducive to the cooling and dehumidification of these relatively large sized greenhouses tested in this study. Passive ventilation via an integrated solar chimney and earth-air heat exchanger was applied in an experimental solar greenhouse. The results showed that when the passive ventilation was turned on, the indoor air temperature in the horizontal and vertical direction could be maintained in the range of 25 ∼ 28 °C and 25 ∼ 30 °C, respectively. The air temperature in the vertical direction had been decreased by approximately 3.5 to 6.5 °C. The passive ventilation effectively prevented continuous increases in indoor temperature, improved indoor air distribution and was conducive to the normal growth of crops.

Analysis Thermal Behavior of a Locally Heated Solar Chimney

This paper presents the thermal behavior of a partially heated solar chimney under hot-humid climate conditions. The solar chimney (SCH) is 2 m high and 0.8 m wide and consists of an absorber plate and a translucent plate. The SCH allows a cavity thickness variation from 0 to 0.28 m, an inclination angle variation from 0 to 90º, and allows varying the amount of energy absorbed by the absorber plate and translucent plate. These plates were heated by resistors, simulating a solar irradiance range of 225 to 900 W/m2 (absorber plate) and from 12.15 to 50 W/m2 (translucent plate). Twelve tests were conducted with different configurations varying the power supplied to both plates, the thickness of the absorber plate cavity, and the 90º inclination angle. The variables measured were temperature, air velocity at the inlet, and heat flow on the side walls and rear wall. As a result, a maximum air renewal of 51.43 ACH was obtained, equivalent to the air changes used in a paint booth. The results show that the partially heated solar chimney can be used as a passive ventilation system for air renewal.

Shape optimization of high-rise solar chimneys to improve the uniformity of flowrate distribution

Solar chimneys (SC) are passive ventilation devices which can induce natural ventilation by utilizing solar radiation. Many studies of SCs have focused on single-storey or low-rise buildings, but much less attention has been given to SCs for high-rise buildings. This paper investigates the airflow induced by 10- to 50-storey SCs using an experimentally validated computational fluid dynamics (CFD) model. The effects of the total number of storeys and the air gap size on the induced average flowrate were first studied, and their correlations were derived through linear regression. The flowrate induced by a conventional SC with a constant air gap size is highly non-uniform. To improve the uniformity of flowrate distributions among storeys, a taper structure with a narrowing air gap downwards was proposed for multi-storey SCs. Numerical simulations show that adopting the taper structure can significantly improve the uniformity of flowrate distributions. For example, in a 20-storey SC, the flowrate difference between the maximum and minimum among the middle 17 storeys, normalised by the average, decreases from 122.8% to only 15.8% when the taper structure is adopted. A parametric study of 441 numerical simulation cases was conducted to derive the optimum ratios of the bottom gap size to the top gap size for taper multi-storey SCs. The results of this paper can provide guidance on how to design multi-storey SCs for high-rise buildings to exploit the potential of natural ventilation and reduce energy demand for cooling and ventilation.

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.

Sustainable production of green hydrogen, electricity, and desalinated water via a Hybrid Solar Chimney Power Plant (HSCPP) water-splitting process

This work presents a novel sustainable approach to producing desalinated water (Wdes), green hydrogen (GH2) and electrical energy (Eelc) using Hybrid Solar Chimney Power Plant (HSCPP) coupled with a water-splitting (WatSp) process. The HSCPP consists of a collector, absorber, chimney, bidirectional turbine outfitted with a seawater pool, and water electrolysis (Watelc) cell. The HSCPP harnesses solar energy to heat the air under the collector creating air movement within the structure, passing the bidirectional turbine, and producing Eelc. Sprinklers were fitted within the structure to operate the HSCPP as a cooling tower (CT) in the absence of solar radiation (Solirr). The Watelc cell directly uses the produced Eelc for the production of Hydrogen (PH2) and oxygen (PO2), while the condensed water at the chimney's inner walls was also collected as Wdes. Results revealed that the continuous operation of the HSCPP has an average annual Eelc of 633 ± 10 MWh that could be efficiently used to generate 21,653 kg of GRH2, 173,244 kg of O2 as well as 190,863 tons of Wdes. The overall efficiency of the HSCPP for the PH2 was found to be 18.5%, which is higher than Solar PV (max∼ 6%) and geothermal Rankine (max∼ 15%). These high efficiencies rank this technology as competitive with other renewable hydrogen production technologies. In conclusion, HSCPP has a promising future as a novel and sustainable solar tower technology to produce hydrogen.

