Many truck drivers and travelers are faced with the need for long-term transportation of products, but not everyone understands how exactly specialized equipment differs from household analogues. Isothermal refrigerator - this is not just a container with thick walls, but a complex engineering solution that allows you to maintain the temperature regime inside the body, regardless of external conditions. Unlike our usual home units, such systems often work in conjunction with external cold sources or their own powerful installations.
The main task of such equipment is to minimize heat inflows from the outside, which is achieved through the use of special materials and a sealed design. If you plan to engage in commercial shipping of perishable goods, you need to clearly understand the difference between simple thermal insulation and full-fledged refrigeration equipment. The safety of the cargo and compliance with sanitary standards during delivery depend on the quality. isothermal van depends on the safety of the cargo and compliance with sanitary standards during delivery.
In this article we will analyze in detail the design, types of insulation used and the principles of operation of such systems so that you can make the right choice for your business. Understanding the physics of processes will help to avoid errors in the operation and maintenance of equipment.
Principle of operation and physics of the process
The fundamental difference between an isothermal container and a conventional one is its ability to maintain the internal temperature at a given level without the active participation of a compressor in real time, if we are talking about the passive phase. Thermal insulation plays a key role here, since it prevents heat from penetrating inside in hot weather and does not let it out in cold weather. The efficiency of operation directly depends on the coefficient of thermal conductivity of the materials used and the absence of “cold bridges” in the body structure.
When a low temperature has already been created inside the body (for example, using pre-cooling or the operation of a refrigeration unit), the isothermal properties of the walls allow this cold to be retained for a long time. Heat transfer between the internal the camera and the external environment occurs very slowly. This allows you to save fuel and engine life during stops, when the main refrigeration unit can be turned off.
It is important to understand that an isothermal van itself does not produce cold, it only preserves the existing temperature. Active cooling is provided by separate units, such as refrigerators or cryogenic cooling systems, which work in tandem with a thermally insulated body. Without high-quality insulation, even the most powerful refrigerator will not be able to maintain a minus temperature at +30°C outside for a long time.
Design and insulation materials
Modern isothermal vans are a multi-layer “sandwich”, where each layer performs its function. The basis is a frame, which can be made of metal or composite materials, providing structural rigidity. Between the outer and inner sheathing sheets there is a layer insulation, the thickness of which varies depending on the class of equipment and the required temperature conditions.
The most common filling material is polyurethane foam (PPU), which is foamed directly in the cavity between the walls. This material has low thermal conductivity and high adhesion, which allows you to create a monolithic structure without voids. Extruded polystyrene foam (XPS) is also often used, which is characterized by high moisture resistance and compressive strength, which is critical for truck floors.
⚠️ Attention: When choosing or ordering a body, be sure to specify the type of foam concentrate used. Some cheap analogues can dry out or absorb moisture over time, which sharply reduces the insulating properties and leads to freezing of the corners.
The external cladding is usually made of stainless steel, aluminum or fiberglass. These materials are resistant to corrosion and mechanical damage. The inner layer is often made of food-grade stainless steel or special plastic, which is easy to clean and disinfect. All panel joints are carefully sealed to prevent moisture from getting inside the “sandwich”, since wet insulation stops working.
Classification of isothermal bodies according to ATP
To standardize the requirements for the transportation of perishable products, the ATP international agreement was adopted. According to this document, all isothermal vehicles are divided into classes depending on their ability to maintain temperature. Classification helps shippers and carriers understand what kind of transport is needed for a particular type of product.
There is a division into isothermal (IN), refrigeration (REF) and freezing (FRO) vans. The former only maintain the temperature, the latter can cool the cargo to 0°C, and the third - to -20°C and below. The temperature retention time without operation of the cooling unit is also an important parameter that determines the class of equipment.
| ATP Class | Type of equipment | Temperature range | Retention time (min.) |
|---|---|---|---|
| IN | Isothermal | No restrictions | ≥ 12 (at ΔT=20K) |
| REF | Refrigeration | from +12°C to 0°C | ≥ 12 (at ΔT=20K) |
| FRO | Freezer | ≤ -20°C | ≥ 12 (at ΔT=20K) |
| IR | With motor | from +12°C to -20°C | ≥ 12 (at ΔT=30K) |
The choice of the right class directly affects the cost of transportation and the ability to work with certain categories of goods. For example, to transport ice cream you will need class equipment FRO, while for fresh vegetables a class REF or even a high-quality isotherm may be sufficient. Violation of the temperature regime can lead to damage to the cargo and fines.
