Roxul Industrial Insulation Process - Manual (Page 133)

3. Tables
3.1 Units, conversion factors and tables
3.1.1a Symbols, definitions and units (US Convention)
Symbol Definition US Unit Notes
A Area ft 2
L Length ft, in
σ
Stefan-Boltzman Constant
0.1714 x 10-8
BTU/hr.ft 2 .°R 4
ε Emittance -
- Specific heat capacity BTU/lb.°F
c
p
Specific heat capacity at constant pressure BTU/lb.°F
c
v
specific heat capacity at constant volume BTU/lb.°F
- thermal diffusivity ft 2 /hr
- thermal capacity BTU/°F
u Heat transfer coefficient (general)
BTU/hr.ft 2 .°F linear orientation
BTU/hr.ft.°F cylindrical orientation
BTU/hr.°F spherical orientation
U Overall Heat Transfer Coefficient (Thermal Transmittance) BTU/hr.ft 2 .°F Flat Wall
h
c
Film conductance
(convective heat transfer coefficient)
(convective heat transfer conductance)
BTU/hr.ft 2 .°F Flat Wall
BTU/hr.ft.°F Pipe
BTU/hr.°F sphere
h
r
Radiant heat transfer conductance
BTU/hr.ft 2 .°F Flat Wall
BTU/hr.ft.°F Pipe
BTU/hr.°F sphere
h
Surface coefficient of heat transfer
(surface transfer conductance)
BTU/hr.ft 2 .°F Flat Wall
BTU/hr.ft.°F Pipe
BTU/hr.°F sphere
C Conductance BTU/hr.ft. 2 .°F
k (or λ) Thermal conductivity
BTU-in/hr.ft 2 .°F (conventional unit)
BTU/hr.ft.°F (alternative)
k
a
(or λ
a
) Apparent thermal conductivity BTU-in/hr.ft 2 .°F
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