Theoretical Analysis and Numerical Simulation of Spectral Radiative Properties of Combustion Gases in Oxy/Air-Fired Combustion Systems

Energy efficiency is one of the major objectives which should be achieved in order to implement the limited energy resources of the world in a sustainable way. Since radiative heat transfer is the dominant heat transfer mechanism in most of fossil fuel combustion systems, more accurate insight and models may cause improvement in the energy efficiency of the new designed combustion systems. The radiative properties of combustion gases are highly wavelength dependent. Better models for calculating the radiative properties of combustion gases are highly required in the modeling of large scale industrial combustion systems. With detailed knowledge of spectral radiative properties of gases, the modeling of combustion processes in the different applications can be more accurate. In order to propose a new method for effective non gray modeling of radiative heat transfer in combustion systems, different models for the spectral properties of gases including SNBM, EWBM, and WSGGM have been studied in this research. Using this detailed analysis of different approaches, the thesis presents new methods for gray and non gray radiative heat transfer modeling in homogeneous and inhomogeneous H2O–CO2 mixtures at atmospheric pressure. The proposed method is able to support the modeling of a wide range of combustion systems including the oxy-fired combustion scenario. The new methods are based on implementing some pre-obtained correlations for the total emissivity and band absorption coefficient of H2O–CO2 mixtures in different temperatures, gas compositions, and optical path lengths. They can be easily used within any commercial CFD software for radiative heat transfer modeling resulting in more accurate, simple, and fast calculations. The new methods were successfully used in CFD modeling by applying them to industrial scale backpass channel under oxy-fired conditions. The developed approaches are more accurate compared with other methods; moreover, they can provide complete explanation and detailed analysis of the radiation heat transfer in different systems under different combustion conditions. The methods were verified by applying them to some benchmarks, and they showed a good level of accuracy and computational speed compared to other methods. Furthermore, the implementation of the suggested banded approach in CFD software is very easy and straightforward.

Mikä on air-fligt-periaate?

kuv., 14 x 22 cm

Mikä on air-fligt-periaate?

kuv., 14 x 22 cm

Air policing turvallisuuspoliittisena kysymyksenä Suomessa

Tutkimuksessa tarkastellaan air policingia turvallisuuspoliittisena kysymyksenä Suomessa, Islannin ilmavalvontahankkeen kautta. Tavoitteena oli selvittää Islannin ilmavalvonnasta käydyn julkisen keskustelun perusteella, miten air policing näyttäytyy Suomen turvallisuuspolitiikassa. Air policingilla tarkoitetaan vieraan suvereenin valtion ilmatilan koskemattomuuden valvontaa ja turvaamista rauhan aikana. Suomen turvallisuuspolitiikassa air policing on aiemmin käyttämätön työväline. Tutkimuksessa analysoitiin Suomessa käytyä julkista keskustelua Islannin ilmavalvonnasta. Keskustelua tutkittiin puolustusvoimien lakisääteisten tehtävien ja Suomen sotilaallisen liittoutumattomuuden näkökulmista. Tarkastelujen perusteella tehtiin johtopäätöksiä air policingista Suomen turvallisuuspoliittisena kysymyksenä. Tutkimuksen aineisto koostui Islannin ilmavalvontaa käsittelevistä Helsingin Sanomien, Uuden Suomen, Kylkiraudan ja Sotilasaikakauslehden kirjoituksista, eduskunnan täysistuntojen pöytäkirjoista sekä keskeisten turvallisuuspoliittisten päättäjien lausunnoista. Tarkasteltava ajanjakso oli vuoden 2009 alusta vuoden 2012 loppuun. Tutkimusmenetelmä oli sisällönanalyysi. Islannin ilmavalvonnasta käyty julkinen keskustelu koostui lyhyestä jaksosta vuonna 2009 sekä vilkkaasta ja laaja-alaisesta keskustelusta vuonna 2012. Tärkeimpiä sisältöteemoja olivat Nato ja Suomen liittoutumattomuus sekä pohjoismainen yhteistyö. Keskustelussa muodostui vastakkainasettelu, jossa toinen mielipide kannatti ja toinen vastusti Suomen osallistumista Islannin ilmavalvontaan. Puolustusvoimien lakisääteisiä tehtäviä käsiteltiin julkisuudessa vähän. Sen sijaan Suomen sotilaallinen liittoutumattomuus oli keskustelun ytimessä. Islannin ilmavalvontahankkeen kriitikot katsoivat osallistumisen vaarantavan Suomen liittoutumattomuuden Islannin Nato-jäsenyyden vuoksi. Hankkeen kannattajat perustelivat osallistumisen olevan osan tiivistyvää pohjoismaista puolustusyhteistyötä. Suomen ylin turvallisuuspoliittinen johto on ollut valmis ottamaan käyttöön air policingin Islannin ilmavalvontahankkeen yhteydessä. Kysymys on osoittautunut poliittisesti vaikeaksi, eikä konsensusta ole saavutettu. Maaliskuussa 2013 näyttää siltä, että mahdollinen osallistuminen Islannin ilmavalvontaan toteutuu harjoitusmuotoisena, jolloin siinä ei ole kyse varsinaisesta air policingista.

