On a hot summer day or during a long trip, keeping food fresh becomes a priority for any tourist or summer resident. Many owners of thermal bags often wonder what exactly is the name of the very element that creates and maintains a low temperature inside the container. In everyday life you can hear many names: ice block, cold element, battery or simply “ice”.
However, the technically correct name of this device is cold accumulator (AH). This is the term used by manufacturers and in technical documentation. Understanding what is inside a sealed container and how it works will help you not only choose the right device, but also significantly extend its service life by avoiding common mistakes during operation.
The effectiveness of all your thermal packaging directly depends on the quality and type of cooler you choose. Simply replacing water with ice in the freezer will not give the same lasting effect as using specialized gels or eutectic solutions. In this article we will analyze in detail the structure of these elements, their differences and rules of use.
Terminology and design of a cold accumulator
The main functional element of any insulated bag is a cold source. In the professional environment and on manufacturers' labels, the term cold accumulatoris most often found. This device is a sealed container filled with a heat-intensive substance that can maintain a low temperature for a long time after preliminary freezing.
Inside the case there is usually not just water, but a special heat-intensive solution. Most often it is a gel-like substance based on an aqueous solution of carboxymethylcellulose (CMC) or propylene glycol. It is the presence of the gel that allows the substance to release cold more slowly compared to ordinary ice, which melts quickly and unevenly.
⚠️ Attention: Never open the housing of the cold accumulator. The gel contained inside may be toxic if swallowed and cause irritation upon contact with skin or mucous membranes.
The body of the device is made of durable, frost-resistant plastic that can withstand repeated cycles of freezing and thawing without cracking. Tightness is a key parameter that ensures safe use. If you notice even a microcrack on the body, use of such an element must be stopped.
Main types of coolers for thermal bags
The market offers several types of cold sources, each of which has its own characteristics and scope of application. The choice depends on how long you plan to store the food and at what temperature.
The most common are gel batteries. They are soft bags or hard containers filled with a viscous solution. Their main advantage is versatility: they operate in a wide range of temperatures and slowly transform from solid to liquid.
There are also eutectic and salt batteries. The former are often used in professional refrigerators for medical supplies, as they maintain a strictly defined temperature. Salt options can cool to lower temperatures, but require longer freezing.
- ❄️ Gel: are universal, keep cold for a long time, suitable for food and drinks.
- 🧊 Water (ice): the simplest and cheapest, but they melt quickly and have a short service life.
- 🌡️ Eutectic: contain salt solutions, keep a strictly specified temperature (for example, -18°C or +2°C).
When choosing, you should pay attention to the markings. Some models are intended exclusively for food products, while others may contain chemical additives that are safe only for cooling non-food cargo (for example, medicines or cosmetics).
Operating principle and physics of the process
The mechanism of action of the cold accumulator is based on a physical phenomenon known as a phase transition. When you place a device in a freezer, the heat-intensive substance inside gives off heat to the environment and freezes, accumulating “cold.”
When you place a frozen element in a thermal bag, the reverse process begins. The substance begins to absorb heat from the interior of the bag, changing from a solid to a liquid (or becoming a soft gel). This process is called latent heat of fusion.
Unlike regular ice, which melts at 0°C, special gel fillers can have a melting point below zero (for example, -10°C or -15°C). This allows them to keep food frozen longer, rather than just chilled.
Why is gel better than water?
The gel structure prevents rapid mixing of layers of liquid, which slows down heat exchange with the environment. The water in the bag begins to melt on the outside, creating a layer of liquid that heats up faster. The gel gives off cold more evenly throughout the entire volume.
It is important to understand that the battery itself does not produce cold, it only preserves it. Therefore, the efficiency of work directly depends on the quality of pre-freezing and thermal insulation of the cooler bag itself.
Instructions: how to freeze and use correctly
To achieve maximum efficiency, you must follow the correct preparation algorithm. Improper freezing may result in the device not reaching full capacity or, conversely, becoming deformed.
First place the cold accumulator in the freezer. Make sure it is positioned horizontally and is exposed to cold air on all sides. Do not place heavy objects on top of soft gel packs while freezing.
The time for complete freezing depends on the volume and type of filler. Standard gel briquettes of 200-400 ml usually require 8 to 12 hours. Larger industrial cassettes can freeze up to 24 hours.
☑️ Correct freezing
When the product is ready for transportation, remove the batteries from the freezer and quickly place them in a thermal bag. Thermal insulation the bags should be closed as quickly as possible to minimize loss of cold on contact with warm air.
⚠️ Attention: If you are using a cooler bag to transport food that should not freeze (for example, some vegetables or drinks in glass), let the battery sit at room temperature for a while before storing it to avoid “freezing” the contents.
Comparison of characteristics of different types
When choosing a cooler for your bag, it is important to consider not only the price, but also the technical characteristics. Different models are designed for different tasks: some are better at holding deep minus temperatures, others are optimal for short-term cooling.
Below is a comparative table of the main parameters that will help you choose the right device for your needs.
| Battery type | Freezing temperature | Working time (on average) | Cost |
|---|---|---|---|
| Water (Ice) | 0°C | 3-5 hours | Low |
| Gel (Standard) | up to -10°C | 8-12 hours | Average |
| Saline (Eutectic) | up to -18°C | 12-24 hours | High |
| Silicone | up to -5°C | 4-6 hours | Medium |
As can be seen from the table, saline solutions provide the longest cold retention, but they also require a more powerful freezer for full activation. Gel options are the “golden mean” for household use.
Service life, replacement and disposal
A high-quality cold battery is a reusable device. With careful use, its service life can be from 3 to 5 years or more. However, over time, the heat capacity of the substance may decrease, and the body may wear out.
The main signs that the element requires replacementsare: loss of tightness (gel leaks), severe deformation of the body, which does not allow it to be tightly packed into the bag, or a sharp reduction in operating time (for example, it melts in 1 hour instead of 8).
Disposing of used batteries requires caution. You can’t just throw them in the general trash, especially if there is a chemical solution inside. It is recommended to take them to special collection points for batteries and chemicals or, as a last resort, tightly pack them in several layers of plastic before disposal.
If you are planning to buy a new cooler, pay attention to the compatibility of the sizes with your cooler bag. Standard sizes are often indicated in liters or grams of weight, but geometric parameters (length, width, thickness) play a decisive role for tight installation.
Frequently asked questions (FAQ)
Can a cold accumulator be used to cool drinks if it is damaged?
Absolutely not. Even microscopic damage to the housing can result in chemical gel leaking into food or drinks. This is dangerous to your health. A damaged battery must be disposed of.
Why does a cold storage battery not freeze to the point of stone?
Many gel fillers remain elastic when frozen and do not become hard like ice. This is a normal property of special solutions (for example, based on propylene glycol), which do not expand when freezing and do not tear the bag.
How many batteries do you need for one cooler bag with a volume of 20 liters?
For effective operation, it is recommended to fill up to 20-25% of the useful volume of the bag with coolers. For 20 liters, it is optimal to use 3-4 standard briquettes of 400-500 grams, distributed evenly (bottom, sides and top).
Is it possible to heat a cold accumulator to defrost it faster?
It is not recommended to use open heat sources (batteries, hair dryers, hot water) for quick defrosting. A sudden temperature change can damage the gel structure or deform the plastic case. It is better to let it thaw at room temperature.