Kurchatov Institute Hydrogen Subsonic Upward Release and Dispersion Experiments in Closed Cylindrical Vessel Denisenko V.P. 1, Kirillov I.A. 1, Korobtsev S.V. 1, Nikolaev I.I. 1, Kuznetsov A.V. 2, Feldstein V.A. 3, Ustinov V.V. 3 1 RRC ”Kurchatov Institute” 1, Kurchatov Sq., Moscow, , Russia 2 NASTHOL 6, Shenogin str., Moscow, , Russia 3 TsNIIMash 4, Pionerskaya, Korolev, , Russia

Kurchatov Institute Context: Russian R&D Programme “Codes an Systems for Hydrogen Safety” grant of Russian Ministry of Science and Education ( , cont. July ): for safety provision of national hydrogen infrastructure scientific basis for development of regulatory documents (codes/standards) … minimal number and allocation of sensors in confined areas … prototypes for subsequent commercialization of tools/components for integrated safety systems … sensors recombiners inhibitors …

Kurchatov Institute Context: Problem: Allocation of sensors in confined areas Technical questions: 1.How many ? What is a minimal number of gas detectors, which should be used in confined area, for safety provision ? 2.Where ? How should they be spatially allocated? Land use problem: absence of free space -> multiple-use of space -> confined sites undeground parking, 100+, ~5 kg H2 per auto

Kurchatov Institute Context: Problem: Allocation of sensors in confined areas Practical reference case: according to current technical regulation of Ministry of Transport (VCN Minavtotrans) Ministry of Emergency (NPB ) gas * - fueled autotransport facilities and premises (parking, workshop, etc.) of category A should be equipped with gas-analyzers and alarm systems * - propane-buthane

Kurchatov Institute Context: Problem - Allocation of sensors in confined areas Empirical approach: Qualitative guidelines “…Sensors should be positioned to detect any gas accumulation before it creates a serious hazard….” The selection and use of flammable gas detectors, HSE, TD05/035, 2004 ( p.8) “…Hydrogen detectors are typically placed above a likely leak point, where hydrogen may accumulate, and at the intake of ventilation ducts….” ISO-TR (p.5)

Kurchatov Institute Empirical approach: Quantitative guidelines TU-gas-86. Requirements on arrangement of the indicators and gas- analysers RD BT Requirements on arrangement of stationary gas- analysers in industrial facilities and on outdoor sites of oil and gas industry 1 sensor per 100 m 2 Restricted application: for propane-buthane only Context: Problem - Allocation of sensors in confined areas

Kurchatov Institute Practical need: Quantitative engineering guidelines (rational procedure) for selection of a minimal number of sensors and their spatial allocation within given confined space, which should be protected Research prior art: indirect relevance only Extensive database for jets/plumes under open space conditions For releases into confined space – fire detectors allocation studies Context: Problem - Allocation of sensors in confined areas

Kurchatov Institute Scope of reported research work: Overall goal experimental characterization of the hydrogen sub-sonic* release and distribution inside of confined, unventilated space baseline (reference) data for subsequent studies: certain, accurate, repeatable, verifiable Technical objectives qualitative characterization of basic gas-dynamic patterns quantitative measurements of ignitable envelope evolution * - “small foreseeable leakage” scenario

Kurchatov Institute Approach: “Schiphol principle”: Mind your uncertainties ! minimize experimental uncertainties ALAPR identify and document uncertainties balance ‘performance - uncertainty“ propose affordable design of experiment

Kurchatov Institute Source of uncertaintyVariableIs controlled byEffect boundary conditionschamber geometryrigid walls"membrane effects" are absent external thermal fluxestemperature difference externally-driven convective effects are absent external mass fluxesgas-tight headleakage effects are absent initial conditionsgas pressurepressure gauge in gas FL+ gas temperaturetemperature sensor in gas FL+ relative humidity of gasRH sensor+ performance conditionschemical composition fieldnet of chemical sensors+ temperature fieldnet of tenperature sensors+ instrumentationsensor size ? sensor geometrycylindrical? sensor positioninghorizontal? data acquisitionfault-tolerant design design+ test procedureinert gas purgingprocedure + Approach: Analysis of experimental uncertainties

Kurchatov Institute Schematic drawing of protective concrete dome (R = 6 m, h = 6 m, H = 12 m) Ambient conditions (inside of dome): Air temperature 23ºC Air pressure 758 mm Hg Relative humidity 64 % Experiment: Site layout

