High-Temperature Hydrogen-Air- Steam DetonationExperiments in the BNL Small-Scale Development Apparatus (NUREG/CR-6213, BNL-NUREG-52414)

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Publication Information

Manuscript Completed: July 1994
Date Published: August 1994

Prepared by:
G. Ciccarelli, T Ginsburg, J. Boccio, C. Economos, C. Finfrock, L. Gerlach
Brookhaven National Laboratory
Upton, NY 11973-5000

K. Sato, M. Kinoshita
Nuclear Power Engineering Corporation
Fujitakanko Building
17-1, 3-chome, Toranomon, Minato-ku
Tokyo 105, Japan

Prepared for:
Division of Systems Research
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

and

Nuclear Power Engineering Corporation
Fujitakanko Building
17-1, 3-chome, Toranomon, Minato-ku
Tokyo 105, Japan

NRC FIN L-1924, A-3991

Availability Notice

Abstract

The Small-Scale Development Apparatus (SSDA) was constructed to provide a preliminary set of experimental data to characterize the effect of temperature on the ability of hydrogen-air-steam mixtures to undergo detonations and, equally important, to support design of the larger scale High-Temperature Combustion Facility (HTCF) by providing a test bed for solution of a number of high-temperature design and operational problems. The SSDA, the central element of which is a 10-cm inside diameter, 6.1-m long tubular test vessel designed to permit detonation experiments at temperatures up to 700K, was employed to study self-sustained detonations in gaseous mixtures of hydrogen, air, and steam at temperatures between 300K and 650K at a fixed initial pressure of 0.1 MPa. Hydrogen-air mixtures with hydrogen composition from 9 to 60 percent by volume and steam fractions up to 35 percent by volume were studied for stoichiometric hydrogen-air-steam mixtures.

Detonation cell size measurements provide clear evidence that the effect of hydrogen-air gas mixture temperature, in the range 300K–650K, is to decrease cell size and, hence, to increase the sensitivity of the mixture to undergo detonations. The effect of steam content, at any given temperature, is to increase the cell size and, thereby, to decrease the sensitivity of stoichiometric hydrogen-air mixtures. The hydrogen-air detonability limits for the 10-cm inside diameter SSDA test vessel, based upon the onset of single-head spin, decreased from 15 percent hydrogen at 300K down to between 9 and 10 percent hydrogen at 650K. The one-dimensional ZND model does a very good job at predicting the overall trends in the cell size data over the range of hydrogen-air-steam mixture compositions and temperature studied in the experiments. The experimentally measured detonation velocity generally agrees within 2 to 3 percent with predictions based upon Chapman-Jouget theory over the temperature range considered, and measured peak detonation pressure agrees within 10 percent of the calculated Chapman-Jouget pressure. In these fixed initial pressure experiments, the peak pressure is found, both experimentally and according to the theory, to decrease with increasing temperature.

Preliminary experiments. indicated that the maximum temperature for which it was found possible to load combustible gases into the test vessel without an immediate bum was 650K. Experiments were conducted to measure the rate of hydrogen oxidation in the absence of ignition sources at temperatures of 500K and 650K, for hydrogen-air mixtures of 15 percent and 50 percent, and for a mixture of equimolar hydrogen-air and 30 percent steam at 650K. The rate of hydrogen oxidation was found to be significant at 650K. Reduction of hydrogen concentration by chemical reaction from 50 to 44 percent hydrogen, and from 15 to 11 percent hydrogen, were observed on a time frame of minutes. The DeSoete rate equation predicts the 50 percent experiment very well, but greatly underestimates the reaction rate of the lean mixtures.