212
6 Fans and Flow Control Devices
Case 2:
Pressure
SP
VP
TP
Point
1
0
0
0
2
−400
80
−320
3
0
80
80
4
0
0
0
FTP = TP 3 − TP 2 = 80 − (−320) = 400
FSP = FTP − VP 3 = 400 − 80 = 320
Case 3:
Pressure
SP
VP
TP
Point
1
0
0
0
2
−80
80
0
3
400
80
480
4
0
120
120
5
0
0
0
FTP = TP 3 − TP 2 = 480 − 0 = 480
FSP = FTP − VP 3 = 480 − 80 = 400
6.2.6 Fan Losses
A fan is a machine that accumulates a series of operating losses. A general compilation of these is shown in Fig. 6.13 by means of a Sankey diagram (ATECYR
2012).
With all the above, the total efficiency (η t ) of the system can be defined as the
quotient between the power received by the fluid (Pw v ) and that supplied to the fan
shaft (Pw shaft ) (Eq. 6.5).
η t =
Pw v
Pw shaft
(6.5)
That is to say, the total efficiency of the system is the ratio of the final useful energy
to the total energy supplied to the fan shaft, the formulation of which is (Eq. 6.6):
6 Fans and Flow Control Devices
Case 2:
Pressure
SP
VP
TP
Point
1
0
0
0
2
−400
80
−320
3
0
80
80
4
0
0
0
FTP = TP 3 − TP 2 = 80 − (−320) = 400
FSP = FTP − VP 3 = 400 − 80 = 320
Case 3:
Pressure
SP
VP
TP
Point
1
0
0
0
2
−80
80
0
3
400
80
480
4
0
120
120
5
0
0
0
FTP = TP 3 − TP 2 = 480 − 0 = 480
FSP = FTP − VP 3 = 480 − 80 = 400
6.2.6 Fan Losses
A fan is a machine that accumulates a series of operating losses. A general compilation of these is shown in Fig. 6.13 by means of a Sankey diagram (ATECYR
2012).
With all the above, the total efficiency (η t ) of the system can be defined as the
quotient between the power received by the fluid (Pw v ) and that supplied to the fan
shaft (Pw shaft ) (Eq. 6.5).
η t =
Pw v
Pw shaft
(6.5)
That is to say, the total efficiency of the system is the ratio of the final useful energy
to the total energy supplied to the fan shaft, the formulation of which is (Eq. 6.6):