The solid dust, ammonia sulfide, condensate, water and other liquid substances carried by natural gas in the pipeline transport process do serious harm to the safe operation of pipelines and instrumentation equipment along the way. The performance of the filter installed in the natural gas station and the user entrance is the key to the quality and flow of gas supply. The performance of the filter element changes dynamically with the use. If the filter element cannot be cleaned and replaced in time, the passing efficiency of gas will be seriously affected and the local resistance will soar and the passing flow will drop sharply, thus causing the safety problem of gas supply. In this paper, based on the investigation and analysis of the working condition of natural gas filter in actual engineering, a numerical model of natural gas filter was established, and the flow field inside the filter was simulated by means of CFD tool. The research shows that the change of inlet velocity has a great influence on the filtering effect. When the inlet velocity is about 13m/s, the filtering effect is the best, reaching more than 96%. Under limited conditions, it is recommended to give priority to the replacement of the lower filter element.
Air compressor is an important sub-component in fuel cell systems. Previous experimental and numerical studies still cannot provide an effective method for the quick and deep modification for fuel cell centrifugal compressor structure. To improve the compressor pressure ratio and efficiency, this paper develops a novel artificial intelligence (AI) framework for fuel cell centrifugal compressors by integrating three-dimensional (3D) computational fluid dynamics (CFD) models, machine learning and genetic algorithm. Based on the simulated results, the surrogate model is developed, which is subsequently coupled with NSGA-III algorithm to find the Pareto-optimal front. A set of optimized parameters are obtained. Based on the CFD model, the performance of the optimized compressor is comprehensively compared with the original compressor design. It is found that the flow uniformity inside compressor is greatly enhanced, leading to a better performance.
In this paper, a three-dimensional multi-phase non-isothermal numerical model is formulated to investigate the applicability of MF (metal foam) as flow distributor in AAEM (alkaline anion exchange membrane) fuel cell. The performance of the cell with MF flow field is compared with that of the cell with traditional channel-rib structure (serpentine channel flow field), the simulation results clearly show that using MF as flow distributor improves the performance greatly, and the improvement gets more and more obvious as the current density increases. The transport and distribution of water (including liquid water, membrane water, and water vapor) and reactants are analyzed to illustrate the performance improvement, and the analysis results agree with the conclusion.
An effective battery thermal management system (BTMS) is of great significance to ensure safety and extend the service life for lithium-ion batteries (LIBs). In this paper, to obtain a more suitable operating temperature and a better temperature uniformity for the battery module, an ultrathin flat heat pipe-liquid cooling BTMS is proposed. The effect of different influence factors are investigated through the numerical simulation and the optimization is conducted on this basis. The results suggest that the heat can removed efficiently through the proposed BTMS, and the maximum temperature can be controlled below 43â„ƒ. Additionally, a variable heat pipe length scheme is proposed for the BTMS, which can significantly improve the temperature uniformity of the battery module. The average temperature difference can be controlled below 2â„ƒ under the high discharge and current changing discharge process in comparison with the original system. The study facilitates a guideline for the optimization design of a BTMS.
The purpose of present paper is to investigate the flow and heat transfer characteristics of single smooth or dimpled sphere in the square channel by numerical simulation. Three-dimensional Navier-Stokes equations and SST k-Ï‰ turbulence model are adopted for the simulations. The effects of channel to particle diameter ratio and particle surface shape were discussed and presented in the present paper. It is found that, with the same inlet velocity and particle surface shape, when the ratio of channel to particle diameter is less than 4, as W/D decreases, the drag coefficient and Nusselt number increases rapidly. In addition, compared with smooth sphere particles, the presence of dimples decrease flow drag. Furthermore, at Re=29000, although there is little difference of Nusselt number between smooth and dimpled particles, the surface heat transfer characteristics of different particles are quite different.
