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How Does the Refrigeration Equipment Operate?
Commercial refrigeration equipment is one of the most common types of commercial kitchen equipment, and knowing how they operate can help us understand them better, and is important for maintenance and repair. As a commercial kitchen equipment manufacturer with extensive experience, Chefmax shares this article to provide an in-depth analysis of the operating principles of refrigeration equipment.
Table of Contents
1. Which components make up the refrigeration system?
A. Compressor
The compressor is a kind of machinery that raises the low-pressure gas to high-pressure gas, and is the heart of the refrigeration system.
It draws in low temperature and low pressure refrigerant gas from the suction pipe, compresses it by running the motor, and then discharges the high temperature and high pressure refrigerant gas to the pipe to provide power for the refrigeration cycle.
There are five major types of compressors used in the refrigeration industry: reciprocating, screw, rotary, scroll and centrifugal, of which the reciprocating type is the most used compressor in small and medium-sized commercial refrigeration systems.
B. Condenser
Condenser can convert gas or steam into liquid and transfer the heat from the tube to the nearby air. It is mainly divided into water-cooled and air-cooled models according to the form of cooling.
Water-cooled models use cooling water to carry away heat, and the cooling water can either flow through at once or be recycled.
The air-cooled model cools down by air, and it mainly uses several groups of copper (aluminum and iron will also be used) tubes to form, while using fans to accelerate the air flow and cooling effect.
C. Expansion valve
The expansion valve is usually installed between the liquid storage tank and the evaporator, so that the medium temperature and high pressure liquid refrigerant becomes low temperature and low pressure wet steam through its throttling, and then the refrigerant absorbs heat in the evaporator to achieve the refrigeration effect, and the expansion valve controls the valve flow through the change of super-heat at the end of the evaporator. Small refrigeration equipment will use to capillary tube to replace.
D. Evaporator
Evaporator is a very important part of the four major components of refrigeration, low-temperature condensing liquid through the evaporator, and the outside air for heat exchange, gasification and heat absorption, to achieve the effect of refrigeration. The evaporator is mainly composed of two parts: the heating chamber and the evaporation chamber.
The air-cooled model uses finned evaporator, and the wind direct-cooled and direct-cooled type uses coil evaporator, which is made of iron and copper. The fin spacing is about 4mm for refrigerated models and about 6mm for frozen.
Other detail accessories:
Drying filter
It mainly plays the role of filtering impurities, with coarse metal mesh at the inlet end and fine metal mesh at the outlet end, containing desiccant to absorb moisture and impurities in the refrigerant to ensure the capillary tube is smooth and the refrigeration system works normally.
Solenoid valve
Solenoid valve mainly plays the role of defrosting, through electromagnetic induction to control the high-pressure gas flowing into the sub-condenser (evaporator) from the high-pressure tube in the compressor, to achieve the purpose of defrosting the evaporator and ensure the continuous and stable operation of the system. It can be replaced by the frost pipe.
Refrigerant
Refrigerant is placed in the reservoir of the refrigeration equipment system and is a substance that can condense and liquefy under pressure and evaporate under pressure to absorb heat.
The refrigerants commonly used in commercial refrigeration equipment are R134A, R404A, R600a, R290, etc. The refrigerant R290 is environmentally friendly and is a natural hydrocarbon refrigerant that can be obtained directly from liquefied gas. Compared with Freon, a synthetic refrigerant, R290 does not contain chlorine atoms in its molecules and has no destructive effect on the ozone layer.
2. Four steps of refrigeration equipment work
When working, the gaseous refrigerant is compressed into high temperature and high pressure gas through the compressor, and then enters the condenser, which is equivalent to a heat exchange equipment, and the high temperature and high pressure gaseous refrigerant is heat exchanged into the low temperature and high pressure liquid refrigerant.
Liquid refrigerant then through the expansion valve, the so-called expansion valve is a throttling device, because the refrigerant out of the expansion valve is curbed, so out of the refrigerant pressure decreases, the temperature continues to fall, (the refrigerator expansion valve is generally used instead of capillary tube, because from the large tube suddenly to the small tube, the same can play the effect of throttling) into the gas-liquid two-phase, and then into the evaporator.
At this time the refrigerant then evaporator for heat exchange gasification, become high temperature low pressure gaseous refrigerant back to the refrigeration equipment compressor to continue the cycle.
A. Compression
Refrigerant is easy to be liquefied at room temperature. The refrigerant evaporates into low temperature and low pressure vapor by heat absorption in the evaporator, and in order to make the refrigerant vapor into high temperature and high pressure vapor, which is easy to liquefy at room temperature, it must be compressed by the compressor.
The compressed high-temperature and high-pressure vapor is then transported to the room temperature environment for liquefaction through the pipeline.
B. Condensation
After compression of high-temperature and high-pressure refrigeration vapor in the condenser by the air (or cooling water) cooling heat released and condensed into a liquid. The premise of the refrigerant to produce refrigeration effect from the liquid into a gas, so the role of condensation is very important.
C. Expansion
After the refrigerant is liquefied, it is first expanded by throttling, so that the pressure is reduced and the flow rate is adjusted and then enters the evaporator. After condensing the high-pressure liquid in the expansion valve, the pressure suddenly drops, the liquid expands sharply, thus transforming into a low temperature and low pressure mist into the evaporator.
According to the requirements of refrigeration temperature, the flow rate can be adjusted so as to control the evaporation temperature in the required range of stability.
D. Evaporation
Here the refrigerant absorbs heat and evaporates to become gas. After the expansion of the fog refrigerant into the evaporator, it absorbs heat and vaporizes, so that the surrounding temperature drops within the required low temperature range, thus achieving the purpose of refrigeration.
3. The difference between direct cooling and air cooling types
Direct cooling model is also known as the natural convection model of cold air. Refrigeration equipment refrigeration room has an evaporator, the size of the evaporator is based on the size of the room and temperature requirements to a reasonable ratio, the cooling method is through the natural convection of cold air to cool the food.
The air-cooled model is equipped with a finned evaporator and a set of duct circulation components. The fan motor will form an up-and-down circulation of the air inside the chamber after cooling through the evaporator to achieve the purpose of refrigeration.
Features of the direct cooling model:
• Low noise level
• Lack of components such as fans, the price is usually lower
• Natural convection, uneven temperature
• Low power consumption
• Tends to frost on the inside of the storage wall, requiring manual defrosting
Characteristics of air-cooled models:
• Noise from extra fans
• Higher price
• Convection circulation of cold air for uniform cooling
• Higher power consumption
• Air-cooled model of cold air flow will not absorb water from the food, so the air-cooled model is also called frost-free model. This frost-free is only the inner wall surface without frost, the evaporator surface will still frost, but without manual defrost but automatic defrost
4. Summary
Although there will be differences in equipment size and refrigerant type, the nature of operation of all commercial refrigeration equipment is the same, and after reading this article, you can understand all refrigeration equipment by understanding the simple refrigeration cycle. If you have any suggestions or comments, or need more specialized information, please contact Chefmax and we would be glad to discuss it with you.