Yes, if the supply water temperature from the water-side economizer is too close to that of the chiller (typically around 40°F to 45°F), and the return water temperature doesn’t increase significantly due to a lower cooling load or inefficient heat transfer, it could contribute to or worsen low delta-T syndrome. This occurs when the temperature differential (delta-T) between the supply and return water is too small, reducing system efficiency. However, water-side economizers are designed to avoid low delta-T syndrome through several strategies: 1. Free Cooling in Favorable Conditions: The economizer operates during cooler outdoor conditions (e.g., during colder months), when it can completely or partially meet the cooling load without the chiller running. When the economizer is fully handling the load, the chilled water system can be isolated from the process, preventing issues with delta-T altogether. 2. Modulating Control: In hybrid operation with the chiller, the economizer often operates under modulating control, meaning it only provides cooling as much as needed. This avoids sending overly chilled water to the system, which can cause low delta-T conditions if the cooling load is not high enough to raise the return water temperature. 3. Load Distribution: The system may prioritize either the economizer or chiller to meet the cooling demand more efficiently, balancing the load between them and ensuring sufficient heat exchange in the air-handling units (AHUs) or fan coils. This helps maintain an adequate temperature rise across the system, preventing a situation where the return water is only slightly warmer than the supply water. How Economizers Avoid Low Delta-T in Mixed Operation: Temperature Setpoints: Economizers often supply water at a slightly higher temperature (e.g., 45°F) when in hybrid mode with the chiller to allow the system to raise the return water temperature sufficiently, thus maintaining a healthy delta-T. Staged Cooling: Systems may stage cooling between the economizer and chiller to adjust the supply water temperature dynamically based on the actual load, ensuring the return water temperature doesn’t stay too close to the supply. Conclusion: While there is a risk of low delta-T syndrome when the water-side economizer’s supply temperature is similar to that of a chiller, smart control strategies and operational practices are implemented to avoid this by managing the load distribution, modulating temperature setpoints, and ensuring adequate heat transfer in the system.
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Great content as always ! This channel has become one of my most recommended YT channels to my fellow colleagues
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Awesome thanks i was trying to make sense of the heat exchanger, since a chiller has an evaporator now i understand is for free cooling.
Glad it helped. Thanks for watching.
seems like this would introduce low-delta-T syndrome, if the CHW return starts to approach the supply CHW temp
Yes, if the supply water temperature from the water-side economizer is too close to that of the chiller (typically around 40°F to 45°F), and the return water temperature doesn’t increase significantly due to a lower cooling load or inefficient heat transfer, it could contribute to or worsen low delta-T syndrome. This occurs when the temperature differential (delta-T) between the supply and return water is too small, reducing system efficiency.
However, water-side economizers are designed to avoid low delta-T syndrome through several strategies:
1. Free Cooling in Favorable Conditions: The economizer operates during cooler outdoor conditions (e.g., during colder months), when it can completely or partially meet the cooling load without the chiller running. When the economizer is fully handling the load, the chilled water system can be isolated from the process, preventing issues with delta-T altogether.
2. Modulating Control: In hybrid operation with the chiller, the economizer often operates under modulating control, meaning it only provides cooling as much as needed. This avoids sending overly chilled water to the system, which can cause low delta-T conditions if the cooling load is not high enough to raise the return water temperature.
3. Load Distribution: The system may prioritize either the economizer or chiller to meet the cooling demand more efficiently, balancing the load between them and ensuring sufficient heat exchange in the air-handling units (AHUs) or fan coils. This helps maintain an adequate temperature rise across the system, preventing a situation where the return water is only slightly warmer than the supply water.
How Economizers Avoid Low Delta-T in Mixed Operation:
Temperature Setpoints: Economizers often supply water at a slightly higher temperature (e.g., 45°F) when in hybrid mode with the chiller to allow the system to raise the return water temperature sufficiently, thus maintaining a healthy delta-T.
Staged Cooling: Systems may stage cooling between the economizer and chiller to adjust the supply water temperature dynamically based on the actual load, ensuring the return water temperature doesn’t stay too close to the supply.
Conclusion:
While there is a risk of low delta-T syndrome when the water-side economizer’s supply temperature is similar to that of a chiller, smart control strategies and operational practices are implemented to avoid this by managing the load distribution, modulating temperature setpoints, and ensuring adequate heat transfer in the system.
I would to learn more about this interesting 😮 so cool
Thanks. Keep watching as there will be more on this topic later.
Thank you
You're welcome
Robin Williams?
No.