1,720,987 research outputs found
Fluid dynamic performances of a prototype solar chimney plant: analysis of experimental data and CFD modelling
No full textA pilot plant of a solar chimney was tested for about 7 months in a suburban area near Naples (Italy) from February to August 2020. The solar chimney is 5 m high with a square-shaped collector of 4.5 m length on each side. In this paper we report and analyse data with the aim to study the fluid dynamic performances. Correlations between air flow and ambient parameters (solar irradiance, temperature, and relative humidity) are studied. A CFD model is developed to simulate the thermal and fluid dynamic behavior of the chimney. Results are useful for a better knowledge of the performances of solar chimneys and their main operating parameters such as air velocity, flow rate, temperature, and residence time that are very useful for the correct design of solar chimneys both as electrical power plants and as atmospheric pollutant abatement plants
Sustainable Development of the Historic Centre of Naples: The Impact of Vehicular Traffic and Food Service Business on Air Quality
No full textMonitoring campaigns were carried out to assess the impact of vehicular traffic and food service business on the air quality in the historic centre of Naples. These campaigns monitored fine particles (FPs) from 20 to 1000 nm, using a condensation particle counter (CPC) in four connected streets, during a period of four weeks, from 7 November to 7 December 2019. Two streets were pedestrian only, while the others had average traffic. The following variables were considered while analysing the data—street geometry, and traffic and food service business emissions. The results showed prevalent air contamination, with some critical situations. The FP concentration values in the pedestrian streets were similar to the average values measured at the roadside of other European cities. However, the FP concentration values measured on the streets with average traffic, were twice that of their European counterparts. Spatial maps of FP concentration were produced to assess the impact of food service business emissions at the street level. The maps showed an insignificant contribution to FP pollution. However, it must be noted that emissions of the food service businesses were not measured at the roof top level in this study. The aspect ratio (H/W) played a relevant role on FP concentration, as an increase in aspect ratio correlated to an increase in FP concentration. These findings showed critical preliminary information for the sustainable development of the historic centre of Naples, which should be confirmed through a long-term monitoring campaign
The effect on air quality of lockdown directives to prevent the spread of SARS-CoV-2 pandemic in Campania Region-Italy: Indications for a sustainable development
Full text linkData on air quality collected by the regional network of fixed stations in the most urbanized areas of the Campania region in the south of Italy are examined. Two periods are considered: before and during the adoption of the main directives limiting human activities to fight the spread of SARS-CoV-2 infection. The first period is from 5 February to 5 March, and the second is from 13 March to 13 April. Meteorological conditions in the two periods were compared and significant differences were not observed. Therefore, the comparison of air quality data is feasible. During the second period, an intercontinental transport of particulate matter occurred. Data collected during this event (4 p.m. on 30 March to 4 p.m. on 31 March) were excluded from the analysis. The main reduction of pollutant concentration is observed for NO2 (-48% of the period average). PM10 shows a lower reduction (-17%). The PM2.5 average period concentration was quite constant, while the 98° percentile was reduced by -21%. Ozone shows, on the contrary, an increase in concentration due mainly to an increase in solar irradiation during the 2nd period, but also due to the decrease of NOx concentration. The reduction or the increase of pollutant concentration depends on the category of the station: background, industrial, residential, and traffic. In addition to air quality, the reduction of anthropogenic emissions is also studied. All the information available on the reduction of emissions from transport, industry, heating, and other main emissive sectors were collected. The results give useful insights for the development of air quality management policies that could be adopted when the sanitary emergency will end to guarantee the sustainable development of the Campania region
Atmospheric ship emissions in ports: A review. Correlation with data of ship traffic
