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Invited researcher Philip Karl Hopke
Contract number
14.Z50.31.0041
Time span of the project
2017-2019

As of 30.01.2020

26
Number of staff members
31
scientific publications
2
Objects of intellectual property
General information

Name of the project: Empirical kinetics of new phase nuclei generation and synthesis of materials in sub-critical and near-critical conditions

Strategy for Scientific and Technological Development Priority Level: б


Goals and objectives

Research directions: Chemical technologies

Project objective:

- Developing fundamental basics for developing scientific understanding about kinetics of nucleation in meta-stable systems and basics of nucleation (including aerosol) technologies for creating new materials

- Solving scientific problems related to developing fundamental basics of generating nanoparticles from supercritical solutions and creating new aerosol technologies based on accumulated knowledge


The practical value of the study

  • We have developed software for quantitative solutions of the Navier-Stokes problem for axis-symmetrical non-ideal (real) vapor-gas flows in the range or pressures of up to 150 bar and    nucleation temperatures coordinated with state equations. We have provided a user guide as well as results of quantitative computation of nucleation speed of gas-vapor mixtures during their flow in tubes with cold walls depending on pressure and mode parameters. Results of quantitative computations have allowed to determine main constructive dimensions and allowed operation modes of flow diffusion chamber depending on the type of a gas-vapor mixture.
  • Our researchers have developed technical design specifications that were the basis for draft design of a high pressure flow diffusion chamber, a high pressure aerosol particle counter to study kinetics of generation of new phase nuclei in sub-critical and near-critical conditions at pressures of up to 15 MPa as well as a spray reactor for nanoparticle generation.
  • We have theoretically justified a new approach to determining how aerosols are affected by electric field as a system containing dielectric dipole components. It has been shown that impact of electrostriction pressure gives significant effect at 1 MV/cm. This can be reached in a high pressure diffuse chamber while using SF6 as an environment during aerosol formation from glycerin. We have produced new expressions for determining the state of extent impact of electric field that allow for their experimental checking.
  • Two methods have been have been proposed and justified for experimental study of heat exchange crisis in non-metallic heat carriers. The methods allow to research joint kinetics of nucleation processes of gas and solid phases in oversaturated water solutions of salts of various degrees of solubility under controlled conditions. The first method is designed to determine main laws and comparative characteristics of nucliation dynamics in drops, thin films and large volumes of solutions on horizontal heated surfaces at temperatures of up to 700°С at atmospheric pressure. The second is aimed at studying impact of pressure on processes of initiation and suppression of boiling during forced flows of saturated solutions in a channel that is heated and transparent for visible and heat radiation. On the next stage we are planning to empirically establish validity of the hypothesis of dominating impact of volume crystallization on development and termination of heat exchange crisis at increased pressure, to determine applied aspects of obtained results.
  • We have shown that by varying conditions of synthesis it is possible to significantly change morphology of products: to produce nanoparticles of oxides of various forms, nanoparticles of the «nucleus-shell» types, nanoparticles with hierarchical structure of pores, dens or highly porous surfaces. We have reviewed types of aerosol particle generators providing various dimensions of particles and velocities of particle generation. Our researchers have described theoretical approaches to describing processes occurring during aerosol synthesis, possibilities of controlling and scaling processes to transition to industrial production of nanomaterials using aerosol technologies.

Implemented results of research: We have obtained a Russian Federation patent No 175873 on 21 December 2017 for the useful model «Flow diffusion chamber». This equipment is the experimental basis for conducting further aerosol research within the project.

Education and career development:

  • We have published the «Surfaces of velocities of nucleation» monograph that features thorough analysis of the current state of research of nucleation in oversaturated vapor, examples of constructing semi-empirical constructions of velocities of nucleation are provided. The bibliography features 166 sources. In the future we expect the approach proposed in the monograph to allow for creation of a database of topologies and scientific basics of nucleation.

Organizational and structural changes: The Laboratory has equipped its facilities according to objectives of its research and safety regulations to accommodate its employees and conduct experiments. New devices and materials have been purchased.

Collaborations:

Kutateladze Institute of Thermophysics of the Siberian Department of the Russian Academy of Sciences (Russia): joint research

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