×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

FUEL OIL ADIMENSIONAL NUMBERS (PRANDTL & GRASHOF)

FUEL OIL ADIMENSIONAL NUMBERS (PRANDTL & GRASHOF)

FUEL OIL ADIMENSIONAL NUMBERS (PRANDTL & GRASHOF)

(OP)
does anyone know where i could find the prandtl and grashof numbers for the fuel oil?????

RE: FUEL OIL ADIMENSIONAL NUMBERS (PRANDTL & GRASHOF)

Santiago,

These dimensionless numbers depend on a variety of thermophysical fuel properties all of which vary with temperature and fuel oils are of various specifications. Besides, the Gr also depends on physical dimensions whether plates, pipes, etc., and the ΔT between surface and bulk, or a given heat flux, and the gravitational constant.

For example take a fuel, within a 6" (Sch 40) pipe and an internal ΔT of 10oC, kept at ~100oC with the following properties:

β = 7×10-4/K
ν = 30×10-6 m2/s
κ = 0.14 W/m.K
Cp = 2,2 kJ/(kg.K)
g = 9.8 m/s2

The resulting values would be:

Pr ~ 420
Gr ~ 8×108.  

Así que no creo que puedas encontrar dichos valores publicados y tendrás que calcularlos por ti mismo.   

RE: FUEL OIL ADIMENSIONAL NUMBERS (PRANDTL & GRASHOF)

(OP)
Gracias 25326 por tu respuesta,

so, according to your response, in order to calculate Pr and Gr I need the thermophysical fuel properties, in my case of fuel oil. Ive been searching for the latter, but unfortunaty I could'nt find them. Do you know any source where to find them?

thanks again for your answer, its been of great help.

RE: FUEL OIL ADIMENSIONAL NUMBERS (PRANDTL & GRASHOF)

IRstuff is right. There are many types of fuel oils.
If this is just a school exercise, I think you"ll find a useful example of thermophysical properties at various temperatures for an unused engine oil in table A-4 on Heat Transfer by J.P. Holman, McGraw-Hill International Student Edition.
Chapter 7 of the same book deals with natural-convection systems.
Don't forget Gr requires also (geometrical) dimensions in its calculations.  

RE: FUEL OIL ADIMENSIONAL NUMBERS (PRANDTL & GRASHOF)

(OP)

thanks again 25362,

Actually, its not for school. Anyway, youre right, i didnt specified the fuel oil. Its Fuel Oil Nº6, and ill be needing as you said before, the following thermophysical properties,

β, Cp, ν, κ

So, do you know where i could find them?

RE: FUEL OIL ADIMENSIONAL NUMBERS (PRANDTL & GRASHOF)


Even HFO No.6 has a wide range of viscosities, for example, from 15 to 50 cSt at 100oC. Therefore, it seems to me there are no tabulated values for these properties of HFO No.6.

I still suggest you exploit the data given in Holman's book (probably available in any technical library) to get some "approximate" figures.

   

RE: FUEL OIL ADIMENSIONAL NUMBERS (PRANDTL & GRASHOF)

santiagooo stugatsa

peace
Fe

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources