Computational Analysis of the Thermal States of BM-P and BM-LR Experimental Facilities
 —A hydrogen recombiner based on high-porosity cellular materials is currently studied at the Russian Federal Nuclear Center VNIITF. The hydrogen recombiner is used for flameless hydrogen combustion. Hydrogen flowing through a porous catalyst in the recombiner induces various physical and chemical processes essentially including the exothermal chemical reaction of hydrogen oxidation on the catalyzing surfaces of the recombiner and a convective flow of a gas mixture through the catalyst unit. These processes determine the technical characteristics of the recombiner including the most important efficiency measured at a given input gas composition. The BM-LR and BM-P chambers are used to conduct experiments to estimate the hydrogen concentration range within which the recombiner operates in a flameless mode at atmospheric pressure, high temperatures, and humidity, which are characteristic of severe nuclear power plant accidents [1, 2]. The BM-LR chamber includes an internal chamber (5-t railway container) and a thermally insulated external shell consisting of a mineral wool layer and a glass–magnesium plate. The internal chamber is airtight, one of the walls being covered with a polycarbonate sheet to provide video recording of experimental results. The sheet is pushed away when pressure increases during hydrogen ignition to preserve the integrity of the metal part of the chamber. Heat guns maintain the temperatures required for the experiments. The BM-P chamber is a 4-m-high steel cylinder 2 m in diameter. The walls of the chamber are equipped with windows for high-speed video recording of condensation and flame propagation processes. The chamber is designed to keep air-tightness at high pressures and to withstand high explosive loads produced by an ignited vapor–water mixture. The temperature fields in the BMLR and BM-P chambers for different recombiner operation modes have been computationally analyzed. The maximum temperatures and velocity fields are determined for the gas mixture flowing within the chambers when the recombiner is in operation. 