Consultative Committee for Thermometry ‐ CCT Dr Yuning DUAN CCT President and CIPM member (NIM – China) 25 th meeting of the CGPM
Main Areas • Temperature • Primary thermometry • Temperature scales • Fixed points and interpolation equations • Thermodynamic temperature → new de fi ni � on of the kelvin • Secondary contact thermometry • Humidity • Thermophysical quantities • CCT meetings in 2012 and 2014 • Next meeting planned for 2017 Consultative Committee for Thermometry / Dr Yuning DUAN *
Areas of priority and potential • High ‐ accuracy determination of the Boltzmann constant using different techniques in view of a new definition of the kelvin • Ensure world ‐ wide equivalence of temperature in a mixed situation of ITS ‐ 90 and thermodynamic temperature primary standards • Anticipating a new temperature scale • Give support to climate studies • Thermal imaging • Expanding activities in humidity world wide. Towards a universal definition of humidity quantities and measurands (traceable to the SI) • Challenge to investigate thermophysical measurements to support climate and energy sectors, and to identify reference materials Consultative Committee for Thermometry / Dr Yuning DUAN *
Areas of priority and potential • High ‐ accuracy determination of the Boltzmann constant using different techniques in view of a new definition of the kelvin • Ensure world ‐ wide equivalence of temperature in a mixed situation of ITS ‐ 90 and thermodynamic temperature primary standards • Anticipating a new temperature scale • Give support to climate studies • Thermal imaging • Expanding activities in humidity world wide. Towards a universal definition of humidity quantities and measurands (traceable to the SI) • Challenge to investigate thermophysical measurements to support climate and energy sectors, and to identify reference materials Consultative Committee for Thermometry / Dr Yuning DUAN *
Towards a new definition of the kelvin • Progress on the determination of the Boltzmann constant for a future re ‐ definition of the kelvin using different methods Acoustic Gas Thermometry 2 = kT / m u 0 = c p / c V Dielectric Constant Gas Thermometry D = [2 kT /(mc 0 2 )] 1/2 � 0 Johnson Noise Thermometry <U 2 > = 4 kT R Doppler Broadening Thermometry p = kT 0 ( r ‐ 1)/ 0 Consultative Committee for Thermometry / Dr Yuning DUAN *
Towards a new definition of the kelvin Values considered by CODATA in 2013 Recommendation T 1 (2014) to the CIPM: (extract) recommends that a fixed numerical value of the Boltzmann constant will be adopted, when the following two conditions are met: • the relative standard uncertainty of the adjusted value of k is less than 1 × 10 − 6 ; • the determination of k is based on at least two fundamentally different methods, of which at least one result for each shall have a relative standard uncertainty less than 3 × 10 − 6 . Consultative Committee for Thermometry / Dr Yuning DUAN *
Towards a new definition of the kelvin Values considered by CODATA in 2013 Recommendation T 1 (2014) to the CIPM: (extract) recommends that a fixed numerical value of the Boltzmann constant will be adopted, when the following two conditions are met: • the relative standard uncertainty of the adjusted value of k is less than 1 × 10 − 6 ; • the determination of k is based on at least two fundamentally different methods, of which at least one result for each shall have a relative standard uncertainty less than 3 × 10 − 6 . k = 1.380...10 ‐ 23 J/K ... at the next CGPM Consultative Committee for Thermometry / Dr Yuning DUAN *
Stakeholder involvement NMIs and DIs, themselves precursor to other stakeholders • International Association on Properties of Water and Steam (IAPWS) • International Surface Temperature Initiative • International Union of Pure and Applied Chemistry (IUPAC) • International Confederation for Thermal Analysis and Calorimetry (ICTAC) • International Association of Chemical Thermodynamics (IACT) • World Meteorological Organisation (WMO): • • WMO ‐ CIMO (Commission for Instruments and Methods of Observation) • WMO GCOS ‐ GRUAN (Global Climate Observing System – Reference Upper ‐ Air Network) Consultative Committee for Thermometry / Dr Yuning DUAN *
Achievements 2011 ‐ 2014 • MEMBERSHIP INMETRO (Brazil) member and CMI (Czech Republic) , HMI/FSB ‐ LPM (Croatia) observers • CCT strategy drafted in 2012 following the BIPM time schedule • Reduced number of WGs from 10 to 6 • …shorter term projects covered by Task Groups; wider exchange in Forum format • Strengthened WG ‐ KC – guarantees quality and validity of published data • Created a Task Group on Environment • RMO TC Chairs invited to the CCT 2014 and selected WG meetings • Drafted Mise en Pratique to anticipate the new definition of the kelvin • Launched 2 CCT comparisons (radiation thermometry and SPR Thermometers) • CCT ‐ K6 in humidity completed • Initiated exchange with the WMO ‐ CIMO • Launched monthly internal news letters Consultative Committee for Thermometry / Dr Yuning DUAN *
Future Strategy • Encourage result oriented groups • Improved exchange with international stakeholders • Prepare the new definition of the kelvin • Solid international basis for the determination of the Boltzmann constant • Close contact with CODATA • Guidance on the Realization of the ITS ‐ 90 • Long ‐ term work towards a new temperature scale • Review of the CIPM ‐ MRA from the CCT perspective • Study impact of the new GUM ‐ Guide to the Expression of Uncertainty in Measurement from the CCT perspective • Continued guidance for secondary thermometry • Identify how to best contribute to environmental and climate issues • CCT strategy will be reviewed by 2017 Consultative Committee for Thermometry / Dr Yuning DUAN *
Thank you
Interdisciplinary issues • Temperature issues involved in ALL areas of high precision metrology • Thermometry and amount of substance – to determine the Boltzmann constant via the speed of sound – or dielectric gas constant Thermometry and photometry – spectral emissivity for solar thermal measurements Humidity and chemistry – linked to traces of water in gas and moisture in materials Humidity, temperature and global warming Consultative Committee for Thermometry / Dr Yuning DUAN *
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