Static pressure and wall shear stress distributions in air flow in a seven wire-wrapped rod bundle

An experimental investigation is performed in a turbulent flow in a seven wire-wrapped rod bundle, mounted in an open air facility. Static pressure distributions are measured on central and peripheral rods. By using a Preston tube, the wall shear stress profiles are experimentally obtained along the perimeter of the rods. The geometric parameters of the test section are P/D=1.20 and H/D=15. The measuring section is located at L/D=40 from the air inlet. It is observed that the dimensionless static pressure and wall shear stress profiles are nearly independent of the Reynolds number and strongly dependent of the wire-spacer position, with abrupt variations of the parameters in the neighborhood of the wires.

Indoor air quality at a waste incineration plant in Finland

Waste has been incinerated for energy utilization for more than a hundred years, but the harmful emissions emitted from the incineration plants did not begin to cause concern until the 1980s. Many plants were shutdown and the waste incineration plant in Kyläsaari Helsinki was one of them. In later years, new landfill regulations have increased the interest in waste incineration. During the last year, four new plants were taken into operation in Finland, Westenergy in Vaasa among them. The presence of dust has been observed indoors at Westenergy waste incineration plant. Dust is defined as particles with a diameter above 10 μm, while fine particles have a diameter smaller than 2.5 μm, ultrafine under 0.1 μm and nanoparticles under 0.05 μm. In recent years, the focus of particle health research has been changed to investigate smaller particles. Ultrafine particles have been found to be more detrimental to health than larger particles. Limit values regulating the concentrations of ultrafine particles have not been determined yet. The objective of this thesis was to investigate dust and particles present inside the Westenergy waste incineration facility. The task was to investigate the potential pollutant sources and to give recommendations of how to minimize the presence of dust and particles in the power plant. The total particle number concentrations and size distributions where measured at 15 points inside the plant with an Engine Exhaust Particle Sizer (EEPS) Spectrometer. The measured particles were mainly in the ultrafine size range. Dust was only visually investigated, since the main purpose was to follow the dust accumulation. The measurement points inside the incineration plant were chosen according to investigate exposure to visitors and workers. At some points probable leakage of emissions were investigated. The measurements were carried out during approximately one month in March–April 2013. The results of the measurements showed that elevated levels of dust and particles are present in the indoor air at the waste incineration plant. The cleanest air was found in the control room, warehouse and office. The most polluted air was near the sources that were investigated due to possible leakage and in the bottom ash hall. However, the concentrations were near measured background concentrations in European cities and no leakage could be detected. The high concentrations were assumed to be a result of a lot of dust and particles present on surfaces that had not been cleaned in a while. The main source of the dust and particles present inside the waste incineration plant was thought to be particles and dust from the outside air. Other activities in the area around the waste incineration facility are ground work activities, stone crushing and traffic, which probably are sources of particle formation. Filtration of the outside air prior entering the facility would probably save personnel and visitors from nuisance and save in cleaning and maintenance costs.

[Air de Laodice]

Soitinnus: lauluääni (sopraano), piano.

Leaf contents of nitrogen and phenolic compounds and their bearing with the herbivore damage to Tibouchina pulchra Cogn. (Melastomataceae), under the influence of air pollutants from industries of Cubatão, São Paulo

The Atlantic Forest on the slopes of Serra do Mar around Cubatão (São Paulo, Brazil) has been affected by massive emissions of pollutants from the local growing industrial complex. The effects of air pollution on the amounts of leaf nitrogen, total soluble phenols and total tannins of Tibouchina pulchra Cogn., a common species in the area of Cubatão, were investigated, as well as the possible influence of the altered parameters on the leaf area damaged by herbivores. Fully expanded leaves were collected at two sites: the valley of Pilões river (VP), characterized by a vegetation virtually not affected by air pollution and taken as a reference; and valley of Mogi river (VM), close to the core region of the industrial complex, and severely affected by air pollution. No differences were observed for any parameters between samples collected in the summer and winter in both sites. On the other hand, compared to VP, individuals growing in VM presented higher amounts of nitrogen and lower amounts of total soluble phenols and total tannins, as well as higher percentages of galls per leaf and higher leaf area lost to herbivores. Regression analysis revealed that the increase in leaf area lost to herbivores can be explained by the increase of the content of nitrogen and decrease in the contents of total soluble phenols and total tannins. Although significant, the coefficients of explanation found were low for all analyses, suggesting that other biotic or abiotic factors are likely to influence leaf attack by herbivores.