Experimental and Numerical Investigation on Design Optimization of a Roof Skylight Combined with Solar Chimney

Experimental and Numerical Investigation on Design Optimization of a Roof Skylight Combined with Solar Chimney

Enhancement of Building Thermal Performance: A Comparative Analysis of Integrated Solar Chimney and Geothermal Systems

Enhancement of Building Thermal Performance: A Comparative Analysis of Integrated Solar Chimney and Geothermal Systems

Efficiency improvement of the solar chimneys by insertion of hanging metallic tubes in the collector: Experiment and computational fluid dynamics simulation

The solar chimney power plant (SCPP) is a straightforward and clean technique to generate electricity from solar radiation. However, this technology still faces major challenges, such as low efficiency, which has hindered its industrialization. This study experimentally develops a novel collector design to improve the solar chimney collector's efficiency. The new design includes metallic tubes as solar radiation absorbers hung from the canopy of the collector. The metallic tubes are open at the top and sealed with transparent sheets at the bottom to decrease the solar radiation reflected into the ambient air. Experimental and 3-D computational fluid dynamics (CFD) analyses are performed to validate the new design. The effects of hanging metallic tubes on temperature and velocity distribution are explored. The temperature increased by about 5 K at the chimney inlet, causing a roughly 8% rise in collector efficiency due to the fact that metallic tubes operate as an extended surface. The impact of various tube geometries on solar chimneys' efficiency is examined. The CFD findings reveal that the metallic tube geometry variation has considerably impacted the collector's efficiency. Thus, the collector efficiency is increased by changing tube diameter by around 33.7%, similar to changing tube length by 30%.

A high-performance solar chimney in building integrated with photocatalytic technology for atmospheric methane removal

The techniques for the removal of methane from the atmosphere are highly challenging due to its stable chemical properties, dispersed sources, and low concentrations. This paper proposes a practical small-scale solar chimney (SC) in buildings with photocatalytic reactors (PCRs) for atmospheric methane removal. Two comprehensive numerical models on photocatalytic reaction and indoor ventilation are developed. The numerical simulation considers the performance of methane removal and indoor air ventilation of the proposed system, as well as its specific crucial parameters such as the type of PCRs, solar radiation, and flow channel width. The obtained results show that the SC with honeycomb photocatalytic reactor (HPCR) is more able to remove atmospheric methane than SC with plate photocatalytic reactor (PPCR) under the premise of meeting the ventilation standards. In addition, there is a maximum methane purification rate of 57.27 μg/s under the condition that the air gap width is 0.3 m, the length of the HPCR is 1.5 m, and the porosity is 0.85. It is then proved that the SC in buildings with PCRs can allow small-scale, zero-energy consumption, continuable, and decentralized low-concentration atmospheric methane removal while improving the indoor ventilation.

Implementation of active and passive control strategies for power generation in a solar chimney power plant: A technical evaluation of Manzanares prototype

Nowadays, it is necessary to develop sustainable energy suppliers according to the concerning environmental issues. Solar energy is one of the appropriate solutions. Solar Chimney Power Plant (SCPP) represents a viable form of solar thermal electricity generation technology. Temporal variations in the driving factors of the plant, especially solar radiation, cause significant fluctuations in output power. This study evaluates active and passive control strategies for achieving more stable power generation in SCPP using Fuzzy Logic Control (FLC) and Thermal Energy Storage (TES) systems. The governing equations for performance modeling have been solved by a developed MATLAB code and validated with experimental data from the Manzanares prototype. Using TES reduced output power fluctuations and showed daily electrical energy generation of 331.9, 314.3, and 308.7 kWh for sand, limestone soil, and water-filled bags, respectively. Implementing an active control strategy with the FLC system alone provided a 25 and 30-kW baseload generation in the mid-hours of the day. Finally, integrating the FLC and TES systems in a hybrid control strategy continued a base load power generation of 12 and 16 kW up to 4 h after sunset, utilizing limestone soil and water-filled bags, respectively.

Natural ventilation enhancement through solar chimney in buildings: A technical review

The energy demand is increasing day by day in present era and due to increasing the cost of energy by increasing the cost of fossil fuel. The fossil fuel is limited for the future and researchers are continuously working on new options for energy saving or other renewable option. The solar chimney is one of the most feasible retrofit for the buildings which operated by solar irradiance and saved the much of energy used in ventilation cooling and heating of building. The paper is reviewed the solar chimney with various integrated approaches, modeling, simulation, optimization and the techno-economic analysis. The work can be used for the future researchers in this area.

