KEVIN CONNOR (1)
(1) Dow Chemical, Midland, MI
The ability to accurately control temperature throughout the brewing
process plays a critical part in producing high-quality beer with
desirable and reproducible flavor characteristics. Often a secondary
refrigerant such as propylene glycol is used along with a
non-ozone-depleting primary refrigerant like ammonia to provide
necessary cooling. The food grade status of propylene glycol makes it an
attractive secondary refrigerant, particularly in the event of
accidental spills or leaks, and solutions with water are non-flammable,
have low environmental impact, and provide effective heat transfer down
to temperatures as low as 0°F. When propylene glycol is properly
formulated to include suitable corrosion inhibitors, long-term corrosion
protection of pipes, pumps, tanks, and chillers is readily achievable.
However, poorly formulated or badly neglected propylene glycol-based
secondary refrigerants are more corrosive than plain water and can also
contribute to other problems such as a build-up of mineral scales,
bio-film fouling, decreased pump performance, and inefficient heat
transfer. Most of these problems don’t happen overnight and in fact are
not normally noticed until they reach a point where they can affect
cooling capacity, which in turn affects production and/or product
quality. By then, the problem has caused irreversible damage which can
only be corrected by shutting down the refrigeration system to replace
the fluid and to clean, repair, or replace damaged system components.
Avoiding the pitfalls of improper selection and operation of propylene
glycol-based secondary refrigerants is not difficult and it can
contribute towards lower operating costs and help avoid costly
shutdowns. A “how-to” guide and review of effective practice for
propylene glycol-based secondary refrigerants is presented.
Kevin Connor received his B.S. degree in chemistry from the
University of Waterloo (Canada) in 1985. He has worked for The Dow
Chemical Company for 25 years and is currently a senior development
specialist responsible for technical support of the DOWTHERM™ and
DOWFROST™ inhibited glycol heat-transfer fluids product line. Kevin has
been a member of ASHRAE for the past 10 years and currently serves as a
voting member for TC 3.1 Refrigerants and Secondary Coolants. He is
married and has two children ages 16 and 18.
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