Environmental Engineering Reference
In-Depth Information
Constructing the Composite Curves
1. Draw the hot composite curve and the cold composite curve via developing the following
tables.
2. These tables list all the hot and cold streams temperatures in an ascending order with the
cumulative enthalpy corresponding to the lowest hot temperature and lowest cold
temperature respectively equal to zero.
3. In every temperature interval the cumulative hot load is calculated using the following
formula
H= FCp * (Tsupply - Ttarget)
4.
In every temperature interval the cumulative cold load is calculated using the following
formula
H= FCp * (Ttarget - Tsupply)
Hot streams temperature list
Cumulative Enthalpy (H)
T0=30
H0=0.0
T1=70
H1=800
T2=120
H2=2300
T3=170
H3=2800
Cold streams temperature list
Cumulative Enthalpy (H)
T0=20
H0=0.0
T1=50
H1=450
T2=90
H2=2650
T3=110
H3=3450
As we mentioned before the cold composite curve shall lie completely below the hot
composite curve and this can be done via dragging the cold composite curve to the right on
the enthalpy axis (H). This process shall stop at a vertical distance between the cold and the
hot composite curve for a temperature equal to the minimum temperature approach selected
earlier.
Table 1. Data for Constructing Composite Curves
Supply Temp
(º C)
Target Temp.
(º C)
FCp (kW/ ºC)
170
70
10
120
30
20
50
90
40
20
110
15
