Many owners of commercial equipment and restaurant business owners often wonder how exactly their equipment functions, ensuring the safety of products. Understanding how a chest refrigerator works is necessary not only for effective use, but also for timely diagnosis of faults. Unlike conventional vertical cabinets, chests have a unique design, where cold air does not “escape” when the lid is opened due to physical laws.
The basic principle is based on the circulation of refrigerant inside a closed circuit, which takes heat from the inner chamber and releases it to the environment. This process is continuous until the thermostat registers that the set temperature has been reached. It is important to note that compressor in such systems it often works in a more intensive mode due to frequent contact with warm air when loading goods.
In this article we will analyze in detail each element of the cooling system, consider the role of different types of refrigerants and explain why chests are considered more energy efficient for storing large volumes products. You will learn about the intricacies of the operation of the evaporator and condenser, as well as how modern control systems optimize energy consumption.
The basic principle of the refrigeration cycle
The foundation for the functioning of any refrigeration equipment, including chests, is a closed cycle of converting the refrigerant from a liquid to a gaseous state and back. The key element here is compressor, which acts as the heart of the entire system. It compresses the freon gas, increasing its pressure and temperature, after which it directs the hot gas to the condenser.
In the condenser, which is usually located on the rear or bottom panel of the device, heat is released into the environment. Passing through the winding tubes, the refrigerant cools and turns into a liquid state. The flow then passes through a filter drier, where residual moisture that can cause clogging of the system is removed and is directed to a capillary tube or thermostatic valve.
What is a capillary tube?
A capillary tube is a long copper tube of very small diameter that serves throttle. It is this that creates the pressure difference between the (high) and bottom (low) circuits of the system, allowing the refrigerant to sharply expand and cool.
When entering the evaporator, which is located inside the chest chamber, the liquid refrigerant expands sharply and boils at very low temperatures. At this moment, active absorption of heat from the internal volume of the chest occurs. After the evaporator, the substance returns to the compressor in the form of gas, and the cycle repeats. This process ensures stable maintenance low temperature inside the chamber.
- 🌡️ The compressor compresses the refrigerant, increasing its temperature and pressure.
- 💧 In the condenser, the gas cools and turns into liquid, releasing heat.
- ❄️ In the evaporator, the liquid boils, actively taking heat from the products.
- 🔄 The cycle is closed by returning the gas to the compressor to repeat the process.
The design of the compressor and its role in the system
The compressor is the most energy-consuming and important component, the serviceability of which determines how the chest refrigerator as a whole works. Modern models most often use sealed piston units, although rotary options are also available. Inside the housing there is an electric motor and a mechanical part, immersed in a special refrigeration oilwhich lubricates the rubbing parts and helps remove heat.
When the thermostat is turned on, voltage is applied to the motor windings, the rotor begins to rotate, driving the piston. The piston, moving up and down, sucks in refrigerant vapor from the evaporator through the suction valve and compresses it, pushing it into the discharge pipe. It is important to understand that the operation of the compressor is designed for certain intervals, and frequent switching on can reduce its resource resource.
The compressor housing is always hot during operation, which is a normal physical process. However, if the temperature becomes extremely high, this may indicate an overload of the system, a dirty condenser, or a ventilation problem. In such cases, it is necessary to check the cleanliness of the radiators and the presence of gaps for air circulation around the unit.
⚠️ Attention: Never try to repair a sealed compressor yourself! There may be high pressure inside, and opening the case without special equipment will lead to irreversible damage to the unit and loss of refrigerant.
Features of the evaporator and defrosting system
The evaporator in chests is a pipeline that can be located around the perimeter of the internal chamber (static system) or hidden behind the back wall (No Frost system, although this is rare for chests). It is on the surface of the evaporator that active cooling of the air occurs. When warm air comes into contact with cold tubes, moisture condenses, which turns into frost or ice.
In static chests, which are most common in trade, defrosting occurs manually. Periodically, when the layer of ice becomes too thick, it begins to act as a heat insulator, interfering with effective heat transfer. In this case, the equipment is turned off and the ice melts naturally. More complex models may use a defrosting system with heating elements that turn on on a timer.
The thickness of the ice crust directly affects how efficiently the chest refrigerator operates. Excessive ice causes the compressor to work longer and harder in an attempt to compensate for the reduced heat output. This leads to excessive energy consumption and accelerated wear of mechanical parts.
To maintain efficiency, it is important to monitor the condition of the lid seals. If the elastic band has lost its elasticity or is damaged, warm moist air constantly enters the chamber, which leads to accelerated formation snow coat on the evaporator.
The role of the thermostat and automation
Responsible for maintaining the set temperature thermostat (thermostat) or, in more modern models, an electronic control unit. A mechanical thermostat is a device with a capillary tube, the end of which is fixed to the evaporator or placed in a chamber. When the temperature inside the tube changes, the pressure of the gas or liquid changes, which leads to the opening or closing of electrical contacts.
Electronic control systems use thermal sensorswhich transmit accurate temperature data to the controller. This allows you to minimize temperature fluctuations and more accurately control the operation of the compressor. In addition, the electronics can monitor operating time and, if necessary, initiate a defrost cycle or signal a malfunction.
