Refrigeration system diagram, structure and detailed operating principle

Refrigeration system diagram is an important factor in the design and operation of industrial and commercial refrigeration systems. Understanding and correctly applying this diagram not only helps to optimize refrigeration performance but also ensures safety and durability for the entire system. Let's Tan Long Learn more about the refrigeration system schematic diagram in the article below!

What is industrial refrigeration system?

Before learning about refrigeration system diagram Then let's think with Tan Long industrial refrigeration system What is it. Industrial refrigeration is a method of cooling and refrigerating over a large area, capable of reducing the temperature to the lowest level. This system utilizes the energy from the moisture in the air to evaporate, creating a cold air flow.

The equipment required for an industrial refrigeration system includes an evaporator, condenser, compressor and control equipment. In addition, depending on specific needs, this system can use additional equipment such as a cooling tower.

Industrial refrigeration system
Industrial refrigeration system

Uses of industrial refrigeration systems

Industrial refrigeration systems are widely used in many fields due to their high applicability. Users can apply this system in the refrigeration, air conditioning, refrigeration systems and chemical industries. 

In addition, industrial cooling systems also ensure that food stays fresh for a long time. They are capable of cooling large areas such as restaurants and hotels, where household air conditioners cannot meet the requirements.

Advantages of industrial refrigeration systems

Industrial refrigeration systems today have many types of machines with outstanding uses and advantages, becoming the ideal choice for many different industries and applications.

  • High load capacity: The system can handle loads from 5 tons to several thousand tons, suitable for large-scale projects thanks to its durability and stability.
  • Multi-stage offload function: Equipped with power adjustment capability with 3-5 unloading levels, making the system operate more flexibly and efficiently.
  • Compact design: The cold water pipe is compactly designed, convenient for use in buildings and small piping systems.
  • Space saving: The system prioritizes saving installation space, avoiding the need to install multiple separate devices in each area.
  • High flexibility: The system allows for easy expansion of the cooling surface and can be upgraded to larger capacities without the need for additional new equipment.
Advantages of industrial refrigeration systems
Advantages of industrial refrigeration systems

Industrial refrigeration system diagram

Each refrigeration system typically uses only one controller and control panel to simplify operation. Refrigeration system diagram will include refrigeration compressor, condenser, condensers, cooling towers, separators, cold storage and cooling pumps.

Refrigeration system diagram details
Refrigeration system diagram details

According to refrigeration system diagram Primary compressor, refrigerant is compressed and circulated in 4 steps: Compressor, evaporator (cold coil), battery, condenser (hot coil).

First, the refrigerant vapor coming out of the coil is sucked into the compressor, compressed into high temperature and high pressure vapor and then enters the condenser. At this time, the high pressure vapor is cooled in the refrigerant and condensed into high pressure liquid in the state of saturated steam, non-boiling liquid or boiling liquid, then transported to the device.

In the expansion device, the high-pressure liquid is pressurized and cooled to a low-pressure liquid before entering the evaporator. In the condenser, the refrigerant receives heat from the surrounding environment, is cooled, evaporates, and is drawn into the compressor. And so on, the cycle repeats the above process.

Operating principle of refrigeration system

From refrigeration system diagram, scientists have applied it to the design of specific devices such as cold storage system, vapor compression air conditioners, chillers and many other devices. The process of creating a cold environment is usually done through the following two common ways:

  • Using phase change method for cooling: When the phase changes from one state to another, the matter absorbs some heat, which is called the heat of phase transition. Air conditioners based on this principle have been developed and are widely used today. In this process, the liquid gas changes into vapor in the evaporator, absorbing heat from the surrounding environment.
  • Sudden pressure drop of high pressure gas stream: Either an expander or a valve can be used to accomplish this process. With an expander, work is used to compensate for energy. With a valve, throttling is performed to suddenly reduce the pressure, making the air flow colder without adding any additional power. Once the pressure has been reduced, the air source becomes colder.
Operating principle of refrigeration system - Refrigeration system diagram
Operating principle of refrigeration system – Refrigeration system diagram

Refrigeration system operation and maintenance manual

Besides knowing refrigeration system diagram Along with its operating principles, you also need to know how to operate and maintain this system. 

Temperature controller

Check the setting values
  • Press the (▲) button to display the upper limit temperature value.
  • Press the (▼) button to display the lower limit temperature value.
  • Press the “Set” button to display the defrost cycle.
  • Press the “Rst” button to display the defrost time.
Change the setting valuesHold the “Set” button for 3 seconds to enter the Menu. 

In the Menu there are 6 items from F1 to F6. Use the (▼) or (▲) button to move to these items.

