Understanding and maximizing the use of eutectic plates in the supply chain
9 January 2025 by Edina GÁLFI
In the sector of transporting temperature-sensitive products, maintaining a continuous specific temperature is crucial for ensuring product quality and safety. Eutectic plates are thermal devices that use the principle of latent heat to regulate the temperature inside containers. This article explores the role of eutectic plates, their operation, and best practices for using them effectively.
What is a eutectic plate?
A eutectic plate is a rigid container, typically made of stainless steel or plastic, containing a eutectic solution. This mixture has the unique property of melting and solidifying at a constant temperature, which helps maintain a stable temperature. The phase change process, from solid to liquid and vice versa, allows the plate to absorb or release heat, ensuring a constant cooling effect that is crucial for preserving temperature-sensitive products.
Better suited for medium-sized operations, the eutectic plate is a simple cooling system that can maintain the temperature of goods for up to 12 to 24 hours. The duration can be extended depending on the amount of cooling required.
Nature and composition of cold accumulators
Cold accumulators, also known as eutectic plates, come in two main categories: rigid and flexible.
Rigid accumulators
Rigid accumulators, such as Olivo’s rotationally molded plates, are preferred in logistics for several reasons:
- Stable shape: They maintain their rectangular shape when frozen, which facilitates handling and storage.
- Durability: Designed to be leak-proof, they withstand impacts, thus extending their lifespan.
- Longevity: These plates have a longer lifespan compared to their flexible counterparts, making them a more cost-effective choice in the long run.
Soft accumulators
In contrast, flexible accumulators have several drawbacks:
- Shape instability: Their shape can vary depending on freezing conditions, making handling less predictable.
- Fragility: They are more vulnerable to impacts, which can cause leaks, product damage, and reduced effectiveness.
- Shorter lifespan: These accumulators need to be replaced more frequently, increasing long-term costs.
What is eutectic refrigeration?
The chemistry behind eutectic liquids
A eutectic liquid is a mixture of two or more pure substances that, unlike traditional mixtures, melt or solidify at a uniform temperature, known as the eutectic point. This unique behavior makes eutectic solutions ideal materials for precise temperature control.
- Melting point: Also called the eutectic point, it is the temperature at which the mixture melts or solidifies uniformly. To ensure the effectiveness of this process, eutectic plates must be frozen at least 5°C below the eutectic point.
- Latent heat: This property is crucial for understanding how the plates regulate temperature. For water, for example, the latent heat of fusion is 334.8 kJ/kg. This means that a specific amount of energy is required to change the state of water from solid to liquid without changing its temperature.
Eutectic liquids in Olivo’s range
Olivo’s range of eutectic liquids features formulas designed for a wide range of melting temperatures, tailored to various logistical needs. For example, the eutectic liquid at -21°C, while commonly used, requires special attention. To ensure complete solidification, it must be frozen in an environment where the temperature drops 5°C below -22.5°C, its actual melting temperature.
Heat transfer of eutectic plates
Heat transfer is at the core of how eutectic plates work. When a plate is in a solid state, it absorbs energy from the environment, gradually warming up until it becomes liquid. Conversely, when it is liquid, it releases energy, cooling down until it solidifies.
Implementing eutectic plates
Before use, eutectic plates must be stabilized at the appropriate temperature in a freezer or refrigerator. This stabilization process is essential to ensure that the plates are ready to maintain the desired temperature throughout transport.
Key preparation factors:
- Cooling power: The freezer must have enough capacity to freeze the required amount of accumulators within a limited time.
- Ventilation: Optimal air circulation around the plates is necessary for uniform freezing. It is recommended to use freezing racks and avoid stacking them.
- Freezing temperature: For complete solidification, plates must be frozen at a temperature 5°C below their eutectic point.Store the eutectic plates in a cold chamber with a stabilized temperature.
Store the eutectic plates in a cold chamber with a stabilized temperature.
Cold chamber temperature < -5°C the eutectic plate’s melting temperature. The plate should be charged for a minimum of 24 hours. Without meeting these conditions, we cannot guarantee the quality of freezing or the maintenance of the transported products’ temperature.
Usage strategies based on ambient temperatures
Eutectic plates can be used reversibly, in either a liquid or solid state, depending on various logistical parameters.
- Maintaining products above external temperature : when the temperature inside the container needs to be maintained above the outside temperature, the eutectic liquid should be in its liquid phase initially. By gradually absorbing cold from the outside, the liquid keeps the inside of the container at the desired temperature.
- Maintaining products below external temperature : conversely, when the temperature inside the container needs to be maintained below the outside temperature, the eutectic liquid should be in its solid phase. It absorbs heat from the outside to keep the inside of the container cool.
Conclusion
Eutectic plates are essential tools for the safe transport of temperature-sensitive products. Their ability to maintain a constant temperature, whether above or below the ambient temperature, makes them an ideal choice for logistics companies. By understanding their operation, composition, and best practices for implementation, professionals can optimize their supply chain, reduce product loss, and ensure customer satisfaction.
Optimizing the use of eutectic plates requires a thorough understanding of thermodynamics and attention to detail at every stage of the logistics process.
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