Overview of the working process of the refrigerated dryer

The refrigerated dryer is a widely used equipment in the industrial field, mainly used for drying compressed air. It removes moisture from the compressed air through the combination of refrigeration cycle and compressed air process to achieve the purpose of drying. The following is a detailed overview of the working process of the refrigerated dryer. If there are any inappropriate parts, please criticize and correct them.

1. Basic composition of the refrigerated dryer

The refrigerated dryer is mainly composed of the following key components:

1. Refrigeration compressor: The refrigeration compressor is the core component of the refrigeration system, responsible for compressing and transporting refrigerant vapor. In the refrigerated dryer, the refrigeration compressor usually adopts a fully sealed reciprocating compressor or a screw compressor, which has the characteristics of large refrigeration power and stable operation.
2. Condenser: The condenser is an important component for converting the refrigerant from gas to liquid. It uses materials such as copper tubes and aluminum foil to force heat exchange between the refrigerant and air or cooling water to reduce the temperature of the refrigerant, thereby achieving condensation.
3. Evaporator: The evaporator is the main heat exchange component in the refrigerated dryer. The liquid low-temperature refrigerant exchanges heat with the compressed air being processed through the evaporator, so that the compressed air is forced to cool, and most of the water vapor condenses into liquid water and is discharged outside the machine, thereby achieving the purpose of drying.
4. Precooler: The precooler plays the role of recovering cold in the refrigerated dryer. It uses the cold carried by the compressed air cooled by the evaporator to cool the high-temperature compressed air carrying a large amount of water vapor, thereby reducing the heat load of the refrigeration system and reducing energy consumption.
5. Throttling mechanism: The liquid refrigerant passing through the throttling device changes from high temperature and high pressure to low temperature and low pressure and enters the evaporator. Common throttling devices include expansion valves, capillaries, etc.
6. Hot gas bypass valve: The hot gas bypass valve is used to control the temperature of the evaporator to prevent the refrigerant evaporation temperature from being too low to cause freezing. When the evaporation pressure drops to a certain level, in order to prevent ice blockage; the hot gas bypass valve opens, and the high-temperature and high-pressure gas enters the evaporator to maintain the temperature of the evaporator heat exchange surface not lower than the freezing point.
7. Gas-water separator: The gas-water separator is used to separate the precipitated liquid water to ensure that only dry air is discharged from the dryer.
8. Dry filter: The dry filter is used to remove moisture and impurities in the refrigeration system to ensure the stable operation of the system.
9. Working process of refrigerated dryer

The working process of refrigerated dryer can be divided into two system processes: compressed air process and refrigeration cycle process.

1.Compressed air process

(1) Precooling: The compressed air entering the dryer first enters the precooler and exchanges heat with the low-temperature cold air leaving the evaporator to reduce the temperature and water content. The pressure dew point of the precooled compressed air has been reduced, but it is not dry enough.

(2) Evaporation: The precooled compressed air then enters the evaporator and exchanges heat with the refrigerant. The temperature of the compressed air continues to drop to the dew point. At the outlet of the evaporator, the temperature of the compressed air reaches the required pressure dew point, and most of the water vapor condenses into liquid water.

(3) Gas-water separation: The gas-water mixture leaving the evaporator enters the gas-water separator, and the separated water is discharged through the electronic drain. After that, the compressed air enters the precooler and exchanges heat with the hot air entering the dryer. After the temperature rises, it is discharged from the dryer.

2. Refrigeration cycle process

(1) Compression: The refrigeration compressor discharges high-temperature and high-pressure gaseous refrigerant into the condenser.

(2) Condensation: In the condenser, the refrigerant gas passes through copper tubes, aluminum foil and other materials to force heat exchange with air or cooling water, releases heat, and the refrigerant condenses into liquid.

(3) Throttling: The liquid refrigerant leaving the condenser passes through a dry filter and then through a throttle mechanism to reduce pressure and cool, becoming a low-temperature gas-liquid two-phase state.

(4) Evaporation: The low-temperature gas-liquid two-phase refrigerant enters the evaporator and exchanges heat with the compressed air being treated. In the evaporator, the refrigerant vaporizes, absorbs the surrounding heat, reduces the temperature of the compressed air, and condenses the water into liquid water.

(5) Gas-liquid separation: The gaseous refrigerant leaves the evaporator and flows through the gas-liquid separator to achieve gas-liquid separation, preventing the liquid refrigerant from entering the compressor and causing liquid hammer.

(6) Hot gas bypass: In order to ensure that the temperature of the evaporator is not lower than 0℃ and prevent freezing, a hot gas bypass valve is set.

III. Market application and characteristics of refrigerated dryers

Refrigerated dryers have become one of the basic configurations of compressed air drying and purification systems, and are widely used in pneumatic tools, instruments, dust removal and other scenarios. Its characteristics include:

1. High efficiency and energy saving: The precooler recovers cold energy to reduce energy consumption; the hot gas bypass valve controls the evaporation temperature to prevent freezing and improve energy efficiency.
2. Stable and reliable: The refrigeration system uses a fully sealed reciprocating compressor or a screw compressor, which operates stably; the drying filter removes moisture and impurities to ensure stable operation of the system.
3. Easy operation: The degree of automation is high and the operation is simple; a drain valve and a drain device are provided for easy drainage.
4. Strong adaptability: Different models and specifications can be selected according to different needs; it can be used to treat non-air media, such as carbon dioxide and hydrogen.

The refrigerated dryer realizes the drying of compressed air by combining the refrigeration cycle and the compressed air process. Its workflow includes two system processes: compressed air process and refrigeration cycle process. Through precooling, evaporation, gas-water separation and other steps, the moisture in the compressed air is removed to achieve the purpose of drying. The refrigerated dryer has the characteristics of high efficiency and energy saving, stability and reliability, easy operation, and strong adaptability. It is widely used in pneumatic tools, instruments, dust removal and other scenarios. When selecting and using it, it is necessary to select the appropriate model and specifications according to actual needs, and pay attention to the maintenance and maintenance of the system to ensure its normal operation and extend its service life.