ClassX Video Lessons Youtube Channel The Engineering Mindset How Air Handling Units work AHU working principle hvac ventilation
Welcome to an exploration of Air Handling Units (AHUs), essential components in HVAC systems that play a crucial role in maintaining indoor air quality and comfort. This article will guide you through the workings of AHUs, their typical locations, and their components, providing a comprehensive understanding of their function in modern buildings.
Air Handling Units, commonly found in medium to large commercial and industrial buildings, are integral to HVAC systems. They are typically located in basements, on rooftops, or on various floors, serving specific zones such as office areas or restrooms. In older high-rise buildings, a single large AHU might supply the entire building, but modern designs favor multiple smaller units for enhanced efficiency and control.
The primary purpose of an AHU is to condition and distribute air within a building. They draw in fresh air from outside, filter it, adjust its temperature, and distribute it through ductwork to designated areas. Used air is often returned to the AHU, where it can be exhausted or partially recirculated to conserve energy. In cases where recirculation is not feasible, thermal energy recovery systems can be employed to enhance efficiency.
A standard AHU consists of several key components:
These grills prevent foreign objects and wildlife from entering the AHU, protecting the mechanical components inside.
Located at the fresh air inlet and return air discharge, dampers regulate airflow by opening or closing as needed.
Filters capture dust and dirt, ensuring clean air enters the building. Pressure sensors monitor filter condition, alerting maintenance teams when replacements are necessary.
These coils adjust the air temperature to meet the desired set point for comfort. Heating coils add warmth when needed, while cooling coils remove excess heat.
Fans draw in air and propel it through the AHU components. While older units often use centrifugal fans, modern AHUs increasingly incorporate energy-efficient EC fans. Pressure sensors help control fan speed based on duct pressure.
Ducts distribute conditioned air throughout the building and return used air to the AHU. In colder climates, pre-heaters may be installed to prevent frost damage.
Humidity sensors monitor moisture levels, and humidifiers can add moisture to the air if necessary to maintain optimal indoor conditions.
To enhance energy efficiency, AHUs can incorporate energy recovery systems. A run-around coil, for example, transfers waste heat from the exhaust air to the supply air. Alternatively, a heat wheel can transfer heat between exhaust and fresh air streams without mixing them.
Air Handling Units are vital for maintaining indoor air quality and comfort in large buildings. By understanding their components and functions, building managers and engineers can optimize HVAC systems for efficiency and performance. For further learning, consider exploring resources like the Danfoss Learning portal, which offers a wealth of engineering-focused lessons and certifications.
Finally, to answer a common query: the difference between an AHU and an FAHU (Fresh Air Handling Unit) is that an FAHU exclusively handles 100% fresh outside air, while an AHU can recirculate some return air.
Engage in a virtual lab where you will identify and label the components of an Air Handling Unit. This activity will help you familiarize yourself with the key parts such as inlet grills, dampers, filters, and fans. Use the interactive tool to test your knowledge and receive instant feedback.
Analyze a case study of a building’s HVAC system focusing on the AHU’s role in energy efficiency. Evaluate the use of energy recovery systems and propose improvements. This will enhance your understanding of how AHUs contribute to sustainable building management.
Participate in a simulation exercise to visualize airflow dynamics within an AHU. Adjust variables such as fan speed and damper positions to see their effects on air distribution and energy consumption. This hands-on activity will deepen your comprehension of airflow management.
Join a group discussion to explore recent innovations in AHU design, such as the integration of EC fans and advanced humidity control systems. Share insights and debate the potential impact of these technologies on future HVAC systems.
Arrange a field visit to a local facility to inspect an operational AHU. Observe its components and functions in a real-world setting. This practical experience will solidify your theoretical knowledge and provide a tangible understanding of AHU operations.
Sure! Here’s a sanitized version of the YouTube transcript:
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Hey there, everyone! Paul here from TheEngineeringMindset.com. In this video, we’re going to discuss air handling units (AHUs). We’ll look at some typical examples to understand how they work and where to find them. Before we dive in, I want to thank Danfoss for sponsoring this video. Danfoss is dedicated to spreading engineering knowledge worldwide by partnering with channels like this one and offering free online classes through their Danfoss Learning portal. They have hundreds of lessons available on various topics, including relevant classes for air handling units. You can also take exams and earn certifications to boost your career and confidence. Just click the link in the video description below to create your free Danfoss Learning profile and gain access to a wealth of knowledge.
Here’s a quick engineering quiz: What is the difference between an FAHU and an AHU? Let me know your answers in the comments below. If you’re unsure, give it your best shot, and I’ll provide the answer at the end of this video.
