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Leveraging a high-resolution 3D dust map of the solar neighborhood from Edenhofer et al., we derive a new 3D model for the dust-traced surface of the Local Bubble, the supernova-driven cavity surrounding the Sun. We find that the surface of the Local Bubble is highly irregular in shape, with its peak extinction surface falling at an average distance of 170 pc from the Sun (spanning 70–600+ pc) with a typical thickness of 35 pc and a total dust-traced mass of (6.0 ± 0.7) × 105 M ⊙. The Local Bubble displays an extension in the Galactic northern hemisphere that is morphologically consistent with representing a “local chimney.” We argue this chimney was likely created by the “bursting” of this supernova-driven superbubble, leading to the funneling of interstellar medium (ISM) ejecta into the lower Galactic halo. We find that many well-known dust features and molecular clouds fall on the surface of the Local Bubble and that several tunnels to other adjacent cavities in the ISM may be present. Our new, parsec-resolution view of the Local Bubble may be used to inform future analysis of the evolution of nearby gas and young stars, the investigation of direct links between the solar neighborhood and the Milky Way’s lower halo, and numerous other applications.

The article deals with the effects of change in dimensions of solar chimney upon the thermodynamic characteristics of the air flowing inside it. The solar chimney at Manzanares (Spain) has been selected as the base model for this study. ANSYS-Discovery-Aim 2019 R1 has been used for the simulation of different geometric variations of solar chimney along with its validation with the work by Haaf et al. It is found that of all the geometric changes, the increase in roof height is undesirable. While for others like increase in chimney height, increase in chimney diameter and increase in collector radius gives desirable results in terms of increase in velocity of air. Also, for the case with an increase in chimney diameters; it is found to be suitable if the turbines are placed at the outlet of the collector and not within the chimney.

With energy resources being fossil fuel-based, increasing energy production has already reached levels that threaten human health. In this situation, the use of alternative energy sources is seen as the only solution. Solar energy is seen as the most promising source among these alternative energies in terms of its potential. Hence, therefore, this study focuses entirely on one of the solar energy sources. This research aims to assess the impact of the design and underground additional heat source (AHS) on the system performance based on the Manzanares pilot plant (MPP), the first on-site practice of solar chimney power plants. Divergent chimney-SCPP with sloping collector (DISCPP) is analysed in the present work. For DISCPP, the influence of the underground AHS in the range of 50–250 °C on the system outputs is examined. The study demonstrates a remarkable enhancement in power output (PO), with the plant generating 51,545 kW under the reference case conditions. The findings signify that when utilising the DISCPP system, the output soars to 247,672 kW under identical climatic conditions. During sunless hours, a PO of 61,956 kW is achieved with the DISCPP at an underground AHS temperature of 50 °C. Moreover, when the source temperature reaches 250 °C during sunless hours, the DISCPP system continues to deliver a significant output of 450 kW. These outcomes underscore the exceptional performance and reliability of the DISCPP system, even under varying conditions.

Solar energy is one of the most feasible options to produce energy in countries where unexploited desert areas or solar radiation are abundant. An energy tower is an effective system for electrical power generation that can perform more efficiently along with solar radiation. As the primary aim of the present study, effects of different environmental parameters on total efficacy of energy tower were investigated. In this study, the efficiency of the energy tower system is investigated experimentally by an indoor fully adjustable apparatus. In this regard, a comprehensive set of influencing parameters like air velocity, humidity, and temperature and the effects of tower height on the performance of the energy tower are individually assessed. It is demonstrated that there is a direct relationship between an increase in humidity percentage of the surrounding and performance of energy tower, meaning that a 274% increase in humidification rate led to 43% elevation in airflow velocity. The kinetic energy increases in the direction of airflow from top to bottom, and as the height of the tower lengthens, the kinetic energy enhances and subsequently increases the overall efficiency of the tower. An elevation about 2.7% in airflow velocity was seen due to an increase from 180 to 250 cm in chimney height. Although the energy tower performs efficiently in the nighttime, airflow velocity increases averagely about 8% during the daytime and at the peak of the solar radiation, the airflow velocity enhances by 58% compared to nighttime.

Solar chimney power plant (SCPP) is an interesting project to produce clean and sustainable energy. An efficient SCPP system requires a very high chimney, and thus the optimization of the chimney shape presents an important way to enhance the SCPP performance. The aim of this paper is to analyze the effect of the divergent chimney shape on the airflow behavior inside SCPP. A comparison between four chimney shapes is carried out using CFD method: two cylindrical chimneys with different diameters and two divergent chimneys with different shapes. Indeed, both parameters were studied: the ratio of the inlet and outlet diameter of the chimney and the shape of the chimney which both hyperboloid and conical. The SCPP prototype was tested numerically and experimentally to validate the present computational outcomes. The obtained results confirm that the divergence shape affects directly the efficiency of the SCPP system. Moreover, the hyperboloid chimney presents the efficient solution which produces an important power output with keeping the chimney height constant.

