WOLFRAM|DEMONSTRATIONS PROJECT

Heat Transfer in a Heat Exchanger

​
heat transfer,
q
A
​, in watts/
2
meter
​
heat transfer rate range
low
high
temperature difference,
ΔT
m
(°C)
5.
barrier thickness, x (mm)
3.
thermal conductivity, k (W/m°C)
100.
heat transfer coefficients
inside surface,
h
sin
W/
2
m
°C
500.
outside surface,
h
sout
W/
2
m
°C
250.
This Demonstration calculates and plots the heat flow,
q
A
(in watts/
2
m
), through a heat exchanger's wall of a chosen thickness,
x
(in mm), and thermal conductivity,
k
(in watts/m °C), with chosen surface heat transfer coefficients at either side of the wall,
h
sin
and
h
sout
(in watts/
2
m
°C), and logarithmic mean temperature difference, Δ
T
m
(in °C), between them. Since the heat transfer coefficients can vary over a very large range, the
h
sin
and
h
sout
parameters can be specified as being high or low using a setter bar. The calculations are done using the equation
q
A
(Δ
T
m
)=Δ
T
m
/(1/
h
sin
+x/(1000k)+1/
h
sout
)
, whose parameters can be modified by moving sliders. The red dot on the plot marks the heat flow per unit area for a Δ
T
m
chosen by moving the top slider. The top graphic depicts the heat resistances as a schematic diagram (not to scale).