Isothermal reaction calorimetry using Peltier elements for exothermic reactions in microreactors

2020 ◽  
Vol 92 (9) ◽  
pp. 1341-1341
Author(s):  
T. A. Frede ◽  
D. Sürig ◽  
N. Kockmann
Keyword(s):  
Reaction Calorimetry ◽  
Exothermic Reactions ◽  
Isothermal Reaction

Reaction Calorimetry for Exothermic Reactions in Plate-Type Microreactors Using Seebeck Elements

2017 ◽  
Vol 40 (11) ◽  
pp. 2144-2154 ◽  
Author(s):  
Felix Reichmann ◽  
Stefan Millhoff ◽  
Yannick Jirmann ◽  
Norbert Kockmann
Keyword(s):  
Reaction Calorimetry ◽  
Exothermic Reactions ◽  
Plate Type

Mixing Time Scale Measurement With Fast Exothermic Reactions Using Microchannel Reaction Calorimetry

2018 ◽  
Author(s):  
Felix Reichmann ◽  
Yannick Jirmann ◽  
Norbert Kockmann
Keyword(s):  
Heat Flux ◽  
Time Scale ◽  
Mixing Time ◽  
Main Reaction ◽  
Reaction Calorimetry ◽  
Flow Rates ◽  
Exothermic Reactions ◽  
Reaction Progress ◽  
Reaction Calorimeter ◽  
Mixing Time Scale

Continuous reaction calorimetry in microreactors is a powerful technology for the investigation of fast and exothermic reactions regarding thermokinetic data. A Seebeck element based reaction calorimeter has been designed, manufactured, and its performance has been shown in previous works using neutralization reaction in a microreactor made from PVDF-foils [1]. The Seebeck elements allow for spatial and temporal resolution of heat flux profiles across the reactor. Therefore, hot spots and regions of main reaction progress are detected. Finally, heat of reaction has been determined in good agreement with literature data [1]. However, more information can be retrieved related to chemical transformations using the continuously operated reaction calorimeter. In this work, mixing time scale is determined for instantaneous and exothermic reactions. Volumetric flow rate is varied and the region of main reaction progress is shifted within the microreactor. The reaction occurs near the reactor outlet for low flow rates. Here, mixing is dominated by diffusion. However, the reaction and hot spot are shifted towards the reactor inlet for high flow rates as convective mixing regime is reached and secondary flow profile with Dean vortices develop due to curvature of the reaction channel. Finally, mixing time scales can be derived from the location of heat flux peaks. Results display a decrease in mixing time at increased flow rates. Additionally, passive micromixers can be evaluated regarding their efficiency and comparison can be drawn. Moreover, pumps can be characterized and evaluated regarding low-pulsation dosing using the Seebeck element based reaction calorimeter.

Seebeck Calorimeter for the Characterization of Highly Exothermic Reactions in a Microreactor Made From PVDF-Foils

2017 ◽  
Author(s):  
Felix Reichmann ◽  
Stefan Millhoff ◽  
Yannick Jirmann ◽  
Norbert Kockmann
Keyword(s):  
Heat Flux ◽  
Reaction Calorimetry ◽  
Acid Base ◽  
Chemical Reactors ◽  
Exothermic Reactions ◽  
Thermoelectric Voltage ◽  
Calibration Methods ◽  
Transfer Measurement ◽  
Color Indicator

Reaction calorimetry is one of the most important steps in designing chemical reactors. This contribution describes a continuously operated micro calorimeter using Seebeck elements for microreactors made of PVDF-foils. Seebeck elements allow for local and temporal resolution of heat flux profiles. Various calibration methods for the Seebeck effect based heat flux sensors are presented. Here, the direct correlation between measured thermoelectric voltage and heat flux is found to be the most promising one. Commissioning of the calorimeter and validation of its performance are done by means of heat transfer measurement of warm water and an acid base reaction. Obtained reaction enthalpy values of the neutralization reaction of acetic acid and sodium hydroxide agree very well with literature data. The progression of the reaction can be followed optically using phenolphthalein as color indicator and can be compared to measured data. Heat profiles over the course of the microreactor were shown and checked for consistency. Consequently, this approach helps to characterize reactors and aids reactor development.

Isothermal reaction calorimetry as a tool for kinetic analysis

2004 ◽  
Vol 419 (1-2) ◽  
pp. 1-17 ◽  
Author(s):  
Andreas Zogg ◽  
Francis Stoessel ◽  
Ulrich Fischer ◽  
Konrad Hungerbühler
Keyword(s):  
Kinetic Analysis ◽  
Reaction Calorimetry ◽  
Isothermal Reaction

Enhanced heat transfer by exothermic reactions in laminar flow capillary reactors

2016 ◽  
Vol 141 ◽  
pp. 356-362 ◽  
Author(s):  
Sebastian Schwolow ◽  
Jing Ying Ko ◽  
Norbert Kockmann ◽  
Thorsten Röder
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Enhanced Heat Transfer ◽  
Exothermic Reactions ◽  
Flow Capillary

scholarly journals Exergy efficiency of thermochemical syngas-to-ethanol production plants

2021 ◽  
Vol 3 (5) ◽  
Author(s):  
Marcos Paulo Gabriel da Costa e Silva ◽  
Júlio Cesar de Carvalho Miranda
Keyword(s):  
Ethanol Production ◽  
Process Improvement ◽  
Second Generation ◽  
Exergy Efficiency ◽  
Exergy Destruction ◽  
Exothermic Reactions ◽  
Production Processes ◽  
Different Temperatures ◽  
Exergy Analyses ◽  
Second Generation Ethanol

Abstract This work presents exergy analyses applied in four different conceptual second-generation ethanol production processes through a thermochemical route using catalysts based on Molybdenum (P-1), Copper (P-2), and Rhodium (P-3 and P-4), aiming to assess their exergetic efficiencies. The results show that the conceptual processes have satisfactory exergy efficiencies in both cases, when compared among themselves and when compared with other processes reported in literature. The processes’ efficiency for P-1, P-2, P-3 and P-4 were, respectively, 52.4%, 41.4%, 43.7% and 48.9%. The reactors were the sections in which exergy destruction was more significant, due to the exothermic reactions and mixing points (where streams with different temperatures were mixed). Such results show the potential of thermochemical ethanol production, besides opening the possibilities of process improvement. Graphic abstract

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