Die Präsentation wird geladen. Bitte warten

Die Präsentation wird geladen. Bitte warten

T Physikalisch-Technische Bundesanstalt Hannes SchmidtPhysikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig Universität Rostock, Lehrstuhl.

Ähnliche Präsentationen


Präsentation zum Thema: "T Physikalisch-Technische Bundesanstalt Hannes SchmidtPhysikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig Universität Rostock, Lehrstuhl."—  Präsentation transkript:

1 t Physikalisch-Technische Bundesanstalt Hannes SchmidtPhysikalisch-Technische Bundesanstalt, Bundesallee 100, Braunschweig Universität Rostock, Lehrstuhl für Technische Thermodynamik, Albert-Einstein-Straße 2, Rostock Baku, Realisation of a Substitution Method to Perform High Precision Density Measurements of Seawater Hannes Schmidt Henning Wolf Egon Hassel

2 2 Physikalisch-Technische Bundesanstalt, Bundesallee 100, Braunschweig Content Introduction Importance of thermo physical properties of seawater Simplifications in calculation of thermo physical properties of seawater Motivation Practical salinity and conductivity Possible inconsistency Approach Traceability of salinity to density Substitution method Technical realisation Demands on equipment Density at atmospheric pressure Density at high pressure Results Measurement results Summary

3 3 Physikalisch-Technische Bundesanstalt, Bundesallee 100, Braunschweig Importance of thermo physical properties of seawater /2000-years-of-global-temperatures-small.gif content/uploads/climate-model-2.jpg /climate_files/ClimateSimulation_ _IPCC2007.JPG Measurement data is used for understanding and prediction of climate on long term scales. Measurement data is used for understanding and prediction of climate on long term scales.

4 4 Physikalisch-Technische Bundesanstalt, Bundesallee 100, Braunschweig Deviations in density – meaning salinity and temperature – are driving forces of subsurface currents (below 400 m). Surface currents are mainly driven by wind. Thermohaline circulation Conveyor belt Importance of thermo physical properties of seawater

5 5 Physikalisch-Technische Bundesanstalt, Bundesallee 100, Braunschweig SourceTheoretical Measurand Pressure, Temperature, Conductivity Pressure, Temperature, N-1 amounts of substances Resulting relation e.g. heat capacity Simplification in calculation of thermo physical properties of seawater Conductivity replaces information on amounts of substances in calculations.

6 6 Physikalisch-Technische Bundesanstalt, Bundesallee 100, Braunschweig Possible inconsistency Sources Simplification by using conductivity Practical salinity determination salt composition is changingsalt composition is changing (!) not all dissociated salts are contributing to conductivity (silicates,..) reference substance not certified (purity,..) Especially a change in salt composition can cause inconsistency.

7 7 Physikalisch-Technische Bundesanstalt, Bundesallee 100, Braunschweig Substitution Method Seawater Ultrapure water Procedure Sea water density (Sample) Ultrapure water density (Reference) Seawater density Ultrapure water density …10 times… Substitution method decreases measurement uncertainty about factor bottle (200 ml) = 1 temperature = 8 h

8 8 Physikalisch-Technische Bundesanstalt, Bundesallee 100, Braunschweig Density at atmospheric pressure 998,205 A. Paar DMA 5000M FRONTREAR FAN USB VGA S-BUS RS232 ETH CAN AIR IN ONSEC 0,1 MPa M VAISALA 1, ,1 MPa M H2OH2O SSW SSW Standard Sea Water H 2 O Ultrapure Water Measurand Measurement uncertainty (k = 2) Reproducibility (Std. deviation) Temperature5 mK1 mK Pressure0.007 kPa0.002 kPa Density0.002 kg/m kg/m 3 MeasurandSpecification range Temperature0..40 °C

9 9 Physikalisch-Technische Bundesanstalt, Bundesallee 100, Braunschweig Density at high pressure (2) Teledyne ISCO 100DM Syringe pump and controller DHI RPM4 Pressure measuring unit DMA HP Densitometer DMA 5000M master device

10 10 Physikalisch-Technische Bundesanstalt, Bundesallee 100, Braunschweig Measurement results Seawater measurement values were corrected by appr kg/m ppm 0.4 ppm Time in s Density (Water) in kg/m 3 Density (Seawater) in kg/m 3 Ultrapure water Seawater Substitution result

11 11 Physikalisch-Technische Bundesanstalt, Bundesallee 100, Braunschweig Summary Calibration and measurement routines for seawater have a risk of data inconsistency when data is collected over decades. The solution is tracing back salinity to density directly by high precision density measurements and electrolytic conductivity measurements. A fully automated density measurement device was built and measurement uncertainties of 2 ppm at 1 bar (20 ppm at > 1 bar) were reached. Atmospheric density measurements are finished and high pressure density measurements will start soon.

12 12 Physikalisch-Technische Bundesanstalt, Bundesallee 100, Braunschweig


Herunterladen ppt "T Physikalisch-Technische Bundesanstalt Hannes SchmidtPhysikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig Universität Rostock, Lehrstuhl."

Ähnliche Präsentationen


Google-Anzeigen