Workshop « Towards More Accurate Fixed Points » – St Denis – 23-24 november 2006 1 LNE Center...

Workshop « Towards More Accurate Fixed Points » – St Denis – 23-24 november 20061

LNECenter for Scientific and Industrial

Metrology (CMSI)Thermal & Optical Division29, avenue Roger Hennequin

78197 Trappes, France

Development of a new deviceDevelopment of a new devicefor realizing the indium fixed-pointfor realizing the indium fixed-pointin quasi-adiabatic conditionsin quasi-adiabatic conditions

Development of a new deviceDevelopment of a new devicefor realizing the indium fixed-pointfor realizing the indium fixed-pointin quasi-adiabatic conditionsin quasi-adiabatic conditions

R. Morice ([email protected]),

G. Bonnier, J.C. Barbaras, N. Fleurence, V. Le Sant,G Le Dortz, A Lesauvage, G Failleau, P. Ridoux, J.R. Filtz


Introduction

Euromet 732 project

WP6 Indium fixed point

PTB (WP leader), LNE-CMSI, METAS

LNE-CMSI general objective :

Develop enclosures for realizing ITS-90 fixed

point (t>0.01°C) in quasi-adiabatic conditions


Assess uncertainties due to thermal

parasitic effects in ITS-90 fixed points

Thermal Properties of Materials programme

of LNE-CMSI

TP of pure metals

To facilitate and to improve PRTs calibration ?

65 PRTs / year calibrated or

checked at Ga, In- More simple (limited radiative heat flux …)

- Wide variety of materials available up

to 200 °C

INDIUMFIXEDPOINT

Introduction


Therm om eter

Environm ent

G uard cell

F ixed point ce ll

• Fixed point cell placed in a guard containing a metal of the same nature

• Cell+guard system placed in a thermal enclosure

• Temperature of enclosure adjusted below the melting temperature of the metal

• Fixed point cell melted using heat pulses, in quasi-adiabatic conditions

Principle - new device

• Additional heater to maintain permanently the guard in its phase transition

Heat


The project

to investigate / assess the

previous principle

to understand thermal

aspects of phase transition

(permanent heat flux or heat

pulses)

to optimise the final design

Development of an experimental prototype• construction ( nov 06)• metrological assessment

( march 07)

Development of a thermal model ( end 07)

First step : experimental prototype

Second step : final design ( end 07)


Experimental prototype

Scheme

Constructed for operation with

a well known, « traditional »

indium cell (LNE-INM type)

investigate phase transition

using permanent heat flux

method or calorimetric method

(heat pulse technique)

2 indium guards, 5 guard

heaters, 3 heaters for the indium

cell, 1 TC/heater, 3 heat flux

sensors

Ind ium guardAuxilliaryheaters

Indium cell

Ind ium guard

A irpulsedfurnace

O uter casing

Therm om eter


Preliminary tests - Thermal control of the In guard (1)

Method envisaged : Furnace temperature maintained below melting temperature of indium

Melt initiated in the In guard using heat pulses (heating mode)

Detection of local presence of interface using heat pulses (detection mode)


Indium cell

Ind ium guard

A irpulsedfurnace

O uter casing

Therm om eter

tim e

Tem peraturesensor

Indium(Liquid)

Indium(Solid)

W alls


Preliminary tests - thermal control of the In guard (2)

Temperature of auxilliary heater - « Heating mode »

0

1

2

3

4

0 4 8 12 16

time (min)

in meltend of meltoutside melt

T(t

ime)

- T

(bef

ore

pul

se)

/°C


Temperature of auxilliary heater - « Detection mode »

0

0.5

1

0 100 200 300 400

time (sec)

During phasetransition

Outside phasetransition

ther

mal

pul

se (

norm

alis

ed to

1)

Preliminary tests - thermal control of the In guard (3)

tnorm = (tt-tmin)/(tmax-tmin)



Indium cell

Ind ium guard

A irpulsedfurnace

O uter casing

Therm om eter

Preliminary tests – In lateral guard and In cell (1)

Ind ium cell

Ind ium guard

Therm om eter

H eat fluxsensor

A irpulsedfurnace


155.5

156.0

156.5

157.0

157.5

158.0

158.5

159.0

0 5 10 15 20

time (hours)

tem

pera

ture

(°

C)

Melt of In guard

Melt of In cell

Successive melts of the In guard and In cell usingpermanent heat flux method

Temperature displayed in the thermometer well



Limited heat flux from auxilliary heaters

Possible detection of local L/S interface along indium cell

Possible detection of non-adiabaticity ( out of heating period) along indium cell

Heat pulses technique :Heat exchange between In guard and In cell when both are melting

= (tg-tc)/Req

Heat pulse 1W / 500 J



Melt of the indium cell by heat pulses (guard in phase transition)

156

156.2

156.4

156.6

156.8

157

157.2

0 50 100 150 200 250time (min)

tem

pera

ture

(°C

)



Experimental prototype set up

Cross cut

Details : In lateral guard, In cell, In upper guard


Follow up …

Work currently in progress

• prototype now constructed• assessment : confront methods, numerical model, melt / freeze• uncertainties ?

Next steps

• final design of the setup• aluminium (phD student)

Workshop « Towards More Accurate Fixed Points » – St Denis – 23-24 november 2006 1 LNE Center...

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Transcript of Workshop « Towards More Accurate Fixed Points » – St Denis – 23-24 november 2006 1 LNE Center...