Bitumen Cooling Properties

[bmzhp]

Hello All,

I am working on a conceptual design of a fibreglass roofing manufacturing automation equipment. The fibreglass is mated using Bitumen and will be cut into sheets. Prior to cutting the material I have to allow for cooling/hardening, the target is to get from 100 Celsius to between 20-40 degrees. I am trying to calculate the duration of time that this would take, in ambient temperature.

Thanks in advance.

 

[dvd]

If you are developing the process of shingle making without the benefit of making shingles, good luck. Don't calculate the cooling time, measure it.

 

[racookpe1978]

That time depends too much on ambient conditions (including relative humidity, but temperature primarily.) indoor cooling or outside? Shaded or in the sunlight?

 

[bmzhp]

This would be for indoor production, and can be in a temperature controlled environment. Also, I am planning a water cooling and re-circulation system to apply water directly to the bitumen sheeting. I am trying to identify the length of this system, so I would like to take into account worst case scenario, ie. 25-degrees Celsius, indoor.

 

[ione]

If the thickness of the bitumen layer is thin you could check the Biot number and evaluate whether a lumped capacitance model is applicable.

There are also available free tools which allow to derive the cooling curve of bitumen used in paving applications (

http://www.eng.auburn.edu/users/timmdav/MultiCool/FinalRelease/Main.html#MS)

but frankly I don’t know whether they could be applied to your specific case.

Best suggestion to me remains that of carrying out direct measurements.

 

[racookpe1978]

I'm very skeptical about the practicality, wisdom, spray and too-rapid a cooling, final surface finish, contamination aspects (of getting the spray water across a very hot bitumen surface), coating the water-contaminated surface after cooling, continuous recovery and re-cleaning of the now-dirty water and other aspects of pouring water across a melted tar-like surface for shingles.

It's your process - not mine! - but I don't think its going to work very well compared to a wider-area but slow and cleaner and more controlled cooling by clean air.

 

[StoneCold]

I'm with racookpe on this. I think forced air cooling with the exhaust vented either outside or to a scrubber is what you need. Water is going to be a big mess to deal with.

Regards
StoneCold

 

[bmzhp]

Thank you all for the input.

I agree that the best method would be experimental.

Some more background on this, the application is for roofing sheets and the bitumen will be mated with fiberglass for rigidity. The fiberglass rolls are past through a bitumen tank and than scrubbed to desired thickness (1/8" - 1/4"), following this it would have to be cooled prior to cutting. The rolls are 4' wide and are cut in lengths of 5 feet. The thickness is obtained utilizing scrubbers. The customer recommended to keep those wet during production to avoid material build up, can some comment on that?

The customer wants the system to produce 5 sheets per minute, this means a speed of 25 feet per minute and I an concerned about the length of the machine required to cool the material properly.

Many of the operations and material behavior characteristics came form the customer, who is using this material on a daily basis and have seen it's production. I became skeptical when they just asked to increase capacity without consideration for cooling and suggested we add water to speed up the process.

thanks again.