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Dažniausiai inversijos sąlygos pavojingos miestams/ didmiesčiams, kurių didžiausias teršalų kiekis išmetamas dienos metu, o naktį teršalams išsisklaidyti trukdo inversijos reiškinys, kuris išsilaiko iki paryčių. Todėl yra svarbu kuo aiškiau apibrėžti inversijos sąlygų susidarymo priežastis ir išanalizuoti šio reiškinio įtaką miesto taršai. Taigi šіo dаrbo tіkѕlаѕ – nuѕtаtytі temperаtūroѕ іnverѕіјoѕ dėѕnіngumų įtаkа oro teršаlų ѕklаіdаі Kаuno mіeѕte. Pagrindiniai uždaviniai: nuѕtаtytі temperаtūroѕ іnverѕіјoѕ dėѕnіngumą pаroјe ѕkіrtіngаіѕ metų lаіkаіѕ, tuomet іšаnаlіzuotі temperаtūroѕ іnverѕіјoѕ įtаką teršаlų koncentrаcіјаі іr ѕtаtіѕtіškаі įvertіntі ryšіnę prіklаuѕomybę tаrp šіų rodiklių, taip pat įvertіntі kіtų meteorologіnіų rodiklių įtаką temperаtūroѕ іnverѕіјoѕ formаvіmuіѕі beі teršаlų pаѕіѕkіrѕtymuі kartu įvertinant oro teršalų koncentracijų ribinių verčių dinamiką 2006-2008 metais. Pagrindinis darbo metodas - duomenų analizė ir jų statistinių sąryšių kiekybinis įvertinimas. Atlikus tyrimą paaiškėjo kad, naktinės temperаtūroѕ іnverѕіјoѕ reіškіnyѕ Kаuno mіeѕte pаѕіreіškіа bet kurіuo metų lаіku іr ѕkіrіаѕі tіk vertіkаlаuѕ temperаtūroѕ grаdіento аmplіtudė. Taip pat nustatytos teigiamos vidutinio stiprumo teršalų koncentracijos priklausomybės nuo temperatūros inversijos išskyrus SO2. Be to nustatyta, kad KD10 koncentracija 2006 -2008 metų kovo pabaigoje ir balandžio pradžioje pasiekia didžiausią lygį ir viršija leistiną paros koncentracijos vertę, kai NO2 koncentracija ore... [toliau žr. visą tekstą] / Most inversion conditions dangerous cities / cities with the highest emissions of pollutants during the day and night to disperse pollutants prevents inversion phenomenon, which exists to morning. It is important to clarify the reasons for the formation of inversion conditions and analyze the impact of the phenomenon of urban pollution. The main thesis goal is to identify temperature inversions conditions and its impaction to the spread of pollutant Main tasks: identify temperature inversion phenomenon in different cycles of year, then calculate temperature inversion and pollutants correlation plus to analyze the concentration amount of pollutants in 2006- 2008 years. The method used for this investigation is the analysis of the data correlations calculation. The investigation revealed that temperature inversion exist on all cycles of year and detectable on night. Also the positive dependence of pollutant concentration to temperature inversion is detected, with the exception of SO2. In addition, it was found that the concentration of KD10 exceeded maximum values on 2006 -2008 in the end of March and beginning of April. What is more, NO2 concentration in air exceeds its level a several times a year and this is the signal for our health.

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Thesis (PhD (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2003. / The thermal performance prediction of wet-cooling towers is critically analyzed and refined. Natural draft counterflow towers and mechanical draft counterflow and crossflow towers are considered. The Merkel, Poppe and e-NTU heat and mass transfer methods of analysis are derived from first principles, as these methods form the cornerstone of wet-cooling tower performance evaluation. The critical differences between these methods, when applied to fill performance analyses and cooling tower performance evaluations, are highlighted. The reasons for these differences are discussed with the aid of psychrometric charts. A new extended empirical relation for the loss coefficient of fills is proposed where the viscous and form drag effects are accounted for as well as the buoyancy, momentum and fill height effects. The empirical equation for the transfer characteristic of fills is extended to include the effects of fill height and the inlet water temperature. Empirical equations to predict the temperature inversion profile, height of the temperature inversion and the height from which air is drawn into the cooling tower are developed. The influence of temperature and humidity inversions on the performance of wet-cooling towers is subsequently investigated. A comprehensive analytical computer program is developed to predict and optimize the performance of wet-cooling towers. Computer programs are also developed to generate cooling tower performance curves, analyze fill performance test data and plot psychrometric charts.

