Eutectic refrigeration

Eutectic refrigeration

Reloadable cooling

OLIVO eutectic plates are professional cold accumulators. Simply freeze them to benefit from the frigories accumulated. A simple, economical and effective cooling system.

Choose the temperature of the eutectic plate from 7 eutectic liquids capable of maintaining sub-zero (-20°C), positive (+2°C) or ambient (+20°C) temperatures.

Other terms such as eutectic cartridge, eutectic block or brick, coolant gel or ice pack are also used to talk about eutectic plates.
Discover a wide choice of eutectic plates that can refrigerate a large capacity insulated container such as a ROLL container or a small volume BOX type package.

Eutectic liquid

Seven qualities of eutectic liquid are used to maintain positive, negative or “warm” temperatures in all the climatic conditions encountered in transport.

Choosing the coolant pack suited to your needs requires combining the thermal power of the plate and the temperature required. Don’t hesitate to contact us, we can advise you easily on:

  • the choice of the temperature of the plate
  • how many eutectic plates you will need to use

The temperature in an insulated container refrigerated with cold eutectic plates can be maintained for 24 hours or more.

 

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Sustainable cooling

OLIVO eutectic plates are non-toxic.

 

All OLIVO eutectic solutions are stable, non-toxic and do not degrade over time.
This means you can use the eutectic packs for an unlimited time as they retain their cooling capacity.

Transparent cold

OLIVO has chosen to use transparent envelopes as each eutectic solution is a different colour. This means that if the marking on the eutectic plate becomes less legible over time, you will still be able to tell which plate you are using by the colour. This is of interest especially to users handling goods at two different temperatures who need to be able to distinguish without any risk of error between CHILL cold accumulators and FREEZE accumulators.

 

The envelopes of our cold accumulators are made of food grade polyethylene.
For the larger accumulators, the shell is made by rotational moulding for greater solidity. Integrated handles are moulded in to facilitate handling.

 

The envelope of the small accumulators is blow moulded to reduce the weight.

Thermodynamic principle

OLIVO eutectic liquids are aqueous solutions containing mineral salts and cooling media.

A eutectic solution is basically a mixture of water and salts whose melting point (or freezing point) is constant and lower than that of water. For example, a -17°C eutectic liquid will melt (or solidify) at -17°C: its melting point is considerably lower than 0°C, the melting point of water.
The best known eutectic solution is the mixture of salt and water: think of the salt that is spread on the roads in winter to reduce the temperature at which the road surface freezes.

When a pure liquid thaws (phase change) its temperature is constant until the liquid is fully melted.
The capacity of a eutectic liquid is similar: it maintains a constant temperature (that of the melting point) throughout the time it takes to thaw (phase change).
The quality of a eutectic solution is judged by the stability of its temperature plateau. When it thaws, the eutectic liquid slowly releases its frigories at a perfectly stable temperature. This is called a temperature plateau because if we measure the temperature of a -17°C eutectic liquid in the thawing phase, the temperature curve is flat and continuous at the fixed temperature of -17°C.
The quality of a eutectic solution is defined by the cooling capacity it provides while it is thawing and by the fixity of its temperature plateau.

Accumulating and releasing

The way a cold accumulator works is very simple. The eutectic plate is frozen before being placed inside the insulated container.

During the freezing phase, the eutectic liquid accumulates frigories. This is why eutectic plates are often called cold accumulators.
Once placed in the insulated container, the plate releases the frigories accumulated when it was frozen, thereby providing constant, regulated cooling to the inside of the container.
The eutectic plate is “recharged” by freezing it again ready for reuse.

The eutectic plate or plates must be placed in the top of the container, if possible above the load of goods. OLIVO insulated containers have grooves on the inside walls that serve to optimise the natural convection inside the insulated container and allow the cold air coming from the eutectic plate to circulate around and through the load being transported.

Freezing the plates

t is essential that the eutectic liquid be perfectly frozen and solidified before the eutectic plate is used. If it is not frozen all the way through, the eutectic liquid will not accumulate enough frigories and its cooling capacity will be reduced.

At what temperature should the plate be frozen? The freezing temperature of the eutectic plate must be at least 5°C lower than the eutectic liquid’s melting temperature. For example, a -17°C eutectic plate, i.e. one whose melting point is -17°C, will need to be frozen at least at -22°C.

For faster freezing, the eutectic plates must be separated from each other inside the freezing chamber. Stacking them without allowing the cold to circulate considerably increases the freezing time.
The correct freezing of cold accumulators can be checked either visually if the envelope is transparent, or dynamically by shaking the accumulator: any movement resulting from a liquid or semi-liquid state means that the eutectic solution is not frozen through.

The freezing time can vary from 6 to 24 hours depending on the freezer chamber used. Using two sets of eutectic plates means that you can guarantee immediate cooling power, by keeping one set recharging while the other is in use.

 

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Handling eutectic plates

For operations using a large number of cold accumulators, it is important to plan their management.
OLIVO offers special plate-carrier trolleys useful for:

  • collecting returned melted eutectic plates
  • freezing them in best possible conditions, as the eutectic plates are stored tilted and far enough apart to optimise freezing
  • organising the handling of frozen eutectic plates as far as the place where they are loaded into the insulated containers
  • limiting the manual handling of frozen eutectic plates

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Use of hot eutectic plates

“Hot plate” is probably not the best term to use as in fact OLIVO hot eutectic plates are used to maintain an interior temperature of between +15°C and +25°C if the external atmosphere is extreme, whether this means very cold or very hot.

  • keeping chocolate at about +20°C when it is +35°C outside
  • keeping a pharmaceutical product at about +20°C when the winter temperature is -10°C

Hot plates are used in the same way as cold eutectic plates. Simply the preparation before use is different.

In winter conditions (ambient temperature -10°C):

  • the hot eutectic plate must be heated in a chamber at a temperature higher than +25°C
  • above +25°C the solid eutectic solution turns to liquid
  • placed in the container in a liquid state the plate absorbs the heat loss from the load

In summer conditions (ambient temperature +35°C):

  • the hot eutectic plate must be cooled in a chamber at a temperature lower than +15°C
  • below +15°C the liquid eutectic solution turns to solid
  • placed in the container in a solid state the plate releases its frigories to compensate for the heat input in the insulated container

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