WHAT EXACTLY IS EUTECTIC REFRIGERATION?

In a conventional compressor powered refrigeration system the 'cold side' of the system is called the 'evaporator'. The evaporator is mounted inside the fridge cabinet and makes everything cold when the compressor is running. When the compressor turns off, the fridge warms up. The system starts up again to bring the temperature down. This process continues constantly and is controlled by the thermostat - all very simple and in most cases reliable.

Eutectic refrigeration is simply the use of a compressor-driven refrigeration system coupled to a cold storage device, i.e. eutectic tank (sometimes called 'ice bank' or 'ice wall'). The eutectic tank contains a liquid which is chilled and frozen during the refrigeration cycle. This mass of ice housed within the tank is capable of keeping the temperature of an insulated box at refrigeration temperatures for long periods of time WITHOUT RUNNING THE COMPRESSOR. When the eutectic tank or ice bank has thawed, the refrigeration system is run again to re-establish the ice bank. In a properly designed eutectic system the refrigeration system only needs to be run once or twice daily with very long periods between each run.

ADVANTAGES

The advantage of the eutectic system is that the refrigeration unit does not need a power source on a continuous basis, whereas a conventional system must have power available at all times. The eutectic refrigeration system can be run when sufficient power is available (when driving a vehicle or running an engine in a boat or when solar power is available or when running a generating set).

The main advantage of the eutectic refrigeration system is that it will use much less power over time than a conventional system. The basis of this statement lies in the physics of 'phase change compounds'. Phase change is simply the phenomenon of changing vapour to liquid, liquid to solid and vice versa. The obvious example of this is boiling water to produce steam (liquid to vapour) or freezing water to produce ice (liquid to solid). These changes occur when a large amount of energy (heat) is added to or taken from a particular compound. The heat taken from water to form ice is referred to as the 'latent heat of fusion'. The latent heat of fusion can only be released by water when its temperature falls to zero degrees and it begins to freeze.

During the freezing process, large amounts of heat energy are removed but the temperature of the water remains at zero degrees until all the water has frozen. Now, if this frozen mass was then allowed to thaw (Ice to Water/Solid to Liquid), then large amounts of heat would be absorbed by the ice but the temperature would remain at zero degrees until all the ice has thawed - THIS IS THE EUTECTIC PRINCIPLE.

A common, everyday example of eutectics at work is the use of ice cubes in a glass of water. Whilst the ice cubes are present, the water is cold. After the ice has melted, the water will warm up. Throw in more ice cubes and  the water temperature will fall, but it will never actually freeze - even though there is ice present in the water.

BUT IS IT EFFICIENT?

Take the same compressor system in the same refrigerator and replace the original, conventional evaporator with a EUTECTIC TANK. The tank is filled with a 'cold storage compound' which 'freezes' when the compressor runs. This frozen compound has a very high thermal capability and brings down the temperature inside the fridge and keeps it there even when the compressor is off. This frozen 'ice bank' provides cold temperature holdover for the refrigerator's contents. The efficiency of the refrigeration system is improved by utilising the availability of the latent heat, which is being given off by the liquid as it changes to a solid state. The compressor performance can be matched exactly to the heat load during the change of state - this allows the compressor to operate at it's optimum speed and refrigeration capacity which improves the overall efficiency of the system. 

The degree of improvement will depend on how well the system is set up, but efficiency gains of around 30% are very common and can be more in some designs. The 'holdover times' of the eutectic system depend on a number of factors, but a well designed system can generally remain cold overnight and much longer in most cases. Considering the potential efficiency improvements and the fact that the compressor does not need to run overnight, these are distinct advantages in this type of system. EUTECTIC systems can reduce the need for large battery requirements, In most vehicle applications, it is not necessary to have an auxiliary battery just to run the EUTECTIC fridge. If a vehicle is being used regularly the EUTECTIC fridge can be 'charged up' during driving periods and turned off when stopped, meaning that the EUTECTIC fridge does not need any battery power overnight.

Why You Should Buy an AUTOFRIDGE

Over the last 25 years AutoFridge has stood out as the most efficient camping fridge on the Australian market. Its EUTECIC ICE BANK and highly tuned refrigeration system will deliver to you the following advantages over traditional camping fridges:

Maximum Power Efficiency

The AUTOFRIDGE doesn’t cool the air inside the fridge compartment like other fridges. It actually freezers a EUTECTIC ICE BANK housed within the walls of the fridge.

Why is this Better?

This system is better for a number of reasons but the main ones are that the heat transference from the EUTECTIC SYSTEM into the refrigeration system creates much more cooling power than relying on the air inside a conventional fridge to transfer heat. High heat transfer (‘heat load’) means higher efficiency; and, most importantly, due to the efficiency of the refrigeration system in the AUTOFRIDGE it only needs to run for a few hours per day to give you 24 hours of cooling!

Why is this Important?

This is important due to a basic thermal dynamic principal related to heat transference. On a fridge it’s the condensers job to transfer the heat out of the fridge and into the atmosphere. AUTOFRIDGE uses two large surface area condensers to make this as efficient as possible, but this whole process works most efficiently when the atmosphere is cool and the hot condenser can transfer its heat load easily. As you can imagine on a 40+ degree day the compressor in your fridge has to work overtime as the hot condenser is trying to transfer heat out into an already hot atmosphere!

How does the AutoFridge do this Better?

The EUTECTIC (Ice Bank) System inside the walls of the AUTOFRIDGE allows the fridge to keep cool all day without the compressor having to run at all. This means you can choose to run the AutoFridge during to coolest part of the day or night to reduce the strain on the Refrigeration System thereby saving you a massive amount of battery power.

Superior Insulation & Reflectivity

The box on an AUTOFRIDGE uses high quality fibreglass to reflect heat and specially formulated high density foam in the walls to keep the heat out and the inside of the fridge cold. What this amounts to is a highly efficient cabinet design which reduces loss of cold in the fridge and reduces the need for the refrigeration system to work as hard, especially in 40+ degree temperatures!

No Compromises

Many people think a combined fridge/freezer is a good idea, but when you try and do both things in one fridge with a single compressor you compromise the performance of the fridge and in turn use much more power. The AUTOFRIDGE is designed and tuned to be the most efficient fridge on the market to ensure maximum efficiency and minimum power use. It sounds good to have a freezer but do you really need it? Meat can be cryovaced these days reducing the need for a freezer.

Equals Longer Battery Life

Having a super efficient box design, a highly tuned refrigeration system and the EUTECTIC ICE BANK system all amounts to AUTOFRIDGE being the most efficient fridge on the market in real Australian conditions, and its designed specifically to handle Australia’s tough 40+ degree outback!

Maximum Reliability

AUTOFRIDGE has been making portable fridges for Australia’s tough conditions for the last 25 years. They’ve learnt a thing or two in that time about what it takes to make a fridge reliable. The AUTOFRIDGE range is designed to handle harsh vibrations from extreme off-road tracks and uses simple electronics to ensure maximum reliability!

Hygienic Design

Because the AUTOFRIDGE doesn’t have the cooling plates (evaporator) inside the fridge compartment like many traditional fridges there are no places for germs and bacteria to hide! The AUTOFRIDGE fibreglass design means the fridge compartment is easy to clean and very hygienic. This has the added advantage of giving you more usable space inside the fridge as your food and drinks don’t have to share room with cooling plates inside the fridge compartment.

Australia’s Best Portable Camping Fridge!!!

All these features and the years of fine tuning the AUTOFRIDGE range means you cannot go past this fridge if you are a serious traveller!!