What temperature will the air from a screw compressor reach after passing through an air dryer?

Principle of Temperature Change After Treatment by a Refrigerant Dryer

The compressed air discharged from a screw-type box‑type air compressor typically has high temperature and humidity. When this hot air enters a refrigerated air dryer (commonly referred to as a cold dryer), it undergoes forced cooling via the refrigeration system. During this process, the reduction in air temperature serves two primary purposes: first, to condense the gaseous moisture in the air into liquid water for removal; and second, to lower the final outlet temperature of the gas.

Core temperature indicators: pressure dew point and outlet temperature

To accurately determine the temperature of gas after it has passed through a refrigerant dryer, it is necessary to distinguish between two key temperature concepts:

• Pressure dew point temperature: This is the key metric for evaluating the dehumidification performance of a refrigerant dryer. The pressure dew point temperature of conventional refrigerant dryers is typically designed to be around2°C to 10°CWithin this temperature range, the water vapor in the compressed air will condense extensively into liquid droplets and be discharged from the system via an automatic drain.
• Final outlet temperature: The cold air, which has been cooled by the evaporator to near the dew point temperature, passes through a regenerator (an air-to-air heat exchanger) before exiting the refrigerant dryer. Here, it exchanges heat with the high‑temperature, humid air that has just entered the dryer. As a result, the temperature of the exhaust air rises slightly. Under normal operating conditions, the final outlet temperature of the refrigerant dryer is approximately20℃ to 40℃Between.

Key factors affecting the final exhaust gas temperature

The specific outlet temperature of a refrigerant dryer is not a fixed value; rather, it is influenced by a variety of actual operating conditions.

• Cooling methodThe outlet temperature of an air-cooled refrigerant dryer is typically 5°C to 10°C higher than the ambient temperature, while the outlet temperature of a water-cooled refrigerant dryer is 5°C to 10°C above the inlet temperature of the cooling water.
• Intake conditionsIf the initial temperature of the compressed air entering the refrigerant dryer is too high, or if the air flow rate exceeds the dryer’s rated capacity, heat exchange will be inadequate, resulting in a higher-than‑expected outlet temperature.
• Equipment Operating Status: A dirty or blocked condenser, insufficient refrigerant, or a decline in the heat exchanger’s efficiency will all directly affect the cooling performance and the final gas outlet temperature.

Precautions for Temperature Control

In practical industrial applications, the temperature of compressed air at the outlet of a refrigerated dryer is not necessarily better the lower it is. If the evaporator temperature is set too low—below 0°C—the moisture condensed on the evaporator surface can freeze, blocking the airflow and thereby reducing drying efficiency or even damaging the equipment. Therefore, maintaining the pressure dew point above 2°C while ensuring an appropriate outlet temperature is essential for stable system operation. Regularly cleaning the condenser and monitoring refrigerant pressure are fundamental maintenance tasks that help sustain the dryer’s optimal temperature performance.