DX Coil in AHU

Dx coil in ahu

DX coil (Direct Expansion coil) in an AHU (Air Handling Unit) is a type of evaporator coil that is commonly used in air conditioning systems. The DX coil is responsible for cooling the air that is passed over it by using a refrigerant to absorb heat from the air.

The AHU draws in air from the building, passes it over the DX coil, and then delivers the cooled air back into the building. The refrigerant inside the DX coil absorbs heat from the air, which causes it to evaporate and turn into a gas. The gas is then compressed by a compressor, which raises its temperature and pressure. The hot, high-pressure gas is then passed through a condenser coil, where it gives off heat and turns back into a liquid.

The liquid refrigerant is then passed back through the DX coil to repeat the cooling cycle. The DX coil is typically made of copper or aluminum tubing and is designed to provide efficient heat transfer between the refrigerant and the air.

The DX coil is an essential component of an AHU and plays a critical role in maintaining comfortable temperatures and air quality in a building.

DX coils are commonly used in commercial HVAC systems, particularly in buildings that require precise temperature control, such as hospitals, laboratories, and data centers.

DX coils can be designed to operate with various refrigerants, including R-22, R-410A, and R-134a. However, as of 2021, the use of R-22 refrigerant has been phased out in many countries due to its ozone-depleting properties.

The size and capacity of a DX coil depend on several factors, such as the required cooling load, the airflow rate, and the refrigerant type and pressure. Proper sizing and selection of the DX coil are critical to ensure efficient and reliable operation of the HVAC system.

The performance of a DX coil can be affected by various factors, such as the cleanliness of the coil surface, the airflow rate and direction, and the refrigerant charge level. Regular maintenance, such as cleaning and inspection, is necessary to maintain the DX coil's performance and prevent issues such as freezing or reduced efficiency.

In some cases, a DX coil may be combined with other types of coils, such as a heating coil or a heat recovery coil, to provide additional functionality and energy savings. For example, a heat recovery coil can recover waste heat from exhaust air and use it to preheat incoming fresh air, reducing the HVAC system's energy consumption.