The differences and roles of AHU, DDC, DHU in air conditioning systems
AHU modular air conditioning unit: mainly extracts indoor air (return air) and some fresh air to control the outlet temperature and air volume and maintain indoor temperature.
PAU pre cooling air conditioning unit: The Primary Air Unit preprocesses outdoor fresh air and sends it to the Fan Coil Unit (FCU).
RCU（Recycled Circulating air conditioning unit.
MAU brand new fan unit: It is an air conditioning device that provides fresh air. Functionally, it can achieve constant temperature and humidity or simply provide fresh air according to the requirements of the usage environment. The working principle is to extract fresh air outdoors, which is then treated with dust removal, dehumidification (or humidification), cooling (or heating), and sent indoors through a fan. When entering the indoor space, it replaces the original indoor air. Of course, the functions mentioned above need to be determined according to the requirements of the usage environment, and the more complete the functions, the higher the cost.
DCC dry cooling coil (referred to as dry coil or dry cooling coil): It is used to eliminate sensible heat indoors
Direct Digital Control
HEPA, meaning high-efficiency filter in Chinese, is a filter that meets the HEPA standard and has an effective rate of 99.998% for 0.1 microns and 0.3 microns. The characteristic of HEPA is that air can pass through, but small particles cannot pass through. It can achieve a removal efficiency of over 99.7% for particles with a diameter of 0.3 microns (hair diameter 1/200) or more, including smoke, dust, and fine particles
The most effective filtering medium for pollutants such as bacteria. The smoke particles produced by smoking have a diameter of 0.5 microns and are internationally recognized as highly efficient filtering materials. Widely used in high cleanliness places such as operating rooms, animal laboratories, crystal experiments, and aviation.
FCU fan coil unit: Fan Control Unit is the terminal device of the air conditioning system. Its working principle is to continuously circulate the air in the room inside the unit, so that the air is cooled (heated) after passing through the cold water (hot water) coil to maintain a constant room temperature. Mainly relying on the forced action of the fan, the air is heated when passing through the surface of the heater, thus strengthening the convective heat exchanger between the radiator and the air, which can quickly heat the air in the room.
Control principle of VAV variable air volume air conditioning system: The variable air volume controller and room temperature controller together form indoor cascade control, using indoor temperature as the main control variable and air flow as the auxiliary control variable. The variable air volume controller compares the actual temperature detected by the room temperature sensor with the set temperature, outputs an adjustment signal for the required air volume, adjusts the air valve at the end of the variable air volume, changes the air supply volume, and maintains the indoor temperature within the set range. At the same time, the air duct pressure sensor detects the pressure changes inside the air duct, uses PI or PID regulation, and controls the speed of the variable air volume air conditioning fan through a frequency converter to eliminate the influence of pressure fluctuations and maintain the air supply volume.
DHU means "low humidity air conditioning unit" in Chinese. Low humidity air conditioning unit is an efficient and fast air dehumidification equipment, mainly composed of a dehumidification wheel group, a regeneration heating system, a processing fan, a regeneration fan, front and rear surface coolers, an electrical control cabinet, and a box structure unit. The box material adopts a double-layer coated colored template, and the compartment is filled with polyurethane foam insulation material, which can effectively prevent the interference of external air temperature and humidity.
FFUFan Filter Units "means" fan filter units (units) "in Chinese. That is to say, the fan and filter (HEPA or ULPA) are combined together to form a self powered end purification device. More precisely, it is a modular end air supply device with built-in power and filtering function. The fan sucks in air from the top of the FFU and filters it through HEPA. The filtered clean air is evenly sent out at a wind speed of 0.45m/s ± 20% on the entire outlet surface.
Suzhou Pharma Machinery Co.,Ltd.
2025/05/26
Gino