Nutrient cycling disturbance in Atlantic Forest sites affected by air pollution coming from the industrial complex of Cubatão, Southeast Brazil

Several aspects of nutrient cycling were studied at two sites of Atlantic Forest, in São Paulo State, Southeast Brazil (23o46’ S; 46o18’ W), which exhibited different degrees of forest structure decline caused by the air pollution emitted by the industrial complex of Cubatão, being referred here as the most and least affected sites (MAS and LAS, respectively). These investigations were developed during 1984 - 1986, a period in which the most severe negative effects of air pollution could be observed. Concentrations and amounts of N, P, K, Ca, Mg and S in four ecosystem compartments (leaves, litter layer, soil and roots) and in rainfall, throughfall and litterfall are briefly presented. At each site, the content of mineral elements generally decreased from leaves to litterfall and litter layer on the forest floor. Soil surface layer (0 - 5 cm) in both sites was the richest in mineral elements. Soil fertility was greater at LAS. In general, nutrient amounts remaining in the compartments and cycling through the ecosystem were greater at LAS as well, which could be due to the higher complexity of the forest structure at this site. Rainfall contributed more to soil inputs of K, Ca, Mg and S than litterfall at both sites. The nutrient residence times in the litter layer were higher and the index of nutrient use efficiency was lower at the most affected site. It was concluded that nutrient cycling was disturbed by air pollution at both sites, but to a greater extent at MAS. The main consequences of the air pollution stress were detected in the flux of nutrients through litterfall and in the litter layer on the forest floor.

Influence of air temperature on proteinase activity and beverage quality in Coffea arabica

Fruits were collected from trees of Coffea arabica cv. Obatã grown at Mococa and Adamantina in São Paulo State, Brazil, which are regions with marked differences in air temperature that produce coffee with distinct qualities. Mococa is a cooler location that produces high-quality coffee, whereas coffee from Adamantina is of lower quality. The amino acid and protein contents, amino acid profile, and proteinase activity and type in endosperm protein extracts were analysed. Proteinase genes were identified, and their expression was assayed. All results indicate that temperature plays a role in controlling proteinase activity in coffee endosperm. Proteinase activity was higher in the endosperm of immature fruits from Adamantina, which was correlated with higher amino acid content, changes in the amino acid profile, and increased gene expression. Cysteine proteinases were the main class of proteinases in the protein extracts. These data suggest that temperature plays an important role in coffee quality by altering nitrogen compound composition.

Effects of formaldehyde on the frog's mucociliary epithelium as a surrogate to evaluate air pollution effects on the respiratory epithelium

The increasing use of alcohol as an alternative fuel to gasoline or diesel can increase emission of formaldehyde, an organic gas that is irritant to the mucous membranes. The respiratory system is the major target of air pollutants and its major defense mechanism depends on the continuous activity of the cilia and the resulting constant transportation of mucous secretion. The present study was designed to evaluate the effects of formaldehyde on the ciliated epithelium through a relative large dose range around the threshold limit value adopted by the Brazilian legislation, namely 1.6 ppm (1.25 to 5 ppm). For this purpose, the isolated frog palate preparation was used as the target of toxic injury. Four groups of frog palates were exposed to diluted Ringer solution (control, N = 8) and formaldehyde diluted in Ringer solution at three different concentrations (1.25, 2.5 and 5.0 ppm, N = 10 for each group). Mucociliary clearance and ciliary beat frequency decreased significantly in contact with formaldehyde at the concentrations of 2.5 and 5.0 ppm after 60 min of exposure (P<0.05). We conclude that relatively low concentrations of formaldehyde, which is even below the Brazilian threshold limit value, are sufficient to cause short-term mucociliary impairment.

