scholarly journals Mass Exchange Dynamics During the Second Filtration Drying Period

2009 ◽  
Vol 3 (2) ◽  
pp. 129-137
Author(s):  
Volodymyr Atamanyuk ◽  
◽  
Yaroslav Gumnytskyi ◽  
Keyword(s):  
Heat Exchange ◽  
Physical Model ◽  
Differential System ◽  
Mass Exchange ◽  
Experimental Investigations ◽  
System Of Equations ◽  
Transfer Velocity ◽  
Kinetics And Dynamics ◽  
Dispersion Layer

The work is dedicated to theoretical and experimental investigations of kinetics and dynamics of filtration drying of capillary and pore materials, and mineral granulated fertilizers, in particular. The proposed physical model of a moist particle and the differential system of equations which describes heat exchange in the second drying period enables to determine the transfer velocity of mass-exchange zone in a dispersion layer of the material during filtration drying.

scholarly journals Condensation inside smooth horizontal tubes: Part 1. Survey of the methods of heat-exchange prediction

2015 ◽  
Vol 19 (5) ◽  
pp. 1769-1789 ◽  
Author(s):  
Volodymyr Rifert ◽  
Volodymyr Sereda
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Film Condensation ◽  
Experimental Investigations ◽  
Phase Flow ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Horizontal Tubes

Survey of the works on condensation inside smooth horizontal tubes published from 1955 to 2013 has been performed. Theoretical and experimental investigations, as well as more than 25 methods and correlations for heat transfer prediction are considered. It is shown that accuracy of this prediction depends on the accuracy of volumetric vapor content and pressure drop at the interphase. The necessity of new studies concerning both local heat transfer coefficients and film condensation along tube perimeter and length under annular, stratified and intermediate regimes of phase flow was substantiated. These characteristics being defined will allow determining more precisely the boundaries of the flow regimes and the methods of heat transfer prediction.

scholarly journals Modern approaches to the intensification of heat and mass exchange in multi-temperature condensation filters

2021 ◽  
Vol 2039 (1) ◽  
pp. 012018
Author(s):  
M V Malevany ◽  
D A Konovalov
Keyword(s):  
Mass Transfer ◽  
Heat Exchange ◽  
Heat And Mass Transfer ◽  
Liquid Flow ◽  
Mass Exchange ◽  
Single Phase ◽  
Heat And Mass Exchange ◽  
Analytical Review

Abstract The article considers the problems and features of heat and mass exchange on developed surfaces in the conditions of both single-phase and vapour-liquid flow during its condensation. We give a brief analytical review of studies of hydrodynamics and heat exchange in such systems. We analyzed the efficiency of the working channel of the condensation filter and identified problematic points. We offer possible methods for intensifying heat and mass transfer on working surfaces.

scholarly journals Innovative technology for reducing the rate of sediment formation in the power plants channels

2020 ◽  
Vol 164 ◽  
pp. 01033
Author(s):  
Anatoly Muraviev ◽  
Alexander Nadeev ◽  
Alexander Naumov ◽  
Inna Pereslavtseva
Keyword(s):  
Mathematical Model ◽  
Mass Transfer ◽  
Heat Exchange ◽  
Power Plants ◽  
Particle Distribution ◽  
Innovative Technology ◽  
System Of Equations ◽  
Sediment Formation ◽  
Shell And Tube

This paper considers the increasing the mass transfer intensity due to the use of annular baffles in the tubes of shell-and-tube heat exchange apparatuses. A mathematical model for calculating the system of equations for the evolution of particle distribution in the form of sediments has been developed.

scholarly journals A laboratory exercise using a physical model for demonstrating countercurrent heat exchange

2012 ◽  
Vol 36 (1) ◽  
pp. 58-62
Author(s):  
Catherine Loudon ◽  
Elizabeth C. Davis-Berg ◽  
Jason T. Botz
Keyword(s):  
Blood Flow ◽  
Heat Exchange ◽  
Blood Vessels ◽  
Physical Model ◽  
Circulatory System ◽  
Concentration Gradients ◽  
Laboratory Exercise ◽  
Permeable Barrier ◽  
Countercurrent Exchange ◽  
Physical Principles

A physical model was used in a laboratory exercise to teach students about countercurrent exchange mechanisms. Countercurrent exchange is the transport of heat or chemicals between fluids moving in opposite directions separated by a permeable barrier (such as blood within adjacent blood vessels flowing in opposite directions). Greater exchange of heat or chemicals between the fluids occurs when the flows are in opposite directions (countercurrent) than in the same direction (concurrent). When a vessel loops back on itself, countercurrent exchange can occur between the two arms of the loop, minimizing loss or uptake at the bend of the loop. Comprehension of the physical principles underlying countercurrent exchange helps students to understand how kidneys work and how modifications of a circulatory system can influence the movement of heat or chemicals to promote or minimize exchange and reinforces the concept that heat and chemicals move down their temperature or concentration gradients, respectively. One example of a well-documented countercurrent exchanger is the close arrangement of veins and arteries inside bird legs; therefore, the setup was arranged to mimic blood vessels inside a bird leg, using water flowing inside tubing as a physical proxy for blood flow within blood vessels.

