Properties🔗
The heat exchanger is modelled as a volumetric energy source where the energy transfer between two fluid streams is based on an effectiveness, specified as a function of the mass flow rates.
\[Q_t = e \left(\dot{m}_1 , \dot{m}_2 \right) \left(T_2 - T_1\right) \dot{m}_1 C_p,\]Where:
- \(Q_t\)
- total heat source
- \(e(\dot{m}_1,\dot{m}_2)\)
- effectiveness table
- \(\dot{m}_1\)
- net mass flux entering heat exchanger [kg/s]
- \(\dot{m}_2\)
- secondary mass flow rate [kg/s]
- \(T_1\)
- primary inlet temperature [K]
- \(T_2\)
- secondary inlet temperature [K]
- \(C_p\)
- specific heat capacity [J/kg/K]
The energy source is distributed across the cells according to:
\[Q_c = \frac{V_c |U_c| (T_c - T_{\ref})}{\sum(V_c |U_c| (T_c - T_{\ref}))},\]Where:
- \(Q_c\)
- energy source for cell
- \(V_c\)
- volume of the cell [m3]
- \(U_c\)
- local cell velocity [m/s]
- \(T_c\)
- local call temperature [K]
- \(T_{\ref}\)
- min or max(T) in cell zone depending on the sign of \(Q_t\) [K]
Optional entries:
-
primaryInletT: sets the primary inlet temperature. If not set, the flux-averaged temperature is used -
targetQdot: the secondary inlet temperature is derived from a target heat rejection
Usage🔗
The option is specified using:
heatExchanger1
{
type effectivenessHeatExchanger;
selectionMode cellZone;
cellZone porosity;
secondaryMassFlowRate 1.0;
secondaryInletT 336;
faceZone facesZoneInletOriented;
outOfBounds clamp;
file "effTable";
// Optional
// primaryInletT 293;
// targetQdot 1500;
}
The two-dimensional effectiveness table is specified according to, e.g. for the table
| mfr2,1 | mfr2,2 | mfr2,3 | |
|---|---|---|---|
| mfr1,1 | A | B | C |
| mfr1,2 | D | E | F |
| mfr1,3 | G | H | I |
the equivalent entry becomes:
(
(
mfr1,1
(
(mfr2,1 A)
(mfr2,2 B)
(mfr2,3 C)
)
)
(
mfr1,2
(
(mfr2,1 D)
(mfr2,2 E)
(mfr2,3 F)
)
)
(
mfr1,3
(
(mfr2,1 G)
(mfr2,2 H)
(mfr2,3 I)
)
)
);
Further information🔗
Tutorials
- none
Source code
History:
