Volvo D11 series, Installation Manual

Page: 132 / 212

Exhaust system
30
Example:
Engine: D2MH
Power: 294 kW / 800 rpm
Silencer: 7" HD
Calculation of pressure loss through the silencer.
Bore velocity (m/s) =
Q (flow) = 2952 m
3
/h = = = 0.82 m
3
/s
– the value originates from
Technical Data in Sales Guide Marine Propulsion Diesel Engines.
Pipe area = m 2
D = 7" = 0.75 m
Pipe area will be
A = 0.0240 m
2
Bore velocity = 34. m/s
From the diagram on previous page, one will find the resistance in mm Wc.
The resistance is approx 99 mm Wc.
The pressure loss will be calculated according to the formula:
Pressure loss (mm Wc) = = = 8 mm Wc
T = Exhaust gas Temperature
T = 293 °C (See Technical Data in Sales Guide Marine Propulsion Diesel Engines.)
Pressure loss will be:
P
loss
= 8 mm Wc = .57 kPa
The pressure loss through the silencer is .873 kPa
NOTE! Check that the total backpressure (silencer backpressure and piping backpressure) is within the limits in
table in chapter
Backpressure.
Q (m
3
/min)
Pipe area (m
2
) x 60
2952 m
3
/h
3600 s
Resistance from graph (mm Wc) x 673
T °C + 273
2952
3600
π
x D
2
4
99 x 673
293 + 273