No full textPorts represent a source of atmospheric pollutants that can contribute significantly to jeopardise air quality of port cities. NOx, SOx, PM and VOCs (Volatile Organic Compounds) are emitted by ships during manoeuvring in ports at arrival or departure and during hotelling when moored at wharves. Several methods exist to estimate emissions in function of ships’ activity and engine parameters. However, there is still a significant uncertainty in these calculations. This is a severe limitation to develop effective plans of mitigation of air pollution in port cities. In this paper data of NOx and PM10 emitted in port and traffic of passenger and commercial ships have been reviewed and critically analysed. All vessels are lumped into three categories: cruise, passenger ships other than cruise and commercial ships. Emissions have been correlated with traffic data per year: passengers, hours at hotelling and manoeuvring, calls and tons of goods transported. The result is a summary of regression equations that can be used for the estimation of ship emissions in ports based on traffic data. The analysis does not consider emissions of all the ancillary activities that take place at land inside a port like: upload and download of goods, vehicular traffic, manipulation of containers and others
Development of point sampling technology for identifying high-emitting vehicles in narrow and deep street canyons
No full textSide road measurements of fine particle (FP) concentrations were performed in two narrow and deep street canyons in the historic center of Naples using point sampling technology (PS). The FP concentration in the range of 20–103 nm was measured using a condensation particle number counter (CPC) with a 1 Hz frequency. Video recording was used to detect passing vehicles classified into three categories: motorcycles, cars, and light-duty vehicles. The two monitored streets were adjacent, with similar geometrics and orientation but different high- and low-traffic levels. FP concentration time series data were processed to identify concentration peaks generated by the exhausts of passing vehicles. A sensitivity analysis study was carried out to determine how data processing parameters could affect high-emitting vehicle (high emitter) identification. Once the optimum parameters were defined, the contribution of high emitters exhaust emissions to local air quality was assessed. The results showed that PS technology offered viable opportunities for application in narrow street canyons where deploying more common crossroad and top-down monitoring can be troublesome. However, some issues remain to be solved to accurately identify high emitterss in high-traffic cases. PS technology can be useful for developing effective air quality management policies in historical centres
Effect of balconies on air quality in deep street canyons
No full textThis study discusses the effect of balconies on the dispersion of vehicular pollutants inside a deep street
canyon and on the mass transfer rate between the canyon and the above atmosphere. 3D computational
fluid dynamics (CFD) simulations were performed considering the presence of balconies of different
dimensions in a deep street canyon with aspect ratio H/W 1⁄4 3. The effect of two geometrical parameters
has been investigated: the balcony depth and the horizontal distance between two balconies, the other
geometrical parameters remaining constant. CFD simulations have been carried out adopting the scale
adaptive simulation (SAS) model. Results show that the presence of balconies can determine a significant
modification in the flow field inside the street canyon with a less homogeneous dispersion of pollutants
emitted by vehicles circulating in the street and a less effective mass exchange with the above atmosphere.
At the present models developed to assess pollutant concentration levels in street canyons do not
consider the presence of balconies. As consequence, an underestimation of real concentration levels
could occur. Therefore, results obtained can give a contribution in the development of more feasible air
pollution models in urban areas at local scale, and useful information for design of building facades that
minimize the entrapping of vehicular pollutants at pedestrian level in street canyon
The historical trend of air pollution and its impact on human health in campania region (Italy)
