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Sustainable Skyscrapers: A Review of Green Features
Get PDFIncreasingly, architects and engineers are interested in pursuing sustainable design. Yet, they lack sources that summarize best practices. As such, this review paper maps out and examines prominent examples of "sustainable" skyscrapers of varying geographic locations, climates, and socio-cultural contexts. It discusses the design themes and green features of "LEED skyscrapers" and elaborates on recent developments in architecture and engineering. The presented 12 case studies do not intend to evaluate LEED rating systems. Instead, they illustrate how LEED has advanced the green design agenda and encouraged the pursuit of innovative design and engineering solutions. The mapped-out green features in this article should be helpful to all professionals interested in green architecture
Analysis of Enhancing Coalbed Methane Recovery and Improving Coal Mining Safety by CO2 Injection: Model of the Critical CO2 Volume Fraction
Get PDFCoalbed methane (CBM) is produced before coal mining at the Qinshui Basin in China to utilize CBM and reduce CH4 volume fraction for coal mining. However, the volume fraction of CH4 often reaches the range between lower and upper explosion limits after CBM production, which is a great threat to coal mining safety. In previous work, we analyzed the feasibility of injecting CO2 into coalbeds to control CH4 volume fraction for mining safety and simultaneously enhancing CBM recovery. In this paper, we extended our work to propose a model to calculate the critical CO2 volume fraction for CO2 injection. We simplified the gas mixture during coal mining as the CO2/CH4/air mixture. The model of the critical CO2 volume fraction was then built based on the explosion limit formula for the CO2/CH4/N2 mixture. The formula for the critical CO2 volume was derived using the critical CO2 volume fraction. The model of the critical CO2 volume fraction was applied in a CBM reservoir at the South Shizhuang Block in the Qinshui Basin. The CO2 injection rate for this block was optimized to obtain the highest CBM recovery using the reservoir simulation method. Results show that the critical CO2 volume fraction is 7.97%, which makes the CH4 volume fraction out of the explosion limits. The optimum CO2 injection rate for this block is 8000m3/d which improves the CBM recovery up to 86.24%
The Potential Use of Raw Iron Ore in Fischer-Tropsch Synthesis
Get PDFFischer-Tropsch (FT) synthesis has been studied in the literature as a greener pathway to cleaner and sustainable hydrocarbons production. However, the cost to upscale laboratory FT formulations to pilot scale is significantly expensive. This work proposes a cheaper and scalable low-temperature FT modified iron ore catalyst that is mechanically suited for fixed bed reactors. The mechanical strength reported in this investigation was three times more than commercial alumina spherical pellets and, therefore, suitable for pilot scale scenarios. A manufacturing cost analysis of iron ore was estimated to be US71.44/kg using the same model. The manufacturing cost estimations of modified iron ore were found to be 46% cheaper than a conventional commercial iron catalyst. The catalytic performance of the modified iron ore catalyst showed a CO conversion of 72.1% ±4.24, with WGS and C5+ selectivity 48.6% ±1.96 and 83.2% ± 5.24, respectively. These findings were comparable (both in CO conversion and product selectivity) to the ones reported by other researchers
Investigation of Convective Heat Transfer and Friction Factor in Corrugated Channels with Different Inclination Angles Using Computational Fluid Dynamics
Get PDFConvective heat transfer and friction factor properties for periodic undulating channels are numerically investigated. The finite volume method (FVM) was used in the numerical study. Three different Reynolds averaged numerical simulation (RANS) based turbulence models, shear stress transport SST k-ω and transition SST model were used and compared with each other. Two different channels were used; the first geometry is a sharp corrugated channel with a 30° inclination angle, and the second geometry is a sharp corrugated channel with a 45° inclination angle. The Reynolds number varies in the range of 2000-7500. The Prandtl number was kept constant at 0.7. Nusselt number, friction factor, Reynolds number, and variations of the good factor were investigated. The effect of inclination angle and pitch are discussed
Energy and Environmental Benefit of Solar Charging System for Charging Auto-Rickshaw in Developing Countries
Get PDFThe energy crisis and environmental impact are the major concern mf the present world. Three-wheeler auto-rickshaw becoming an important passenger transport vehicle in a developing country which are indirectly powered by the grid electricity through the batteries. Such vehicle consumes significant grid energy during charging which increases the load in the national grid and put extra stress on the electrification in line with the environmental impact. This paper investigated the existing facilities for charging auto-rickshaw in Bangladesh and designed a proposed solar charging model as a replacement based on the existing model. Then the energy and environmental benefit were estimated to reflect the significance of the proposed model and contribution in the context of the global energy crisis and environmental impact. The investigation found that the daily energy consumption is 290 kWh for a charging station capacity of 30 auto-rickshaws which is significant. The proposed solar model is designed to meet this demand offset. The environmental analysis showed that the proposed model can offset CO2, CH4, and NOx emissions by 54 tCO2eq, 40 kgCO2eq, and 60 kgCO2eq per year respectively of which the contribution of CO2 is significant. Further research could be focused on the economic and financial analysis in-depth to promote the proposed model
Experimental Measurements and Modeling of Vapor-Liquid Equilibrium of Isobutane and Ethyl Mercaptan Binary System
Get PDFIn this work, new isothermal experimental data of vapor-liquid equilibrium of the isobutane and ethyl mercaptan binary system are presented. The pressure and temperature conditions are up to 1 MPa and between 298 and 343K. The experimental apparatus is based on a “static-analytic method” specially developed for low-pressure measurements. Two online capillary samplers are used to take vapor and liquid samples that are analyzed with a gas chromatograph. The classical Peng Robinson Equation of State is used to correlate the experimental data. The van Ness test is used to check the consistency of the data. The measured data are also compared to predicted values from two predictive models, and a good agreement is found between the PSRK UNIFAC and the PPR78 models and the experimental measurements
