THERMAL CONTROL OF MECHANOCHEMICAL REACTION

2021 ◽  
pp. 3-10
Author(s):  
Yu. Tolchinsky ◽  
V. Ved ◽  
I. Rofe-Beketova
Keyword(s):  
Heat Exchange ◽  
Block Diagram ◽  
Mechanical Energy ◽  
Thermal Control ◽  
Solid Particles ◽  
Mechanochemical Reaction ◽  
Flow Mode ◽  
Stress Concentrations ◽  
Reaction Heat ◽  
Crushed Material

Mechanochemistry studies and explains the processes of chemical and physicochemical transformations that are generated by mechanical action on a substance. When carrying out deep mechanochemical transformations, as a rule, it is necessary to transfer to solid reagents a portion of energy comparable to the energy of interatomic bonds. For this, various machines and apparatus are used, such as extruders, in which mechanical energy is constantly transferred to the crushed material. The article discusses the interaction of two reagents in a simple chemical reaction in the state of a mixture of particles of two types, which occurs during compression of particles having a rough irregular shape, and colliding with each other, forming areas of contact. Significant stress concentrations and heating of the substance with the formation of a new phase arise in these regions. Thermal control of the mechanochemical reaction is to maintain an optimal balance of dissipative heat and heat from the coolant in the worm reactor so that the rate of flow and the final product of the reaction meet the specified specifications. The formulas provided in the article for calculating the coefficient of the rate of mechanochemical reaction, heat transfer between worm reactor and jacket channel, heat exchange between jacket and environment allows to calculate the balance conditions for thermal management. The block diagram of the technological line, which is presented in the article, is more economical in comparison with carrying out the same reaction in a solvent. The economic benefit lies in the elimination of the steps of introducing and removing the solvent from the reaction product. At the end, it is indicated that the mechanochemical reaction of the transformation of a mixture of two dispersed materials consisting of solid particles into a liquid can be realized in continuous conditions in a flow mode in a worm machine. And thermal control of the course of a mechanochemical reaction can be carried out using controlled heat exchange with a coolant in a jacket under conditions of turn-around spatial dispersion.

scholarly journals Maximum power point tracking in photovoltaic systems

2019 ◽  
Vol 28 ◽  
pp. 01021
Author(s):  
Grażyna Frydrychowicz-Jastrzębska
Keyword(s):  
Block Diagram ◽  
Mechanical Energy ◽  
Electric Energy ◽  
Energy Conversion Efficiency ◽  
Maximum Power ◽  
Maximum Efficiency ◽  
Maximum Power Point ◽  
Point Tracking ◽  
Power Point Tracking ◽  
Power Point

The subject of the analysis was the optimisation of interoperation between the photovoltaic battery (PV) and DC motor, which drives a fan, with respect to the maximum efficiency of conversion of the electric energy into mechanical energy. Based on the block diagram, a mathematical model of this circuit was developed to ensure the mutual matching between the Maximum Power Point (MPP) of the battery and the receiver operation point. A computer simulation of the battery characteristics was conducted taking into account the changing MPP location on the characteristic vs. changes in solar radiation and temperature. The issue was considered for the optimal motor excitation coefficient, both changing and averaged in time. The energy conversion efficiency was determined for selected PV modules, as well as time.

PZT and Electrode Enhancements of Mems Based Micro Heat Engine for Power Generation

2002 ◽  
Vol 730 ◽  
Author(s):  
A.L. Olson ◽  
L.M. Eakins ◽  
B.W. Olson ◽  
D.F. Bahr ◽  
C.D. Richards ◽  
...  
Keyword(s):  
Bottom Electrode ◽  
Mechanical Energy ◽  
Electrical Power ◽  
Heat Engine ◽  
Mems Devices ◽  
Stress Concentrations ◽  
Process Yield ◽  
Micro Heat Engine ◽  
Reducing Stress ◽  
And Diffusion

AbstractThe P3 Micro Heat Engine relies on a thin film PZT based transducer to convert mechanical energy into usable electrical power. In an effort to increase process yield for these were used on sputtered Ti/Pt bottom electrodes to compare roughness, grain size, and diffusion for annealing temperatures between 550 and 700 °C. For an optimized bottom electrode, process yield for various sized top electrodes were then studied for PZT thickness between 0.54 and 1.62 for reducing stress concentrations. Two PZT etching geometries on 2.3 μm thick Si/SiO2 membranes, with 1.5-3.5 mm side-lengths, were examined and one was used to increase the strain at failure by at least 40%. Integrating improvements in process yield and strain at failure, single PZT based MEMS devices capable of generating power of up to 1 mW and in excess of 2 volts have been demonstrated operating at frequencies between 300 and 1,100 Hz.

