Power Generation: Site Design, Installation, and Connection

[JamesB]

What is the exit velocity from the exhaust of a CAT 3512B 1500KVA Diesel Generator.  I'd like to know either the measured figure or a standard range please.  

Many thanks

[RM_FNTS]

You can calculate this

It is dependent on the pipe diameter, exhaust temp, and engine load

There are two attached formulas, the first calculates the flow rate.

The second formula takes that flow rate plus pipe diameter to determine exhaust velocity.

The exhaust gas flow rate for a given engine and rating can be obtained from the TMI system. It can be closely estimated by using the following formula.

Qe =(Te + 460) x Hp / 214

Qe =(Te + 273) x kW / 3126.52 = (Metric)

Qe = Exhaust gas flow rate [cfm (cubic meters per minute))

Te = Exhaust gas temperature [° F (°C)]

Hp = Engine rated horsepower (kW)

As a rule of thumb, the velocity is best kept to 18,000 ft/min or less. The velocity can be calculated using the following formula

Ve= 183 x Qe / d x d

Ve= 1,270,691.83 x Qe / d x d  = (metric)

Ve = Exhaust gas velocity [ft/min (m/min)]

Qe = Exhaust gas flow rate [cfm (cubic meters per minute))

d = Pipe diameter [inches (mm)]

Hope this help to find the answer your looking for

[JamesB]

Thanks for that I'll give that a go.  

Do you know if there is a standard range for exit velocity from this type of generator?   Eg 20-100m/s for example.

[RM_FNTS]

As stated keep the velocity below 18000 ft/min or 91.44 m/s

If the velocity is too high, excessive noise or whistle may occur and inner pipe and wall surfaces may erode at an unacceptable rate

Smaller pipe = increased velocity and increased backpressure

A long system with many bends needs to be carefully reviewed to minimize backpressure.