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Abstract

The paper presents numerical simulation of two-phase flow in a heated capillary with evaporation on the meniscus. To solve the problem, a model of evaporation from meniscus was developed in which the dynamics of liquid-vapour interface is described by the Cahn-Hilliard equation. The numerical simulations were performed using commercial software for 2D axially symmetric case. The flow evolution was analysed for different values of heat transfer coefficient at the capillary wall and inlet liquid mass flow rate.
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Authors and Affiliations

Jarosław Karwacki
Marcin Lackowski
Helena Nowakowska
Dariusz Butrymowicz
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Abstract

Anaerobic digestion is an important technology for the bio-based economy. The stability of the process is crucial for its successful implementation and depends on the structure and functional stability of the microbial community. In this study, the total microbial community was analyzed during mesophilic fermentation of sewage sludge in full-scale digesters.

The digesters operated at 34–35°C, and a mixture of primary and excess sludge at a ratio of 2:1 was added to the digesters at 550 m3/d, for a sludge load of 0.054 m3/(m3·d). The amount and composition of biogas were determined. The microbial structure of the biomass from the digesters was investigated with use of next-generation sequencing.

The percentage of methanogens in the biomass reached 21%, resulting in high quality biogas (over 61% methane content). The abundance of syntrophic bacteria was 4.47%, and stable methane production occurred at a Methanomicrobia to Synergistia ratio of 4.6:1.0. The two most numerous genera of methanogens (about 11% total) were Methanosaeta and Methanolinea, indicating that, at the low substrate loading in the digester, the acetoclastic and hydrogenotrophic paths of methane production were equally important. The high abundance of the order Bacteroidetes, including the class Cytophagia (11.6% of all sequences), indicated the high potential of the biomass for efficient degradation of lignocellulitic substances, and for degradation of protein and amino acids to acetate and ammonia.

This study sheds light on the ecology of microbial groups that are involved in mesophilic fermentation in mature, stably-performing microbiota in full-scale reactors fed with sewage sludge under low substrate loading.

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Authors and Affiliations

Piotr Świątczak
Agnieszka Cydzik-Kwiatkowska
Paulina Rusanowska
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Abstract

Electromagnetic processing of molten copper is provided in a special kind of electrical furnace called an induction furnace with a cold crucible (IFCC), making it possible to successfully remove impurities from the workpiece. In order to analyze the process in a sufficient way not only electromagnetic, thermal and flow but also metallurgical and mass transfer phenomena in the coupled formulation should be taken into consideration. The paper points to an analysis of the kinetic process of lead evaporation from molten copper. It was shown that mass transport in the gas phase determines the rate of the analyzed evaporation process. The possibility of removal of lead from molten copper is analyzed and described.
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Authors and Affiliations

Albert Smalcerz
1
ORCID: ORCID
Leszek Blacha
1
ORCID: ORCID
Jerzy Barglik
1
ORCID: ORCID
Ivo Dolezel
2
ORCID: ORCID
Tadeusz Wieczorek
1
ORCID: ORCID

  1. Silesian University of Technology Krasinskiego 8, 40-019 Katowice, Poland
  2. Faculty of Electrical Engineering, University of West Bohemia Univerzitní 26, 301 00 Pilsen, Czech Republic
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Abstract

In this paper, the results of the study on aluminium evaporation from the Al-Zn alloys (4.2% weight) during remelting in a vacuum induction furnace (VIM) are presented. The evaporation of components of liquid metal alloys is complex due to its heterogeneous nature. Apart from chemical affinity, its speed is determined by the phenomena of mass transport, both in the liquid and gas phase. The experiments were performed at 10-1000 Pa for 953 K - 1103 K. A significant degree of zinc loss has been demonstrated during the analysed process. The relative values of zinc loss ranged from 4 to 92%. Lowering the pressure in the melting system from 1000 Pa to 10 Pa caused an increase in the value of density of the zinc evaporating stream from 3.82⋅10-5 to 0.000564 g⋅cm-2⋅s-1 at 953 K and 3.32⋅10-5 to 0.000421 g⋅cm-2⋅s-1 for 1103 K. Based on the results of the conducted experiments. it was found that evaporation of zinc was largely controlled by mass transfer in the gas phase and only for pressure 10 Pa this process was controlled by combination of both liquid and gas phase mass transfer.
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Bibliography

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Authors and Affiliations

Albert Smalcerz
ORCID: ORCID
Leszek Blacha
ORCID: ORCID
B. Węcki
1
ORCID: ORCID
D.G. Desisa
2
ORCID: ORCID
J. Łabaj
3
ORCID: ORCID
M. Jodkowski
1
ORCID: ORCID

  1. Department of Testing and Certification "ZETOM", Poland
  2. Department of Industrial, Informatics Silesian University of Technology, Joint Doctorate School, Poland
  3. Faculty of Materials Engineering, Silesian University of Technology, Poland

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