Heat Transfer in Industrial Applications—PRES 2008

This editorial provides an overview of a special issue dedicated to the 11th Conference on Process Integration, Modeling, and Optimization for Energy Saving and Pollution Reduction—PRES 2008. Nine papers have been selected and peer-reviewed covering important subjects of heat transfer engineering. They focus on recent development of various features of heat transfer equipment design and optimization. This issue of Heat Transfer Engineering is the sixth special journal issue dedicated to selected papers from PRES conferences [1 Kleme?, J. and Stehlik, P. 2002. PRES Conference—Challenges in Complex Process Heat Transfer. Heat Transfer Engineering, vol. 23: 1–2.  [Google Scholar], 2 Stehlík, P. and Kleme?, J. 2004. Selected Papers from the PRES 2002 Conference. Heat Transfer Engineering, vol. 25: 1–3.  [Google Scholar], 3 Kleme?, J. and Stehlík, P. 2005. Selected Papers from the PRES 2003 Conference. Heat Transfer Engineering, vol. 26: 1–3.  [Google Scholar], 4 Stehlík, P. and Kleme?, J. 2006. Recent Advances on Heat Transfer Equipment Design and Optimization—Selected Papers from PRES 2004 Conference. Heat Transfer Engineering, vol. 27: 1–3.  [Google Scholar], 5 Stehlík, P. and Kleme?, J. 2008. Achievements in Applied Heat Transfer—PRES 2006. Heat Transfer Engineering, vol. 29: 503–505.  [Google Scholar]].     

Nucleate Boiling of n-Pentane in a Horizontal Confined Space

An experimental study was carried out on n-pentane nucleate boiling at atmospheric pressure and saturation temperature for different gap sizes. The boiling was investigated in a confined space delimited by two horizontal discs, a heated surface and an adiabatic surface, for distances varying between 0.1 mm and 13 mm. Tests were carried out on heated surfaces of 12 mm and 20 mm diameter. The effects of the gap size on the partial boiling curve and the diameter of the heated surface were studied. A dimensionless analysis was carried out and a correlation to describe the phenomenon of confined nucleate boiling is presented.     

Estimating Sediment Loadings in the South Saskatchewan River Catchment

Water Resources Management - In river catchments, sediment fluxes facilitate the transport of nutrients and pollutants and reduce water quality, potentially impacting water body health and altering...     

Oxidation of cysteine and glutathione by soluble polymeric MnO2

The kinetics of reduction of soluble polymeric MnO2 by cysteine and glutathione has been studied in the pH range of 4.0-9.0. The concentration of thiols was varied between 1 and 2 mM, while the MnO2 concentration was varied between 2 and 12 microM. In this pH range, the reaction products were identified as Mn(II) and the corresponding disulfides (cystine and glutathione disulfide). Cysteic or cysteine sulfonic acid was formed only when pH < 2. Experimental data indicate that the rate law over the pH range of 4-9 is first-order in both MnO2 and thiol concentration. Eyring plots for both thiols reacting with MnO2 indicate that the reaction is associative (deltaS(double dagger) approximately -160 J mol(-1) K(-1)) and proceeds via an inner-sphere redox process. The reaction proceeds via the formation of two different inner-sphere complexes [triple bond]Mn(IV)SR- and [triple bond]Mn(IV)SR and their further reaction to products. Both surface species are linked to each other via acid-base equilibria, and the rate constant decreases as pH increases. The presence of two ligand surface species is determined using surface complexation modeling. A reaction mechanism in agreement with the experimental results is proposed.     

TCF bleaching of hardwood pulps obtained in organic acid media: Production of viscose-grade pulps

High-purity, viscose-grade pulps have been produced by means of delignification (in media containing formic or acetic acid) and TCF bleaching (using a E(O)ZP sequence). Aspen or Eucalyptus globulus wood chips were treated in media made up of either acetic acid, water and HCl or formic acid, water and hydrogen peroxide (Acetosolv and Milox technologies). Under selected conditions, unbleached pulps with kappa numbers in the range 14.0–28.5 were obtained at 50.0–53.7% pulp yield. These samples were subjected to E(O)ZP bleaching to reach the viscose-grade target values for chemical and physicochemical properties. Among the pulps tested, the bleached Milox pulp from Eucalyptus wood showed the best properties to be used for viscose manufacture (pentosan content of 1.4%, SCAN viscosity of 598 mL/g, ISO brightness of 89.9% and alkaline resistances of 90.1% and 97.0% in the R-10 and R-18 tests).     

Artificial intelligence techniques point out differences in classification performance between light and standard bovine carcasses

The validity of the official SEUROP bovine carcass classification to grade light carcasses by means of three well reputed Artificial Intelligence algorithms has been tested to assess possible differences in the behavior of the classifiers in affecting the repeatability of grading. We used two training sets consisting of 65 and 162 examples respectively of light and standard carcass classifications, including up to 28 different attributes describing carcass conformation. We found that the behavior of the classifiers is different when they are dealing with a light or a standard carcass. Classifiers follow SEUROP rules more rigorously when they grade standard carcasses using attributes characterizing carcass profiles and muscular development. However, when they grade light carcasses, they include attributes characterizing body size or skeletal development. A reconsideration of the SEUROP classification system for light carcasses may be recommended to clarify and standardize this specific beef market in the European Union. In addition, since conformation of light and standard carcasses can be considered different traits, this could affect sire evaluation programs to improve carcass conformation scores from data from markets presenting a great variety of ages and weights of slaughtered animals.     

