Application of intensive hydrodynamic cavitation in liquids for synthesis of hydrogen and nanoparticles

摘要

In this paper, the results of experimental studies of hydrogen and nanoparticles production using intensive hydrodynamic cavitation in liquids are presented. Physicochemical processes occurring in a cavitation bubble at the last stage of its compression are very similar to processes occurring in the explosion chamber. The values of pressure and temperature achieved in this case ensure the thermodynamic stability of the reaction products and the production of a gaseous hydrogen and nanoclusters as a result of decomposition of molecules of liquid, which is confirmed by theoretical calculations. The controlled addition of hydrogen-containing liquids and the change in the compression conditions of cavitation bubbles make it possible to control the process of hydrogen synthesis, which is an important step in the development of modern high-tech alternative energy methods. The pulsation of a spherical cavity is described by the Kirkwood Bethe equations, which are one of the most accurate mathematical models of pulsation processes at an arbitrary velocity of the cavity boundary. The model allows to describe the process of pulsations of cavitation cavities, conduct comprehensive parametric studies and evaluate the effect of various process parameters on the collapse of cavities. This work continues with the experiments on cavitation synthesis of carbon nano structures. With the rapid movement of chemically pure hydrocarbons along the profiled channel in the form of a Venturi nozzle, cavitation bubbles form in the liquid, which are then compressed in the working chamber, in which a sharp pressure surge is created. The pressure in the shock wave, which reaches 80-90 MPa, ensures the collapse of cavitation bubbles close to adiabatic compression. As a result of the number of rapidly occurring physicochemical processes of evaporation, heating, and thermal dissociation of hydrocarbon vapors, a solid carbon phase including graphene oxide nanoparticles and a gaseous hydrogen-containing phase are synthesized in the cavitation, which is then subjected to separation. Synthesized graphene oxide nanoparticles possess activated surface due to the cavitation action and can be subsequently used as substrates for modification with functional nanoparticles, e.g. silver nano particles with antibacterial properties. The article is of great help to scientists and design engineers who are engaged in the development of promising hydrogen generating facilities and hydrogen complexes. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.