ASHRAE Journal - September 2019 - 84

COLUMN REFRIGERATION APPLICATIONS
Andy Pearson

Refrigeration on a Budget
BY ANDY PEARSON, PH.D., C.ENG., FELLOW ASHRAE

The investment in new refrigeration equipment is one of the largest capital commitments that a cold store or freezer operator can make. There is always pressure to
figure out how to minimize the "sticker shock" associated with the project cost.
Careful purchasing can pay dividends, but there is always the risk that a false economy will result in a significantly higher spend over the life of the project.

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and irreparable damage to reputation that follows all such
incidents, simply isn't worth it.
Having said that, do take stock of the true nature of the
cooling requirements and ensure that the plant is not
oversized for the job required. This might involve installation of modular systems that can be extended as the business grows, or it could simply be a modest increase in the
size of a cold water buffer tank to enable a smaller chiller
to be specified. Even the use of one size larger
diameter chilled water pipe can provide useful
buffer capacity and save on capital plant cost.
Do ensure that sufficient measures are
included for performance measurement, even
if this is only the provision of pockets for temperature probes and a few pressure gages. The
number of systems that are "flying blind" with
no way of knowing how well they are performing is really quite depressing, when for a few dollars more
some simple metrics could have been included.
Do take every possible measure to minimize the heat
load imposed on the refrigeration system. We ought to
measure buildings and production systems on the basis of
the amount of cooling required divided by the minimum
necessary to achieve the output. Currently, this is only
done for data centers with the power usage factor (the
total amount of electricity used divided by the amount
used by the computers). How about introducing a refrigeration usage factor along similar lines?
Most importantly, do specify the plant in sufficient
detail to ensure you get what you need, and then hold the
project team to account to make sure you really get it.
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It can be difficult to get a hard-pressed project manager
to care about this. They will be measured on the bottomline cost of their project, and usually the operating cost
doesn't feature highly in their thinking during the planning stages; they just want a lower capital expense figure.
There are several ways that they can get their life-cycle
cost approach wrong, with expensive consequences, but
also many ways to save money without courting disaster.
Don't economize on the operating perforSaving is cool.
mance of evaporators and condensers by
undersizing them. Putting in air-coolers that
are too small could result in operating a low
suction pressure that could easily add 10% to
15% to the annual electric bill. It might knock
$50,000 off the project cost but will add more
than that every year to the energy tab. Turning
that around, who wouldn't want a payback of
less than a year on an energy saving measure?
Don't skimp on maintenance access provisions that will
result in lack of attention to the condition of equipment.
If it requires a lot of effort to arrange a mobile platform to
clean condensers then they are likely to operate in a dirty
condition more than you might think. This may not have
an obvious effect for most of the year, although energy
consumption could again be higher than it ought to be,
but when the hot summer weather comes the plant may
be unable to cope. The cost then is the consequence of
cooling plant failure and all the panic response that follows, in addition to the hike in annual energy cost.
Don't economize on other health and safety issues
through the project or in the operation of the plant. The
danger of something going wrong and resulting in serious injury or worse, coupled with the business disruption

Andy Pearson, Ph.D., C.Eng., is group managing director at Star Refrigeration in Glasgow, UK.

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ASHRAE Journal - September 2019

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