The carbon dioxide (CO2) emission patterns of urban areas are likely to be closely associated with urban form. Using geographical information of Los Angeles County, this study examines potential linkages between urban form and CO2 emission patterns. For this purpose, we rely on the Local Climate Zones (LCZ) classification system, which is a universal framework for classifying urban areas into different categories according to their urban form characteristics. Our purpose is to see if there are any associations between types of LCZ and emission patterns. First, we developed the LCZ map for the county. Next, we obtained information related to residential and commercial building CO2 emissions across different neighborhoods from the official database of county. Next, we linked the emission data to the LCZ map to estimate per hectare and per capita emissions of each LCZ type. Results show that, in most cases, different LCZ types feature similar per capita emission patterns. This is, particularly, the case for commercial emissions. In terms of residential buildings, however, LCZ NO. 9 that refers to sparsely built development type exhibits significantly higher per capita emissions. This support common arguments regarding the environmental footprints of urban sprawl. Overall, results of this study indicate that the LCZ-based urban carbon mapping can provide useful insights into emission patterns of different urban forms. However, further research is needed to gain a more comprehensive understanding.
A novel pumped thermal energy storage (PTES) system with a heat pump (HP) and an Organic Rankine Cycle (ORC) is built and investigated at the Energie Campus NÃ¼rnberg, Germany. The basic idea is that surplus electricity available during the day is converted into heat with the HP and stored in a sensible hot water thermal storage. This enables a shift of e.g. photovoltaic electricity from day to night, as the stored heat can be converted back into electricity with the ORC at night. In order to examine the economic efficiency of the system, a dynamic simulation was set up using the AnyLogic simulation software. For a small community of 40 houses, it was shown that under current german market conditions, no economic use is possible without a significant cost reduction of the PTES. However, taking into account current trends in the development of feed-in tariffs in Germany, an economic use will be possible within the next few years.
Energy generation and consumption is one of the most significant concerns for South Africaâ€™s growing economy. Efforts to monitor the countryâ€™s overall energy consumption revealed that the industrial sector consistently consumes the highest energy at just under 60%. Policies are informed by an understanding of the current consumption across sectors and also the ability to predict future consumption. It is therefore important to understand the energy consumption of the highest energy user.
This research investigates the characteristics of industrial sector energy consumption, and how it has evolved between the years 1992 and 2018. The findings show that the total industrial consumption is still increasing. Contrary to global behavior, the local industrial consumption is still dominated by Coal; Electricity; Gas and Petroleum products respectively. High intensity industries are still heavily reliant on fossil fuel, regardless of the carbon footprint and GHG effect. This points to cost and availability influence on consumption. Although there is great potential in renewable energy, it is only low-intensive industries that are shifting to new non-conventional energy sources. Further work is required to define non-specified industrial subsectors as they contribute more than 10% to the total industrial consumption, compared to less than 5% in international consumption trends.
Car ownership significantly impacts the patterns in household consumption and time use. In this study, combining microdata from national expenditure survey and time use survey, carbon emissions of 85 daily household activities covering 24 hours in the day are estimated from a novel time-use perspective for Japanese households with and without private car ownership, respectively. Results indicate that while households with cars on average have higher emissions from transportation-related activities, their daily emissions from non-transportation activities are lower than households without cars. Policies targeting consumption behavior should therefore be devised based on the different activity emission patterns of different households.
COVID-19 pandemic brought economic crisis, also in the building sector, with an increase of energy consumption in the residential sub-sector due to the more intensive use. The strategic plans put in place by the European Union to face this crisis look to environmental sustainability, by identifying the building as a key sector. In Italy, it has been offered a tax deduction of 110% (divided into 5 annual quotas) aimed at promoting energy efficiency measures for existing buildings, also for fulfilling the new requirements of the Directive EU 844/2018. This investigation aims to analyse – from energy, environmental and economic points of view – this new funding program. It will be shown how it leads to prefer energy efficiency measures characterized by the best energy performance, and not by the best cost/benefit ratio.