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The Inadequacies
of Glycol
Multiple temperature zones during cold
fermentation
Insufficient temperatures for
cold-stabilization
Studies Reveal Actual
Conditions in Tank during Cooling
Partial Jackets &
Stratification
Icing and Stuck Temperatures
Glycol
too Unresponsive
Proprietary
Cold-Air Technology:
A Revolutionary Alternative to Glycol
Eliminates Tank
Temperature
Stratification
System at a fraction of Glycol Costs
Performance
Far Superior
Minimal Temperature
Variance
Dramatically
Better Control
Rapid Temperature
Adjustment
Addresses
Tanks Individually
Stabilization
in Days
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Announcing a revolution in wine-tank chilling must
strike some as odd. They may not be aware that current
glycol-based systems are inadequate at worst, and inefficient at
best. Some might not be aware that their wine quality is suffering
due to those inadequacies. They may not realize cold-stabilization
is much more costly and time-consuming than is necessary. It is no
fault of their own. Wineries have been left in this sad condition
by a general lack of research into what happens in a wine tank
during cooling by the standard glycol method.
Studies of
the glycol-based cooling are few and far between. Those few that
have been published concentrate primarily upon the relative costs
and effectiveness of pumping chilled glycol through tank jackets
at various speeds, as well as the costs and effectiveness of
various glycol temperatures. Nowhere do you find studies of the
effects of applied glycol coolant upon the FULL wine column inside
the tank. Temperatures are often taken after researchers stir the
wine because they know that temperature variations exist within
the tank.
There are no studies examining the hows and whys
of these temperature variations inside the tank...no studies,
however, with one bright exception. David Rule, founder of Pasco
Poly inc., has conducted over 15 years of research upon
multi-instrumented tanks undergoing glycol cooling to find out
what is really going on inside the tank.
Rule's research
discovered that a partially-jacketed tank creates independent
"weather systems" in the wine column. Temperature
inversions above and below the cooling surface cause barriers
which circulate wine at much different temperatures. Wine trapped
by inversion and stratification is actually fermenting at a much
higher temperature than wine in proximity to the cooling surface.
Further, Mr. Rule's research identified one factor
limiting the low temperatures needed to drop tartrate crystals for
cold stabilization in a non-uniform cold environment. A limiting
factor is ice forming on the cooling surfaces in proximity to the
wine. When ice begins to form on the cooling surface, cooling
stops due to the heat of conversion and the insulative properties
of ice. The cooling graphs are dramatic. The downward temperature
trend abruptly levels off at the point of icing and can even rise
slightly afterward. If the cooling surface is too cold, this
sticking point can occur as much as 20° above the wine's
freezing point, well above the optimal temperature for cold
stabilization. The wine temperature will be stuck at this point
until the inner cooling surface is de-iced.
From these
research projects, and others like them, Rule became aware of the
limitations and inefficiencies of glycol-based chilling. A brine
media is too unresponsive to achieve the temperature control
needed for maximum efficiency. Multiple numbers of wineries have
contacted Pasco Poly™ to find solutions to existing wine
refrigeration difficulties. A combination of minimal
tank-jacketing and the limitations of glycol-based chilling have
often made solutions elusive. Over a period of time, it became
obvious that the glycol cooling medium itself was a large part of
the problem.
COLD
AIR TECHNOLOGY: WHAT IS IT?
The system that Rule has developed
replaces a glycol brine with cold air as the coolant. A
thermodynamically engineered system encased in a fully-insulated
cavity directs re-circulated chilled air against the sides of the
wine tank.
This sytem converts the full length of the
tank's side walls into a cooling surface. A proprietorially
designed chiller re-circulates air into the system, creating an
envelope of cooling for the whole length of the tank. Studies have
shown that Rule's KiLR-CHiLR™ sytem virtually eliminates the
problem of temperature stratification in wine tanks. Tests have
shown that cooling curves at the bottom of the tank, the center
and top, are identical with KiLR-CHiLR™. This is not the case
with standard glycol jacketed tanks. Glycol-cooled tanks suffer
temperature stratification, with higher zones in various parts of
the tank. Rule's system eliminates these multi- temperature zones.