Thermodynamic Aspects of the Use of Heat Exchangers in Low-Temperature Power Systems
No full textThe problems of thermodynamic analysis associated with the heat exchangers that used in cryogenic technology are discussed. A method and an algorithm for calculating the components of losses from irreversibility in these heat exchangers are proposed. The exergy method of thermodynamic analysis was used to calculate the components of these losses for some two-flow heat exchangers. The investigation of the obtained calculation results is presented
Characterization of Filmogenic/Edible Covering Based on Pectin Extracted from Cajá (Spondias mombin) Applied to Coating Green Acerolas (Malpighia emarginata)
Get PDFFilmogenic coatings can be used as a post-harvest strategy to extend shelf life and ensure improvements in fruit quality and safety given their perishable nature. Due to their edibility, the composition of the coverings is a determining factor for their application, and for this reason, it is interesting and desirable that the constituents come from natural sources. The objective of the present study was to develop and characterize a pectin-based film extracted from cajá peel (Spondias mombin) and verify its efficiency as an edible coating in postharvest acerolas (Malpighia emarginata). The film was characterized in terms of mechanical properties by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM); as well as in terms of chemical properties using the analysis of structural bonds by Fourier Transformed Infrared Spectroscopy (FTIR) and X-Ray Diffraction (XRD). In addition, the antimicrobial activity against two bacteria was evaluated. The analyzed film was presented as a dense membrane, with the presence of pores, fissures, and a very rough surface. The degree of esterification of pectin extract from cajá peel was 44%, and for this reason it was classified as low methocxyl (LM) pectin. The filmogenic solution presented antimicrobial activity against the bacteria Pseudomonas aeruginosa and Staphylococcus aureus. The applicability of the edible coating was tested on green acerolas, monitoring their maturation stage through analyzes such as weight loss, titratable acidity, and total soluble solids. At the end of the 7 days of storage, acerolas with the application of the coating showed 8.97% weight loss while acerolas without coating showed 9.89%; the percentage of total soluble solids was 7.68% higher for acerolas with the coating, as well as ascorbic acid content was higher for the protected fruits, indicating that the coverage favored the delay in the maturation of acerolas
Diatom of the Bacillariophyceae Class in Thermophilic Microbial Mats Present in Sulphurous Hot Springs and their Possible Biotechnological Application
Get PDFThe diversity of diatoms in the hot springs of the Comanjilla geothermal zone in northern Guanajuato, Mexico was studied. Hot springs are extreme ecosystems that, despite having high temperatures, constitute an environment for many thermophilic microorganisms (bacteria, cyanobacteria, and diatoms). The thermal water studied is classified as hyperthermal water (45°C to 100°C), of deep origin, and with low mineralization, are of type sulfuric sodium chloride, since the dissolved content of hydrogen sulfide (H2S) is found in concentrations higher than 1mg/L, and its smell is similar to the one of rotten eggs, presents a pH of 7.6 to 9.1 that represents neutrophilic to alkaliphilic environments, with a variable electrical conductivity (EC) (658-698 µs / cm) and total dissolved solids (TDS) (314-24 ppm). In the same way, these hot springs present microbial mats that consist of several stratified layers of green and orange color of 100 cm2, each one, which are dominated by specific types of microorganisms such as bacteria, cyanobacteria, but mainly diatoms, the latter were studied applying the scanning electron microscope and the optical microscope. The morphological characteristics observed in the optical microscope and in the scanning electron microscopy indicate the presence of diatoms of the Bacillariophyceae class, represented by Sellaphora disjuncta (55%), Achnanthes brevipes var. intermedia (45%). This diatom present in thermophilic microbial mats in the sulphurous geothermal zone of Comanjilla represents: a) the first report of said microorganisms in the study area and Mexico; b) an ecosystem of great interest from the biotechnological and industrial point of view; c) an important taxon in terms of diversity and technology; d) an applications in biofuels, environmental monitoring, wastewater treatment, manufacture of fertilizers, production of secondary metabolites, medical compounds, energy sources and food industry and within nanotechnology. It is important to mention that the physical and chemical characteristics of thermal water such as temperature, pH, dissolved solids, electrical conductivity, hardness, alkalinity and silica concentrations, were the major environmental factors influencing the distribution of diatoms in sulphurous hot springs
Seamless Switching Technology of UPQC Based on Improved Power Angle Control
Get PDFThis paper presents a novel seamless switching technology between different operating conditions of the Unified Power Quality Conditioner (UPQC) with the energy storage system. Frequent start and stop of the series inverter will cause shock and loss under the conventional control method. Moreover, it is a key issue to achieve seamless switching when the UPQC operating condition changes. This paper proposes an improved power angle control (PAC) method to solve these problems. An agile power angle is calculated by this method under stable operating conditions. This feature enables the series inverter to share the load reactive power with the shunt inverter. On the other hand, both the series and shunt inverters are in an easy-to-switch operating state which can help achieve better seamless switching between different operating conditions. Simulation results show the shunt inverter capacity can be reduced up to 47% due to the reactive power sharing by both the inverters which means the reactive power burden of the shunt inverter is great lightened. It is also found that the switching time is about 300μs faster and the maximum voltage fluctuation amplitude is about 90V smaller under improved PAC than the conventional control method