McGill Thermal Mgmt Perm Mold 4casting
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Transcript of McGill Thermal Mgmt Perm Mold 4casting
Thermal Management of Permanent MoldsThermal Management of Permanent Moldsfor the Casting of Aluminum Alloysfor the Casting of Aluminum Alloys
Chunhui Zhang Frank Mucciardi
andJohn Gruzleski
Dept. of Mining, Metals and Materials EngineeringMcGill University
[email protected] Site: www.mmpc.mcgill.ca/~frank
McGillMcGill
Objectives:
• Control the cooling of a permanent mold toproduce aluminum castings of superior quality.
• Use heat pipes to control the heat transfer.
• Selectively cool: specific locations, atspecific times.
Methodology:
History of the Heat Pipe
• Dates back to the early 1960’s
• Used extensively in electronics
• NASA and Los Alamos Labs were prime developers
• Used extensively in satellites, Space Shuttle and Space Station
• sealed chamber wherein a working substance evaporates and condenses
• passive device (no moving parts)
• extremely high, effective thermalconductivity (as much as 1,000 timesthat of Cu)
(Heat outHeat out)
(Heat inHeat in)Evaporator Section
Condenser Section
Liquid Pool
Condensate Film
Vapor
Heat Pipe Wall
Capillary Wick
Classical Heat Pipe
Major Problems with Classical Heat PipesMajor Problems with Classical Heat Pipes
While the potential of heat pipes is enormous,There are 2 major problems:
1.1. Film boilingFilm boiling2.2. Entrainment of returning liquidEntrainment of returning liquid
McGill Heat Pipe (patents pending)McGill Heat Pipe (patents pending) overcomes theseproblems and thus makes heat pipe technology viablefor high heat flux systems.
Details of the McGill Heat Pipe will be disclosed as soon as we are allowed to.
McGillMcGill
What Was Done:
• Designed and built waterwater--basedbased McGill Heat Pipes.
• In casting systems - permanent molds- DC casters
• Incorporated such pipes in a permanent moldpermanent mold atMcGill.
Applicability of Results:
• Found an industrial partner, Grenville Grenville CastingsCastings, tosponsor and conduct plant trials (Oct. 2002).
Features of the McGill Heat PipeFeatures of the McGill Heat Pipe
Can handle heat flux loadings of Can handle heat flux loadings of 1 MW/m2 andmore with water as the working substance..
ON/OFF heat extraction capability.heat extraction capability.
External chill absorbs the heat duringExternal chill absorbs the heat duringON mode.mode.
Cooling air dissipates the heat stored in the chill Cooling air dissipates the heat stored in the chill duringduring OFF mode.mode.
McGillMcGill
Permanent Mold Cooled by Heat Pipes
Unit: mm
è èè
è
Unit: mm
Cooling Air Lines
Permanent mold
Heat pipes
Data acquisition system
On/Off Valve Configuration
McGillMcGill
Heat pipes
X
ZY
Simulation by SOLIDCast
Heat pipes
Heat pipe
Plan View of the Casting, Heat Pipes and Plan View of the Casting, Heat Pipes and the Thermocouplesthe Thermocouples
TC1
TC2
TC3
Heat Pipe 1 Heat Pipe 2 Heat Pipe 3
0
100
200
300
400
500
600
700
800
0 20 40 60 80 100
Time (s)
Tem
per
atu
re (o C
)
Casting in the parting plane
Mold without HP
Mold with HP
Typical Casting Experiment
Using Heat Pipe 1 only
Al 356 alloy
Initial mold temperature of 200oC
0
100
200
300
400
500
600
700
0 50 100 150 200 250
Time (s)
Tem
pera
ture
( oC
) TC2 Casting on the parting plane
TC3 Mold without HP
TC1 Mold with HP
Air gap formation
HP ON
HP OFF
A: The side without heat pipe, DAS=40±6µm B: Center, DAS=41±10µm
C: The side with heat pipe cooling, DAS=27±3µm
Alloy A356Tmold= 200oC
Typical Casting Experiment
Using Heat Pipes 1, 2 and 3
Al 356 alloy
Initial mold temperature of 300oC
Heat Pipe 1 Heat Pipe 2 Heat Pipe 3
L M S
Thermocouple Locations
0
100
200
300
400
500
600
700
0 50 100 150 200 250 300 350Time (s)
Tem
pera
ture
(oC
)
Casting-L
Casting-MCasting-s
Mold-L
Mold-M
Mold-S
Mold-HP1-L
Mold-HP2-M
Mold-HP3-S
Max. Heat Flux to the Heat Pipes: 500-600 kW/m2
McGillMcGill
HP DAS=27±±2 µµm
Middle DAS=41±±5 µµm No HP DAS=39±±4 µµm
Alloy A356Tmold= 300oC
With HP Cooling
HP DAS=46±±7 µµm
Middle DAS=53±±6 µµm No HP DAS=42±±4 µµm
Alloy A356Tmold= 300oC
With no HP cooling
McGillMcGillEffect of Heat Pipe Cooling on DAS
46±±741±±331±±5 None (Ref)1
Decrease
L(Location C)
M(Location D)
S (Location E)
27±±2 27±±3 24±±4
41%33%21%
S M L2
DASSection withCooling
CASTING
(unit: µm)
McGillMcGill Summary
We have developed a controllable, water-based McGill Heat Pipe for high heat flux applications,such as permanent molds.
Heat dissipation rates equivalent to those associated with conventional water cooled passages are achieved with air cooling.
Cooling with heat pipes is very effective in controlling the microstructure of the casting and the mold temperature.
McGillMcGill
Cont’dSummary
The DAS of A356 alloy is refined considerably with heat pipe cooling of the mold.
Heat pipe cooling of the mold can alter the direction of solidification as well as the location of the shrinkage.
So, where are we now?
McGillMcGillLet’s visit our lab at
Testing the Water-Based Heat Pipein the Gas Furnace
Condenser
Evaporator
Typical Heat Flux:~ 500 kW/m2
Air-cooled condenser
Heat Extraction:~ 6 kW for 10 cm
insertion
McGillMcGill
Testing the Water-Based Heat Pipe Directly in Molten Aluminum
Typical Heat Flux:~ 1,500 kW/m2
The cooling of permanentmolds is simple in
comparison.
Other applications:- Superheat reduction in
DC casting molds- Cooling of the electrolytic
cells- Cooling the off gases
McGillMcGill
Condenser
Insulation
Heat Pipe
Crucible
Aluminum Melt Temperature Data for 5.1 cm Immersion
Leading End of the Heat Pipe After the Test
Note the uniform but roughsolidification surface.
McGillMcGill
So, where are we now?
Full scale oxygen lances for steel refining and lead refining
Cooling elements for aluminum and magnesium casting
Heat pipe units for cooling lead furnace taphole
In addition to our work in the lab, we have a number of industrial sponsors for the following:
McGillMcGill