A modern refrigeration unit is a complex engineering mechanism that is often perceived as a monolithic box that retains cold. However, when you look inside, you discover an amazing combination of physics, chemistry and materials science. Understanding what the refrigerator is made ofis necessary not only for inquisitive users, but also for those who want to properly maintain equipment or choose a durable model.
The design of any household refrigerator is based on a closed heat exchange system surrounded by multi-layer protection. The materials used in production are selected taking into account their thermal conductivity, strength and food safety. In this article, we will examine in detail the anatomy of the device, starting from the outer casing and ending with the microscopic parts of the compressor.
Knowledge of the internal structure helps to quickly diagnose faults. For example, a characteristic sound or specific smell may indicate a problem with a specific material or component. Next, we will look at the main components that turn a pile of metal and plastic into a smart food storage system.
The basis of the design: the outer case and the internal chamber
The appearance of the refrigerator is the first thing that catches your eye, but it is the metal body that acts as a supporting structure. Traditionally, sheet steel with a thickness of 0.6 to 0.8 mm is used for its manufacture. The surface is covered with powder enamel, which protects the metal from corrosion and gives an aesthetic appearance. In premium models you can find stainless steel or even tempered glass, but classic painted steel remains the industry standard due to its durability.
The inside of the chamber is the space with which the products are in direct contact. Here the requirements for materials are radically different. The plastic from which the walls are made must be impact-resistant, non-toxic and resistant to temperature changes. Most often, manufacturers use ABS plastic (acrylonitrile butadiene styrene) or polystyrene. These materials are easy to clean and do not absorb odors, but have their own operating characteristics.
It is important to note the difference between the materials depending on the price segment. In budget models, the internal chamber can be made of thinner plastic, which is prone to microcracks upon impact. Expensive models are often equipped with an interior finish with an antibacterial coating or the use silver nanoparticles in the structure of plastic to suppress the growth of bacteria.
When choosing equipment, you should pay attention to the quality of the plastic joints. If you see gaps or smell a strong chemical smell when opening the door of a new appliance, this may indicate the use of low-quality raw materials. Good plastic should not emit choking odors even in the first days of operation.
⚠️ Attention: When cleaning the inner chamber, never use abrasive powders or solvents. Aggressive chemistry can destroy the structure of ABS plastic, making it brittle and causing cracks to appear through which moisture can penetrate into the thermal insulation layer.
The heart of the system: compressor and refrigerant
The main engine of cold is compressor. It is this unit that creates the pressure necessary to circulate the refrigerant through the system. Most household models are equipped with piston compressors that operate on the principle of a pump. Inside the sealed metal case there is an electric motor and a system of pistons that compress gaseous freon.
Modern refrigerators are increasingly equipped with inverter compressors. Unlike traditional ones, they do not turn off completely, but smoothly regulate the power. This reduces noise levels and energy consumption. The materials from which the internal parts of the compressor are made (shafts, bearings) undergo special treatment for operation under conditions of high pressure and temperature.
Freon is used as a working fluid. Older models used ozone-depleting substances, but today the industry standard is R600a (isobutane) or R134a gases. They are environmentally friendly, but require absolute tightness of the system. refrigerant (freon). Older models used ozone-depleting substances, but today the industry standard is R600a (isobutane) or R134a gases. They are environmentally friendly, but require absolute tightness of the system. Isobutane (R600a) is an explosive gastherefore, when repairing such systems, special equipment and compliance with safety precautions that prevent sparking are required.
Why can’t you just add freon?
If the refrigerator has stopped cooling, simply “topping up” with gas will not help. The system is sealed and a leak means there is a hole in the tubes. It is necessary to find the leak, seal it, evacuate the system (remove moisture and air) and only then fill in the exact amount of refrigerant specified in the passport.
The pipelines through which the gas moves are made of copper or steel. Copper has excellent thermal conductivity and flexibility, but is more expensive. Steel tubes are more often found in budget segments or in circuits where frequent soldering is not required. Connections are made by soldering with silver-containing solders, which guarantees the strength of the seam under high pressure.
Thermal insulation: how the cold is maintained
Between the outer metal wall and the inner plastic box there is a space filled thermal insulating material. 99% of modern refrigerators use polyurethane foam (PPU). This substance foams directly during the assembly process, filling all voids and creating a monolithic layer that does not conduct heat.
The quality of insulation directly affects the energy efficiency of the class A++ or A+++. The more uniform the foam structure and the fewer voids in it, the better the refrigerator maintains its temperature. Manufacturers are constantly improving the PU foam formula, adding components that reduce the thermal conductivity coefficient. The thickness of the layer can vary from 3 to 6 cm depending on the model and dimensions of the device.
It is important to understand that polyurethane foam is not just “foam rubber”. This is a rigid, frozen mass, which also serves as an additional reinforcement of the structure. It gives rigidity to the thin walls of the case and prevents their deformation. Damage to this layer (for example, during careless transportation) can lead to the appearance of “dew” on the outside of the refrigerator and an increase in electricity consumption.
In some older or specialized models you can find mineral wool or glass wool, but in the household segment they are practically not used due to hygroscopicity (the ability to absorb moisture). Wet insulation loses its properties and can cause metal corrosion.
