Pavel Vlasák, Zdeněk Chára, Jan Krupička and Jiří Konfršt
Przewlocki, K., Michalik, A., Wolski, K., Korbel, K., 1979. A radiometric device for the determination of solids concentrationdistribution in a pipeline. In: Burns, A.P. (Ed.): Proc. of 6th International Conference on the Hydraulic Transport of Solids in Pipes HYDROTRANSPORT 6, 1979, Canterbury (UK), BHRA Fluid Engineering Centre, Cranfield (U.K.), Pap. B3, pp. 219-227.
Pugh, F.J., Wilson, K.C., 1999. Role of the interface in stratified slurry flow. Powder Technology, 104, 221-226.
Shook, C.A., Bartosik, A.S., 1994. Particle-wall stresses
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Gilies, R.G., Shook, C.A., Wilson, K.C, 1991. An improved two layer model for horizontal slurry flow. Can. J. Chemical Engineering, 69, 173–178.
Kao, D.T.Y., Hwang, L.Y., 1979. Critical slope for slurry pipeline transporting coal and other solid particles. In: Burns, A.P. (Ed.): Proc. 6th Int. Conf. on the Hydraulic Transport of Solids in Pipes - HYDROTRANSPORT, Canterbury (U.K.), BHRA Fluid Engineering Centre, Cranfield (U.K.), Vol. 1, Pap. A5, pp. 57–74.
Kaushal, D.R., Tomita, Y., 2013. Prediction of concentrationdistribution in
Profiles in High Shear Stress Flows. PhD thesis. Queen’s University at Kingston, Kingston, Canada.
Przewlocki, K., Michalik, A., Korbel, K., Wolski, K., Parzonka, W., Sobota, J., Pac-Pomarnacka, A., 1979. A radiometric device for the determination of solids concentrationdistribution in a pipeline. Proceedings of Hydrotransport 6, Cantenbury, UK.
Shook, C.A., Daniel, S.M. 1965. Flow of suspensions of solids in pipelines: Part I. Flow with a stable stationary deposit. Can. J. Chem. Eng., 43, 2, 56-61.
Concentrations of impurities in fluids often follow Zipf's law, that is, relatively few impurities occur at high concentrations and numerous impurities occur at low concentrations. The concentrations of compounds in air and of elements in ocean water are examples of such distributions. This principle can be used to predict the number of components in a mixture, which occur above certain concentration level, also beyond the range of analytical methods. In most practical applications the existence of minor components can be ignored, but the level of concentration, at which certain component can be ignored depends on the specific problem.
Robert Cichowicz, Grzegorz Wielgosiński and Agata Targaszewska
Analysis of the distribution of CO2 concentrations was performed for a water-and-steam boiler plant located in a detached building supplying thermal energy to a hospital. The boiler plant was equipped with two low-temperature boilers and one high-temperature steam boiler. The maximum thermal energy demand of the hospital was 4280, 3500 kW of which came from the hot-water boilers and the remaining 780 kW from the steam boiler. Due to the operating system there were no permanent job positions in the boiler plant. Servicing consisted only in the supervision, periodic adjustment and maintenance of the equipment. These kinds of working conditions release the employer from the necessity to perform tests and measurements of working conditions in such a building. On the other hand, continuous measurements are made because of the installation safety and emissions of pollutants into the environment. The article presents results of the measurements and analysis of the distribution of CO2 concentrations inside and outside a small boiler plant, due to which it was found that the level of carbon dioxide concentration did not depend on the ambient air temperature. The resulting values are similar regardless of whether the measurements were taken in December 2012 or April 2013. However, there is an evident impact of seasons on the concentrations in the indoor air associated primarily with the demand for heat during the given period, the stay of people in the workplace and the number of working devices.
transport phenomena of dissolved matter in rivers. (PhD Thesis 2796). Technische Universiteit Delft, Delft.
van Mazijk, A., Veling, E.J.M., 2005. Tracer experiments in the Rhine Basin: evaluation of the skewness of observed concentrationdistributions. Journal of Hydrology, 307, 1–4, 60–78.
Velísková, Y., Sokáč, M., Koczka Bara, M., Dulovičová, R., 2013. Hydrodynamický prístup k modelovaniu kvality povrchových vôd. (Hydrodynamic approach to modeling of surface water quality. Acta Hydrologica Slovaca, 14, 1, 145–153. (In Slovak.)
Wang, Z., Xia, J., Deng
Slurry transport in horizontal and vertical pipelines is one of the major means of transport of sands and gravels in the dredging industry. There exist 4 main flow regimes, the fixed or stationary bed regime, the sliding bed regime, the heterogeneous flow regime and the homogeneous flow regime. Of course the transitions between the regimes are not very sharp, depending on parameters like the particle size distribution. The focus in this paper is on the homogeneous regime. Often the so called equivalent liquid model (ELM) is applied, however many researchers found hydraulic gradients smaller than predicted with the ELM, but larger that the hydraulic gradient of liquid. Talmon (2011, 2013) derived a fundamental equation (method) proving that the hydraulic gradient can be smaller than predicted by the ELM, based on the assumption of a particle free viscous sub-layer. He used a 2D velocity distribution without a concentration distribution.
In this paper 5 methods are described (and derived) to determine the hydraulic gradient in homogeneous flow, of which the last method is based on pipe flow with a concentration distribution. It appears that the use of von Driest (Schlichting, 1968) damping, if present, dominates the results, however applying a concentration distribution may neutralise this. The final equation contains both the damping and a concentration distribution giving the possibility to calibrate the constant in the equation with experimental data. The final equation is flexible and gives a good match with experimental results in vertical and horizontal pipelines for a value of ACv = 1.3. Data of horizontal experiments Dp = 0.05-0.30 m, d = 0.04 mm, vertical experiments Dp = 0.026 m, d = 0.125, 0.345, 0.560, and 0.750 mm.
Jolanta B. Królczyk, Andrzej Rezwiakow and Marek Tukiendorf
The purpose of this article is to demonstrate possibilities of mixing coal with biomass using static mixers. The paper present simple and inexpensive methods for producing fuel mixes for heat-generating plants equipped with stoker-fired boilers of power ranging from 3 up to 50 MW. Static mixer proposed in this article may constitute an alternative for currently used solutions in production facility. Based on statistical analysis, the article demonstrates that five mixing elements of the mixer is optimal number to ensure best biomass (chips and pellets) concentration distribution in a mixture with fine hard coal.