Jacques Chaineaux

Large scale characterization of the concentration field of supercritical jets of hydrogen and methane

Abstract This paper reports on an experimental investigation of the concentration field of supercritical jets of methane and hydrogen. The jets were produced by venting a tank containing gas at a pressure of 40 bar (568 psi) to atmosphere through orifices whose diameters ranged from 25 to 150 mm. The concentration measurements were made in the subsonic zone of the jets using an original echnique. This technique employs a sensor using the catalytic oxidation effect and can measure the concentration of combustible gas in highly reactive environments with no risk of ignition. The investigation was designed with experiments on a scale typical of that encountered in industry during accidental discharges of pressurized gas, a scale much larger than that normally used in a laboratory. The results show that when proper allowance is made for the expansion zone of supercritical jets it is possible to relate the results obtained in these jets with those found in variable density subsonic jets. In particular, the rates at which mass concentration decreases along the axes of supercritical and subsonic jets are equal when weighted by an equivalent diameter which takes into account the conditions of both pressure and density in the discharge section.

Experimental determination of flash points of flammable liquid aqueous solutions

The flash point is considered as a determinant parameter to classify the flammable liquids, regarding the European CLP regulation, as well as the transport of dangerous goods regulation. In the case of some low concentrated flammable liquid aqueous solutions, the existence of a flash point is not very well defined, and their flammability is not precisely known. The experimental measurements of flash points are described in numerous national or international standards, which differ by their range of validity and by the specified experimental conditions. The flash point of ethanol, acetone, acetic acid and formic acid aqueous solutions was measured using Abel and Pensky-Martens in close cup methods, chosen regarding predicted values of flash point. Results obtained show that, for the most flammable products, such as acetone or ethanol, weakly concentrated aqueous solutions still remains flammable. In the case of acetic or formic acid aqueous solutions, a threshold concentration can be determined under which the solutions are considered as non flammable, regarding the European CLP regulation and the transport of dangerous goods regulation.

Discharge in air of a vessel pressurized by a flammable gas; volume of the resulting flammable mixture generated

Abstract Assuming a monophasic jet, a computer code was established to described the variation with time of the dimensions of a flammable cloud generated by discharge of a vessel of finite volume. The code was validated by testing the horizontal discharge in air of a 120 dm 3 vessel pressurized by 10 MPa of H 2 or CH 4 , through a hole of diameter d (6 d