vacguy
Mechanical
- May 13, 2002
- 4
I've been following the thread started by Mattwrigg concerning the heating of aluminum plates with thin separators between them, and have a similar question to post.
My company works with the aluminum industry for various heat treating applications, one of which is the heating of coils of sheet aluminum after it is rolled to thickness. Coils are heated to approximately 1000F.
The problem is that it is common to use an oil similar to K1 kerosene as a lubricant/coolant during rolling. The oil remains in the coil when it enters the furnace, and is vaporized during heating. The problem is to determine the rate of vapor evolution during heating in order to calculate the amount of dilution gas required to sweep the oil vapor out of the heating chamber to keep the atmosphere inside the furnace below the point where it is flammable (the LEL is around 6.5%).
The rate of heat transferred by convection to the O.D. of the coil and to the side faces of the coil (edges of the strip) is approximately 9 btu/sq.ft.-hr. The thickness of the strip varies from 28 ga to 1/4". The coil width and diameter are both about 60". There is a 20" dia.- 3/4" wall steel mandrel in the center. I have been using an estimated oil film thickness of 0.005" between the coil wraps. The oil characterists are as follows:
sp. gr. 0.98
boiling point 300F
latent heat of vaporization 750 btu/gal
I have an idea as to one approach to this, but would appreciate any input the group may have.
Thanks
My company works with the aluminum industry for various heat treating applications, one of which is the heating of coils of sheet aluminum after it is rolled to thickness. Coils are heated to approximately 1000F.
The problem is that it is common to use an oil similar to K1 kerosene as a lubricant/coolant during rolling. The oil remains in the coil when it enters the furnace, and is vaporized during heating. The problem is to determine the rate of vapor evolution during heating in order to calculate the amount of dilution gas required to sweep the oil vapor out of the heating chamber to keep the atmosphere inside the furnace below the point where it is flammable (the LEL is around 6.5%).
The rate of heat transferred by convection to the O.D. of the coil and to the side faces of the coil (edges of the strip) is approximately 9 btu/sq.ft.-hr. The thickness of the strip varies from 28 ga to 1/4". The coil width and diameter are both about 60". There is a 20" dia.- 3/4" wall steel mandrel in the center. I have been using an estimated oil film thickness of 0.005" between the coil wraps. The oil characterists are as follows:
sp. gr. 0.98
boiling point 300F
latent heat of vaporization 750 btu/gal
I have an idea as to one approach to this, but would appreciate any input the group may have.
Thanks