Numerical Study of Solar Chimney with Absorber at Different Locations

Heat transfer process and fluid flow in a solar chimney used for natural ventilation are investigated numerically in the present work. Solar chimney was tested by selecting different positions of absorber namely: at the back side, front side, and at the middle of the air gap. CFD analysis based on finite volume method is used to predict the thermal performance, and air flow in two dimensional solar chimney under unsteady state condition, to identify the effect of different parameters such as solar radiation. Results show that a solar chimney with absorber at the middle of the air gap gives better ventilation performance. A comparison between the numerical and previous experimental results shows fair agreement.

Recent Advances, Development, and Impact of Using Phase Change Materials as Thermal Energy Storage in Different Solar Energy Systems: A Review

The efficient utilization of solar energy technology is significantly enhanced by the application of energy storage, which plays an essential role. Nowadays, a wide variety of applications deal with energy storage. Due to the intermittent nature of solar radiation, phase change materials are excellent options for use in several types of solar energy systems. This overview of the relevant literature thoroughly discusses the applications of phase change materials, including solar collectors, solar stills, solar ponds, solar air heaters, and solar chimneys. Despite the complexity of their availability and high costs, phase change materials are utilized in the majority of solar energy techniques because of the considerable technical improvements they provide. While numerous studies have investigated the progress of phase change materials used in solar energy applications such as photovoltaic systems, it is vital to understand the conceptual knowledge of employing phase change materials in various types of solar thermal energy systems. Investigations into the use of phase change materials in solar applications for the purpose of storing thermal energy are still being carried out to upgrade the overall performance. This paper briefly reviews recently published studies between 2016 and 2023 that utilized phase change materials as thermal energy storage in different solar energy systems by collecting more than 74 examples from the open literature. This study focuses on demonstrating the maturity of phase change materials and their integration into solar energy applications. Based on the findings, proposals for new research projects are made.

Sustainability framework of intelligent social houses with a synergy of double-façade architecture and active air conditioning systems

Social houses are built around the world to fulfill the basic needs of the growing population, especially middle-income families. Owing to the low budget available for such houses around the globe, necessary energy codes are often compromised. This research, through a methodological sustainability framework, presents the case study of Mexico with the objective to address this worldwide issue. More than 100,000 social houses were built in Mexico just in the year 2021 without strictly following any definitive building energy codes. Eventually, this is a ticking bomb, if left unaddressed, that can bring serious energy and environmental consequences connected with various social issues. Thus, as a research gap, the conventional 4E (energy, exergy, economic, and environmental) analysis cannot fully address such a complex energy-environmental-economic-social nexus. This work proposes an integrated sustainability framework of the practicability of the bioclimatic architecture of such a social house including energy, economic, environmental, and social assessment (novel addition to the analysis). The novel methodology is implemented on a novel technological advancement where double-façade architecture (i.e., solar chimney) is installed through a synergy and intelligent operation with an active air conditioning system including a desiccant enhanced air cooler and novel dew-point evaporative cooler. The article makes use of conventional physics-based modeling of thermal machines combined with an artificial neural network digital twin-based data-driven non-sorting genetic optimization of solar chimneys for various climatic conditions of Mexico. The optimal points are evaluated using annual climatic data to maintain the thermal comfort conditions and the results have suggested an increase of ∼48% through intelligent integration of double-façade architecture with the Maisotsenko cycle air cooler. Life-cycle economic assessment has suggested the Levelized cost of air conditioning be between 0.0096 and 0.0390 USD/kWh and can save up to ∼273 MXN per month with a real payback period of ∼8 years. Environment assessment has reported mitigation of up to ∼5668.59 kgCO2/year as compared to conventional vapor compression refrigeration systems. The social assessment is conducted on a pilot scale to directly ask the people of Mexico about their perception of the installation of the solar chimney while giving the fact that the initial price of the social houses can increase between 2.5 and 4%. It is reported that ∼62% of the sample is willing to install it even with a high price tag with a motive to initiate the climate change mitigation phenomena. The importance of the work has concluded that the government needs to take drastic and tough decisions to further regulate the energy efficiency in the social houses and limit the constructors to offer sustainable building construction.