In the fields of modern industrial production and scientific research, cleanrooms play an extremely crucial role. To ensure a stable and excellent environmental quality within cleanrooms, the MAU + FFU + DCC system has emerged and become the mainstream air purification solution. This article will explore in depth the control technologies of this system, taking you to understand how it precisely functions in cleanrooms to create an ideal clean space.
I. Overview of the MAU + FFU + DCC System
The MAU (Make-up Air Unit), as the "pioneer of air pretreatment" in the system, undertakes the important tasks of introducing fresh air from the outdoors and performing a series of treatments on it, such as filtering, heating, cooling, humidifying, and dehumidifying. Its aim is to provide fresh air that initially meets the standards of temperature, humidity, and cleanliness for the cleanroom. The FFU (Fan Filter Unit) is like the "air purification elf" in the workshop. It conducts fine filtering of the air through high-efficiency filters to ensure that the air cleanliness in specific areas within the workshop reaches an extremely high standard. Moreover, it can be flexibly combined and distributed, and can be customized according to the purification requirements of different areas. The DCC (Dry Cooling Coil) is like the "master of fine-tuning temperature and humidity". It is mainly responsible for assisting in the temperature adjustment of the air, especially playing a key role in sensible heat control. Working together with the MAU and FFU, it maintains the precise balance of temperature and humidity in the workshop. These three components complement each other and build a complete and efficient air purification and environmental control system for cleanrooms.
II. Key Points of System Control
(I) Temperature Control Strategies
The MAU uses advanced PID control algorithms based on the set temperature value and the actual feedback value in the workshop to precisely adjust the water flow or refrigerant flow of the cooling or heating coils, thus achieving precise control of the fresh air temperature. Although the FFU itself does not directly dominate temperature control, since the air volume of the FFU will affect the air distribution in the workshop and thus indirectly affect the temperature distribution, during the system commissioning and operation, it is necessary to reasonably set and optimize the air volume of the FFU. The DCC further cools or heats the air by adjusting the chilled water flow according to the changes in the sensible heat load in the workshop to ensure the uniformity and stability of the temperature in the workshop. For example, in some semiconductor manufacturing cleanrooms with extremely high requirements for temperature control, the coordinated temperature control among the MAU, FFU, and DCC can strictly limit the temperature fluctuation range within a very small range in the workshop, ensuring that the production process is not interfered by temperature changes.
(II) Key Points of Humidity Control
The humidification and dehumidification modules in the MAU automatically switch working modes and adjust the humidification or dehumidification amount according to the set humidity and the actual humidity in the workshop. Common humidification methods include steam humidification and electrode humidification, while dehumidification methods include condensation dehumidification and rotary dehumidification. Since the FFU does not significantly change the air humidity during the filtering process, it mainly cooperates with the overall air circulation to ensure humidity uniformity. In pharmaceutical cleanrooms, precise humidity control is crucial for the stability of drug quality. The MAU, in conjunction with humidity sensors, monitors and adjusts the humidity in real time. Cooperating with the air distribution in the workshop, it keeps the humidity in the entire workshop within the specific range suitable for drug production all the time, creating an ideal humidity environment for drug production.
(III) Core of Cleanliness Control
The primary and medium-efficiency filters in the MAU intercept larger particulate pollutants in the fresh air, laying the foundation for subsequent air purification. The high-efficiency filters (HEPA or ULPA) equipped with the FFU are the key to achieving high cleanliness standards. They have extremely high filtering efficiencies for tiny particulate pollutants such as dust particles and microorganisms, enabling the cleanroom to meet the corresponding cleanliness level requirements, such as ISO 5 level, ISO 6 level, etc. Meanwhile, the uniform distribution and stable operation of the FFU play a decisive role in ensuring the uniformity of cleanliness throughout the workshop. In the cleanrooms for electronic chip manufacturing, the high-efficiency filtering and reasonable layout of the FFU can effectively prevent dust particles from contaminating the chip production process, greatly improving the yield of chips.
(IV) Key to Pressure Control
By installing pressure sensors in different areas of the cleanroom, the MAU, combined with variable frequency fan technology, adjusts the fresh air supply volume according to the pressure difference feedback to maintain the stability of the pressure gradient between different areas. For example, a positive pressure is maintained between the clean area and the non-clean area to prevent the intrusion of polluted air from the outside. An appropriate pressure difference is also set between areas with different cleanliness levels to ensure that the air in the high-cleanliness area does not flow to the low-cleanliness area. This pressure control mechanism is crucial for protecting the key production processes and products in the cleanroom from external pollution.
III. Application of Intelligent Control Technologies in the System
With the continuous progress of science and technology, intelligent control technologies have been widely applied in the MAU + FFU + DCC system. By adopting PLC (Programmable Logic Controller) or DCS (Distributed Control System), centralized monitoring and intelligent management of the entire system can be achieved. Operators can intuitively understand the operating status and parameter information of each device in the system through the Human-Machine Interface (HMI) in the central control room and conduct remote control and parameter adjustments. Meanwhile, the intelligent control system can also automatically make adaptive adjustments to various working condition changes during the system operation according to the preset control strategies and algorithms. For example, when the production equipment in the workshop is turned on or off, resulting in changes in heat load, moisture load, or the amount of particulate pollutants generated, the system can quickly sense and automatically adjust the operating parameters of the MAU, FFU, and DCC to maintain the stability of the environmental parameters in the workshop. In addition, the intelligent control system also has the functions of fault diagnosis and alarm, which can timely detect potential faults of system equipment and notify relevant personnel for maintenance through sound and light alarms, greatly improving the reliability and stability of the system.
IV. System Commissioning and Optimization
The commissioning of the MAU + FFU + DCC system is a crucial link to ensure its performance meets the standards. During the commissioning process, it is first necessary to conduct individual equipment commissioning to check whether the mechanical performance, electrical performance, and control functions of each equipment are normal. For example, conduct speed tests on the fans of the MAU, pressure difference tests on the filters, check the fan speed, air volume, and filter integrity of the FFU, and verify the water flow adjustment performance of the DCC, etc. After the individual equipment commissioning is qualified, the system linkage commissioning is carried out. By simulating different working condition conditions, such as different temperature and humidity set values and different production load situations, the control effects of the system on temperature, humidity, cleanliness, and pressure are tested and adjusted. During the commissioning process, it is necessary to use professional testing instruments, such as temperature and humidity sensors, dust particle counters, and air volume hoods, to accurately measure and analyze the environmental parameters in the workshop. According to the test results, the control parameters of the system are optimized and adjusted, such as the proportional, integral, and differential parameters of the PID controller, and the air volume and water flow parameters of the MAU, FFU, and DCC, to achieve the best operating effect of the system.
V. Conclusion
The control technologies of the MAU + FFU + DCC system are at the core of ensuring the environment in cleanrooms. Through precise control of key parameters such as temperature, humidity, cleanliness, and pressure, combined with the application of intelligent control technologies and careful system commissioning and optimization, a stable, reliable, and high-quality air environment can be provided for cleanrooms, meeting the stringent requirements of various high-tech production and scientific research activities for clean environments. Guangzhou Cleanroom Construction Co., Ltd. has rich experience and a professional technical team in this field and is committed to providing customers with advanced MAU + FFU + DCC system solutions and high-quality services. We will continue to pay attention to the development trends of industry technologies, continuously innovate and improve, and contribute to the progress of cleanroom technologies. If you have any questions or needs regarding the air purification and environmental control of cleanrooms, please feel free to contact us, and we will serve you wholeheartedly.