scholarly journals EFFECTIVE COEFFICIENT OF THERMAL CONDUCTIVITY OF BIOFUEL IN THE CONDITIONS OF HIGH-TEMPERATURE DRYING

2018 ◽  
Vol 40 (2) ◽  
pp. 49-55
Author(s):  
D.M. Korinchuk
Keyword(s):  
Thermal Conductivity ◽  
Mathematical Model ◽  
High Temperature ◽  
Biofuel Production ◽  
Effective Coefficient ◽  
Drying Process ◽  
Average Value ◽  
Coefficient Of Thermal Conductivity ◽  
Kinetics Of ◽  
High Temperature Drying

The paper is devoted to determining the effective thermal conductivity coefficient of a mathematical model of high temperature drying biomass. The method of experimental research kinetics of drying and theoretical processing of the results is developed. The results of the research are presented. The average value of the effective coefficient of thermal conductivity is calculated and the possibility of its application in calculations of high temperature drying of biomass is substantiated. The modeling of high-temperature drying of biomass and peat will allow developing and substantiat-ing the methods of intensification of the drying process, developing engineering methods for calculating the equipment and ensuring the creation of the most rational designs of drying plants. Increasing the accuracy of mathematical modeling requires conducting experimental studies and de-termining the value of the effective coefficient of thermal conductivity of materials in the dry zone, as well as the influence of the temperature regime and properties of biomass on its value. The aim of the work is to determine the effective coefficient of heat conductivity of biomass in con-ditions of high temperature drying in biofuel production technologies. The methodology of determination of the effective coefficient of thermal conductivity for use in cal-culations of drying process under the model of high temperature drying of biomass is developed. The article presents the results of an experimental study of the kinetics of high- temperature drying of biomass samples of pine, willow and poplar of flat form. The theoretical model of flat particle drying was developed and cal-culations of the process of high-temperature drying of flat bodies were conducted. According to the results of the research, the value of the effective coefficient of thermal conductivity for a series of experiments is de-termined by the method of minimizing the relative error of theoretical and experimental results. The average value of the effective coefficient of thermal conductivity is calculated and the its applicability in the calcula-tions of high temperature drying of biomass using the mathematical model is substantiated. Based on these studies, the validity of the provisions of the developed mathematical model is concluded. The results can be used to upgrade and optimize processes in aerodynamic dryers.

scholarly journals PECULIARITIES OF KINETICS OF THE COEFFICIENT OF THERMAL CONDUCTIVITY DEPENDING ON THE HUMIDITY RATE OF WALL BLOCKS MADE OF AGRICULTURAL WASTES

2019 ◽  
Vol 4 (10) ◽  
pp. 19-28 ◽  
Author(s):  
А. Должонок ◽  
A. Dolzhonok ◽  
А. Бакатович ◽  
A. Bakatovich
Keyword(s):  
Thermal Conductivity ◽  
Building Materials ◽  
Moisture Absorption ◽  
Coarse Aggregate ◽  
Sustainable Use ◽  
Agricultural Wastes ◽  
Hygroscopic Moisture ◽  
Relative Air Humidity ◽  
Coefficient Of Thermal Conductivity ◽  
Kinetics Of

The article considers the prospect of plant wastes usage as aggregates while constructing new building materials in the form of wall blocks. The results of the research on water absorption of the wall blocks at the relative air humidity of 97 % are presented. The kinetics of change in humidity and the coefficient of thermal conductivity of the blocks with the rye and buckwheat straw coarse aggregate, and also the blocks with fine coarse aggregate of flax boon and atomized buckwheat are analyzed. Empirical dependences of the coefficient of thermal conductivity on the rate of humidity of wall blocks are obtained from experimental observations. After the maximum rate of hygroscopic moisture absorption, the best indexes are recorded on the blocks made of flax and straw. The humidity rate of the composite does not exceed 10,9 % with the increase of thermal conductivity up to 0.104 W/(m•°С). In the result of the research, the solution to the sustainable use of agricultural wastes to get environmental responsible building materials is proposed. Blocks can be are used in the erection of supporting and filler walls in one-story buildings and multistoried frame housing construction when filling exterior wall openings.

Examination of Microstructure of Cement Composite Material for Renovation of Horizontal Structures

2019 ◽  
Vol 808 ◽  
pp. 103-108
Author(s):  
Lenka Mészárosová ◽  
Vít Černý ◽  
Rostislav Drochytka ◽  
Winfried Malorny
Keyword(s):  
Thermal Conductivity ◽  
Composite Material ◽  
High Temperature ◽  
Surface Temperature ◽  
Cement Composite ◽  
Volume Weight ◽  
Coefficient Of Thermal Conductivity ◽  
New Material ◽  
Properties Of Materials ◽  
Low Volume

Development of new material is focused on modification of properties of materials with silicate binder so that these could be used for renovation of horizontal structures of high-temperature devices and at the same time contribute to reduction of heat transportation of constructions with higher surface temperature (in this case 200 and 500 °C). Main requirements for this material is low volume weight and low coefficient of thermal conductivity. This paper assesses influence of exposition to higher temperatures on microstructure.

