Convection htc for air

[ProcessJim]

I'm sure this has been covered in a million other threads but I'm looking for some typical values for the heat tranfer co-efficient for air.

1) In the case of indoor air at ambient temp with little circulation.

2) Outdoor process unit exposed to wind and so on.

Thanks,

James

 

[ione]

You can take a glance at the link below for some background theory

http://www.cheresources.com/convection.shtml

Or give a shot to this calculator (I find it quite useful)

http://www.thermal-wizard.com/tmwiz/default.htm

Air properties (to be evaluated at film temperature) are tabulated in the thermal-wizard site, anyway if you have to deal with values not reported there, you can try this site:

http://www.mhtl.uwaterloo.ca/old/onlinetools/airprop/airprop.html

 

[prex]

For 1) take 10 W/sqm degC. For 2) the value will depend on wind speed. 20 W/sqm degC is easily attained with moderate non stormy winds.

prex

http://www.xcalcs.com

: Online engineering calculations

http://www.megamag.it

: Magnetic brakes and launchers for fun rides

http://www.levitans.com

: Air bearing pads

 

[ProcessJim]

Thanks for the info, very usefull. I really should have paid more attention in fluid mechanics!