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3.5. Condenser - COND
T [° C ]
ΔT min ,r ,i
T r ,o
ΔT min ,r ,o
ΔT min ,mp T c ,o
T c ,i
T r ,i
˙Q[kW ]
Figure 3.6: Condenser: Approach temperature differences are calculated both in the ends and at
the middle to make sure that the one being given as a parameter actually is the smallest of them.
The problem can be viewed as having two heat exchangers - one
for the superheated region, and one for the two-phase region. Both
effectiveness are calculated, and the larger of them is the one to be
specified (if not the closest approach temperature difference is specified
instead):
ɛ SH = T r,i − T r,mp
T r,i − T c,mp
(3.21)
ɛ 2P = T c,mp − T c,i
T r,mp − T c,i
(3.22)
Where SH = Super Heated region, and 2P = Two-Phase region.
The refrigerant midpoint temperature (T r,mp ) is calculated from the
saturation temperature at the given pressure. The cooling water
midpoint temperature (T c,mp ) is calculated from an energy balance
between refrigerant inlet and midpoint:
(h c,o − h c,mp ) · ṁ c = (h r,i − h r,mp ) · ṁ r (3.23)
The amount of heat to be removed by the cooling circuit is calculated
by the energy balance, which includes a loss to the surroundings ( ˙Q loss ),
which should be zero (adiabatic component) or positive (heat loss to the
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