So, where do we find air handling units? AHUs are typically found in medium to large commercial and industrial buildings. They are usually located in the basement, on the roof, or on various floors of the building. Many large buildings will likely have a combination of these locations. AHUs serve specific areas or zones within a building, such as office areas or restrooms, so it’s common to find multiple AHUs throughout a building. Older high-rise buildings may have just one large AHU, often located on the roof, supplying the entire building without a return duct. However, this design is less common in new buildings due to inefficiency. Nowadays, multiple smaller AHUs are preferred for better control and higher quality space conditioning, especially since buildings are now much more airtight.
The purpose of an air handling unit is to condition and distribute air within a building. They take fresh ambient air from outside, clean it, heat or cool it, and then distribute it through ductwork to designated areas. Most units also have a duct run to pull used air out from the rooms back to the AHU, where a fan discharges it back into the atmosphere. Some of this return air may be recirculated to save energy. If recirculation isn’t possible, thermal energy can be extracted and fed into the fresh air supply to save energy.
Let’s take a look at a simple, typical AHU design. In this basic model, we have two AHU housings for flow and return air. At the front of each housing, there are grills to prevent objects and wildlife from entering the mechanical components inside the AHU. At the inlet of the fresh air housing and the discharge of the return air housing, we have dampers. These dampers can open or close to control the airflow.
Next, we have filters to catch dirt and dust from entering the AHU and the building. Without these filters, dust would build up inside the ductwork and mechanical equipment, affecting air quality. Across each filter bank, there is a pressure sensor that measures how dirty the filters are and alerts engineers when it’s time for replacement.
Following the filters, we find cooling and heating coils that adjust the air temperature. The air temperature of the supply air is measured as it leaves the AHU to ensure it meets the designed set point for comfort. If the air is too cold, the heating coil adds heat; if it’s too hot, the cooling coil removes heat.
A fan pulls air in from outside and pushes it through the dampers, filters, coils, and out through the ductwork. Centrifugal fans are common in older AHUs, but energy-efficient EC fans are increasingly being installed. Pressure sensors monitor the fan’s operation, and duct pressure sensors can control fan speed based on duct pressure.
The ductwork distributes air throughout the building and brings used air back to the AHU. In colder climates, a pre-heater may be installed to protect components from frost. Humidity control is also important; a humidity sensor measures moisture levels, and if needed, a humidifier adds moisture to the air.
Energy recovery systems can be utilized to improve efficiency. For example, a run-around coil can transfer waste heat from the exhaust AHU to the supply AHU. Alternatively, a heat wheel can transfer heat between exhaust and fresh air streams without mixing them.
Before we wrap up, I want to remind you to sign up for your free Danfoss Learning profile for access to hundreds of engineering-focused lessons, including those about heat exchangers.
Now, back to the quiz: the difference between an AHU and an FAHU is that FAHU stands for Fresh Air Handling Unit, which only handles 100% fresh outside air without recirculating return air. An AHU, on the other hand, can recirculate some return air.
That’s it for this video! Thank you for watching. If you found this helpful, please like, subscribe, and share. Leave your questions in the comments below, and don’t forget to follow us on social media and visit TheEngineeringMindset.com. Thanks again for watching!
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This version maintains the essential information while removing any informal language and ensuring clarity.
Air Handling Units – Devices used in HVAC systems to regulate and circulate air as part of the heating, ventilating, and air-conditioning process. – The design of air handling units is crucial for maintaining optimal indoor air quality in large commercial buildings.
HVAC – An acronym for Heating, Ventilation, and Air Conditioning, referring to the technology of indoor environmental comfort. – The HVAC system in the new laboratory ensures precise temperature and humidity control for sensitive experiments.
Energy Efficiency – The ratio of useful output of a system to the input energy, often used to describe how well a system converts energy into work. – Improving the energy efficiency of the building’s HVAC system significantly reduced operational costs.
Ductwork – A network of ducts used for delivering and removing air in HVAC systems. – Properly sealed ductwork is essential to prevent energy loss and maintain system efficiency.
Filters – Components used in HVAC systems to remove particles from the air, improving air quality and protecting equipment. – Regular maintenance of filters is necessary to ensure the HVAC system operates efficiently and effectively.
Fans – Mechanical devices used in HVAC systems to move air through ductwork and other components. – The selection of high-efficiency fans can lead to significant energy savings in large-scale HVAC installations.
Humidity Control – The process of regulating the moisture level in the air to maintain a comfortable and healthy indoor environment. – Advanced humidity control systems are essential in museums to preserve delicate artifacts.
Thermal Energy – The internal energy present in a system due to its temperature, often used in heating and cooling applications. – The thermal energy storage system allows the building to shift energy use to off-peak hours, reducing costs.
Components – Individual parts or elements that make up a larger system, such as an HVAC system. – Understanding the interaction between different components is crucial for optimizing the performance of an HVAC system.
Recirculation – The process of moving air or fluid through a system more than once, often used to improve efficiency or maintain temperature. – Recirculation of air in the HVAC system helps to maintain consistent temperatures throughout the building.