scholarly journals Rotating cylinder and magnetic field on solid particles diffusion inside a porous cavity filled with a nanofluid

2021 ◽  
Vol 11 ◽  
pp. 184798042110342
Author(s):  
Abdelraheem M. Aly ◽  
Ehab Mahmoud Mohamed ◽  
Hakan F. Oztop ◽  
Noura Alsedais
Keyword(s):  
Magnetic Field ◽  
Porous Media ◽  
Rayleigh Number ◽  
Circular Cylinder ◽  
Solid Phase ◽  
Rotational Frequency ◽  
Solid Particles ◽  
Flow Mode ◽  
Porous Layers ◽  
Darcy Parameter

This study deals with the roles of a magnetic field and circular rotation of a circular cylinder on the dissemination of solid phase within a nanofluid-filled square cavity. Two wavy layers of the non-Darcy porous media are situated on the vertical sides of a cavity. An incompressible smoothed particle hydrodynamics (ISPH) method was endorsed to carry out the blending process concerning solid phase into nanofluid and porous media layers. Initially, the solid phase is stationed in a circular cylinder containing two open gates. Implications of a buoyancy ratio ( N = −2: 2), Hartmann number ( Ha = 0: 100), rotational frequency [Formula: see text], Darcy parameter [Formula: see text], Rayleigh number [Formula: see text], nanoparticles parameter [Formula: see text], and amplitude of wavy porous layers [Formula: see text] on the lineaments of heat/mass transport have been carried out. The results revealed that the diffusion of the solid phase is permanently moving toward upward except at opposing flow mode [Formula: see text] toward downward. The lower Rayleigh number reduces the solid-phase diffusions. A reduction in a Darcy parameter lessens the nanofluid speed and solid-phase diffusions in the porous layers. A reduction in [Formula: see text] from [Formula: see text] to [Formula: see text] diminishes the maximum of streamlines [Formula: see text] by 13.19% at [Formula: see text], by 46.75% at [Formula: see text], and by 74.75% at [Formula: see text].

scholarly journals Design of Hydro Power by Using Turbines Kaplan on The Discharge Channel Paiton 1 and 2

2018 ◽  
Vol 42 ◽  
pp. 01008
Author(s):  
Alvin K. Sosilo ◽  
Harsono Hadi ◽  
Totok Soehartanto
Keyword(s):  
Discharge Channel ◽  
Block Diagram ◽  
Mechanical Energy ◽  
Mechanical Power ◽  
Hydro Power ◽  
Kaplan Turbine ◽  
Turbine Performance ◽  
Power Turbine ◽  
Simulation Results ◽  
The Relationship

Condenser water from the discharge channel PJB Paiton discharged to the sea has the potential mechanical energy, because the flow rate of 7.6 m3 / s (if both discharge PJB Paiton function) and the discharge channel reaches a height of 4m. This paper will describe the design of hydro power (in the form of a block diagram) by using Kaplan turbine driven by utilizing the wastewater condenser. Kaplan turbine performance represented in the form of the relationship between the incoming water flow and the pitch angle (the angle between the propellers with a hub) to the torque generated. The simulation results indicate that the turbine torque is proportional to the mechanical power turbine. The greater the torque, the greater the mechanical power, and vice versa.

Emerging Trends in 222Rn and 220Rn Decay Products Detection

2015 ◽  
Vol 238 ◽  
pp. 134-139 ◽  
Author(s):  
Rosaline Mishra ◽  
B.K. Sapra ◽  
Y.S. Mayya
Keyword(s):  
Background Radiation ◽  
Detection System ◽  
Measurement Techniques ◽  
Decay Product ◽  
Solid Particles ◽  
Wire Mesh ◽  
Flow Mode ◽  
Usual Practice ◽  
Gas Concentration ◽  
Decay Products

