May/June 2020 - 10

EQUIPMENT
TEMPERATURE CONTROL
Running hot and cold
CHECKING IN ON TEMPERATURE CONTROL
FOR BOTH FACILITIES AND FOOD
By Zeke Jennings
Managing Editor
HEATING AND COOLING costs are a
major expense for processing facilities.
Perishable food items require
very specific temperature, humidity
and ventilation conditions before
processing and after processing, if
still remaining in the perishable state,
(i.e., bagged salads, cut fruit).
That's just for the environment of
the food. In many cases of produce
processing, the product itself must be
heated and cooled.
We spoke with two companies, one
an industrial heating and cooling
designer, and the other that deals with
cooling cooked food.
Colmac Coil is an industrial and
commercial temperature-control firm
with production facilities in Washington
and Illinois. The company specializes
in a variety of refrigeration, heating,
drying and air transfer capabilities.
Colmac also has software to maximize
efficiency in its products.
Professional Engineer Bruce Nelson
is the president of Colmac.
Produce Processing: What
are some of the most common
inefficiencies you see?
Nels o n : T h e re are ma n y
opportunities to save energy and
increase operating efficiency with
industrial food refrigeration systems.
Some opportunities are related to
the components themselves, the
compressors, condensers, refrigerant
feed system and pipework, and
evaporators found in the system.
* Were the components selected with
energy efficiency in mind when the
plant was built?
10 MAY/JUNE 2 0 2 0
 Colmac inlet air hoods and discharge duct socks effectively captures this heat resulting in energy
savings, shortened defrost times, and more effective removal of frost and ice. Photo: Colmac Coil
* Have the components been properly
maintained over the life of the plant?
* Was the control system properly
designed and is it being operated
optimally at full and part load?
Other building design and operational
issues will also affect the power
consumption of the refrigeration system
such as, doorway design, activity,
and maintenance, lighting systems,
underfloor heating, and thermal
envelope and vapor barrier integrity.
PP: How can production facilities
improve their energy efficiency?
Nelson: It has been shown that as much
as 60% of the heat that is expended
during a defrost cycle is lost to the
refrigerated space due to convection
of heated air and evaporated moisture.
This wasted heat can very effectively
be captured at the air cooler by
installing return air defrost hoods
and discharge air socks.
Other benefits having to do with
reduced amounts of frost and ice
accumulating on ceilings walls are
also realized when installing these
accessories. The low cost and high
efficiency of the hoods and discharge
socks typically result in a simple
payback of one year or less. With these
devices installed defrost time can be
reduced, in many cases by as much as
50%, and we find that other problems
are solved such as ice accumulation
in drain pans.
Proper hot gas defrost piping both
internal and external to the evaporator
is also critically important to the
energy efficiency of the defrost cycle.
In a word, the fewer and shorter the
defrost cycle for a given evaporator
the better.

May/June 2020

Table of Contents for the Digital Edition of May/June 2020