Flow Fields in Stirred Vessels Depending on Different Internal Heat Exchangers and Vessel Bottoms

Jaehrling, Katja; Schultz, H. J.

doi:10.1002/cite.201800101

Cited by 10 publications

(23 citation statements)

References 26 publications

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“…In follow-up investigations, a variation of the baffle number will be carried out in order to be able to evaluate whether adjustments for multistage systems need to be made and to eventually extend the measurement range into the fully turbulent state above Re R = 10 000 without unwanted vortex formation or surface gassing. Further experiments will focus on effects of different reactor bottom shapes and internals, as previous research [18,19] has proven that single-stage impellers are not sufficient in many such cases.…”

Section: Discussionmentioning

confidence: 99%

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Investigation and Visualization of Flow Fields in Stirred Tank Reactors Using a Fluorescence Tracer Method

Matzke

Behrens

Steins

et al. 2022

Chemie Ingenieur Technik

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In this study, flow fields in stirred tank reactors are investigated by a fluorescence tracer method. For these measurements, a fluorescent dye is inserted into a stirred tank reactor and distributed by the impeller flow, following the characteristic main circulation pathways. By this means, the main flow fields can be detected and visualized. Originally developed and used for the investigation of viscoelastic fluids, the method was adapted for Newtonian fluids with low viscosity in this study, with impeller installation height and impeller Reynolds numbers selected as influencing parameters. The resulting flow fields in both single-and double-impeller setups match the known structures from literature excellently. Therefore, the developed fluorescence tracer method has proven to be a promising supplement to the established repertoire of fluid investigation methods, with little effort in both experiment itself as well as the following data analysis steps.

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Section: Discussionmentioning

confidence: 99%

“…During the reference single-stage experiments, impellers were installed at a bottom clearance of h = D/3, following previous investigations [18,19,41,42], with the Reynolds number as the primarily varied parameter. For the multistage experiments, the installation heights of the impellers were varied in addition to that.…”

Section: Methodsmentioning

confidence: 99%

Investigation and Visualization of Flow Fields in Stirred Tank Reactors Using a Fluorescence Tracer Method

Matzke

Behrens

Steins

et al. 2022

Chemie Ingenieur Technik

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“…Nguyen et al [ 20 ] reported achieving an increase of 22% in the system COP by increasing the heat absorption of the medium in the ground using an IHX with the CO 2 direct expansion ground source heat pump (DX‐GSHP). Jaehrling et al [ 21 ] explored the advantages and disadvantages of IHX with different structures by analyzing the differences in the heat transfer and flow between the refrigerants. Kang et al [ 22 ] embedded an IHX into an HTHPS system with single‐stage compression, and concluded that the system COP increased with decreasing steam temperature as well as with increasing mass flow of water and refrigerant in the evaporator.…”

Section: Structural Characteristics Of Frs‐hthps and Rrs‐hthpsmentioning

confidence: 99%

Performance Analysis of Internal Heat Exchanger‐Based Quasi‐Two‐Stage Vapor Compression Heat Pump System for High‐Temperature Steam Production

Hao

Zhang

Jingyu³

et al. 2020

Energy Tech

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The thermodynamic performance of a high‐temperature heat pump steam (HTHPS) system is determined mainly by its different cycle configurations. The present study involves improving the thermodynamic performance of a quasi‐two‐stage vapor compression high‐temperature heat pump based on a front internal heat exchanger (IHX) cycle and a rear, and analyzing the influence of an IHX. The present study establishes thermodynamic models for front reheating structure (FRS) and rear reheating structure (RRS) models on the basis of conservation of mass and energy. The system is compared to the traditional quasi‐two‐stage compression cycle system in terms of thermodynamic parameters. The results demonstrated that the RRS system exhibits an increase of 4.87% in the coefficient of performance when the exhaust superheats is maintained under 5 K. With an increase in the condensation temperature, the required mass flow of the refrigerant in the traditional system is 9.94–12.36% higher compared to the RRS system, the power consumption of the compressor is increased by 3.9–5.6%, and the steam output per unit refrigerant is decreased by 1.04–5.07%. Furthermore, the Aspen Plus simulation verifies that the reason for the change in the exhaust superheats is the different pressure ratios in the theoretical calculation.

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“…As the flow and mixing ratios, however, depend on many parameters, such as stirrer type, rotation frequency, stirrer and reactor geometry, internals, and so forth, it is questionable whether different, unsystematically set stirring rates are the correct comparison variable, for instance, to transfer findings from inhibitor screenings in a stirred autoclave to the flow conditions in a pipeline [87].…”

Section: Introductionmentioning

confidence: 99%

Influence of different stirring setups on mass transport, gas hydrate formation, and scale transfer concepts for technical gas hydrate applications

2022

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This contribution describes the influence of turbulent flow conditions in the liquid and/or gas phase and directly in the phase interface, different flow patterns (axial/radial), volume‐specific power inputs, mass‐specific energy consumptions, as well as volume‐specific mass transfer coefficients on the gas hydrate formation, derived from an experimental investigation of five different reactor setups. The results correspond to all fields of gas hydrate research, especially actually discussed technical hydrate applications, like hydrate‐based desalination, gas storage, gas separation, biogas and green hydrogen handling, carbon dioxide deposition, new phase transfer materials, and even electrical power supply. Two main objectives, first, to determine favorable hydrate forming conditions in stirred systems to provide competitive hydrate formation processes, and second, the search for a concept to enable the transfer of experimental results, for example, from a stirred reactor to a pipeline system for inhibitor research, through the targeted adjustment of similar and comparable turbulent flow conditions in different reactor setups could be achieved. So far, the targeted formation of gas hydrates has been investigated essentially from the point of view of optimizing the formation conditions with regard to pressure and temperature as well as the addition of auxiliary materials and promoters. In addition, some studies consider different reactor types and setups, for example, spray reactors or bubble columns. In many publications, stirred and cooled pressure autoclaves are described, whereby the gas and the liquid phase are brought into contact with each other by mixing to a greater or lesser extent by an agitator, then forming a solid gas hydrate phase. Often missing in previous research work is a systematic approach for determining the influence of flow conditions on gas hydrate formation. Many different influencing factors in a stirred reactor system can strongly affect the kinetics and formation of gas hydrates, for example, stirrer type, rotational frequency, stirrer and reactor geometry, and filling level. This is the starting point of the present investigation that deals with the influence of the flow conditions on the formation of gas hydrates. Tests were performed in a stirred autoclave to measure the effects of different stirrer configurations. The results obtained contribute to the explanation of the hydrate formation mechanism and can be used to optimize the targeted production of gas hydrates in technical hydrate applications. A rapid, immediate, hydrate formation is advantageous and can be achieved by suitable flow conditions in stirred reactors, which is successfully proven within this study contribution.

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Flow Fields in Stirred Vessels Depending on Different Internal Heat Exchangers and Vessel Bottoms

Cited by 10 publications

References 26 publications

Investigation and Visualization of Flow Fields in Stirred Tank Reactors Using a Fluorescence Tracer Method

Investigation and Visualization of Flow Fields in Stirred Tank Reactors Using a Fluorescence Tracer Method

Performance Analysis of Internal Heat Exchanger‐Based Quasi‐Two‐Stage Vapor Compression Heat Pump System for High‐Temperature Steam Production

Influence of different stirring setups on mass transport, gas hydrate formation, and scale transfer concepts for technical gas hydrate applications

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