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3.7. Evaporator - EVAP
3.7 Evaporator - EVAP
Figure 3.9: The evaporator has two sets of inlet and outlet: refrigerant (r,i and r,o) and chilled
water (chill,i and chill,o).
In the evaporator heat is transferred from an external circuit of
chilling water to the refrigerant. It is assumed that the refrigerant is in
the two-phase region when it enters the evaporator. The refrigerant in
the outlet can either be saturated gas or in the two-phase region.
The closest approach temperature difference is defined as the temperature
difference between the chilled water outlet and the refrigerant inlet,
see figure 3.10.
T [° C ]
T chill , o
T r ,i
ΔT min ,r ,i
T chill ,i
T r ,o
EVAP
˙Q[kW ]
Figure 3.10: Evaporator: The closest approach temperature difference is at the refrigerant inlet.
∆T minr,i = T chill,o − T r,i (3.37)
The effectiveness is determined by the chilled water because it has the
lowest heat capacity flow; both media are water, but the refrigerant
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