Regarding water quality issues in chilled water systems: Why use softened water?
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I really don’t understand why, in air conditioning design, the operating temperature of the circulating water in the central air conditioning chiller system is set at 7–12°C. Currently, all designers use softened water for this purpose. Why is that? Is there any standard or guideline for this?
Prevent scaling in the circulating water from blocking the pipes, as this can affect heat exchange efficiency over time.
Scaling is primarily related to temperature and pressure; at a certain concentration, calcium and magnesium ions will cause scale formation as temperature rises and pressure drops. These days, one and the same system is generally used in both winter and summer. In winter, it’s easy to understand why scale forms: the temperature of the heat exchanger rises, leading to scale formation. In summer, the temperature drops due to the refrigeration unit, but the temperature at the coil area rises as well, which also results in scale formation. Therefore, the current design approach is to remove calcium and magnesium ions from the beginning, thereby preventing the formation of scale.
Softened water is used for chilled water mainly to prevent scaling in the evaporator circuits of central air conditioning chillers, thereby avoiding a reduction in cooling efficiency.
This post was last edited by 20036820 on 2010-6-23 09:52. Can water at 7–12°C form scale? ? Who **can help provide a detailed explanation to clear up these basics?** Thank you
Scaling does occur, but to a very minor extent. In my opinion, the main reason for using soft water is to improve heat exchange efficiency!
It’s likely a scaling issue; the equipment design affects the heat exchange efficiency
For smaller air-conditioning chiller water or industrial refrigeration chiller water systems, it is not necessary to use softened water; tap water can be used directly, although regular cleaning is still advisable.
Poor water quality will definitely lead to phenomena such as scaling and corrosion. The chilled water system is a closed loop with very low make-up water volume. Using soft water reduces unnecessary repairs, extends the equipment’s lifespan, and improves efficiency.
Reply to 9# Cleaning Engineer: That’s completely correct. The main goal is to reduce scaling, and it’s also advisable to take corrosion into consideration.
The key issue is scaling; corrosion is secondary