class 26

# class 26 - Boiling Click to edit Master subtitle style...

This preview shows pages 1–8. Sign up to view the full content.

Click to edit Master subtitle style 8/13/11 Boiling Chapter 10 Sections 10.1 through 10.5

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
8/13/11
8/13/11 Pool Boiling Correlations Minimum Heat flux ( 29 ( 29 4 / 1 2 " min 09 . 0 + - = l v v l v fg g h q ρ σ Why is the transition boiling regime of little practical interest? a) You never want to achieve a minimum heat flux b) This is a theoretical rather than an actual regime c) You can only get there by controlling the surface heater temperature d) The correlation has over 100% error

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
8/13/11 Correlations for the film pool boiling regime a) Tend to have liquid properties b) Tend to have vapor properties c) Have an almost even mixture of liquid and vapor properties d) It depends on the geometry
8/13/11 Film Boiling ( 29 ( 29 4 / 1 3 ' - - = = sat s v v fg v l v conv D T T k D h g C k D h Nu υ ρ C = 0.62 for cylinders; 0.67 for spheres

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
8/13/11 Film Boiling The cumulative (and coupled effects) of convection and radiation across the vapor layer 3 / 1 3 / 4 3 / 4 h h h h rad conv + = Appropriate for Ts 300 oC
A silicon chip of thickness L = 2.5 mm and thermal conductivity ks = 135 W/m-K is cooled by boiling a saturated fluorocarbon liquid (Tsat = 57oC) on its surface. The electronic circuits on the bottom of the chip produce a uniform heat flux of q”o = 5 X 104 W/m2 while the sides of the chip are perfectly insulated. Find the temperature at the bottom of the chip at the given q”o and at 90% of the critical heat flux . Plan:

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

## class 26 - Boiling Click to edit Master subtitle style...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online