In that video about spraying the intercooler black he talks about convection so much as he then goes on tell us about heat transfer. It's actually conductive heat transfer that transfers the heat.
Convection is hot air rising and cold air sinks. Electrical convection heater heats air, that hot air rises and spreads across the ceiling and as it cools sinks down the walls to pass back along the floor to the heater. There is very little convection under a bonnet the draught is forced.
A layer of paint is an insulator. Just like a second pane of glass in double glazing.
Hot air > aluminium oxide > aluminium > aluminium oxide > cooling air.
Hot air > aluminium oxide > aluminium > aluminium oxide > paint > cooling air.
Aluminium 210 W/(m.K)
Aluminium oxide 30 W/(m.K)
Paint (black or white) 0.17 W/(m.K)
Paint (high metal silver etc) 0.19 W/(m.K)
So 0.05mm of black paint is like an extra crusty 8.8mm thick layer of bare aluminium oxide. If you saw that on an IC you would be be reaching for the wet and dry. Even anodising an IC is bad news as that thickens the natural oxide layer which is an insulator compared to the aluminium sheet.
http://www.engineeringtoolbox.com/th...ity-d_429.html
http://www.thefreelibrary.com/Specia...y.-a0228354685
Surface finish is also critical to the thermal transfer of heat from induction air to the alloy and to the cooling air. A nice smooth shiny finish is poor, needs a bit of texture, that's the function of the fins between the plates.
![[Image: hqdefault.jpg]](http://i.ytimg.com/vi/gsLCtSWclZI/hqdefault.jpg)
Convection is hot air rising and cold air sinks. Electrical convection heater heats air, that hot air rises and spreads across the ceiling and as it cools sinks down the walls to pass back along the floor to the heater. There is very little convection under a bonnet the draught is forced.
A layer of paint is an insulator. Just like a second pane of glass in double glazing.
Hot air > aluminium oxide > aluminium > aluminium oxide > cooling air.
Hot air > aluminium oxide > aluminium > aluminium oxide > paint > cooling air.
Aluminium 210 W/(m.K)
Aluminium oxide 30 W/(m.K)
Paint (black or white) 0.17 W/(m.K)
Paint (high metal silver etc) 0.19 W/(m.K)
So 0.05mm of black paint is like an extra crusty 8.8mm thick layer of bare aluminium oxide. If you saw that on an IC you would be be reaching for the wet and dry. Even anodising an IC is bad news as that thickens the natural oxide layer which is an insulator compared to the aluminium sheet.
http://www.engineeringtoolbox.com/th...ity-d_429.html
http://www.thefreelibrary.com/Specia...y.-a0228354685
Surface finish is also critical to the thermal transfer of heat from induction air to the alloy and to the cooling air. A nice smooth shiny finish is poor, needs a bit of texture, that's the function of the fins between the plates.