No full textThe Campania region covers an area of about 13,590 km2 with 5.8 million residents. The area suffers from several environmental issues due to urbanization, the presence of industries, wastewater treatment, and solid waste management concerns. Air pollution is one of the most relevant environmental troubles in the Campania region, frequently exceeding the limit values established by European directives. In this paper, airborne pollutant concentration data measured by the regional air quality network from 2003 to 2019 are collected to individuate the historical trends of nitrogen dioxide (NO2), coarse and fine particulate matter with aerodynamic diameters smaller than 10 μm (PM10) and 2.5 μm (PM2.5), and ozone (O3 ) through the analysis of the number of exceedances of limit values per year and the annual average concentration. Information on spatial variability and the effect of the receptor category is obtained by lumping together data belonging to the same province or category. To obtain information on the general air quality rather than on single pollutants, the European Air Quality Index (EU-AQI) is also evaluated. A special focus is dedicated to the effect of deep street canyons on air quality, since they are very common in the urban areas in Campania. Finally, the impact of air pollution from 2003 to 2019 on human health is also analyzed using the software AIRQ+
Kinetics of sulphur compounds in waste tires pyrolysis
No full textLiquid phase pyrolysis of scrap tyres was carried out in a lab scale autoclave (300 cc) in the presence of 1,2,3,4-tetrahydronaphtalene (tetralin) as hydrogen donor. Experimental runs were carried out at T=380 and T=400°C and at 50 bar inert gas pressure. Liquid phase samples, withdrawn during the reaction runs, were analysed by GC–FPD technique to follow the fate of sulphur compounds. Gas phase was withdrawn at the end of each run and analysed by GC–FPD and GC–TCD. During the pyrolysis process, sulphur compounds undergo formation and consumption reactions. The fate of sulphur compounds has been modelled on the basis of a two-step reaction mechanism. Kinetic constants of sulphur compound reactions were evaluated lumping all sulphur compounds in a single group. Only about 1% of sulphur present in the loaded tyre was detected in the liquid phase, the remaining being released as H2S in the gas phase
A CFD Model to Assess the Impact of Cruise Ship Emissions in the Port of Naples
No full textThe port of Naples is one the most important in the Mediterranean Sea for passengers’ traffic. Due to the proximity of the port to the urban area, ship emissions can have an important impact on air pollution in Naples. The presence of buildings very near to the docks can modify significantly the wind field and, as a consequence, the transport of pollutants emitted when ships are at berth. Models (Calpuff, SPRAY) normally adopted to assess the impact of ship emissions do not take in account this effect. For this reason, a CFD model was developed to assess the impact of cruise ship emissions during the hoteling phase in the port of Naples. A calculation domain of about 7 km2 × 1 km height with 10 million cells has been created. Unsteady CFD simulations have been carried out adopting the Scale Adaptive Simulation (SAS) hybrid model that allows a satisfactory accuracy in the calculation of the turbulence. In particular, the impact of SO2 emissions on seafront building facades and inside the port area are evaluated. Some differences between the results of the CFD model and those obtained by CALPUFF are observed. The CFD model, taking in count the presence of buildings, gives more reliable results about the dispersion of pollutant
Using a CFD model to assess the impact of cruise ship emissions on the façades of waterfront buildings in Naples, Italy
No full textThe port of Naples, with about 1 million of cruise passengers corresponding to about 400 calls and 5000
hours at berth per year, is one the most important in the Mediterranean Sea for cruise ships traffic.
Therefore, cruise ship emissions can have an important impact on air pollution in Naples. Moreover,
cruise ships terminal is very near to the center of the town, with some residential and commercial
buildings at only about 200 m from cruise ships docks. The height of these buildings is very close to
that of cruise ship funnels. Therefore, the impact of cruise ship emissions on the façades of these
buildings may be very high, with negative consequences for indoor air quality and health of people
living or working in these buildings. For this reason, a CFD model has been developed with the aim to
assess the impact of atmospheric pollutants emitted by cruise ships at hoteling on the façades of the
nearest buildings. A calculation domain of about 7 km2 and 1 km height with 10 million cells has been
created. Unsteady CFD simulations have been carried out adopting the Scale Adaptive Simulation
(SAS) hybrid model that allows a satisfactory accuracy in the calculation of the turbulence. Most critical
emissive scenarios have been identified based on cruise ships traffic assuming wind flowing from cruise
ships at berth toward the buildings. Emission rates of each pollutant and each cruise ship, during the
hoteling phase, have been evaluated. These data were used as input for CFD simulations. As a result,
contour maps of SO2 on the ground and on the buildings’ façade were obtained. Results of CFD model
are compared with results of simulations with CALPUFF
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