Settings items
  • F1: Upper temperature limit (°C) – Default: -10°C
  • F2: Lower temperature limit (°C) – Default: -20°C
  • F3: Calibration Degree (°C) – Default: 0°C
  • F4: Defrost cycle (hours) – Default: 8 hours
  • F5: Defrost time (minutes) – Default: 20 minutes
  • F6: Warning temperature (°C) – Default: 20°C
Perform the installationMove to the item whose value you want to change, hold the “Set” button to display the value of that item. Use the (▲) or (▼) button to change the setting value. Always hold the “Set” button when changing the value.

For example: To adjust F1 to 2°C, perform the following operations:

  • Hold the 'Set' button for at least 3 seconds, the screen will display 'F1'.
  • Press 'Set' to start adjusting parameters in F1.
  • Hold the 'Set' button and press (▲) or (▼) to adjust the temperature.
  • When reaching 2°C, press 'Rst' key to save settings or wait 30s for the system to save automatically.

Set the remaining parameters the same as above.

Attention: When the cold storage runs at a temperature of 15°C to 18°C, the defrost function will not be needed, the F5 value will be set to 0.

Refrigeration system operation

Prepare to run the machine

Step 1: Check the voltage of the grid with a voltmeter. If the voltage differs by ±10% from the rated voltage, do not start the machine because it can easily cause problems. Then continue to check the electrical phases for motors using three-phase voltage. Absolutely do not start the machine when the phase is lost because it is very dangerous.

Step 2: Check the electrical control cabinet to determine the condition of electrical devices and appliances such as meters, light bulbs and switches to know the current status of the equipment.

  • Identify devices that are active or inactive.
  • Check the equipment parameters (machine running hours, room temperature, etc.).
  • Check the operating status of automatic devices.

Step 3: Check the compressor lubricating oil level through the oil level indicator. If the oil level is at 3/4 of the oil sight glass, the compressor has enough oil. If it is below 3/4 of the oil sight glass, oil needs to be added before starting the machine.

Step 4: Check the condition of valves on the pipeline leading to the equipment. Open and close necessary valves during machine operation. Make sure the compressor stop valves are fully open before starting the compressor.

Start the machine

The electrical cabinet system is designed to operate fully automatically, with the start-up sequence pre-set by the designer. This automatic mode helps to limit operator errors and ensure high accuracy. The automatic operation steps (AUTO) are as follows:

  • Turn on the main circuit breaker of the power and control cabinets and of all devices in the system that need to run.
  • Turn the device run switches to AUTO mode.
  • Press the START button to start the system. The devices will start in the preset sequence.
  • Open the compressor suction stop valve slowly. Opening it too quickly can cause flooding and opening it too large can cause high motor current to over-current the machine, causing damage.
  • Listen to the machine. If there is an unusual noise or a lot of mist on the suction head, stop the machine immediately. 
  • Monitor the compressor current, make sure it is not too high compared to the regulation. If the current is too high, adjust by closing the suction valve or reducing the load manually. In the initial stage of the star circuit, the system always reduces the load but this stage is very short.
  • Observe the condition of snow accumulation on the compressor body. If there is too much snow accumulation, close the suction stop valve and continue monitoring.
  • Check system pressure: Normal condensing pressure is Pk ≤ 16kg/cm², while suction pressure is in the range Ph = (2.5 ÷ 3) kg/cm².
  • Record all system operating parameters every hour, including: suction pressure, discharge pressure, oil pressure, suction gas temperature, discharge temperature, oil temperature, and stable machine running current.

Stop the compressor

Normal compressor stop
  • Turn off all the switches supplying liquid to the evaporator.
  • When the suction pressure is lower than the evaporation pressure, press the STOP button to stop the machine or wait for the low pressure (LP) relay to automatically stop the machine.
  • Turn off the circuit breaker of the devices.
  • Close the electrical cabinet door.
Stop the compressor in case of failure
  • Press the STOP button to stop the machine.
  • Turn off the main circuit breaker of the electrical cabinet.
  • Quickly find out the cause and find a way to fix the problem.

Note: For pressure related problems, after handling, press the RESET button on the electrical cabinet to restore and run the system again.

Long downtime 
  • Drain the refrigerant from the evaporator and transfer it to the high pressure tank. Repeat this process several times to ensure effectiveness.
  • After stopping the machine, turn off the power circuit breaker and lock the electrical cabinet.

Through the above article, you have grasped refrigeration system diagram is it like that or not?

Thus, the article has provided a comprehensive view of refrigeration system diagram, operating principles and practical applications. Hopefully the useful information that Tan Long provides will help you expand your knowledge and better understand this field.

Read more: What Parts Does a Cold Storage Electrical Circuit Diagram Include?

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