Evaporator and No Frost system
The evaporator is the very element that directly cools the air inside the chamber. Structurally, it is a curved tube with aluminum plates mounted on it. This design increases the heat exchange area. In systems No Frost (without frost), the evaporator is hidden behind the back wall of the freezer.
The principle of operation of the No Frost system is constant air circulation. The fan drives air through the cold evaporator, where moisture freezes on its fins, and dry, cold air is supplied to the chamber. It turns on periodically Defrost heating element, which melts the ice on the evaporator, and water flows into the pan. This eliminates the need for the user to defrost the refrigerator manually.
The materials used in the No Frost system must withstand freezing and defrosting cycles. Aluminum is preferable to copper here due to its lightness and cost, although it is less resistant to mechanical damage. The fans are made of heat-resistant plastic, and their motors are designed to operate at low temperatures.
☑️ Signs of a malfunction of the No Frost system
It is worth noting that the No Frost system dries food faster than the drip system, so storing food in open containers is not recommended. However, the uniformity of temperature in such refrigerators is much higher, which extends the shelf life of many products.
⚠️ Attention: The design and location of the elements of the defrosting system may vary depending on the manufacturer and year of manufacture of the model. Before disassembling the rear panel yourself to check the heating element, be sure to check the technical documentation or diagram of your specific model.
Shelves, drawers and fittings
The internal contents of the refrigerator are shelves, door baskets and drawers. Shelves are most often made of tempered glass. It is stronger than usual and when broken, it crumbles into small, safe crumbs, rather than sharp fragments. The edge of the glass is processed, and the ends are covered with plastic or metal edging for aesthetics and safety.
Drawers for vegetables and the freezer are made from polypropylene. This material remains elastic even at low temperatures, which prevents it from cracking. Cheap plastic becomes as fragile as glass in the cold, so manufacturers of high-quality equipment use special frost-resistant compositions.
Fittings such as handles, door hinges and guides are made from a combination of metals and durable plastics. Door hinges are a critical element, bearing loads of tens of kilograms. They are made of steel with a zinc coating to resist rust. In expensive models, the hinges may be hidden or have a finishing system (soft-close).
Rubber seals on the doors act as a thermal barrier. They are made from special frost-resistant rubber or thermoplastic elastomer. Their task is to ensure a tight seal between the door and the body. Over time, the rubber may become dull or crack, which will require replacement.
Electronics and control system
It is impossible to imagine a modern refrigerator without electronics. Control board is the brain of the device, which reads temperature sensors and controls the operation of the compressor, fans and heating elements. The boards are located in an area protected from moisture and condensation, often in the upper part of the case or behind a decorative panel.
Temperature sensors (thermistors) are small elements whose resistance changes depending on heat. They are located at different points: in the refrigerator compartment, in the freezer, on the evaporator. The accuracy of their readings determines how stable the temperature will be. In models with the Smart or Wi-Fi function, wireless communication modules are added.
The wiring inside the refrigerator is carried out with wires with insulation that is resistant to low temperatures and oil. Regular PVC insulation cracks in the cold, so a specialized cable is used. All connections are securely insulated, since there is high humidity inside the refrigerator.
| Component | Basic material | Function | Service life (approximate) |
|---|---|---|---|
| Housing | Sheet steel | Protection and load-bearing structure | 15-20 years |
| Compressor | Steel, copper, aluminum | Refrigerant compression | 10-15 years |
| Insulation | Polyurethane foam | Cold preservation | 20+ years |
| Shelves | Tempered glass | Placement of products | Indefinitely (until damaged) |
| Sealant | Rubber/Elastomer | Sealing | 5-7 years |
The variety of materials in one device is dictated by their functional purpose. Engineers must balance cost, efficiency, and durability of each element. Understanding what your refrigerator is made of helps you treat your equipment more carefully.
Frequently asked questions (FAQ)
Why is the outside of the refrigerator warm, but cold inside?
This is a normal physical process. The heat extracted from the food, along with the heat from the compressor, must go somewhere. It is output through a capacitor, which in modern models is often built into the side walls or rear panel. Therefore, the sides can heat up to 40-50 degrees.
What is the gas in the refrigerator made of and is it dangerous?
Modern refrigerators use isobutane (R600a) or tetrafluoroethane (R134a). In small quantities contained in the system (about 50-100 grams), they are not dangerous to humans during normal use. The only danger can be an open fire if the system with isobutane is completely depressurized, since it is flammable.
Is it possible to paint the internal plastic of the refrigerator?
It is strictly not recommended. Regular paints contain solvents that are toxic and will come into contact with products. In addition, the paint can react with the plastic, destroying it, or simply peel off in the cold. To restore color, use special food dyes or simply replace the shelf.
Why are shelves made of glass and not plastic?
Glass conducts cold better, ensuring uniform temperature over the entire surface of the shelf. Plastic is a heat insulator, so food on plastic shelves might not cool as well. In addition, tempered glass can withstand significant weight and is easy to clean.
How long does the polyurethane foam inside the walls last?
The service life of polyurethane foam is practically unlimited and is comparable to the service life of the refrigerator itself. It does not rot, does not dry out and does not lose its properties over time, unless it has been damaged mechanically or has not been exposed to an open fire for a long time.