Q & A   (Marine Refrigeration)

Q: Why Eutectic? 

A:  A eutectic system suits applications where power supply is limited and often erratic. (Hold-over Refrigeration.)

Eutectic systems not only use much less electrical power, they will run automatically whenever power is abundant.   see: 'Test Data'.                                                  

A eutectic system will consume up to 50% less power operating as a fridge and up to 20% less as a freezer.

There are three reasons for this power saving...                                     (See a broader explanation at  'Why Eutectic' )

1:  Co efficiency of operation (COP). COP is like MPG (Miles per gallon).  COP is the refrigeration industry reference to system /compressor efficiency. It is the measure of how many watts of heat are absorbed for each watt of electrical energy consumed (W/W).  A eutectic refrigerator will typically have a COP of approx 1.80 while a cyclic refrigerator would typically operate with a COP of approx 1.10.  Therefore the eutectic system removes far more heat for each watt of electrical energy consumed. 

2:  Motor start up inefficiencies. This waste of energy is obviously far less with a eutectic system as it only starts once or twice a day instead of 40 to 60 times as for a cyclic system. Energy is wasted getting the compressor rotating and pumping the pressures up to allow refrigeration. Although each start up loss is minimal, multiplied out over the days start ups and it becomes significant. 

3:  Low or No Battery drain: Refreeze of the eutectic mass can often be when it best suits available power.  The Ozefridge inbuilt ECO2 will cause a refreeze cycle to occur virtually direct from the source when power is abundant, reducing the need to run at other times drawing down battery power! This feature often eliminates the need for an extra battery when adding refrigeration.

(Abundant power is when batteries are fully charged and solar or whatever presented would otherwise be wasted!) 

Q:  Which is best, A480 air cooled or AW480 air and water cooled?

A:  The refrigeration unit’s condenser is responsible for disposing of the heat extracted from the fridge / freezer cabinet, therefore the faster and more efficiently it can dispose of this heat, the better.

Condensers operating in a very cold environment can over condense whilst those in hotter areas will often under condense.  Either will see a reduction of cooling ability and efficiency and this equally affects all types of systems.

Under condensing in hot climates, causes the compressor to work much harder and in extreme situations may eventually fail to function.  With  Ozefridge temperature controlled condensing, the possibility of this problem is prevented.

Water cooling is far superior to air as water dissipates heat many times faster than air, but water cooling on a boat can present its own problems especially when raw (Sea) water is used, while air cooled systems require good ventilation and struggle in extreme heat situations.  We do not recommend any sea water cooling methods... (Prevent electrolysis easily, simply don't create it!)

1:  Air cooled:  (A480)

For many projects an air cooled only system is adequate especially for small to moderate sized cabinets with the refrigeration unit operating in a well ventilated area.

2:  Air cooled with fresh water assist: (AW480)

Best for larger cabinets and combination fridge / freezer projects, also installations when the unit is to operate in a restricted area

(like the engine room / or in an enclosure) or for tropical use.

The AW480 operates as an air cooled only unit until the condenser reaches *43C when the micro water pump is switched on to circulate fresh water via separate food grade tubing in the condenser fins thus avoiding electrical erosion (Electrolysis) and fouling issues (*Off again at 38C for optimum condensing at 38C to 43C)

The AW480 can operate as air only; water only or as recommended automatically from both air and water cooling.

Q:  What is a ‘Soft Start’ compressor?

A:   There is a large amount of energy required to start a compressor. The Ozefridge Motor Driver Module (MDM) starts the BE90 3.5cc compressor slowly, not instantly like Direct on Line (DOL) starters.  This soft /slow start (never exceeding the run ampere rate) prevents the stress and harm that DOL causes. Many know of the high failure rate of the dreaded ‘Black Box’ with its DOL start, expensive faults mostly caused by high current inrush at start ups.  The soft start MDM eliminates those failures.

Q:   What does the ECO2 do?

A:  ECO2 tricks the unit into run mode whenever *abundant power is identified.  *At 13.3 volts, ECO2 knows the battery system is topped up and thereafter energy from solar, generator or wind etc is being wasted. ECO2 causes the unit to run converting that otherwise wasted electrical energy into stored thermal energy. 

This running from abundant energy avoids / reduces running later when on battery alone, reducing battery demand.

Q:  How and why is the condenser controlled?

A:  Marine systems operate in environments from extreme cold to extremely hot, extremes which adversely affect all types of refrigeration systems. . Both of the Ozefridge designed condensers thermostatically control their temperature to within engineered parameters of 38C & 43C avoiding these issues and optimising performance.  

These condensers are of Cupro-nickel tubing and conformal coated as environment protection.

Q:  Why such a large capacity compressor?

A:  The Ozefridge BE90 is a 3.5cc variable speed compressor.  This compares to the BD35 @ 2.0cc and the BD50 @ 2.5cc. Employing a much larger capacity compressor allows it to run easier yet with extra capacity if / when required. This is most important when running on abundant power as the bigger capacity provides more stored thermal energy much quicker.                      A larger compressor draws more current when running but runs proportionately less, so no difference in consumption.

Q:  How long is the pipe run?

A:  This is as long as needed, again something that is sorted prior to us fabricating each system. Nominally 2.0 meters but can be longer or shorter as required. Pipe exit is always at the top of the eutectic plate and can exit either left (as in pics) or right.

Q:  What about warranty and backup service?

A:  The system has a minimum of 12 months warranty as described in the owners manual.  

We supply a 24 page manual but more importantly we provide access to a qualified refrigeration technician seven days a week.

We hold massive volumes of all spare parts and can Express AusPost daily, (Except Sunday) with instructions where needed.

     *Important note: Some countries including Australia, require that R134a gas is only handled by licensed trades-persons.