Radiators - Heat Emission

Heat output from a radiator is determined by the

• ambient surrounding temperature
• temperature of the radiator surface
• surface area of the radiator

The formulas below can be used to estimate the heat emission from radiators where the temperature difference between the radiator surface and the ambient air is 50^oC (inlet water temperature 80^oC, outlet water temperature 60^oC and ambient air 20^oC).   

Heat Emission from Column Radiators

The heat emission from a column radiator can roughly be estimated as

P = k_c V_e                                            (1)

where

P = heat emission (W)

k_c = 15000 - 17000 - constant for column radiator

V_e = external radiator volume (m³)

Heat Emission from Panel Radiators

The heat emission from a panel radiator can roughly be estimated as

P = 41 k_p l (1 + 8 h)                                    (2)

where

P = heat emission (W)

k_p = constant for panel radiator

l = radiator length (m)

h = radiator height (m)

Typical panel radiator configuration constants - k_p:

• 3.1 : for a  single panel
• 4.1 : for a panel - convector
• 4.9 : for two panels
• 5.8 : for a panel - convector - panel
• 7 : for a panel - convector - convector - panel
• 7.6 : for three panels
• 8.8 : for a panel - convector - panel - convector - panel  
• 9 : for four panels

Panel Radiator Calculator

- k_p - panel radiator constant

- l - radiator length (m)

- h - radiator height (m)

Temperature ^oC
K
^oF

Length m
km
in
ft
yards
miles
naut miles

Area m²
km²
in²
ft²
miles²
acres

Volume m³
liters
in³
ft³
us gal

Weight kg_f
N
lbf

Velocity m/s
km/h
ft/min
ft/s
mph
knots

Pressure Pa
bar
mm H₂O
kg/cm²
psi
inches H₂O

Flow m³/s
m³/h
US gpm
cfm