Infrared imaging of temperature profiles in microreactors for fast and exothermic reactions

Though microreactors provide high heat transfer rates, temperature profiles are formed in case of fast and highly exothermic reactions. A method based on non-intrusive infrared thermometry has been developed to track these profiles quantitatively with a resolution of 250 data points/cm(2) and a precision of 1 degrees C. By placing the microreactor at a pressure of 10(-2) mbar, convective heat losses are efficiently suppressed which assures well defined boundaries and reproducible results. The temperature profiles of the fast and exothermic hydrolysis of tetraethoxysilane were measured inside a microcapillary at different flow rates via infrared transparent window. In the reactor provided with a cooling system, the heat transfer coefficient was determined by thermal imaging for different operating conditions. The data obtained are in good agreement with the values reported in literature. (C) 2012 Elsevier B.V. All rights reserved.

[1]  J. P. Longtin,et al.  Laser-based measurement of liquid temperature or concentration at a solid–liquid interface , 2000 .

[2]  Luke P. Lee,et al.  Micro-Raman thermometry for measuring the temperature distribution inside the microchannel of a polymerase chain reaction chip , 2006 .

[3]  King Lun Yeung,et al.  Experiments and modeling of membrane microreactors , 2005 .

[4]  Robin Fortt,et al.  Thermal optimisation of the Reimer-Tiemann reaction using thermochromic liquid crystals on a microfluidic reactor. , 2005, Lab on a chip.

[5]  Albert Renken,et al.  Kinetic and thermodynamic study of the aqueous Kolbe–Schmitt synthesis of beta-resorcylic acid , 2012 .

[6]  J. Hartnett,et al.  Heat transfer to newtonian and non-newtonian fluids in rectangular ducts , 1989 .

[7]  C. Backhouse,et al.  Dynamic temperature measurement in microfluidic devices using thermochromic liquid crystals. , 2008, Lab on a chip.

[8]  Albert Renken,et al.  Heat Management in Single and Multi-injection Microstructured Reactors: Scaling Effects, Stability Analysis, and Role of Mixing , 2012 .

[9]  M. Gaitan,et al.  Temperature measurement in microfluidic systems using a temperature-dependent fluorescent dye. , 2001, Analytical chemistry.

[10]  Norbert Kockmann,et al.  Scale-up concept of single-channel microreactors from process development to industrial production , 2011 .

[11]  M. Morris,et al.  Spatially resolved temperature measurements in electrophoresis capillaries by Raman thermometry. , 1993, Analytical chemistry.

[12]  Eric D. Wetzel,et al.  Thermal Management in Catalytic Microreactors , 2006 .

[13]  Holger Löwe,et al.  Selectivity Gains and Energy Savings for the Industrial Phenyl Boronic Acid Process Using Micromixer/Tubular Reactors , 2004 .

[14]  Kai Wang,et al.  Kinetics research on fast exothermic reaction between cyclohexanecarboxylic acid and oleum in microreactor , 2011 .

[15]  Joung-Man Park,et al.  Study on Thermal Conductivity of Polyetheretherketone/Thermally Conductive Filler Composites , 2007 .

[16]  A. Mosyak,et al.  Infrared temperature measurements in micro-channels and micro-fluid systems , 2011 .

[17]  T. Pottebaum,et al.  Measuring the temperature of fluid in a micro-channel using thermochromic liquid crystals , 2012 .

[18]  Gunther Kolb,et al.  Design and operation of a compact microchannel 5 kWel,net methanol steam reformer with novel Pt/In2O3 catalyst for fuel cell applications , 2012 .

[19]  D. Bornhop,et al.  Noninvasive picoliter volume thermometry based on backscatter interferometry , 2001, Electrophoresis.

[20]  H. Löwe,et al.  Flow chemistry: Imidazole-based ionic liquid syntheses in micro-scale , 2010 .

[21]  B. Ashrafi,et al.  Influence of carbon nanotubes on the thermal, electrical and mechanical properties of poly(ether ether ketone)/glass fiber laminates , 2011, Carbon.

[22]  Wenka Schweikert,et al.  Analysis and Improvement of Strong Exothermic Nitrations in Microreactors , 2003 .

[23]  J. M. Lloyd,et al.  Thermal Imaging Systems , 1975 .

[24]  Albert Mosyak,et al.  Effect of developing flow and thermal regime on momentum and heat transfer in micro-scale heat sink , 2007 .

[25]  King Lun Yeung,et al.  Zeolites in Microsystems for Chemical Synthesis and Energy Generation , 2009 .

[26]  K. Sefiane,et al.  Unsteady-state fluctuations analysis during bubble growth in a “rectangular” microchannel , 2011 .

[27]  Study of the temperature field in microchannels of a PDMS chip with embedded local heater using temperature-dependent fluorescent dye , 2006 .

[28]  A. Webb,et al.  Monitoring temperature changes in capillary electrophoresis with nanoliter-volume NMR thermometry. , 2000, Analytical chemistry.

[29]  Yunhua Gan,et al.  Microscale heat transfer enhancement using thermal boundary layer redeveloping concept , 2005 .

[30]  A. Günther,et al.  Structure of the temperature field in a flow over heated waves , 2002 .

[31]  G. Yaralioglu,et al.  Ultrasonic heating and temperature measurement in microfluidic channels , 2011 .

[32]  S.D. Briles,et al.  Calibration procedure developed for IR surface-temperature measurements , 1989, Fifth Annual IEEE Semiconductor Thermal and Temperature Measurement Symposium.

[33]  R. Schumacher,et al.  Umwelt—Forschung, Gestaltung, Schutz. Hrsg.: Verein Deutscher Ingenieure (VDI), VDI-Verlag, Düsseldorf. Erscheint zweimonatlich; DM: 24.— (Einzelheft DM 5.—) , 1971 .