Correct setting of the thermostat is critical for the safety of products. A setting that is too low can result in goods freezing and icing, while a setting that is too high can lead to damage to the contents. Commercial chests often use remote thermometers for visual control.
Some models provide protection against restarting. After the compressor switches off, the system waits a few minutes before starting it up again. This is necessary to equalize the pressure in the system and prevent the engine from starting under load, which can lead to its combustion.
Refrigerants: types and impact on the environment
Special gases - refrigerants are used as a working fluid in chest refrigeration. Historically, R12 freon was widely used, but due to its destructive effects on the ozone layer, it was banned. Modern devices operate on ozone-safe substances, such as R134a or hydrocarbon mixtures (R600a), which have excellent thermodynamic properties.
Each type of refrigerant requires the use of a specific type of compressor oil. For example, R134a requires polyester oil (POE), which is very hygroscopic (absorbs moisture). R600a (isobutane) is a flammable gas, so when repairing such systems, strict measures are required Fire safety and the use of non-sparking tools.
| Refrigerant type | Chemical formula | Ozone depletion potential | Application features |
|---|---|---|---|
| R12 | CCl2F2 | High (1.0) | Prohibited, found in old models |
| R134a | CH2FCF3 | Zero (0) | Standard for most modern chests |
| R600a | C4H10 | Zero (0) | Ecologically friendly, but flammable, requires caution |
| R404A | Mixture | Zero (0) | Used in chest freezers for low temperatures |
Refrigerant leakage is one of the most common causes of breakdown. If the chest stops freezing and the compressor runs continuously, the tightness of the circuit is most likely broken. In this case, you need to call a specialist to find a leak, evacuate the system and fill it with a new volume of gas.
Energy efficiency and consumption classes
Since refrigerated chests often operate 24/7, the issue of energy consumption is especially acute. Energy efficiency class is designated by letters from A to G, where A (and A+, A++, A+++) are the most economical models. Energy consumption is influenced by many factors: the quality of insulation, the type of compressor, the presence LED backlights and efficiency of heat exchangers.
The thickness and quality of the thermal insulation layer (usually polyurethane foam) play a decisive role. Good insulation minimizes heat gain from outside, allowing the compressor to turn on less often. The location of the chest is also important: installation near heat sources (batteries, solar side) makes the device work with increased load.
☑️ Checking the energy efficiency of the chest
Regular maintenance helps maintain a high energy efficiency class throughout the entire service life. A dirty condenser can increase energy consumption by 20-30%, as heat transfer deteriorates and the compressor is forced to work longer to achieve the set parameters.
⚠️ Attention: Do not cover the top of the chest or ventilation grilles with cloth or other objects. Impaired air circulation around the condenser leads to overheating and an increase in electricity bills.
Frequent malfunctions and their connection with the device
Understanding how a chest refrigerator works helps to quickly identify the cause of the breakdown. If it's warm inside but the compressor is silent, the problem may be with the thermostat or start relay. If the unit is humming, but there is no cold, there is likely a freon leak or a blockage in the capillary system. Extraneous noise may indicate wear on the compressor bearings or improper installation (the chest is not on a level surface). Vibration can also be transferred to the housing if the inner tubes touch each other. In such cases, careful straightening of the pipelines or replacement of shock-absorbing elements is required. capillary system.
Extraneous noise may indicate wear on the compressor bearings or improper installation (the chest is not on a level surface). Vibration can also be transferred to the housing if the inner tubes touch each other. In such cases, careful straightening of pipelines or replacement of shock-absorbing elements is required.
Sometimes users are faced with a situation where the chest “freezes” the products. This is often due to sticky thermostat contacts or incorrect adjustment. In electronic models, it may be necessary to calibrate the sensors or replace the control board Why does the chest make gurgling sounds?.
Why does the chest make gurgling sounds?
Gurgling is the normal sound of refrigerant flowing through the evaporator tubes and capillary. If the sound is not accompanied by a lack of cold or vibration, there is nothing to worry about. This is a sign that the circulation system is working properly.
Is it possible to transport the chest lying down?
Transportation in a horizontal position is undesirable, since oil from the compressor may leak into the refrigerant circuit. If this happens, it is necessary to let the device stand in a vertical position for at least 2-4 hours before turning it on, so that the oil flows back into the crankcase.
How often should you clean the condenser?
It is recommended to clean the condenser grille from dust and lint at least once every six months. In dusty rooms (for example, warehouses or markets), this procedure should be increased to once a quarter to prevent overheating.
What to do if the lid of the chest does not keep the cold?
First of all, check the integrity of the sealing rubber. If it is torn or petrified, it needs to be replaced. Also make sure that the hinges are not skewed and that the lid fits tightly around the entire perimeter. A temporary solution may be to lay an additional layer of insulation (for example, polystyrene foam) on top of the products.
Is it safe to use an extension cord for a chest?
The use of extension cords is not recommended, especially if they have an insufficient cross-section. This can lead to a voltage drop at the start of the compressor, which causes overheating of the wiring and engine failure. If you cannot do without an extension cord, choose a cable with a power reserve.