Convection

Newton’s Law:

Q = hc (Tair — Tw)

O

Where q = heat flux due to convection ( W/m )

Hc = convective heat transfer coefficient (W/m K) Tair = bulk fluid (air) temperature (°C)

Tw = surface temperature (°C)

Newton’s Law can be written as

T — T „ 1

With R = — h

Air w

Convection

T„,

N

O

R=l/hc

 

Tv

V-

 

2 * 2 The hc is related to flow state. hc = 3 ~ 6 W/m K for natural convection and 6 ~ 35 W/m K for air

Flow in and around buildings.

Posted in Fundamentals of Heating. Ventilating, and Air-Conditioning


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