Cold accumulators are designed to sustain a low temperature over an extended period within an isothermal bag, thermo boxes or car cooller chamber. Essentially, these are cooling elements that store cold energy and gradually release it. However, it is important to note that some types of cold accumulators can also function as heating elements. We will delve into this aspect in more detail later in the text.

Cold accumulators typically feature an outer case made of a rigid polymer material, which provides structural integrity. These cases are often designed to have a flat or rectangular shape, allowing for a larger contact surface. In some cases, you may also come across cold accumulators with cases made of durable polymer film, which can be molded into various shapes before freezing to accommodate specific storage needs.

Cold accumulators typically contain a solution of carboxymethyl cellulose as the active substance. This solution serves the purpose of binding and preventing the accumulator from defrosting. Additional additives like glycerin, alcohol, and table salt are sometimes included to enhance the heat capacity of the solution. Broadly speaking, cold accumulators can be categorized into three main groups based on the type of refrigerant they use: water-salt, gel, and silicone.

Types of cold accumulators

Water-salt

Water-salt cold accumulators contain a water-salt solution and are enclosed in a plastic container with a tight lid. These types of cold accumulators are capable of maintaining very low temperatures, as low as -20 °C, for approximately 20 hours. However, the actual duration of cold retention can vary depending on factors such as the volume of the thermal bag, the heat capacity of the contents inside it, and how frequently the lid is opened.

A water-salt solution can be prepared and poured into cold accumulators independently.

Water-salt cold accumulators offer the convenience of being able to prepare and pour the solution by yourself if the design of the pack allows it. However, they also have drawbacks. For instance, if the container gets damaged and the liquid spills, there is a significant risk of food spoilage.

Helpful advice. One of the simplest recipes for preparing a water-salt solution involves mixing approximately 450 g of table salt with 1 liter of water. The mixture is heated slightly to ensure the salt crystals dissolve in the water. The resulting liquid is then poured into the cold accumulator and placed in the freezer until it is completely frozen. Similar solutions can also be made using water mixed with wallpaper glue (40 g of dry glue per 1 liter of water) or gelatin (300 g of salt per 1 liter of water, followed by the addition of 3 liters of water and 10 g of gelatin). These recipes offer alternatives for creating cold accumulators with different materials.
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Gel

Gel refrigerants have the advantage of being versatile, as they can be used for both cooling and heating purposes. When used for cooling, gel-filled cold accumulators can withstand temperatures as low as -5 °C. Conversely, when used for heating, they can tolerate temperatures up to +80 °C. To use them for heating, the gel accumulators are typically placed in a container of water and heated on a stove or in a microwave. This is enough for about a day.

Gel-filled cold and heat accumulators are often made in soft packaging.

The gel-like composition does not leak out of the container in case of damage, and if it comes into contact with food, it is absolutely safe. Gel models of cold accumulators captivate with their versatility of application and are rightfully considered the most effective.

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Silicone

Cold storage devices with silicone-containing filling typically consist of polymers with silicon crystals. When using these accumulators, the temperature within the thermal box can be maintained between 0 °C to +2 °C for a duration of 6-7 days. Usually, such models are sold in sturdy film bags with the filling included.

Silicone-containing cold accumulators are often presented in a bright and unusual design.

Silicone cold storage containers are particularly well-suited for long hikes, long-distance road trips and situations where the transportation of medicines or the maintenance of a consistently low temperature is necessary.

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How to use cold accumulators properly

When selecting cold accumulators, it is recommended to consider their weight based on the estimated volume of the isothermal box It is necessary to be guided here by the following rule: for 10 liters of volume there should be 600 g of cold storage.

Before placing the cold accumulators inside the thermal bag, it is important to "charge" them by placing them in the freezer compartment of fridge. The exact time required for the working medium of the cold accumulator to crystallize and freeze depends on factors such as the type of filler and the size of the product. On average, it takes around 8 to 12 hours for the cold accumulators to freeze completely and be ready for use.

An important point. When it visually seems that the cold accumulator has already frozen, it is necessary to keep it in the freezer for some more time — freezing of the outer case is not evidence that the refrigerant inside has reached the required condition.

To enhance the cooling effect, it is advisable to place pre-cooled products inside the thermal bag or isothermal box. For larger containers, multiple cold accumulators can be used, with one placed at the bottom, another at the top, and additional ones positioned between the layers of products. In the case of a small cooler bag with fewer products, a single cold storage unit placed on top can be sufficient. The cold from the top unit will naturally distribute downward, ensuring even cooling.

Cold accumulators are selected at the rate of 600 g of weight for approximately 10 liters of thermal bag volume.

When it comes to keeping food warm, such as with gel-filled cold accumulators, the preparation process differs significantly. To warm a gel battery, it needs to be heated in a container of water. This container can be placed either on a stove or in a microwave, with the recommended heating time and temperature typically specified on the product itself. Another alternative method is to place the gel accumulator on a hot surface, such as a hot radiator.

After each use, it is recommended to wash the cold accumulators under running water, dry thoroughly and place them in the freezer again. This hygiene care routine helps eliminate any dirt or odors that may have been absorbed from the food. It is best to store cold accumulators in cool, dark places, with the freezer being an ideal option. With proper care, the service life of cold accumulators is essentially unlimited.

Where else can be use cold accumulators

It is not widely known, but cold accumulators can be useful for an ordinary household fridge. Placing several cold accumulators in the freezer helps stabilize the temperature, especially when the fridge door is frequently opened or when there is a heavy load in the freezer compartment. By maintaining a stable temperature, the fridge's compressor is required to operate less frequently, thereby extending the lifespan of the equipment. Additionally, cold accumulators enhance the freezing performance of the freezer and can prolong the storage time of food in the fridge during power outages.

Cold accumulators not only “charge” in the freezer, but also help maintain a more stable temperature in it.

Cold accumulators are also used in various applications, including isothermal chambers found in retail outlets. These chambers are often used to store and display cooled drinks and ice-cream. Some courier delivery services use cold accumulators to transport frozen products. Additionally, there are specialized cold springs designed to serve as trays, enabling food or drinks to be either cooled or kept warm for an extended period.

Finally, cold accumulators are very important in medicine. Thermal refrigerators equipped with cold accumulators are commonly used as a safety measure for transporting drugs, vaccines, and biological tissues. There are a number of medicines that can be stored exclusively at low temperatures, otherwise they lose their medicinal properties. Also, cold accumulators are often used as compresses for bruises.


Summarizing, it is necessary to highlight the main purpose of different types of cold accumulators. So:

  • Water-salt cold accumulators are well-suited for maintaining very low temperatures, and user can also prepare a solution for them.
  • Gel accumulators is used for both keeping cold and warm.
  • Silicone cold accumulators are the best option for long-term use.

While using homemade alternatives like frozen water in a bottle with added salt or alcohol that can provide some level of cooling, specialized cold accumulators are far more efficient in maintaining the freshness of products and ensuring optimal temperature conditions. Actually, this is the main task of cold accumulators.