The difference between an isotherm and a refrigerator
Often in everyday life these concepts are confused, but technically these are different things. Isothermal van is just a thermos on wheels. It does not have its own source of cold. Its task is to change the temperature inside as slowly as possible, be it high or low. If you load warm goods into it, it will slowly cool down, if cold, it will slowly heat up.
Refrigerator is an isothermal van equipped with an autonomous or driven refrigeration unit. Such a system actively produces cold or heat, maintaining the set parameters with high accuracy. The presence of an evaporator inside the body and a condenser unit outside is the main visual difference between a refrigerator and a simple isotherm.
Is it possible to turn an isotherm into a refrigerator?
Theoretically, it is possible to install a refrigeration unit on an isothermal body, if it Thermal insulation characteristics meet the requirements for working with this type of installation. However, this requires serious engineering work, strengthening the frame and passing certification.
The cost of operating a refrigerator is much higher due to the fuel or energy consumption for operating the refrigeration unit. Therefore, for short transportation or delivery of goods that do not require strict temperature control, conventional isothermal bodies with cold accumulators are often used. This allows you to save resources using passive cooling.
Scope of application and types of cargo
The area of use of isothermal technology is extremely wide and covers almost all areas of human life. First of all, this is the food industry: transportation of meat, fish, dairy products, fruits and vegetables. Each product category has its own sanitary standards that require the use of certified transport.
However, the scope of application is not limited to food. The pharmaceutical industry has perhaps the most stringent temperature requirements when transporting vaccines, drugs and reagents. Here the slightest deviation from the norm can make the load useless or even dangerous. Also, insulated containers are used for transporting flowers, live fish and even some types of chemical cargo.
- 🚛 Food retailers: daily delivery of goods to supermarkets and restaurants.
- 💊 Pharmaceutics: logistics of medicines that require a “cold chain.”
- 🌸 Floristry: transportation of cut flowers, sensitive to temperature changes.
- 🧪 Laboratory: transportation of biological samples and reagents.
⚠️ Attention: It is strictly prohibited to transport food together with chemicals or sources of strong odors in the same insulated compartment, even if they are packaged. Porous insulation materials can absorb odors, which will make the body unsuitable for food transportation.
Care, maintenance and leak testing
In order for an isothermal refrigerator to serve for a long time and efficiently, it must be properly cared for. The main enemy of insulation is moisture. If water gets inside the sandwich panels through microcracks or poor-quality joints, the thermal conductivity of the material will increase significantly and the body will no longer maintain temperature. Regular inspection of the integrity of the lining is a mandatory procedure.
The inside of the body should be washed with special disinfectants after each unloading, especially if products of animal origin were transported. It is important to use detergents that do not contain high concentrations of chlorine to avoid damaging the anti-corrosion coating and sealants. After washing, the body must be completely dried before the next loading.
☑️ Daily check of the isothermal body
Particular attention should be paid to door seals. Rubber profiles lose elasticity over time, crack or deform. A loose fit of the doors negates all the advantages of thick walls, since warm air will constantly be sucked in through the cracks. Replacing seals is a simple but critically important maintenance procedure.
Frequently asked questions (FAQ)
Is it possible to use an isothermal van as warehouse?
It is not recommended to use an isothermal body as a stationary warehouse. The design is designed for dynamic loads during movement, and not for constant static pressure. In addition, without air circulation inside a closed volume, mold can form, and the insulation can pick up moisture from the soil or air if proper ventilation is not provided.
How long does the isotherm keep the cold without the refrigerator running?
The time the temperature is maintained depends on the ATP class, the thickness of the walls, the initial temperature of the cargo and external conditions. A high-quality isothermal van can maintain temperature for 8–12 hours or more, subject to pre-cooling (pre-cooling) and a minimum number of door openings during unloading.
What are the dangers of “cold bridges” in a structure?
“Cold bridges” are sections of the frame or fasteners where metal connects the outer and inner lining, bypassing the insulation. In these places, intense heat exchange occurs, which leads to local freezing, the formation of condensation inside the walls and eventual corrosion of the metal frame, destroying the body from the inside.
Do you need to warm up the isothermal body in winter?
Yes, if you are transporting products that should not freeze (for example, some types of vegetables or groceries). An isothermal van can be equipped with a heating system powered by a car engine or an autonomous fuel heater. This allows you to maintain a positive temperature even in severe frosts, preventing damage to the cargo.