Five Roadblocks to a Chiller’s Efficiency02 July 2019
A single performance bottleneck can inhibit chiller
efficiency. A building’s cooling plant, having experienced one such output hit,
can no longer maintain a comfortable environment. Things get stiflingly hot.
Maybe the equipment hasn’t been properly maintained for some time, or maybe the
machinery has aged prematurely. Now, multiplied five times over, the
performance roadblocks become practically unmanageable.
Troubled by Maintenance Gaffes
If two or three issues strike simultaneously, that’s a
red flag. Basically, several seemingly disconnected mechanical defects are
continually cropping up, so there’s a problem with the maintenance plan. That’s
not a sustainable mode of operation, not when chillers can consume up to 51% of
a building’s power. To keep energy expenditure low and equipment lifespan high,
a predictive maintenance program should be introduced.
Cooling Tower Neglect
Even maintenance programs can go astray. A 0.50 to
0.60 kW per ton efficiency rating is possible when chillers are in tip-top
shape. If, however, that rating drops and the plant room maintenance measures
are no longer having any effect, then it’s time to look further afield. The
system cooling towers have become suspect. To assure peak output efficiency,
these waste heat rejectors must be inspected regularly.
Beware Of System Sizing Inadequacies
Buildings tend to grow. They gain more personnel,
extra rooms, and renovated environmental control subsystems. Energy efficient
windows are installed, too, probably because a building manager has frowned at
a particularly unpleasant energy bill. Whatever the reason is, the chillers
inside that property no longer kick out enough cooling power. Cooling loads
should be audited regularly to avoid such system sizing shortfalls.
A Stuck-In-A-Rut Management Demeanour
It’s time to replace the ailing machinery. A busy
manager, not knowing the gear consumes so much electrical energy, opts for an
identical replacement system. The chillers, having worked on electric-drive
centrifuge technology, are swapped out, then another set of identically specced
units take their place. Technology has moved on, so low-energy natural-gas
driven units and gas-absorption models should be prioritized over older
Number five in this five roadblocks list comes right at the end. There’s a good reason for leaving this performance bottleneck to the end. This time out, all of the chillers are operating at peak efficiency. They’re also being maintained and looked after in every conceivable way. Only, there are strange operating practices being applied to the coolers. By way of example, flow rate increases are dialled into the control panels to squeeze out more cold water, but that move puts stress on the equipment. Recommended settings exist for a reason, so don’t ignore those limits.
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