Investigation of the System Coupling Regenerative Heat Exchange and Selective Catalytic Reduction for Heat Exchange and NOx Removal

2014 ◽  
Vol 955-959 ◽  
pp. 2087-2092
Author(s):  
Zhong Jun Tian ◽  
Shi Ping Jin ◽  
Yu Ming Liang
Keyword(s):  
Heat Exchange ◽  
Selective Catalytic Reduction ◽  
Power Plants ◽  
Switching Time ◽  
Catalytic Reduction ◽  
Coupled System ◽  
Experimental Investigations ◽  
Regenerative Heat ◽  
System Coupling ◽  
Peak Value

In conjunction with theoretical heat exchange model, experimental investigations have been conducted for a coupled system of Selective Catalytic Reduction (SCR) and Regenerative Heat Exchange (RHE), to reduce nitrogen oxides (NOx) from coal-fired boilers and High Temperature Air Combustion (HiTAC) furnaces. Results indicate there is no effect of catalysis reactions on heat transfer; catalysts serve the function of heating elements. The outlet NO concentration periodically decreased in an almost linear fashion. NO conversion: i) rose slowly with a longer switching time; and ii) reached the peak value of temperature with a delay compared with the steady state. The coupled system requires less space and hence is a suitable option for SCR renovations in coal-fired power plants.

scholarly journals Modeling of the Stepping Process of Negative Lightning Stepped Leaders

2017 ◽  
Author(s):  
Vernon Cooray ◽  
Liliana Arevalo
Keyword(s):  
Physical Model ◽  
Reasonable Agreement ◽  
Propagation Speed ◽  
Step Length ◽  
Experimental Investigations ◽  
Small Length ◽  
Return Stroke ◽  
Subsequent Formation ◽  
Peak Current ◽  
Model Based

A physical model based on the mechanism observed in experimental investigations is introduced to describe the formation of negative leader steps. Starting with a small length of a space leader located at the periphery of the negative streamer system of the stepped leader the model simulates the growth and the subsequent formation of the leader step. Based on the model, the average step length, the average step forming time and the average stepped leader propagation speed is estimated as a function of prospective return stroke peak current. The results show that the average step length and the average leader speed increases with increasing prospective return stroke current. The results also show that the speed of the stepped leader increases as it approaches the ground. For a 30 kA prospective return stroke current the average leader speed obtained is about 5 x 105 m/s and the average step length was about 10 m. The results obtained are in reasonable agreement with the experimental observations. 

Some Features of Pulse-Periodic Energy Supply in Supersonic Flow

2010 ◽  
Vol 5 (2) ◽  
pp. 43-54
Author(s):  
Vladimir N. Zudov ◽  
Pavel K. Tretyakov ◽  
Andrey V. Tupikin
Keyword(s):  
Physical Model ◽  
Energy Supply ◽  
Aerodynamic Drag ◽  
Reverse Flow ◽  
High Sensitivity ◽  
Quantitative Agreement ◽  
Frequency Effect ◽  
Experimental Investigations ◽  
Supply Source ◽  
Thermal Wake

In the present work, the results of numerical and experimental investigations of supersonic flows with a localized energy supply are considered. The energy supply region (the heat source) was formed by the plasma created by a focused pulsed-periodic laser emission either by combustion in the separation zone upstream of the blunted body. The main attention is paid to the unsteady effects the role of which is determining at the integral flow structure formation. A physical model of energy source is formulated. The numerical and experimental data on the structure of the flow around the source and the characteristics of a thermal wake arising behind the source are compared. The energy pulses frequency and capacity are shown to determine the wake properties: the formation and development of subsonic regions, vortex structures, and reverse flow regions. It follows from an analysis of the aerodynamic drag variation at a flow with a thermal wake of the energy supply source around blunt bodies that the energy and pulse as well as its duration are the main parameters determining the efficiency of the frequency effect. A high sensitivity of the results to the physical model accepted in numerical investigation is shown. The pressure variation dynamics on a conical surface is presented versus the frequency of pulses. Comparison with experiment has shown a good quantitative agreement.

scholarly journals Experimental investigations of thermal performance improvement of aluminum ceiling panel for heating and cooling by covering its surface with paint

2018 ◽  
Vol 44 ◽  
pp. 00002 ◽  
Author(s):  
Łukasz Amanowicz ◽  
Janusz Wojtkowiak
Keyword(s):  
Heat Exchange ◽  
Performance Improvement ◽  
Aluminum Surface ◽  
Experimental Investigations ◽  
Cooling Performance ◽  
Heating Performance ◽  
Heating And Cooling ◽  
Heat Exchange Surface ◽  
Low Energy Buildings ◽  
Exchange Surface

Due to the low emissivity of raw metal surface (i.e. aluminum), the specific heating or cooling performance of non-painted surfaces is powered mainly on the natural convection and is relatively small. It can be sufficient for low energy buildings but not for the traditional ones. To increase the heat exchange through the radiation one can cover the raw surface with paint to increase its emissivity. To investigate the influence of paint cover on the heating and cooling performance of the ceiling-oriented flat aluminum surface the experimental investigations were done. The experiment was conducted on the aluminum ceiling panel with heat exchange surface of the dimensions 0.32 ⨯ 3.0 m. Heating performance of painted surface increased from 2.3 to 2.8 times and cooling performance increased from 1.5 to 1.7 times in the comparison to the non-painted one.

Experimental Investigations of the Characteristics of Heat-Exchange and Temperature Fields in the Channels and Fuel-Element Assemblies of Lead-Cooled Fast Reactors

Atomic Energy ◽  
2015 ◽  
Vol 118 (5) ◽  
pp. 307-317 ◽  
Author(s):  
V. I. Rachkov ◽  
A. P. Sorokin ◽  
A. V. Zhukov ◽  
Yu. A. Kuzina ◽  
V. V. Privezentsev
Keyword(s):  
Heat Exchange ◽  
Fuel Element ◽  
Temperature Fields ◽  
Experimental Investigations ◽  
Fast Reactors
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