Evolution of microstructure and combustion reactivity of lignite during high-temperature drying process

2018 ◽  
Vol 36 (10) ◽  
pp. 1170-1178 ◽  
Author(s):  
Chen Mu ◽  
Shouyu Zhang ◽  
You Li ◽  
Hao Li ◽  
Shunyan Wu ◽  
...  
Keyword(s):  
High Temperature ◽  
Drying Process ◽  
Combustion Reactivity ◽  
Evolution Of Microstructure ◽  
High Temperature Drying

scholarly journals Model for the analysis of thermal conductivity of composite material of natural origin

2019 ◽  
Vol 23 (6 Part A) ◽  
pp. 3513-3523
Author(s):  
Ilija Milicic ◽  
Radomir Folic ◽  
Aleksandar Prokic ◽  
Arpad Ceh
Keyword(s):  
Thermal Conductivity ◽  
Mathematical Model ◽  
Composite Material ◽  
Measurement Data ◽  
Experimental Tests ◽  
Wall Structure ◽  
Passive House ◽  
Average Value ◽  
Passive Houses ◽  
The Continuum

Thermal properties of the wall structure elements made from gel and straw (?Ethno-eco-passive houses?) have been investigated. The gel was made from a mixture of clay, lime, and water. A 1-D mathematical model based on the continuum mechanics, for predicting the thermal conductivity, is proposed. The results obtained by applying the proposed mathematical model were compared with the measurement data of experimental tests, using the Isomet 2114 instrument. The program envisages the measurement of thermal conductivity of three specimens, 5-year-old, comprising three series within 365 days. In the theoretical analysis, the same parameters of thermal stability were treated as in the experiment. The average value of the material thermal conductivity is 0.0990 W/mK, so it can be concluded that, the composite material intended for the envelope of the proposed constructive system ?Ethno-eco-passive house? is verified as thermally suitable.

scholarly journals Characteristics of supercritical heat transfer during filmboiling of nanofluids on a vertical heated wall

2018 ◽  
pp. 29-35
Author(s):  
А. Avramenko ◽  
M. Kovetskaya ◽  
A. Tyrinov ◽  
Yu. Kovetska
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Mathematical Model ◽  
Mass Transfer ◽  
Heat Flux ◽  
High Temperature ◽  
Heat And Mass Transfer ◽  
Heated Surface ◽  
Heated Wall ◽  
Film Boiling

Nanofluid using for intensification of heat transfer during boiling are analyzed. The using boiling nanofluids for cooling high-temperature surfaces allows significantly intensify heat transfer process by increasing the heat transfer coefficient of a nanofluid in comparison with a pure liquid. The properties of nanoparticles, their concentration in the liquid, the underheating of the liquid to the saturation temperature have significant effect on the rate of heat transfer during boiling of the nanofluid. Increasing critical heat flux during boiling of nanofluids is associated with the formation of deposition layer of nanoparticles on heated surface, which contributes changing in the microcharacteristics of heat exchange surface. An increase in the critical heat flux during boiling of nanofluids is associated with the formation of a layer of deposition of nanoparticles on the surface, which contributes to a change in the microcharacteristics of the heat transfer of the surface. Mathematical model and results of calculation of film boiling characteristics of nanofluid on vertical heated wall are presented. It is shown that the greatest influence on the processes of heat and mass transfer during film boiling of the nanofluid is exerted by wall overheating, the ratio of temperature and Brownian diffusion and the concentration of nanoparticles in the liquid. The mathematical model does not take into account the effect changing structure of the heated surface on heat transfer processes but it allows to evaluate the effect of various thermophysical parameters on intensity of deposition of nanoparticles on heated wall. The obtained results allow to evaluate the effect of nanofluid physical properties on heat and mass transfer at cooling of high-temperature surfaces. The using nanofluids as cooling liquids for heat transfer equipment in the regime of supercritical heat transfer promotes an increase in heat transfer and accelerates the cooling process of high-temperature surfaces. Because of low thermal conductivity of vapor in comparison with the thermal conductivity of the liquid, an increase in the concentration of nanoparticles in the vapor contributes to greater growth in heat transfer in the case of supercritical heat transfer.

High-temperature drying behavior and kinetics of lignite tested by the micro fluidization analytical method

Fuel ◽  
2019 ◽  
Vol 253 ◽  
pp. 180-188 ◽  
Author(s):  
Xi Zeng ◽  
Fang Wang ◽  
Mohammed Haruna Adamu ◽  
Lijuan Zhang ◽  
Zhennan Han ◽  
...  
Keyword(s):  
High Temperature ◽  
Analytical Method ◽  
Drying Behavior ◽  
Kinetics Of ◽  
High Temperature Drying

scholarly journals Two-dimensional mathematical model for simulation of the drying process of thick layers of natural materials in a conveyor-belt dryer

2017 ◽  
Vol 21 (3) ◽  
pp. 1369-1378 ◽  
Author(s):  
Dusko Salemovic ◽  
Aleksandar Dedic ◽  
Nenad Cupric
Keyword(s):  
Mathematical Model ◽  
Conveyor Belt ◽  
Convective Drying ◽  
Drying Process ◽  
Moist Air ◽  
Automated Control ◽  
Linear Differential ◽  
The Mathematical Model ◽  
Kinetics Of ◽  
Thick Layers

This paper presents the mathematical model and numerical analysis of the convective drying process of thick slices of colloidal capillary-porous materials slowly moving through conveyor-belt dryer. A flow of hot moist air was used as drying agent. The drying process has been analyzed in the form of a 2-D mathematical model, in two directions: along the conveyor and perpendicular on it. The mathematical model consists of two non-linear differential equations and one equation with a transcendent character and it is based on the mathematical model developed for drying process in a form of a 1-D thin layer. The appropriate boundary conditions were introduced. The presented model is suitable for the automated control of conveyor-belt dryers. The obtained results with analysis could be useful in predicting the drying kinetics of potato slices and similar natural products.

Transformation of the reabsorption characteristics of lignite treated by low and high temperature drying process

2019 ◽  
Vol 38 (14) ◽  
pp. 1857-1868
Author(s):  
Yuanmo Wu ◽  
Shouyu Zhang ◽  
You Li ◽  
Hao Li ◽  
Xiaobing Song
Keyword(s):  
High Temperature ◽  
Drying Process ◽  
High Temperature Drying
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