It can also eliminate the erratic wine quality often suffered
during cold fermentation due to such temperature stratification.
Why is this true? Why does this proprietorial airsystem
have such an advantage over glycol cooling in the area of
temperate stratification? The answer is three-fold: economic
reasons, physical differences between air and liquid as the
cooling medium, and the uique oven design.
The KiLR-CHiLR™
system is a fraction of the cost of standard glycol jackets. To
withstand the pressures of the pumped brine, glycol jackets are
reinforced structures and more than just stainless tanks within a
stainless tank. At a cost of $40 per square foot or more, the
industry has been forced to use partial jackets for most tanks.
KiLR-CHiLR™ systems, however, do not need to contain pressurized
liquid and no such expensive jacket is required. All KiLR-CHiLR™
system jackets are fully insulated for the complete height of the
tank, and that fact alone gives Rule's cold air system a head
start over most glycol jackets.
The performance of air vs.
liquid brine as the cooling medium also helps eliminate
temperature stratification. Liquid brine must be pumped much more
slowly and will encounter greater resistance through pipes and
jackets. This resistance must be overcome by pump pressure.
Overcoming resistance with pressure causes heat. The heat
coefficient due to friction is much greater for liquid brine than
it is for cold air. Temperature variations of the brine in contact
with the tank will be much greater. To illustrate this point, an
Australian study found that they could not increase the flow rates
of a glycol brine to increase cooling efficiency. Increases in
cooling loss due to increased friction concealed any advantage
they gained.
KiLR-CHiLR™systems, on the other hand, are
designed for minimal restriction. The chilled air moves much more
rapidly through the jacket than is true of glycol jackets. Because
of this there is much less loss of temperature than is true of
glycol.
KiLR-CHiLR™ system achieves a fully insulated,
fully jacketed tank with minimal temperature variance of the
cooling media. There is simply no place for temperature
stratification to gain a foothold.
The most dramatic
difference, however, between KiLR-CHiLR™system and standard
glycol brine cooling is in efficiency and control.
KiLR-CHiLR™systems work
by drying and cooling ambient air, channeling it through the
jacket, and re-circulating that air to sustain the desired
temperatures. The cavity-encased guided air then becomes a true
"cooling medium." Unlike glycol systems which usually
operate at a fixed temperature of around 20°, KiLR-CHiLR™
systems can adjust temperatures quickly and precisely.
When
wine temperatures are high, the air cooling medium can be set as
low as minus 10° F for maximum cooling. As wine temperatures
drop towards the freezing point of wine---and possible icing---he
air temperature can be raised to prevent ice formation inside the
tank, thus preventing "temperature sticking" in the
wine.
If ice does form, The KiLR-CHiLR™system
can adjust temperatures to rapidly melt the ice and let cooling
recommence. A glycol system simply could not duplicate this. It
could take hours to drop glycol temperatures 30° and then it
would force all tanks connected to the system to use that lower
temperature. Similarly, warming glycol would proceed at a snail's
pace.
The KiLR-CHiLR™ system can address each tank
individually because the cost of the Pasco poly™ air chiller is
minimal compared to the cost of glycol chillers. High tonnage
refrigeration units with expensive circulation control devices are
not required. This cost-effectiveness of an air chiller allows
each tank to have a dedicated unit. Each cooling operation can be
addressed individually, and the winemaker is not forced into the
"one temperature fits all" mode of glycol cooling.
For
the first time, winemakers are given the opportunity to achieve
maximum efficiency cooling. Tests have shown that the
KiLR-CHiLR™system can cool a wine tank at a rate of .5-2°
per hour in a nearly straight-line temperature drop. This means
that wine processing operations that used to take weeks or months,
can now be achieved in days. For example, temperatures can be
dropped from 70° to a cold-stabilization temperature near 30°
in less than two days. These efficiencies can be achieved in
ambient conditions previously regarded as extreme. Outdoors during
the summer? The KiLR-CHiLR™ sysrtem can cold stabilize.
The
system offers food-processing power to the winery. A single unit
can process a multiple number of wines on schedule. Bottling need
no longer be delayed because of erratic and unpredictable cold
stabilization. The KiLR-CHiLR™ system does indeed offer a
revolution in wine chilling.
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