As, Hg, and Se flue gas sampling in a coal-fired power plant and their fate during coal combustion

As, Hg, and Se are the most volatile elements in the flue gas from a coal-fired power plant. Significant amounts of these elements cause an undesired direct gaseous emission, which leads to a serious environmental health risk. The main focus of this study is to evaluate the possibility of simultaneous sampling of these volatile elements using an accurate official method for Hg (the most volatile element). A study of As, Hg, and Se emissions from a 1400 MW coal-fired power plant equipped with electrostatic precipitators (ESPs) was carried out for the combustion of a mixture of two types of coal. Simultaneous sampling of coal, bottom ash, fly ash, flue gas, and particles associated with the gas phase has been performed. Flue gas has been sampled by the Ontario Hydro Method Sampling Train, an ASTM method for Hg speciation. This sampling method was tested for As and Se sampling. As and Se determinations have been performed by HG-AAS, and Hg has been determined by CV-AAS. The results were used to examine the following: overall mass balances, relative distribution of these elements in the coal-fired power plant; As, Hg, and Se concentrations in coal and combustion residues; and predominant oxidation state for Hg in flue gas. The mass balances obtained for As, Hg, and Se were satisfactory in all cases; nevertheless, relative enrichment values in fly ash for As and Se were low; therefore, we concluded that As sampling in flue gas can be conducted by application of the Ontario Hydro Method; nevertheless Se released in the gas phase is not completely collected by this sampling train. Application of this sampling method allowed for performance of Hg speciation. The results indicated that Hg(II) was the predominant species in flue gas. It has also been proved that 24%, more than 99.8%, and 90% for As, Hg, and Se in the stack emissions, respectively, were in the gaseous phase.     

Use of multiwavelength transmission spectroscopy for the characterization of Cryptosporidium parvum oocysts: quantitative interpretation

Combined scattering and absorption properties of suspended particles can be obtained as a function of wavelength by measuring the complete ultraviolet-visible (UV-vis) spectrum. This research reports on the quantitative interpretation of measured UV-vis spectra of Cryptosporidium parvum oocyst suspensions obtained from several commercial sources and evaluated using two different purification techniques. The reproducibility of the measured spectral data was assessed, and the quantitative interpretation of the oocyst spectra in terms of the particle size and the chemical composition of the particles are reported herein. The interpretation model of the spectra is based on light scattering theory, spectral deconvolution techniques, and on the approximation of the wavelength-dependent optical properties of the basic constituents of living organisms. A characteristic set of optical properties for C. parvum oocysts has been determined as a function of wavelength and used for the quantitative interpretation of UV-vis spectra. The results from the spectral deconvolution show quantitative differences among oocyst preparations. These results represent the first step in establishing a set of critical parameters (e.g., oocyst size and chemical composition) necessary for the detection and identification of C. parvum oocysts in water using spectroscopy.     

Effect of inoculum size, relative humidity, storage temperature, and ripening stage on the attachment of Salmonella Montevideo to tomatoes and tomatillos

The influence of inoculum populations and environmental factors on attachment of Salmonella Montevideo to the surface of tomatoes and tomatillos was evaluated. To study the effect of inoculum size, red, ripe tomatoes were spot-inoculated with bacterial suspensions (10(5) and 10(8) CFU/fruit) and stored at 22 degrees C under 100% relative humidity. The effects of temperature (12, 22, and 30 degrees C) and relative humidity (75, 85, and 97%) on attachment of the pathogen (10(7) CFU/fruit) to tomatoes (red and green) and ripe tomatillos were also evaluated. Inoculated fruits were stored for 90 min at all combinations of temperature and relative humidity, and after rinsing with water, the number of cells attached to the surface was determined. Salmonella Montevideo attached to the surface of tomatoes within 90 min. A direct correlation between the number of attached cells and the population in the inoculum was observed. The percentage of cells that attached immediately after inoculation was approximately 0.3% for the three test products. After storage for 90 min at various temperature and relative humidity conditions, the number of adhering cells ranged from 4.0 to 5.4 log CFU/fruit (1.2% of inoculum). Both the type of product and the temperature/relative humidity combination had a significant (P < 0.05) effect on attachment of Salmonella Montevideo to the surfaces of tomatoes and tomatillos. Scanning electron micrographs of the cuticles of inoculated washed tomatoes and tomatillos revealed typical skin cell patterns, and only a few randomly dispersed Salmonella Montevideo were observed. Deposition of Salmonella Montevideo on the surface of tomatoes and tomatillos could result in attachment and subsequent colonization under suitable conditions.     

Fluorometric determination of chemically available lysine: adaptation, validation and application to different milk products

A spectrophotometric method based on the reaction between available lysine and ortho-phthaldialdehyde (OPA) was adapted and validated for fluorometric determination of the chemically available lysine contents in milk matrices (UHT and conventional in-bottle sterilized cow milk, milk-based infant formulas and infant formula ingredients). The values of the analytical parameters show its usefulness as a routine method (linearity, r = 0.9992; detection limit, 0.0066 mg/mL assay; accuracy, 99-108%; precision, intra-day 2.1-5.9% and inter-day 3.5 10.2%). No statistically significant differences (p < 0.05) were found between the values obtained with the adapted method and those obtained applying the 1-fluoro-2,4-dinitrobenzene (FDNB) (Carpenter) technique. The OPA method was used to measure the chemically available lysine contents in UHT and sterilized milk marketed in Spain, to study the evolution of chemically available lysine during the shelf-life of UHT milks, and finally the quality of name- and store-brand UHT milks was also compared. No statistically significant differences (p < 0.05) were found between either the available lysine contents of the same type of UHT or sterilized milk or between store- and name-brand UHT milks. Statistically significant differences (p < 0.05) were found between the chemically available lysine contents in UHT and sterilized milk. Losses of chemically available lysine ranging from 2.7 to 29% were obtained during the shelf-life of UHT milk.