Under the old way of designing a cooling system, you'd hire an engineering firm to come in and do a Doppler flow study on your water distribution pipes to make sure that the pumps when running at full speed were providing enough gallons per minute to your air conditioning units to remove enough BTUs from the air. Then you would manually adjust flow restricting valves that would "balance" your system to the proper amount.
This is highly inefficient because pumps running at 100% are using most of their energy to achieve the last 30% of the motor curve. Also, when the amount of water the pump is able to move is restricted, it works harder, uses more energy and reduces its effective life.
State of the Art VFD and Computer Optimizing Systems
To avoid wasting this energy we use Variable Frequency Drives (VFDs) on our air conditioning pumps and fans. A VFD will provide the right amount of electricity so the motor can operate in the most efficient manner. It's not working harder just smarter.
We're also cutting energy usage on the cooling fans on our water chillers in our green data center. They used to be run by a sensor that would turn them on or off at a certain water temperature. This meant that the motors were constantly cycling on and off. A large amount of current is required for a startup and as the motor ran a full capacity it was wasting half of its input energy.
Now our building computer monitors the water temperature. And by using VFD's to control the speed of the fans, they run efficiently all the time, avoiding the startup draw and doing a better job of maintaining a constant temperature. Again, this saves money on power cost and on equipment wear and tear.
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