The ozefridge Eutectic
System has all of its components assembled into two distinct sections.
(Keeping it simple and tidy!)
Eutectic tank: The stainless steel Eutectic tank is located
inside the cabinet and has an insulated hose that carries refrigeration
pipes, filter and the temperature sensor wire to the C450's location.
The eutectic tank acts like a large renewable block of low temperature ice,
refrigerated automatically by the C450 condensing unit.
Refrigeration condensing unit: The C450 condensing unit houses the Danfoss BD50
compressor, water and air cooled condensers, fan, 12-24 &110- 240 volt
electrical components, controller, LED readout, failsafe protection and
refrigeration couplings.
We all
know that a drink with ice in it will stay cold and drinkable at a
constant temperature while the ice remains, but warm rapidly once
the ice thaws. The ice was an example of a eutectic system
absorbing relatively huge amounts of heat while it thawed from a
solid to a liquid. (Phase changed)
The
term 'Eutectic System' refers to a refrigeration system that uses
the phase change of a liquid medium to absorb and dissipate large
amounts of thermal energy while remaining at a constant
pre-arranged temperature. Phase Change occurs when we freeze a
solution solid by removing its heat or as it thaws into a
liquid again while it absorbs heat. The phase change medium or
eutectic solution is stored in the stainless steel eutectic tank
and acts like a re-new able ice block, freezing solid during the
refrigeration run cycle and thawing during off periods and all the
time maintaining a constant cabinet temperature like the ice did
for the cool drink!
Any
product such as an aluminum cold plate can absorb and dissipate
thermal energy but when a relatively large volume of solution is
used and it is allowed to freeze solid on the refrigeration run
cycle, then thaw during the off cycle, a relatively massive amount
of stored thermal energy is in play.
In
comparison with an aluminum cold plate, the first and most obvious
advantage the eutectic system has is its far greater mass and
therefore thermal hold-over storage capacity.
But
this thermal storage advantage pales into insignificance compared
to the other unique benefit that the eutectic system's phase
change phenomenon delivers. This phenomenon called 'Latent heat',
multiplies the eutectic's thermal storage capacity many times
providing huge hold-over periods where the unit stays off for many
hours even days in cooler times.
As an
example, using a quantity of water as a eutectic solution and
knowing that water's phase change occurs at approximately 0°C, this
water will absorb and dissipate 80* (Yes eighty!) times as much
thermal energy while freezing and thawing as it would for any other
rise or fall of a degree centigrade.
(*All
eutectic solutions with a lower phase change point than water also
have a lower Latent Heat value. Expect low temperature eutectic
mixes to absorb and dissipate approximately 65 to 70 watts while
phase changing)
With a
system refrigerating a solution through its' phase change
temperature until frozen solid during each run cycle, then staying
off for very long periods while this thermal mass thaws completely
before running again, many advantages become obvious including the
following..
*
Tremendous 'hold-over' off periods due to the thermal mass of
the stored eutectic solution and more importantly because of the
eutectic's phase change.
*
Refrigeration run periods can be at a time that suits individual
variations of power supply, or during cooler periods of the day when
all refrigeration system are more efficient.
* Much lower overall power consumption due to more efficient
refrigerant evaporation in a saturated environment, and far less
stop / start operations.
* The
eutectic solution can be varied to have a phase change point at much
lower temperatures than water to suit refrigerator or freezer
cabinets.
* As
a eutectic system is virtually 'cooling in advance', use of shore
power or other abundant power supplies allows a day or so of
refrigeration in storage.
* A
day or two or three of sailing without the need of additional
cooling is possible if battery power supply is down. (i.e.. solar
but no sun!)
*
The eutectic system stores energy at a third of weight that would be
required in batteries to provide the same refrigeration effect.
