Uninterruptible Power Supplies and Standby Power Systems
Written by two experienced engineers, this book covers rotary UPS systems and battery selection, and offers complete, up-to-date guidance on design, installation, operation, and maintenance.
TABLE OF CONTENTS Uninterruptible Power Supplies and Standby Power Systems
Engine Room Ventilation
The temperature within the engine room must be maintained at a reasonable level, and the heat losses from the engine and generator have to be removed by a flow of ventilation air. The heat losses will be mainly from the engine, the losses from the generator will be only a few percent (typically 5 percent) of its rating; the heat losses from a turbine and its gearbox will be much less than from a diesel engine of comparable rating.
The quantity of air entering the room will always exceed the quantity leaving; combustion air is drawn into the engine and is dispersed in the exhaust gases. The combustion air requirement is small and for diesel engines may be assumed to be 0.17 m 3/s for a 100 kW set and pro rata for other ratings. A gas turbine requires more, typically twice as much as a diesel engine (3.4 m 3/s for a 1 MW set).
Water-Cooled Diesel Engines
It is necessary to estimate the heat losses into the engine room; these will originate from the engine casing, the generator, and the exhaust system. The generator efficiency will be of the order of 95 percent and the heat balance figures from the previous section may be rearranged as:
| Useful energy (kWe) appearing at the generator terminals | 36.5 percent |
| Engine-driven radiator fan | 1.5 percent |
| Heat lost in exhaust gases | 30 percent |
| Heat lost from radiator | 25 percent |
| Heat lost from engine casing | 5 percent |
| Generator losses |
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