Analytic calculations of ozone concentration in an oxygen-fed wire-to-cylinder ozonizer and comparison with the Vasil'ev relation

An analytical model for ozone concentration calculations in an oxygen-fed wire-to-cylinder ozonizer is presented in order to improve our basic knowledge on ozone generation. This approach takes into account the physical and chemical phenomena. The Becker parameter is introduced and the ozone concentration deduced from this model is compared to the Vasil'ev relation, the macroscopic coefficients for ozone formation and destruction being expressed as functions of the kinetic coefficients. The general results (electron density, ozone concentration, macroscopic coefficients) are compared with experiments and a good agreement is observed

Water Vapour Condensation in a Partly Closed Structure. Comparison between Results Obtained with an inside Wet or Dry Bottom Wall

International audienceWe are interested in the determination of the more significant parameters acting on the water vapour condensation in a partly closed structure, submitted to external constraints (temperature and humidity), in view to recover the generated droplets as an additional source of potable water. External temperature variations, by inducing temperature differences between outside and inside of the structure, lead to convective movements and thermal variations inside this structure. Through an orifice, these movements permit a renewing of the humid inner air and can lead to the condensation of the water vapour initially contained in the inner air volume and/or on the walls. With the above hypotheses, and by using a numerical simulation [1] based on the ambient air characteristics and a finite volumes method, it appears that condensed water quantities are mainly depending on the boundary conditions imposed. These conditions are: 1) dimensions of the structure; 2) external temperature and relative hygrometry; 3) the phase \varphi (T/RH) linking thermal and hydrometric conditions; 4) the air renewing and its hygrometry for each phase; and 5) for each case, the fact that the inside bottom wall can be wet or dry. The resulting condensed water vapour quantities obtained, for the width section, point out clearly that they are very depending on this phase \varphi (T/RH) which appears as the more significant parameter and can be modified by the presence or not of a thin layer of water vapour on the inside bottom wall. Condensation phenomenon could be increased if \varphi could be optimized. \textcopyright 2018, Springer-Verlag GmbH Germany, part of Springer Nature

Removal of H

The aim of this work is to study a reactor submitted to a gaseous flow, using gliding discharges along several divergent electrodes supplied by an AC high voltage power supply. This reactor was used for the treatment of gaseous pollutants (such as hydrogen sulfide H2S) generally contained in industrial effluents. A systematic survey of the sulfide hydrogen destruction yield was undertaken according to several variables (H2S initial concentration, hygrometry, gas flow rate, electric power, shape of the electrodes...). We have pointed out also the importance of the residence time of pollutants in the reactor. The best conditions for treatment were defined for the available power supply. A minimum energy density in the 0.1−0.18 kWh/m3 range and a destruction yield > 95% were obtained for a 100 ppmv H2S initial concentration. Finally, we started a discussion about the formulation of the reactional mechanisms leading to the H2S removal and about the energy distribution inside the reactor

Self-Sustained Conditions in Inhomogeneous Fields

A theoretical model allowing to plot the breakdown voltage $V\rm _B$ as a function of the product $p_{\rm d}$ (pressure $\times$ interelectrode distance) is presented for a D.C. corona discharge. For a parabolic point, it is shown that the Paschen curve can be generalized to inhomogeneous fields, since the homogeneous fields are the asymptotic limit of this theory. The analytical expression obtained from this model is finally plotted and compared to experimental results in nitrogen and dry air.Un modèle théorique permettant de tracer le potentiel disruptif $V\rm _B$ en fonction du produit $p_{\rm d}$ (pression $\times$ distance interélectrodes) est présenté pour une décharge couronne en tension continue. On montre, pour une pointe parabolique, que la corbe de Paschen peut être généralisée au cas des champs inhomogènes, le cas du champ homogène étant la limite asymptotique de cette théorie, l'expression analytique obtenue à partir de ce modèle est finalement tracée et comparée aux résultats expérimentaux obtenus dans l'air et l'azote