AN APPLICATION OF CALPUFF DISPERSION MODEL TO A NON-STANDARD PROBLEM
Pulp and paper mill situated in the complex terrain of northern Slovakia, in the close vicinity of the city of Ružomberok, continuously releases to atmosphere 30 kg of water vapor per second. Impressive clouds above the industrial complex have given rise to concerns from the side of local citizens, suspecting the emissions to be responsible for the local increase in precipitation. Therefore, a complex study has been initiated, including model simulation of the dispersion of water vapor from the paper mill focused on the domain of 8 x 7 km in close vicinity of the paper mill. Phase conversions of water vapor in the atmosphere are a complex thermodynamic process involving many factors. However, we found out that for some practical applications a simplified approach is sufficient to assess the magnitude of the above mentioned effects. A combination of CALMET-CALPUFF models were applied to compute hourly concentrations of water vapor added to the atmosphere by emissions from the paper mill; these were compared to the hourly absolute humidity values as measured by the meteorological stations in the region, which are not supposed to be affected by the paper mill. The interest was focused on those hours in which the “background” absolute humidity was below saturation value, but additional vapor from the paper mill would bring the value to or above the saturation point. Winter periods of two years (2005, 2006) were modeled and analyzed, during which 66 hours occurred when the additional water from the paper mill caused the humidity to exceed the saturation point, compared to 478 hours with 100% background relative humidity, when the additional vapor from the mill could possibly strengthen the icing effect which would occur anyway. The study concludes that the contribution of the paper mill to total precipitation is negligible even in the close vicinity of the factory. However, in certain cases it can cause icings on a nearby E50 road communication; although these cases are not frequent, they can lead to fatal outcomes. The uncertainties associated with the study method are also discussed.
Coalescence Enhancement in large Multicell Storms Caused by the Emissions from a Kraft Paper Mill
Abstract While conducting a randomized seeding experiment, a storm was selected whose microphysical characteristics were so far from what was expected, given the existing thermodynamic environment, that some explanation was needed to account for the apparent errant behavior of this storm. More than a decade of sampling at −10°C using the project Lear jet has led to a simple classification technique, based on cloud-base temperature and buoyancy, which predicts the absence or presence, and to some extent the degree of coalescence (coalescence-freezing) precipitation growth in local convective storms. The unusual nature of this storm was recognized against this extensive microphysical database. The probable cause is attributed to emissions from a Kraft paper mill 10 km south of the storm's position. The mill had recently undergone an expansion program that had quadrupled its output of paper products. Using the radar characteristics of this unusual storm as a guide, a search of one season of radar data reveal...
Particulate emissions from ‘in-use’ motor vehicles—II. Diesel vehicles
A detailed study has been undertaken of the exhaust particulate matter (EPM) emitted by 19 light-duty and 13 heavy-duty diesel vehicles. Eighteen of the light-duty vehicles were of the indirect injection types, whereas the heavy-duty ones were all four stroke. The light-duty vehicles were tested under a standard city drive cycle, the heavy-duty vehicles being subjected to a multi-mode test cycle. Although considerable variability was found in emission rates between individual vehicles of the same make and model, light-duty diesel vehicles emitted 3–6 g EPM kg−1 of fuel consumed, which was six times as much as spark ignition (S.I.) vehicles. The heavy-duty diesel vehicles emitted most EPM, giving rise to >6.6g EPM kg−1 on average. For both classes of diesel vehicles, higher EPM rates were generally associated with higher CO emission rates. Light-duty diesel EPM was found to consist mostly of C, two-thirds of which was in the ‘sooty’ or elemental (EC) form with the remainder organic (OC). The heavy-duty diesel EPM contained a higher proportion of OC than that from the light-duty diesels. Tests carried out with 13C-labelled lubricating oil indicated a significant oil contribution to EPM from diesel vehicles. In addition to measuring variations in EPM emission rates between different diesel vehicles, the influences of fuel supply, injection timing and fuel quality were also studied, using a light-duty indirect injection engine. Injection timing was found to have the greatest influence, with EPM emissions decreasing on retardation. The influence of injection timing was also assessed using a direct injection vehicle.