Kurchatov Institute External (left) and internal (right) views of the experimental chamber Experiment: Experimental chamber

Kurchatov Institute Experiment: Gauge net layout 2,22 м hydrogen source: circular tube (internal diameter - 0,012 m)

Kurchatov Institute Thermal Conductivity Gauge TCG-3880 (is shown with open cap) by Xensor Integration (Netherlands) Acoustic sensor mounted at electronic card (for data processing and transmission) by RRC ”Kurchatov Institute” Experiment: Hydrogen sensors

Kurchatov Institute gas mixture preparation device (GMPD): gas mixture compositionup to 8 components steady gas flow rate [5*10 -6, 7*10 -4 ] m 3 /s (from 20 to 2560 l/h). Experiment: Gas supply and control

Kurchatov Institute Experiment: Procedure and Parameters Series 3 consecutive runs (inert gas purging between) with the same parameters Ambient conditions standard Hydrogen injection directionupward duration10 min flowrate0,46 l/sec Data acquisition Durationduring injection and 15 min after its end Temperature sensors24 (inside), 4 (outside) Hydrogen sensors24 (inside) Pressure gauge1 (inside), 1 (outside)

Kurchatov Institute Time histories for the hydrogen concentrations (% vol.) for the 24 gauges (time duration min) Experiment: First results: Hydrogen concentration time histories

Kurchatov Institute Three-phase evolution of ignitable gas mixture cloud Step 1 – upward propagation of emerging jet/plume, Step 2 – impinging of jet/plume with ceiling and outward expansion of cloud, Step 3 – downward expansion of cloud from ceiling to floor. Experiment: First results: Basic flow patterns: Pre-test simulations Evolution of Ignitable Hydrogen-Air Gas Mixture Cloud

Kurchatov Institute Evolution of Ignitable Hydrogen-Air Gas Mixture Cloud 1 min 5 min 10 min 10,05 min 15 min 25 min hydrogen concentration in % vol. Experiment: First results: Basic flow patterns: Experimental results

Kurchatov Institute Definition of averaged speed using sensor 4 and sensor 21 Averaged speed of envelope (2 % vol.) front propagation UNVENT#1 series (3 runs) envelope propagation speed Vert. (upward) - 0,33 m/sec, Horiz.(outward) - 0,055 m/sec. Experiment: First results: Experimental data for ignitable mixture front speed

Kurchatov Institute Time histories for three different test runs (sensor 10) Experiment: First results: Reproducibility of results

Kurchatov Institute Experiment: Synchronous behavior of sensors at symmetric points Symmetrical character of hydrogen flow in experimental vessel

Kurchatov Institute The experimental set-up for pre-normative studies of hydrogen release and dispersion inside of a medium-scale (4 m 3 ), closed horizontal cylindrical vessel was prepared and adjusted. The first precise measurements (3 test runs) of the time evolution of explosive hydrogen cloud after hydrogen injection under the well- controlled boundary/initial conditions have been carried out using spatially distributed 24 hydrogen sensors and 24 thermocouples. Analysis of the simultaneous experimental records for the different spatial points permits to delineate the basic flow patterns of hydrogen subsonic release in closed vessel in contrast to hydrogen jet release in open environment. The quantitative data were obtained for the averaged speeds of ignitable cloud envelop (50% fraction of the Lower Flammability Limit (LFL) – 2 vol.%) propagation in the vertical and horizontal directions. It was proposed to use the uncertainty analysis of the experiments and simulations for benefit of the hydrogen safety studies Conclusions:

Kurchatov Institute ACKNOWLEDGMENTS This work was supported by Russian Ministry of Science and Education and EU HYPER project (partially).

Kurchatov Institute Thanks for your attention ! Questions/comments:

Kurchatov Institute SBEP-V1 From: Figure 1. (a) Shape of the experimental vessel Figure 8. Comparison between models (250 min after the end of release). Experiment vs Simulation (VNIIPO, 1988)(HySafe, 2005) Context: Problem – Uncertainties in hydrogen safety studies

Kurchatov Institute Experimental uncertainty: during measurement phase (250 min), it was impossible to control the thermal boundary conditions Context: Problem – Uncertainties in hydrogen safety studies SBEP-V1