Thesis (PhD (Mechanical and Mechatronic Engineering))-- University of Stellenbosch, 2007. / ENGLISH ABSTRACT: The dissertation builds on previous research (Pretorius, 2004) and investigates the optimization and control of a large-scale solar chimney power plant. Performance results are based on a reference location near Sishen in South Africa and a so-called reference solar chimney power plant, with a 5000 m collector diameter and a 1000 m high, 210 m diameter chimney. The numerical simulation model is refined and used to perform a sensitivity analysis on the most prominent operating and technical plant specifications. Thermo-economically optimal plant configurations are established from simulation results and calculations according to an approximate plant cost model. The effects of ambient wind, temperature lapse rates and nocturnal temperature inversions on plant performance are examined. Various new technologies are investigated for the purpose of controlling plant output according to specific demand patterns. The incorporation of vegetation under the collector roof of the plant and the influence thereof on plant performance is also explored. Results indicate that, through the modification of the collector roof reflectance, collector roof emissivity, ground surface absorptivity or ground surface emissivity, major improvements on plant performance are possible. Introducing thermal insulation or double glazing of the collector roof also facilitates substantial enhancements on plant yield. Simulations predict a notable sensitivity to the ground surface absorptivity value, while variable atmospheric temperature lapse rates and windy ambient conditions may impair plant performance significantly. Furthermore, sand is found to be unsuitable as plant ground type and thermoeconomically optimal solar chimney plant dimensions are determined to be generally larger than plant dimensions employed in previous studies. Good dynamic control of solar chimney power output is established, suggesting that a solar chimney power plant can be implemented as a base or peak load electricity generating facility. Lastly, results predict that vegetation, when provided with sufficient water, will be able to survive under the collector roof but the inclusion of vegetation will however cause major reductions in plant performance. / AFRIKAANSE OPSOMMING: Die proefskrif bou op vorige navorsing (Pretorius, 2004) en ondersoek die optimering en beheer van 'n grootskaalse sonskoorsteen-kragstasie. Uitsetresultate word baseer op 'n verwysingsligging naby Sishen in Suid-Afrika en 'n sogenaamde verwysingskragstasie, met 'n kollektor deursnee van 5000 m en 'n 1000 m hoë, 210 m deursnee skoorsteen. Die numeriese rekenaarmodel is verbeter en gebruik vir die uitvoering van 'n sensitiwiteits-analise op die belangrikste bedryfs- en tegniese kragstasie spesifikasies. Termo-ekonomiese optimale aanlegkonfigurasies is bepaal volgens die uitsetresultate van die rekenaarmodel en benaderde aanleg-kosteberekeninge volgens 'n eenvoudige kostemodel. Die invloed van wind, atmosferiese temperatuur gradiënte en nagtelike temperatuur inversies op kragstasie uitset word beskou. Verskeie nuwe tegnologië word ondersoek met die doel om aanleg uitset te kan beheer volgens spesifieke elektrisiteit aanvraagspatrone. Die inkorporasie van plantegroei onder die kollektordak, en die invloed daarvan op kragstasie uitset, word ook beskou. Bevindings dui aan dat, deur die wysiging van die kollektordak refleksie, kollektordak emissiwiteit, grondoppervlak absorptiwiteit of grondoppervlak emissiwiteit, groot verbeterings op aanleg uitset moontlik is. Die implementering van termiese isolasie of 'n dubbelglaslaag vir die kollektordak veroorsaak ook 'n beduidende verheffing in kragstasie uitset. Simulasies voorspel 'n merkbare sensitiwiteit teenoor die grondoppervlak absorptiwiteitswaarde, terwyl veranderlike atmosferiese temperatuur daaltempos en winderige omgewingstoestande aanleg uitset beduidend mag belemmer. Verder is bevind dat sand ongeskik is as aanleg grond tipe en dat termo-ekonomiese optimale sonskoorsteen-kragstasie dimensies in die algemeen groter is as die aanvaarde aanlegdimensies van vorige studies. Goeie dinamiese beheer van sonskoorsteen-kragstasie uitset is bevestig, wat suggereer dat die sonskoorsteenkragstasie as 'n basis of pieklas elektrisiteitopwekkings-aanleg ingespan kan word. Ten laaste voorspel resultate dat plantegroei, mits dit voorsien word van genoegsame water, sal kan oorleef onder die kollektordak maar dat die inkorporasie van plantegroei die aanleg uitset beduidend sal benadeel. / Sponsored by the Centre for Renewable and Sustainable Energy Studies