Ing. Jiří Křišťál, Ph.D.

Position: 
Deputy Head of Department, Scientist

Phone: 
+420 220 390 237
E-mail: 
kristalaticpf [dot] cas [dot] cz

Address: 
Rozvojová 135/1, 165 02 Praha-Lysolaje, Česká republika
Room number: 
167

Current Projects
    F3 Factory: Flexible, Fast, Future 
    F3 Factory is an European research program developing more flexible, faster and future production methods for chemical industry. It is one of the leading projects in the Nanotechnologies, Materials and Production research priority of the European Community’s Seventh Framework programme. 
    Our team focuses on methods for the surfactant manufacturing utilizing the microstructured devices and process intensification strategies.
    MicroLab 
    Since 2010, I've been supervising the design and installation of a new laboratory setup based on Ehrfeld Modular Micro Reaction System. The equipment was funded by an internal grant of Czech Academy of Sciences and currently we use the installation for further research of microreaction applications in different fields of chemistry (gas-liquid reactions, photochemistry, catalytic reactions, enzymatic reactions,...).

    MicroPROCESSING of Fluids
    Within the frame of a dedicated research agreement between ICPF and Procter & Gamble, I'm participating in the research related to microprocessing of fluids, focusing mainly on microprocessing equipment and control system design, characterization of microreactors and emulsification process.

    Hydrodynamics of Microreaction Systems 
    Since 2005, I've been involved in the research of hydrodynamic behaviour of microreaction systems. My PhD thesis was focused on hydrodynamic study of gas-liquid flow in a thin-gap microchannel. Namely, I studied the bubbly flow behaviour inside the rectangular channel with high aspect ratio, with flow visualisation and image processing being used as the main techniques for description and analysis of the system.
    PIV in Microchannels 
    In cooperation with INP-ENSIASET-CNRS (Toulouse), we have a bilateral research project on two-phase hydrodynamics in microchannels. Within this project the behaviour of single bubbles, bubble chains and (Taylor flow) and 2D micro bubble columns is characterized with microPIV and flow visualisation.
    Electrochemistry in Microreactors 
    Between 2005 and 2009, our team participated in the EU project IMPULSE. IMPULSE stands for Integrated Process Units with Locally Structured Elements; basically, it was a project dealing with the research of microdevices and their application into industrial production processes. Our group was concerned mainly with investigation of hydrodynamical behaviour of a thin-gap electrochemical microreactor. My PhD thesis was completed withing the IMPULSE project and was focused on application of microreactors for electro-organic synthesis.

Education

    2008 Ph.D. in Chemical Engineering, ICT Prague & ICPF, Academy of Sciences, Czech Republic.
    2003 M.Sc. in Computing and Control Engineering, ICT Prague, Czech Republic.

PhD Project

    Between 2005 and 2009, I was involved in the EU project IMPULSE. IMPULSE stands for Integrated Process Units with Locally Structured Elements; basically, it's project for integration of microdevices into industrial production processes. Our group focused mainly on the investigation of the hydrodynamic behaviour of a thin-gap microreactor.
    Process intensification in production of fine chemicals can be achieved using various types of microreactors. One of suitable arrangements for electrochemical reactions is a thin-gap microreactor. Thin-gap microreactor can be used as a single-pass flow-through reactor, with electrodes built in front and rear walls. In case of electroorganic oxidation, the desired reaction takes place on anode, whereas on cathode hydrogen is generated from the solvent as a counter reaction. Evolution of gas leads to formation of a two-phase system inside the microreactor.
    Bubble presence near the electrode has negative effect on reactor efficiency due to hindrance of electrode active surface. If the bubble covers large part of electrode (its diameter is much larger than reactor thickness), it blocks electrode surface from the bulk liquid. Only a thin liquid film exists between the bubble and electrode. Mass transfer from the bulk liquid to this film is slow and the electrode area is not fully utilized for the reaction. Therefore, for the efficient reactor design, the understanding of the bubble size distribution and flow patterns is essential.
    Another parameter considered in reactor design is the pressure drop. For individual microreactor, the pressure drop is not so high because of its low value. However, in the case of reactor stack, pressure drop can play significant role when determining optimal operating condition. Two-phase pressure drop has been intensively studied during last years and several correlations are already available in literature.
    My main area was an experimental investigation of the two-phase flow in a rectangular microchannel. Channel dimensions were width 1 cm, length cca 10 cm and thickness between 0.1 and 1 mm. Orientation was vertical and horizontal. Flow in the thin-gap microchannel was visualized using digital camera for a range of operating conditions (liquid flow rate and current densities). Image processing was than used for the evaluation of bubble size distribution. From these data, basic flow map was formulated. The applicability of previously proposed correlations for two-phase frictional pressure drop to thin-gap channel was investigated. Finally, two-phase pressure drop was identified with flow patterns existing in microreactor.

Research Interests

  • Microreaction technology, design and modelling of microreactors
  • Multiphase hydrodynamics
  • Process intesification
  • Flow visualization
  • Digital image processing - Matlab
  • Laboratory control and data acquisition systems - NI Labview, Hitec-Zang Labvision
  • Computational Fluid Dynamics - Fluent, Comsol
  • Laboratory hydrodynamical and electrochemical experiments
  • Three dimensional electrodes

Leisure Interests

  • Trekking, squash, ballroom dancing
  • Dog walking
  • Travelling
  • DTP, typography

List of papers published during last 4 years (journals and books only):