Colder Water, Cooler Air: The Impact on Cooling Efficiency in Air Units

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Discussion Overview

The discussion revolves around the impact of water temperature on the cooling efficiency of air units, specifically examining how lower water temperatures affect the temperature of the air produced. The scope includes theoretical considerations of heat transfer and practical implications for cooling systems.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant inquires about the cooling efficiency when water temperatures are lowered from 7C to 2C, questioning if the resulting air temperature will be significantly cooler.
  • Another participant agrees that colder water will enhance cooling efficiency but notes that the increase in thermal resistance may limit the extent of cooling achieved.
  • A third participant introduces the concept of "approach temperature," suggesting that a larger temperature difference between the water and air will improve heat transfer, potentially leading to cooler air, but also mentions that the chiller's performance may be negatively impacted.
  • A later reply seeks clarification on how to calculate the total cooling effect in Watts resulting from the changes in water temperature.

Areas of Agreement / Disagreement

Participants generally agree that colder water can improve cooling efficiency, but there are differing views on the extent of this improvement and the implications for the chiller's performance. The discussion remains unresolved regarding the precise calculations for the cooling effect.

Contextual Notes

Limitations include assumptions about thermal resistance and the specific characteristics of the cooling system, which may affect the outcomes discussed.

Who May Find This Useful

Individuals interested in HVAC systems, thermodynamics, and cooling efficiency may find this discussion relevant.

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If a cooling element in an air unit was designed for water temperatures of 7C in and 12C out, how much "better" will it become if it receives water at 2C ? Let's say the return is then 7C, will the effect then be the same since the delta T is the same as it was with 7/12 ? It just seems so logical to me that bringing colder water in will result in cooler air...
 
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Correct, although you won't get quite 5C colder air, the greater water-air temperature difference will cause more heat to flow but it will also increase the effects of anny thermal resistance.
 
This is called improving your "approach temperature". A bigger approach temperature will improve heat transfer and therefore you will pull more energy out of the air. So the delta T will go from, say, 5 C to 6C and you'll get perhaps 8 C return water. Of course, the approach temperature of the chiller that is making that water gets worse when you do that...
 
Thx guys, just one more thing; if this will indeed make the air cooler, how can I calculate the total effect in Watts?
 

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