On large vessels the Pressure and Temperature control becomes a significant cost, and has the
potential to create packaging problems because of the large fans. The EVC1's Intelligent Fan
Control Logic allows the fans to change from intake to exhaust as the situation requires. This type
of system design is an evolution of the full pressure and temperature controls that have been in
use for years but have never taken full advantage of the fans capacities.
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In the diagram a four fan system is shown. As the
main engines are brought online at the dock, the
system uses two fans as intakes and two as exhaust
providing adequate exhaust air for cooling. As the
main engines increase in RPM and the combustion air
requirement reaches the capacity of the two
dedicated intake fans, one of the exhaust fans
performs a controlled stop and reverses.
The fourth fan remains controlled by temperature until the
combustion air requirements reach the capacity of the
other fans, and then becomes an intake as well.
Because of the large volume of air through the space
for combustion, the exhaust air required for cooing is
completely taken care of by the main engines freeing
the exhaust fans to provide combustion air.
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In the traditional pressure/temperature configuration the capacity of the exhaust fan is mostly
unused while underway. This configuration allows the use of much smaller intake fans because very
little capacity is wasted throughout the entire operating range of the engines due to full utilization of
the exhaust fans. The principals of this system can be applied to two fan systems as well, with
slightly less flexibility.
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ADVANTAGES:
- Precise control of pressure and temperature
- Little or no cost increase over a traditional
four fan system
- Reduced opening and moisture eliminators
size
- Reduced fan sizes makes packaging easier
- Automatic operation both underway and
dockside
| DISADVANTAGES:
- Fans sizing becomes critical
- Significant Cost
- Complexity
- Large electrical loads
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