Scott I would disagree on several points: My recall of heat transfer says that forced convection (i.e. high velocity forced air cooling) that turbulent air is roughly twice as effective at cooling as laminar flow air. Therefore a rough finish or ribbed finish would be used. For natural convection smooth finish would aid laminar flow and therefore be desirable. (Turbulent air flow is not normally achieved without a forcing function.) Just backwards of what you indicated.
As for color, convective heat sinks will still achieve some radiated heat loss, particularly at higher temperatures. Therefore the heat sink should have an emistivity as close to one as possible. This is best achieved with a "black body", not polished aluminum. Fred Townsend Scott Lacey wrote: > As a general rule of thumb, use polished aluminum fins (no finish) > for high velocity forced air cooling (maximum thermal transfer to the > airstream). > > Black anodized works well with more gentle airflow, and you would > want a rough cast or sandblasted blackened finish when relying > solely on natural convection. The rough surface increases both > surface area and turbulence. > > scott Lacey > > > On 9 May 2003 at 9:50, LEUNG YAT WAH DEREK wrote: > > > > > > > > > Could anyone tell me about the heatsink is really in lighter colour > > can release heat faster ( similar to we wearing lighter clothes in > > summer), but why people always painted the heatsink in black or very > > dark colour, and the material of the coating on heatsink will affect > > their performance? Thanks. > > > > > > > > ------------------------------------------- > > This message is from the IEEE EMC Society Product Safety > > Technical Committee emc-pstc discussion list. > > > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > > > To cancel your subscription, send mail to: > > majord...@ieee.org > > with the single line: > > unsubscribe emc-pstc > > > > For help, send mail to the list administrators: > > Ron Pickard: emc-p...@hypercom.com > > Dave Heald: davehe...@attbi.com > > > > For policy questions, send mail to: > > Richard Nute: ri...@ieee.org > > Jim Bacher: j.bac...@ieee.org > > > > Archive is being moved, we will announce when it is back on-line. All > > emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: emc-p...@hypercom.com > Dave Heald: davehe...@attbi.com > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > Archive is being moved, we will announce when it is back on-line. > All emc-pstc postings are archived and searchable on the web at: > http://www.ieeecommunities.org/emc-pstc This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
