genva, january 23, 2001h.-g. moser mpi, munich a quick and clean method to measure thermal...
TRANSCRIPT
Genva, January 23, 2001 H.-G. Moser MPI, Munich
A quick and clean method to measure
thermal conductivity
Application: QA and QC of spinesStandard Method: T between heat source and heat sinkDisadvatage: depends on thermal coupling of heaters, sensors etc....
Genva, January 23, 2001 H.-G. Moser MPI, Munich
Ballistic Methodheater
pt100 pt100
T
t
T
t
Measure reponse T(t): time constant depends on c/ck(c: specific heat, ck: thermal conductivity)
Genva, January 23, 2001 H.-G. Moser MPI, Munich
Ballistic Methodheater
pt100 pt100
t=0: T0
t>0: Tr
T(t,x)=Tr-(Tr-T0)ciexp(-²t/L²)cos[(x-L)/L]i=/2, 3/2 , 5/2ci=4 sin(i)/[2i sin(2i)]=ck/c
LX=0
Genva, January 23, 2001 H.-G. Moser MPI, Munich
TPG bar 12 cm
Title:/mnt/home/afmp08/moser/simulation/time.ps (Portrait A 4)Creator:HIGZ Version 1.25/05Preview:This EPS picture was not savedwith a preview included in it.Comment:This EPS picture will print to aPostScript printer, but not toother types of printers.
Title:/mnt/home/afmp08/moser/simulation/time.ps (Portrait A 4)Creator:HIGZ Version 1.25/05Preview:This EPS picture was not savedwith a preview included in it.Comment:This EPS picture will print to aPostScript printer, but not toother types of printers.
Theoretical solution for T=const boundary condition!
Genva, January 23, 2001 H.-G. Moser MPI, Munich
Measurements
In practice: use heater (constant power) instead of constant temperature bathSpine is a composite object
=> Calibration necessary
Genva, January 23, 2001 H.-G. Moser MPI, Munich
TPG/CuCu
t-log(T*)-Graph
-2,500
-2,000
-1,500
-1,000
-0,500
0,000
00:00:17 00:00:35 00:00:52 00:01:09 00:01:26 00:01:44 00:02:01
Zeitlo
g(T
*)
Sensor 1 Sensor 2 Sensor 3 Sensor 4 Sensor 5
TPGt-log(T*)-Graph
-2,500
-2,000
-1,500
-1,000
-0,500
0,000
00:00:17 00:00:35 00:00:52 00:01:09 00:01:26 00:01:44 00:02:01
Zeit
log
(T*)
Sensor 1 Sensor 2 Sensor 3 Sensor 4 Sensor 5
TPG bar Copper barLn[(T-Tmin)/(Tmin-Tmax)]
Genva, January 23, 2001 H.-G. Moser MPI, Munich
Effect of different power
One practical problem is bad reproducibility of the coupling heater/sample (and sensor/sample)Can be checked by varying the heater power1.7, 3.2, 6.6 W
Vergleich Sensor1 U=var.
-0,600
-0,500
-0,400
-0,300
-0,200
-0,100
0,00000:00:17 00:00:26 00:00:35 00:00:43 00:00:52 00:01:00
Zeit
5V 7V 10V
Ln[(T-Tmax)/(Tmin-Tmax)]
Genva, January 23, 2001 H.-G. Moser MPI, Munich
Conclusions
Time constant (almost) independent ofheater power, coupling of heaters and sensors
Fast response: small effect of ambient temperature
Robust and reproducible measurement of Ck
-> develop a simple QC setup for spine