A refrigerator is a device that allows for refrigeration. To maintain a system or body at temperatures lower than its surroundings (atmospheric temperature). A system that is kept at a lower temperature than its surrounding environment is called a refrigerated system.
Refrigerator Principle
The principle of thermodynamics cycles is the basis of refrigeration. The thermodynamic cycle is basically a closed cycle where the working substance goes through a series of steps and is then brought back to its initial state. Most commonly, the vapour compression refrigeration system is used for refrigeration. A vapour compression refrigeration system is used to achieve refrigeration. The refrigerant evaporates through the absorption of latent heat from vaporization (storage space), and the liquid refrigerant transforms into vapour.
The compressor’s mechanical energy is the input. These systems are also known as mechanical refrigeration systems. These systems can use a wide range of refrigerants to suit different capacities and applications.
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Construction and working
A refrigerator is made up of many components, including a compressor, condensers, expansion devices, evaporator, and other accessories that allow for proper functioning such as controls (temperature control devices), filters, defrost systems, etc. It is important to match all components according to their function and requirements in order for the refrigerator to work properly. Each component has its own function, so it is important to correctly assemble them all.
Compressor:
The refrigerator’s most crucial component is its compressor. It is essential for the operation of any refrigerator. A compressor is a mechanical device that transfers mechanical energy to work fluids, i.e. refrigerant. The compressor functions in the same way as the heart of the human body. The compressor is responsible for controlling the refrigerant within the whole unit. refrigerant. The compressor draws refrigerant from the evaporator. Its main function is to draw the refrigerant from the evaporator. This allows the compressor to maintain low pressure and temperature in order to extract heat from the refrigerated space. The compressor then raises the temperature and pressure of the refrigerant until it can condense in a condenser.
Condenser:
A refrigeration system’s main component is the condenser. It is a heat exchanger. As mentioned above, the refrigerant is superheated from the compressor when it enters the condenser. The refrigerant is first de-superheated, then it is condensed by rejecting heat from an external medium. The temperature of the outside medium and the design of the condenser may determine whether the refrigerant leaves the condenser as either a saturated liquid or a subcooled liquid. Condenser heats away the refrigerant from the working fluid by cooling copper-coated coils into the same atmosphere as domestic refrigerators. The compressor’s refrigerant is heated to high pressure and is then cooled in the condenser. The expansion devices are filled with refrigerant after it has been condensed.
Condensers are classified based on their external fluid.
- Condenser air-cooled
- Condenser water-cooled
Condenser air-cooled As the name suggests, air is the fluid that acts as a coolant in condensers. The refrigerant is responsible for absorbing heat from the air. The two types of air-cooled condensers are forced convection and natural convection. Natural convection air is naturally circulated, while forced convection requires an external medium such as a fan to ensure proper functioning.
Water-cooled condenser Water is the external fluid in water-cooled condensers Water is used as a cooling fluid to extract heat from the refrigerant.
Throttling/Expansion devices:
Another component of a refrigeration system is the expansion device. An expansion device is used in refrigeration systems to reduce the pressure of the working fluid that comes from the condenser and flows into the evaporator. It regulates refrigerant flow into the evaporator, and maintains a flow rate equal to that of the evaporator. The temperature of the refrigerator can be controlled and maintained by using expansion devices. We can adjust the opening to suit our needs. We require a lower temperature in summer than winter, so the expansion device can be adjusted to suit our needs.
There are two types of expansion devices that can be used in refrigerators: There are two types of expansion devices for refrigerators: fixed opening type and variable open type. Fixed openings have a fixed flow area, while variable openings allow for flow to change with changes in mass flow rates. These are some of the expansion devices that can be used in refrigerators to meet their needs.
- Expander hand (manual)
- Capillary tube
- Orifice
- A constant pressure or an automatic expansion valve (AEV).
- Orifice and capillary tube belong to the fixed-opening type, while the other belongs the variable-opening type.
Evaporator:
It is used to store or freeze food. The throttling device, which is refrigerant, enters the evaporator at very low pressure and temp. The cooling coils cool the refrigerant in an evaporator. The refrigerant heat is absorbed in the evaporator. As the temperature rises, liquid refrigerant evaporates and becomes vapours. After that, the refrigerant goes into the compressor. The heat exchanger that evaporator uses is between cooling coils and storage space. This cycle continues indefinitely.
Refrigerants:
Refrigerator fluids are working fluids that are used in refrigerators. They work in a cyclic manner and help maintain a lower temperature in the evaporator (freezer). The refrigerant is absorbed heat from the storage area and evaporates when it enters the evaporator. This phase change process maximizes the cooling effect. Good refrigerants must be nontoxic, nonexplosive, and non-corrosive. They also need to be leak-free. Different refrigerants can be used depending on their needs. R-12 is used for domestic refrigerators and water coolers.
Temperature controlling devices:
These devices can be used to regulate the temperature of the refrigerator. These devices can be attached to expansion devices. The thermostat attached to the evaporator helps maintain a certain temperature.
Refrigerator Applications
A refrigerator, as we have seen in the above article, is a device that maintains a lower temperature than its surrounding by absorbing heat and releasing it back into the environment. The primary purpose of a refrigerator used to be to produce ice. However, the number of uses for the refrigerator is increasing as new technology improves.
Here are some major uses of the refrigerator:
- The refrigeration of food is essential for preservation and processing.
- The refrigeration is used in industries like the chemical and petroleum industries.
- One special type of application
- Food preservation and processing
Storing fruits and vegetables: Certain perishable foods, such as fruits and vegetables, can rot at high temperatures due to the rapid growth of some bacteria. Low temperatures reduce the growth of bacteria. The refrigerator prolongs the shelf life of fruits or vegetables.
Meat and poultry: Because of the high growth rate of bacteria in meat and poultry, refrigeration is required after slaughter. The temperature for short-term storage should be 0°C. Storage at -25oC is required for long-term storage.
Dairy Products: There are a few dairy products, including butter, milk, curd, and ice cream. Refrigerators are used to store and transport milk. Refrigerators slow down the growth of bacteria and milk can be kept for up to three days after pasteurization. Refrigerators are also required to preserve the quality of dairy products such as butter, curd, and ice cream.
Beverages: Certain beverages, such as beer, wine and soft drinks, taste better when chilled. To preserve their nutritional value and flavor, fruit juices also need refrigeration. Wine making and brewing require refrigeration as well. However, fermentation is exothermic and requires that these processes be performed at a specific temperature. Refrigerators are needed to maintain a desired temperature.
Candy: If you want to preserve chocolate and candy, it needs to be kept in a refrigerator.
Refrigerators are used various Industries
Condensation: By cooling, gases are made liquid. Liquid gases are easy to store and transport. In liquid state gases requires less space.
Preservation: Many compounds can be preserved at room temperature, or they evaporate very quickly like certain drugs, chemicals and explosives. If you use a refrigerator, they can be kept for a long time.
Concrete setting is an exothermic process. Concrete will expand and crack if heat is not removed. You can cool the concrete with water or pass chilled water through the concrete pipes.
Various Other applications of Refrigerator
Ice Manufacture was the most common use of refrigerators. By dipping water containers into chilled brine, ice was made in plants. These plants produce ice on a large scale that can be used in other areas. However, ice can now be made easily by refrigeration. Domestic refrigerators can be used to make ice.
Medical science: Some antibiotics and blood plasma are stored at low temperatures. Other drugs, such as those used in medical science, require lower storage temperatures and can’t be kept at room temperature.