Abstract Solar chimney technology is a new generative technology that generates electricity from the direct incident solar radiation from the sun. It is a low-temperature operating solar thermal system that generates power on the basis of three technologies (chimney/draft technology, wind turbine technology, and greenhouse effect technology). It consists of three fundamental parts: turbine, vertical chimney of decent height and a collector made up of glass panes to absorb the radiations from the sun. Effective use of this technique can generate electricity in abundance and can operate twenty-four hours nonstop annually and can solve the electricity shortage issue in a country like India where the sunlight radiations are immense in intensity and stretch to the major parts of the country. Since its inception, solar chimney technology has seen prosperous advancement but has not witnessed full-scale utilization because of various techno-economic and environmental aspects. This study discusses the critical review of the solar updraft/chimney technology in various parts of the world and emphasizes its important aspects.

Evidence has mounted in recent decades that outflows of matter and energy from the central few parsecs of our Galaxy have shaped the observed structure of the Milky Way on a variety of larger scales 1 . On scales of 15 parsecs, the Galactic Centre has bipolar lobes that can be seen in both the X-ray and radio parts of the spectrum 2 , 3 , indicating broadly collimated outflows from the centre, directed perpendicular to the Galactic plane. On larger scales, approaching the size of the Galaxy itself, γ-ray observations have revealed the so-called ‘Fermi bubble’ features 4 , implying that our Galactic Centre has had a period of active energy release leading to the production of relativistic particles that now populate huge cavities on both sides of the Galactic plane. The X-ray maps from the ROSAT all-sky survey show that the edges of these cavities close to the Galactic plane are bright in X-rays 4 – 6 . At intermediate scales (about 150 parsecs), radio astronomers have observed the Galactic Centre lobe, an apparent bubble of emission seen only at positive Galactic latitudes 7 , 8 , but again indicative of energy injection from near the Galactic Centre. Here we report prominent X-ray structures on these intermediate scales (hundreds of parsecs) above and below the plane, which appear to connect the Galactic Centre region to the Fermi bubbles. We propose that these structures, which we term the Galactic Centre ‘chimneys’, constitute exhaust channels through which energy and mass, injected by a quasi-continuous train of episodic events at the Galactic Centre, are transported from the central few parsecs to the base of the Fermi bubbles 4 . Huge X-ray structures, termed Galactic Centre ‘chimneys’, extending hundreds of parsecs above and below the Galactic plane, appear to be exhaust channels connecting the Galactic Centre region to the Fermi bubbles.

Influence of area ratio (AR) on main performance parameters of solar chimney power plants (SCPPs) is investigated through a justified 3D axisymmetric CFD model. Geometric characteristics of Manzanares pilot plant (MPP) are taken into consideration for the numerical model. AR is varied from 0.5 to 10 to cover both concave and convex (convergent and divergent) solar chimney designs. Following the accuracy verification of the CFD results and proving mesh-independent solution, main performance oriented parameters are assessed as a function of AR such as velocity, temperature and pressure distribution within MPP, temperature rise of air in collector, mass flow rate of air around the turbine area, dynamic pressure difference across the turbine, minimum static pressure in the entire plant, power output and system efficiency. The results reveal that AR plays a vital role in performance figures of MPP. Mass flow rate of air ($\\dot{m}$) is found to be 1122.1 kg/s for the reference geometry (AR = 1), whereas it is 1629.1 kg/s for the optimum AR value of 4. System efficiency (η) is determined to be 0.29% for the reference case; however, it is enhanced to 0.83% for the AR of 4.1. MPP can generate 54.3 kW electrical power in its current design while it is possible to improve this figure to 168.5 kW with the optimal AR value.

According to Directive 2010/75 / EU and Law 278/2013 on industrial emissions, operators of large combustion plants (IMA) must carry out continuous self-monitoring of pollutant emissions and are required to perform parallel measurements with accredited laboratories, to certify results. Thus, INCD INSEMEX Petroșani, through the Testing Laboratories Group, accredited by RENAR, offers these type services to various economic agents. The curent paper presents measurements performed at two IMA exhaust chimneys, in two different stages, to quantify pollutants released into the atmosphere and to establish the impact they generate on health of population in the area of the study. Analysis of results showed that the maximum allowed value for the SO 2 was exceeded, so that, at the end of this paper, some recommendations were reviewed, according to BAT (Best Available Techniques), to support the economic agent and inhabitants of the area in haveing a cleaner environment.

Solar chimney systems which consist of three main parts (collector, chimney, turbine) are one of the main thermal methods that produce electricity using solar energy. In a solar chimney, the high-power generation that can be obtained by increasing the design dimensions can also cause ineffective high investment costs. In this study, differing from the traditional design approach, a heuristic optimization method based on the Bees Algorithm is present to obtain the optimum design parameters (the chimney and collector dimensions) that are provided the more effective solutions. It is made for 3 configurations in order to prove the accuracy of the optimization study using different algorithm parameters. By using the obtained mathematical equations and the defined non-currency investment cost unit for a traditional solar chimney, the optimum design parameters that can provide more power output with acceptable costs are investigated. Two main objectives are taken into consideration namely maximizing efficiency of solar chimney system and minimizing investment cost. In the optimization process, within the ranges determined for the decision variables, the maximum and minimum dimensions are determined as 1293.05–1330.47 m for the collector diameter, 94–99 m for the chimney diameter and 783–792 m for the chimney height. The obtained results showed that this open to develop approach proposed within the scope of the study can be useful in the optimal design of solar chimney systems.