Direct Expansion (DX) is a term specifically used in vapor compression systems, where the refrigerant evaporates directly in the cooling coil. In vapor absorption systems, the term DX is not commonly used because the principles and configurations differ from those of vapor compression systems. Vapor absorption systems are typically described based on their absorption process and components.
Big topic to type. Anyhow in nut shell.....FCUs are like small air conditioners, perfect for single rooms like offices or hotel rooms. Meanwhile, AHUs are big, handling airflow for entire buildings, delivering it through ducts to different rooms. FCUs suit smaller areas, while AHUs are for larger spaces or whole buildings. FCUs usually have a fan, heating or cooling coils, and sometimes basic air filters, whereas AHUs have more parts for treating and distributing air. Though AHUs are bigger and more complex, they're not just enlarged FCUs; they're designed differently to suit various building sizes and needs. FCUs are usually proposing to the spaces to take entire heating or cooling load except ventilation load and ventilation will be delivered by a central FAHU. AHUs can handle cooling/heating without ventilation, cooling/heating with ventilation, or ventilation only applications.
During the HAP heat load calculation i got required cfm per tonnage of refrigeration as 270 cfm Is it correct..? Why this value shows a huge variation from the thumb rule (400 cfm )
It's essential to move beyond relying on thumb rules, as they often lack accuracy. Machine flow rate varies based on factors like room load, coil entering and leaving temperatures, ADP, and supply temperature etc. While many manufacturers produce machines with airflow rates around 350 to 400 cfm per TR for comfort air conditioning systems, everyone used to follow that. But, As discussed in our earlier sessions, thumb rules can lead to oversizing or undersizing the system. Using HAP calculations provides accurate and optimized outputs, including machine coil load, airflow rate, entering and leaving temperatures, ADP, and other details necessary for selecting the right machine from the technical data sheet, as explained in last session on HAP. With HAP, you can identify a perfect model, from technical data sheet with options for medium-speed operation. While 270 CFM per TR may seem less common, it's important to note that it's not necessarily incorrect. Factors such as lower room loads and greater differences in coil entering and leaving dry bulb temperatures can justify a lower airflow rate. I recommend reviewing your inputs to ensure accuracy. If everything is in order, then the calculated airflow rate is likely correct.
Thank you for share this informative video. Could you please make a video on desiccant dehumidifier sizing & selection?
Thank you. When I find the time, I'll produce a video on the topic you suggested.
Good vedio
Thank you ❤️
Thank you sir.... I'm your 1000th subscriber
Thanks alot Arjun❤️
Can we call DX (Direct Expansion) in Vapor absorption system?
Direct Expansion (DX) is a term specifically used in vapor compression systems, where the refrigerant evaporates directly in the cooling coil. In vapor absorption systems, the term DX is not commonly used because the principles and configurations differ from those of vapor compression systems. Vapor absorption systems are typically described based on their absorption process and components.
@@amnearmep Thanks
What is key difference between FCU and AHU?
Big topic to type. Anyhow in nut shell.....FCUs are like small air conditioners, perfect for single rooms like offices or hotel rooms. Meanwhile, AHUs are big, handling airflow for entire buildings, delivering it through ducts to different rooms. FCUs suit smaller areas, while AHUs are for larger spaces or whole buildings. FCUs usually have a fan, heating or cooling coils, and sometimes basic air filters, whereas AHUs have more parts for treating and distributing air. Though AHUs are bigger and more complex, they're not just enlarged FCUs; they're designed differently to suit various building sizes and needs. FCUs are usually proposing to the spaces to take entire heating or cooling load except ventilation load and ventilation will be delivered by a central FAHU. AHUs can handle cooling/heating without ventilation, cooling/heating with ventilation, or ventilation only applications.
@@amnearmep Thanks
During the HAP heat load calculation i got required cfm per tonnage of refrigeration as 270 cfm
Is it correct..?
Why this value shows a huge variation from the thumb rule (400 cfm )
It's essential to move beyond relying on thumb rules, as they often lack accuracy. Machine flow rate varies based on factors like room load, coil entering and leaving temperatures, ADP, and supply temperature etc. While many manufacturers produce machines with airflow rates around 350 to 400 cfm per TR for comfort air conditioning systems, everyone used to follow that. But, As discussed in our earlier sessions, thumb rules can lead to oversizing or undersizing the system. Using HAP calculations provides accurate and optimized outputs, including machine coil load, airflow rate, entering and leaving temperatures, ADP, and other details necessary for selecting the right machine from the technical data sheet, as explained in last session on HAP. With HAP, you can identify a perfect model, from technical data sheet with options for medium-speed operation.
While 270 CFM per TR may seem less common, it's important to note that it's not necessarily incorrect. Factors such as lower room loads and greater differences in coil entering and leaving dry bulb temperatures can justify a lower airflow rate. I recommend reviewing your inputs to ensure accuracy. If everything is in order, then the calculated airflow rate is likely correct.
Mixing means which air is mixing return or fresh air, 10 % of which air
Please watch the video fully. In this video it's fresh air.