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Thermomechanical Homogenization in Steam Explosion

Pavlenkо Anatoliy, Koshlak Hanna, Basok Borys, Hrabova Tatiana

Rocznik Ochrona Środowiska

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2023

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Tom 25

9--15

EN

A steam explosion results from intense heat transfer when a thermolabile liquid phase comes into contact with a hot liquid. As a result of such contact, microdispersed fragmentation of a high-boiling liquid occurs. A mathematical model is proposed to describe the thermomechanical crushing process, considering the formation of a vapour layer at the interface between two phases and the force interaction concerning several simultaneously boiling particles of the dispersed phase.

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Determination of the Specific Heat Flux During Boiling of the Dispersed Phase of the Emulsion

Pavlenkо Anatoliy, Koshlak Hanna, Basok Borys, Hrabova Tatiana

Rocznik Ochrona Środowiska

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2023

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Tom 25

16--24

EN

The intensity of heat exchange between the boiling emulsion and the enclosing surfaces is associated with the physical phenomena of the formation, growth, and destruction of vapour bubbles of the low-boiling component in the liquid phase. This article presents a methodology to assess the intensity of heat exchange processes. Using this technique, it is possible to predict the energy parameters of heat exchange equipment and the degree of intensification of heat transfer processes.

3

Method of Analysis of Thermophysical Properties and Composition of Nuclear Fuel During Modernization of Active Zones of Nuclear Power Reactors

Vashchenko Volodymyr, Skalozubov Volodymyr, Korduba Iryna, Komarov Yuriy, Zhukova Olena

Ecological Engineering & Environmental Technology

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2023

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Vol. 24, iss. 6

186--191

EN

The developed alternative method of analyzing the safety of the active zone of reactor installations is justified for improving the thermophysical properties and composition of nuclear fuel, designs of heat-releasing assemblies, reactor operation modes at increased or reduced power, etc. The impact of modernization on the safety criteria and conditions of reactor installations (RF) was analyzed. Attention was focused on the fact that until now there have been no sufficiently substantiated and accepted criteria and conditions for "steam" explosions in the Russian Federation. It was shown that when analyzing the safety of HF modernization with deterministic codes, it is necessary to take into account the possibility of negative effects of "user code" (EUC) and "code difference" (ECD), which can significantly affect the results of re-simulation of accidents with deterministic codes taking into account modernizations.

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The study of chemical composition and enzymatic hydrolysis efficiency of poplar wood (Populus deltoides x maximowiczii) after steam explosion pretreatment

Antczak A., Szadkowski J., Marchwicka M., Akus-Szylberg F., Bytner O., Zawadzki J.

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

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2018

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No. 104

139--146

EN

A beneficial influence of the steam explosion pretreatment on simple sugars yield after enzymatic hydrolysis was observed. The highest average glucose content (25.8%) in the hydrolysate after steam explosion pretreatment at 190 oC was achieved. In turn, an application of steam explosion pretreatment at 205 oC resulted in a decrease of enzymatic hydrolysis efficiency and 21.8% of glucose was obtained only. In case of xylose, a similar correlations were observed. The highest average xylose content (4.0%) at 190 oC was obtained and the decrease of xylose content (to the level of 2.4%) after enzymatic hydrolysis of biomass pretreated at 205 oC was observed. Probably, the decrease of the sugars content was caused by a condensation reactions of lignin and polysaccharides. Other explanation of the obtained results may be formation of inhibitors, which could hinder enzymatic hydrolysis. This reason may be especially important, because in these studies to enzymatic hydrolysis process unwashed solid fraction was used. Obtained results were correlated to the chemical composition of the studied wood. The partial hemicelluloses degradation and dissolution led to decrease in its content and at the same time increased the content of extractives. Lignin content stayed roughly the same for both untreated material and steam explosion pretreated at 160 oC and 175 oC. However, its content increased rapidly after steam explosion pretreatment at 190 oC and 205 oC. Cellulose content was not a subject to significant changes, although its apparent increase, when compared to cellulose content in untreated wood, was probably due to decline in hemicelluloses content.