Fifty Years of Moment Technique for Dynamic Analysis of Chemical Reactor Parameters

2019 ◽  
Vol 17 (5) ◽  
Author(s):  
Gülşen Doğu ◽  
Timur Doğu
Keyword(s):  
Dynamic Analysis ◽  
Reaction Rate ◽  
Chemical Reactor ◽  
Axial Dispersion ◽  
Moment Analysis ◽  
Transport Parameters ◽  
Transfer Coefficients ◽  
Engineering Research ◽  
Single Pellet ◽  
Fixed Beds

Abstract Moment technique has been extensively used for the evaluation of the rate and equilibrium parameters in chemical reactors and also in adsorption vessels, for about five decades. Adsorption and reaction rate parameters, as well as axial dispersion constants, effective diffusivities within porous catalysts and heat and mass transfer coefficients were shown to be effectively evaluated by analyzing the moments of the response peaks, which could be obtained from pulse-response experiments performed in a reaction/adsorption vessel. A detailed review of chromatographic processes, involving moment analysis of adsorption equilibrium and rate constants in fixed beds, dynamic analysis of batch adsorbers, moment analysis of fluidized bed, slurry and trickle bed reactors are reported in this manuscript. Applications of the single-pellet moment technique, which was developed for the effective investigation of intrapellet rate and equilibrium processes, by eliminating the contributions of axial dispersion and external transport parameters, are comprehensively discussed. Recent studies for the analysis of reaction rate parameters using the TAP reactor approach, use of single pellet system for the investigation of catalytic and non-catalytic solid-gas reactions and extension of the moment technique to non-linear systems opened new pathways in reaction engineering research.

Extra-Column Effects in Determination of Rate Parameters by the Chromatographic Method

1996 ◽  
Vol 61 (6) ◽  
pp. 844-855 ◽  
Author(s):  
Olga Šolcová ◽  
Petr Schneider
Keyword(s):  
Chromatographic Method ◽  
Dynamic Method ◽  
Axial Dispersion ◽  
Transport Parameters ◽  
Porous Particles ◽  
Loop Detector ◽  
Single Pellet ◽  
Set Up ◽  
Extra Column Effects

It was shown that the sampling loop, detector and connecting elements in the chromatographic set-up for determination of transport parameters by the dynamic method significantly influence the response peaks from columns packed with porous or nonporous particles. A method, based on the use of convolution theorem, was developed which can take these effects into account. The applicability of this method was demonstrated on the case of axial dispersion in a single-pellet-string column (SPSR) packed with nonporous particles. It is possible to handle also responses from columns packed with porous particles by a similar procedure.

scholarly journals Heat transfer in fluidized and fixed beds of adsorption chillers

2019 ◽  
Vol 128 ◽  
pp. 01003 ◽  
Author(s):  
Jaroslaw Krzywanski ◽  
Karolina Grabowska ◽  
Marcin Sosnowski ◽  
Anna Zylka ◽  
Anna Kulakowska ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Fluidized Bed ◽  
Fluidized Beds ◽  
Fixed Bed ◽  
Wall Heat Transfer ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Innovative Idea ◽  
Fixed Beds

An innovative idea, shown in the paper constitutes in the use of the fluidized bed of sorbent, instead of the conventional, fixed-bed, commonly used in the adsorption chillers. Bed–to–wall heat transfer coefficients for fixed and fluidized beds of adsorbent are determined. Sorbent particles diameters and velocities of fluidizing gas are discussed in the study. The calculations confirmed, that the bed–to–wall heat transfer coefficient in the fluidized bed of adsorbent is muchhigher than that in a conventional bed.

Switched Model and Dynamic Analysis of a Hydroturbine Governing System in the Process of Load Rejection Transient

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Huanhuan Li ◽  
Diyi Chen ◽  
Feifei Wang ◽  
Hao Zhang
Keyword(s):  
Mathematical Model ◽  
Dynamic Analysis ◽  
Numerical Simulations ◽  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
Hydropower Station ◽  
Transfer Coefficients ◽  
Operational Conditions ◽  
Governing System ◽  
Hammer Impact

In this paper, we pay attention to studying the switched model of the hydroturbine governing system (HTGS) by introducing the concept of the switching of operational conditions. More specifically, utilizing the data of an existent hydropower station in China, we propose six nonlinear dynamic transfer coefficients of the hydroturbine, which can better describe the dynamic characteristics of the HTGS in the process of load rejection transient. Moreover, the elastic water hammer-impact of the penstock system and the nonlinearity of the generator for the process of load rejection transient are considered. Based on the combination of the different regulation modes of the governor and the corresponding running conditions of the hydroelectric generating unit, a novel nonlinear dynamic switched mathematical model of the HTGS is finally established. Meanwhile, the nonlinear dynamic behaviors of the governing system are exhaustively investigated using numerical simulations. These methods and analytical results will provide some theory bases for running a hydropower station.

Axial dispersion in single pellet-string columns with non-porous packing

2004 ◽  
Vol 59 (6) ◽  
pp. 1301-1307 ◽  
Author(s):  
Olga Šolcova ◽  
Petr Schneider
Keyword(s):  
Axial Dispersion ◽  
Single Pellet

scholarly journals Dynamic Analysis of the Natural and Mechanical Ventilation of a Solar Greenhouse by Coupling Controlled Mechanical Ventilation (CMV) with an Earth-to-Air Heat Exchanger (EAHX)

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3676 ◽  
Author(s):  
Sara Bonuso ◽  
Simone Panico ◽  
Cristina Baglivo ◽  
Domenico Mazzeo ◽  
Nicoletta Matera ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Heat Exchanger ◽  
Dynamic Analysis ◽  
Air Conditioning ◽  
Well Being ◽  
Temperate Climate ◽  
Agricultural System ◽  
Transfer Coefficients ◽  
Solar Greenhouse ◽  
Controlled Mechanical Ventilation

Greenhouse crops represent a significant productive sector of the agricultural system; one of the main problems to be addressed is indoor air conditioning to ensure thermal well-being of crops. This study focuses on the ventilation analysis of solar greenhouse with symmetrical flat pitched roof and single span located in a warm temperate climate. This work proposes the dynamic analysis of the greenhouse modeled in TRNsys, simultaneously considering different thermal phenomena three-dimensional (3D) shortwave and longwave radiative exchange, airflow exchanges, presence of lamps with their exact 3D position, ground and plant evapotranspiration, and convective heat transfer coefficients. Several air conditioning systems were analyzed, automatic window opening, controlled mechanical ventilation systems (CMV) and horizontal Earth-to-Air Heat Exchanger (EAHX) coupled with CMV, for different air volume changes per hour. In summer, the exploitation of the ground allows having excellent results with the EAHX system, reducing the temperature peaks of up to 5 °C compared to the use of CMV. In winter, it is interesting to note that, although the EAHX is not the solution that raises the temperature the most during the day, its use allows flattening the thermal wave more. In fact, the trend is almost constant during the day, raising the temperature during the first and last hours of the day.

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