hydrogen – methane mixtures: dispersion and stratification studies a. marangon, m.n. carcassi
DESCRIPTION
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES A. Marangon, M.N. Carcassi. Università di Pisa. Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione (DIMNP), University of Pisa. - PowerPoint PPT PresentationTRANSCRIPT
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
HYDROGEN – METHANE MIXTURES:DISPERSION AND STRATIFICATION STUDIES
A. Marangon, M.N. Carcassi
Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione (DIMNP),(DIMNP),
University of PisaUniversity of Pisa
Università di Pisa
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
Why the hydrogen – methane mixtures could represent the transition phase towards hydrogen economy?
Experience gained over many year of distribution and use of natural gas
(transportation, energy production, domestic application, etc.).
Greater acceptance by the Public Authority and general public with
respect to pure hydrogen.
Limited investment in the short term and a significant reduction in
emissions, both local and global (greenhouse gases).
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
UNIPI – DIMNP Research activities on HCNG mixtures: 10-90 and 30-70 %vol. hydrogen in methane.
Investigation of the diffusion and stratification properties in confined and
semi-confined environments (typical of most of the industrial and
commercial environments).
Investigation with the help of the gas-chromatography technique of the
tendency or less to separate in different layers for the mixture’s
constituents (hydrogen and methane).
CFD simulations of the experimental tests (not presented in the paper).
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
DESCRIPTION OF THE TEST FACILITY
Volume: ca. 25 m3
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
DESCRIPTION OF THE TEST FACILITY
Ventilation openings
0,063 m x 0,560 m each.
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
GAS SUPPLY AND INSTRUMENTATION:
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
OXYGEN SENSOR – GAS CHROMATOGRAPHY:
Immediate manual immission in the gas chromatograph
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
OXYGEN SENSOR - VENTILATION OPENINGS POSITION:
n.7 oxygen sensors
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
MIXTURE CONCENTRATION MEASURED BY THE OXYGEN SENSORS:
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
TEST MATRIX:
MIXTURE30 H2 – 70 CH4
MIXTURE10 H2 – 90 CH4
CVE TOTALLY CLOSED
CVE WITH 2 OPENINGS ON
OPPOSITE SIDES
CVE WITH 1 OPENING IN
THE BOTTOM PART
CVE WITH 1 OPENING IN THE UPPER
PART
X - X - - -
X - X - - -
X - X - - -
X - - X - -
- X X - - -
- X - X - -
- X - X - -
- X X - - -
X - X - - -
- X - - X -
- X - - - X
X - - - - X
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
SOME EXPERIMENTAL DATA:
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
CVE TOTALLY CLOSED: Release time: 530 s
Release flow rate: 2,016 g/s
TENDENCY TO HOMOGENEIZATION
STRATIFICATION NOT WELL DEFINED IN THE HORIZONTAL
PLANES
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
CVE TOTALLY CLOSED : Release time: 1580 s
Release flow rate: 1,16 g/s
TENDENCY TO HOMOGENEIZATION
STRATIFICATION WELL DEFINED
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
VENTILATION WITH OPENINGS ON OPPOSITE SIDES:
Release time: 2890 s
Release flow rate: 1,23 g/s
FAST DECREASE OF THE CONCENTRATION ONCE THE
RELEASE WAS STOPPED
STRATIFICATION WELL DEFINED
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
VENTILATION WITH ONE OPENING IN THE UPPER PART:
Release time: 2560 s
Release flow rate: 1,32 g/s
STRATIFICATION WELL DEFINED IN THE HORIZONTAL
PLANES
ΔT (int-ext)= 5 °C
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
VENTILATION WITH ONE OPENING IN THE UPPER PART:
Release time: 2750 s
Release flow rate: 1,31 g/s
ΔT (int-ext)= 15 °CSTRATIFICATION NOT WELL DEFINED IN THE HORIZONTAL PLANES
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
VENTILATION WITH ONE OPENING IN THE BOTTOM PART:
Release time: 2023 s
Release flow rate: 1,5 g/s
STRATIFICATION WELL DEFINED IN THE HORIZONTAL
PLANES
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
METHANE CONCENTRATION (sensors vs. gas chromatograph):
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
CONCLUSIONS:
In all the experiments a non homogeneous concentration was observed
within the CVE, both with and without natural ventilation and
independently of natural ventilation openings position.
For test carried out with a higher mixture release flow rate, the gas
concentration measured at the centre of the celing of the CVE (Sens. N.1 –
2,82 m above the release point), was higher than the concentration
measured by sensor located at the same height but not directly above the
release. Instead for smaller release flow rate the concentration was well
stratified in the horizontal planes.
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
CONCLUSIONS:
For test carried out without natural ventilation a tendency to
homogenization was observed over long residence time (more than 10000
seconds).
For test carried out with natural ventilation openings, both well defined
stratification in horizontal planes and not well defined (with concentration
higher far from the opening location) was observed. This phenomenon
depending on the ΔT between the internal volume of the CVE and the
external atmosphere (higher the ΔT, worst the stratification).
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
CONCLUSIONS:
Sample analysis with gas chromatograph showed that for the presented
experiment configurations and mixture’s residence time within the CVE,
the non separation between the mixture constituent gases (hydrogen and
methane).
ICHS 2011 - San Francisco, USA - September 12 -14
HYDROGEN – METHANE MIXTURES: DISPERSION AND STRATIFICATION STUDIES
THANK YOU.
Contact Author:
Alessia Marangon (UNIPI-ITALY)
Presented by:
Martino Schiavetti (UNIPI-ITALY)