heat flux measurement
DESCRIPTION
Heat Flux Measurement. Adrian Sabau Metals and Ceramics Division Oak Ridge National Laboratory, Oak Ridge, TN 37831 Oak Ridge, TN August 29, 2006. Die Lubricant Experiments Were Conducted at Initial Plate Temperatures of 150, 200, 250, and 300 o C. - PowerPoint PPT PresentationTRANSCRIPT
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Heat Flux Measurement
Adrian SabauMetals and Ceramics Division
Oak Ridge National Laboratory, Oak Ridge, TN 37831
Oak Ridge, TNAugust 29, 2006
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Die Lubricant Experiments Were Conducted at Initial Plate Temperatures of 150, 200, 250, and 300 oC
Initial plate temperature:
Water vapors preclude an effective cooling at longer times
0
0.2
0.4
0.6
0.8
1
-1
2
5
8
11
14
200 250 300 350 400 450 500 550
Weight (mg)
Temperature Difference (oC)
Wei
ght
frac
tion
Tem
peratu
re Differen
ce (oC)
Temperature (oC)
150 oC
300 oC.
TGA (solid line) and DTA (dotted line) data for Diluco 135. Data relates to the amount of volatilization products in the die.
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Proof of Principle: Heat Flux Test Stand Can Be Used Very Efficiently to Evaluate Die Lubricants
•Lower heat fluxes are expected for water spray at higher temperatures.•Test stand designed adequately reproduced water spray characteristics.
2000
3000
4000
5000
6000
7000
8000
100 125 150 175 200 225 250 275 300 325 350
HT
C [
W/m
2 K]
Surface Temperature [ oC]
Initial plate temperature [oC]
150200 250 300 350
400
2000
3000
4000
5000
6000
7000
8000
100 125 150 175 200 225 250 275 300 325 350
HT
C [
W/m
2 K]
Surface Temperature [ oC]
Initial plate temperature [oC]
150200 250
300
350400
Diluco-water spray (1/15 parts).water spray
•Die-lube sprays have a different signature than water sprays due to the volatilization of lubricant compounds at different temperatures.
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Accomplishment: For the first time, Pulse and sweep experiments were successfully conducted at 250 oC
nozzle-plate distance (7.5 in), perpendicular jet (90o) .Diluco-water spray (1/15 parts).
The sweep application was the best for total amount of heat removed per unit mass of lubricant, i.e., cost effective criterion.
Pulse experiment.
1000
104
105
106
107
0 1 2 3 4 5 6 7 8 9 10
P250a P250b
Hea
t F
lux
[W/m
2 ]
Time [s]
1000
5.01 105
1.001 106
1.501 106
2.001 106
2.501 106
3.001 106
0 1 2 3 4 5 6 7 8 9 10
Hea
t F
lux
[W/m
2 ]
Time [s]
Sweep velocity (20 cm/s).
Pulse spray is the best for total amount of heat removed per unit time, i.e., productivity criterion
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Industry Benefits due to the ORNL work on lubricant application process
Validated test stand using heat flux sensors for die lubricants. Heat transfer coefficient was determined from heat flux measurements,
More benefits: Heat flux measurements can be used to determine: optimum nozzle distance, desired application technique (sweeping or pulsing) optimum timing of nozzle spray pulse, optimum spray parameters (spray flow rate, water pressure, air pressure, time of spraying, nozzle velocity, or pulse duration)
Two lubricant companies have expressed interest in using the ORNL approach.
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
The sensor was mounted such that its surface was flushed with that of the mold
The thermocouple was in contact with molten metal and mold.The thermocouple junction is visible.
Plate dimensions: 7x4x1 cm
Due to surface tension effects, the metal did
not wet the thermocouple wires.
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Measurement of Heat Flux at Metal-Mold Interface During Casting Solidification
II
1 105
4 105
7 105
1 106
1.3 106
1.6 106
1.9 106
2.2 106
2.5 106
0 2 4 6 8 10
g_1g_g2g_g3g_bn4g_bn5
Hea
t F
lux
[W/m
2 ]
Time [s]
I III IV
Main domains for heat flux variation during casting
Very fast response time allows data measurement at short times.
h q",TC ,TM q"
TC TMHeat transfer coefficient