The importance of measuring the decay products of 222Rn (radon) and 220Rn (Thoron) is being realized by researchers as these are the major inhalation dose givers to the general population. Basically the decay products are radioisotopes of Polonium, Bismuth and Lead, which are solid particles. Upon inhalation, these particles deposit in different parts of the respiratory tract, undergo radioactive decay and irradiate the nearby tissues. So, the study of the behavior of the decay products in indoor air is important for assessing the natural background radiation exposures received by general populations through the inhalation route. Although the inhalation doses are predominantly due to decay products yet it had been the usual practice to measure the gas concentration rather than the decay products because of the complexities involved in their detection. The most common method is to derive the progeny concentration from the measured gas concentration using an assumed equilibrium factor. While this is fairly justified for radon in view of the short-lived nature of the progeny as compared to the gas, this approach is beset with serious limitations in thoron-rich environments. However, the development of passive detection system for the decay products known as deposition-based Direct Radon and Thoron Progeny Sensors, has provided a solution to the long standing problem of measuring the time integrated decay product activity concentration. These deposition sensors are calibrated against active measurement techniques, and provide an easy to use method for passive and simultaneous time integrated decay product measurement. In addition, for multi-parametric study, the different modes of these passive sensors, like flow-mode and wire-mesh capped mode, are also used. These are further discussed in the manuscript.

Approximation of Reaction Heat Effects in Cylindrical Catalyst Particles with Internal Voids Using CFD

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
M. Ertan Taskin ◽  
Anthony G. Dixon ◽  
E. Hugh Stitt ◽  
Michiel Nijemeisland
Keyword(s):  
Particle Surface ◽  
Solid Particles ◽  
Temperature Fields ◽  
Cfd Simulations ◽  
Reaction Heat ◽  
Diffusion Limitations ◽  
Particle Dimension ◽  
Heat Effects ◽  
Lower Temperature ◽  
Selection Of

Steam reforming reaction heat effects were implemented in CFD simulations of different packed tube models of 1-hole and 4-hole cylinders. A computationally less expensive 120° wall segment approach was utilized for the simulations in this study. Heat effects of the reactions were introduced by heat generation/consumption terms in the catalyst particles considering suitable reaction kinetics proposed in the literature. Due to strong diffusion limitations the activity of the catalyst particles is confined to a thin layer at the particle surface. Therefore, the energetic effects of the reactions were restricted to the outer 5% of the particle dimension by a user-defined code. The selection of the correct active region was verified for both the particle external and internal–hole surfaces. Simulation results of the reaction heat effects were qualitatively and quantitatively compared to cold flow cases where there were no heat effects but only tube wall heat transfer. Due to the endothermic nature of the reactions, relatively lower temperature fields were observed when the heat effects were introduced, where the positions of the solid particles play an important role. The implications of introducing the detailed reaction heat effects were emphasized in the development of suitable packed tube models.

scholarly journals A theoretical and experimental study of transient characteristics of the heat exchange in a thermal control system

Vestnik MGSU ◽  
2021 ◽  
pp. 720-729
Author(s):  
Rustam Sh. Mansurov ◽  
Yuri E. Voskoboinikov ◽  
Vasilisa A. Boeva
Keyword(s):  
Control System ◽  
Heat Exchange ◽  
Impulse Response ◽  
Exchange Process ◽  
Thermal Control ◽  
Impulse Responses ◽  
Transient Characteristics ◽  
Thermal Control System ◽  
Noisy Input ◽  
Non Parametric

Introduction. The “Heater-Blower-Room” thermal control system represents three different interconnected subsystems. It is necessary to study the transient characteristics of the heat exchange process, that is underway in the subsystems, including informative impulse responses, to stabilize the system operation. It is a non-parametric problem, and its solution requires identification algorithms. Materials and methods. Mathematical models of the subsystems represent the Volterra integral equation of the first kind with an undetermined difference kernel, or an impulse response. An impulse response evaluation is a solution to this equation in respect of registered noisy input and output values. The problem is to evaluate unknown impulse responses for the subsystems where the output of one subsystem is the input of another one. This problem is ill-posed, and features of identification-focused experiments do not allow to apply computational methods of classical regularization algorithms. The co-authors propose two specific non-parametric identification algorithms where impulse responses are evaluated using stable first derivatives by means of smoothing cubic splines through the optimal smoothing parameter selection on the basis of the statistical optimality criterion. Results. The co-authors solve inverse problems of impulse response identification and direct problems of heat flux reaction prediction. The research results demonstrate a high level of convergence between the evaluated data and observation findings. Both experimental and theoretical results represent the findings of the research performed by the co-authors. Conclusions. The results have proven the efficiency of the algorithms proposed for the identification of solutions to the problems of complex technical systems.

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