In situ variation of cervical mucus pH during exposure to atmospheric air

The objective of the present study was to determine if exposure of cervical mucus to air during specular examination could modify mucus pH. Detection of changes is justified because of their possible interference with sperm-mucus interaction, since an acidic pH is unfavorable to sperm penetration and is associated with infertility due to the cervical factor. Twenty women with good quality mucus were evaluated. pH measurements of ecto- and endocervical mucus were made in situ using a glass electrode after 0-, 5- and 10-min exposure to air. There was a progressive alkalinization of mucus pH. Mean values of ectocervical mucus pH were 6.91, 7.16 and 7.27, while mean values of endocervical mucus pH were 7.09, 7.34 and 7.46 at 0, 5 and 10 min, respectively. Significant differences were found between the mean values obtained at 0 and 5 min, and at 0 and 10 min (P<0.05), whereas the differences in mean values at 5 and 10 min were not significant at either site. We conclude that 5 to 10 min of exposure to atmospheric air affects cervical mucus pH in a significant way. Since tests used to evaluate sperm-mucus interaction generally have not considered this possibility, we suggest that they should be performed immediately after mucus collection in order to avoid misinterpretation of the results.

Different biochemical strategies of two Neotropical fish to cope with the impairment of nitrogen excretion during air exposure

The exposure of fish to air is normally expected to interfere with the nitrogen excretion process. Hoplias malabaricus and Hoplerythrinus unitaeniatus, two teleost species, display distinct behaviors in response to decreases in natural reservoir water levels, although they may employ similar biochemical strategies. To investigate this point, plasma levels of ammonia, urea, uric acid, and the two urea cycle enzymes, ornithine carbamoyl transferase (OCT) and arginase (ARG), as well as glutamine synthetase (GS) were determined for both species after exposure to air. Plasma ammonia increased gradually during exposure to air, but only H. malabaricus showed increased concentrations of urea. Plasma uric acid remained very low in both fish. Enzymatic activities (mean ± SD, µmol min-1 g protein-1) of H. malabaricus showed significant increases (P<0.05, N = 6) in OCT from 0.84 ± 0.05 to 1.42 ± 0.03, in ARG from 8.07 ± 0.47 to 9.97 ± 0.53 and in GS from 1.15 ± 0.03 to 2.39 ± 0.04. The OCT and ARG enzymes remained constant in H. unitaeniatus (N = 6), but GS increased from 1.49 ± 0.02 to 2.06 ± 0.03. Although these species are very closely related and share the same environment, their biochemical strategies in response to exposure to air or to increased plasma ammonia are different.

Comparative performance of two air samplers for monitoring airborne fungal propagules

Many studies have attempted to evaluate the importance of airborne fungi in the development of invasive fungal infection, especially for immunocompromised hosts. Several kinds of instruments are available to quantitate fungal propagule levels in air. We compared the performance of the most frequently used air sampler, the Andersen sampler with six stages, with a portable one, the Reuter centrifugal sampler (RCS). A total of 84 samples were analyzed, 42 with each sampler. Twenty-eight different fungal genera were identified in samples analyzed with the Andersen instrument. In samples obtained with the RCS only seven different fungal genera were identified. The three most frequently isolated genera in samples analyzed with both devices were Penicillium, Aspergillus and Cladophialophora. In areas supplied with a high efficiency particulate air filter, fungal spore levels were usually lower when compared to areas without these filters. There was a significant correlation between total fungal propagule measurements taken with both devices on each sampling occasion (Pearson coefficient = 0.50). However, the Andersen device recovered a broader spectrum of fungi. We conclude that the RCS can be used for quantitative estimates of airborne microbiological concentrations. For qualitative studies, however, this device cannot be recommended.

Air pollution and neonatal deaths in São Paulo, Brazil

Air pollution has been associated with health effects on different age groups. The present study was designed to assess the impact of daily changes in air pollutants (NO2, SO2, CO, O3, and particle matter (PM10)) on total number of daily neonatal deaths (those that occur between the first and the 28th days of life) in São Paulo, from January 1998 to December 2000, since adverse outcomes such as neonatal deaths associated with air pollution in Brazil have not been evaluated before. Generalized additive Poisson regression models were used and nonparametric smooth functions (loess) were adopted to control long-term trend, temperature, humidity, and short-term trends. A linear term was used for holidays. The association between air pollutants and neonatal deaths showed a short time lag. Interquartile range increases in PM10 (23.3 µg/m³) and SO2 (9.2 µg/m³) were associated with increases of 4% (95% CI, 2-6) and 6% (95% CI, 4-8), respectively. Instead of adopting a two-pollutant model we created an index to represent PM10 and SO2 effects. For an interquartile range increase in the index an increase of 6.3% (95% CI, 6.1-6.5) in neonatal deaths was observed. These results agree with previous studies performed by our group showing the deleterious effects of air pollutants during the perinatal period. The method reported here represents an alternative approach to analyze the relationship between highly correlated pollutants and public health problems, reinforcing the idea of the synergic effects of air pollutants in public health.