207 research outputs found
Mass, heat and momentum transfer in natural draft wet cooling tower with flue gas discharge
The paper presents CFD simulation results of a natural draught wet-coolingtower (NDWCT) with flue gas discharge. The problem considered is mixing of the fluegases with the rising plume and possible corrosion of the tower shell due to acid condensate.A previously developed CFD model of a NDWCT has been used in the analysis. Nowind conditions have been assumed and the results have shown that under this conditionthe corrosion is unlikely to occu
Thermophoresis and its effect on particle impaction on a cylinder for low and moderate Reynolds numbers
The effect of thermophoresis on the impaction of particles on a cylinder is
investigated for different particle sizes, particle conductivities, temperature
gradients and for Reynolds numbers between 100 and 1600. Simulations are
performed using the Pencil Code, a high-order finite difference code. An
overset-grid method is used to precisely simulate the flow around the cylinder.
The ratio of particles impacting the cylinder and the number of particles
inserted upstream of the cylinder is used to calculate an impaction efficiency.
It is found that both the particle conductivity and the temperature gradient
have a close to linear influence on the particle impaction efficiency for small
particles. Higher Reynolds numbers result in higher impaction efficiency for
middle-sized particles, while the impaction efficiency is smaller for smaller
particles. In general, it is found that thermophoresis only has an effect on
the small particles, while for larger particles the impaction efficiency is
controlled by inertial impaction.
Finally, an algebraic model, developed based on fundamental principles, which
describes the effect of thermophoresis is presented. The model is found to
accurately predict the DNS results. As such, this model can be used to
understand the mechanisms behind particle deposition due to the thermophoretic
force, and, more importantly, to identify means by which the deposition rate
can be reduced
X-ray determination of dislocation density and arrangement in plastically deformed copper
Monitorowanie losów absolwentów. Zarys metodologii i metodyki badania w Uniwersytecie Ekonomicznym w Poznaniu
W artykule przedstawiono przegląd polskich i zagranicznych doświadczeń z badań losów absolwentów. Zaprezentowano również charakterystykę okresu przejściowego między edukacją a pracą, w którym znajdują się absolwenci wkraczający na rynek pracy. Zdaniem autorów, specyfika aktywności ekonomicznej w tym okresie powinna zostać uwzględniona przy projektowaniu systemów monitorowania losów absolwentów. Na tym tle zaprezentowano zarys metodyki i metodologii monitorowania losów absolwentów w Uniwersytecie Ekonomicznym w Poznaniu
Electron diffraction analysis of dislocation-induced substructure evolution of Al crystals in compression
Dynamic modelling and operational optimisation of natural draft cooling towers
YesNatural draft cooling towers are subjected to dynamic air temperature and humidity ratio of air throughout the day. Their performances based on steady state model is restricted to single air temperature and humidity ratio of air values and thus are not accurate. In this work, a dynamic model for a natural draft cooling tower is developed. Air temperature and relative humidity data for Johannesburg were acquired to develop dynamic correlations for these two parameters and are embedded in the process model together with the dynamic model of the collection basin of the tower. A simple algorithm is proposed to solve the resulting boundary value problem. Finally, the common perception that seawater/river water should be used instead of freshwater as cooling medium is tested via optimisation where the operating costs of the process for two cooling mediums is minimised. The freshwater has been found to be cost effective cooling medium
Densities and character of dislocations and size-distribution of subgrains in deformed metals by X-ray diffraction profile analysis
Characterization of dislocations in germanium layers grown on (011)- and (111)-oriented silicon by coplanar and noncoplanar X-ray diffraction
Effects of fertilization and soil management on crop yields and carbon stabilization in soils. A review
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