The issue of replacing the heat exchange medium from cooling water to chilled water
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A plate heat exchanger with water as the medium on both sides. Previously, cooling was achieved using cooling water (28 degrees Celsius, also known as circulating water), and it is now intended to switch to chilled water (7 degrees Celsius) for cooling. Will the chilled water flow rate need to be reduced? I used software to calculate it and found that the amount of chilled water used actually increased – what’s going on? Help needed. . . . (Any recommended software?)
The water volume will decrease because the temperature difference has increased
The amount of water increases because, with the volume remaining constant, the density of water rises from that of cooled water to that of chilled water; as a result, the mass of water also increases.
Assuming there is no energy loss, according to the law of conservation of energy, although the chilled water used by the original poster has a lower temperature, if the temperature difference between the cold fluid and that in Yuen Long remains unchanged, then since the density and specific heat capacity of water vary little within such temperature ranges, the volume of chilled water should be roughly the same as before; it might be slightly less, but not by much.
The temperature difference between the inlet and outlet water of your chiller unit is 5 degrees; the cold water temperature ranges from 28 to 35 degrees, resulting in a temperature difference of 7 degrees. The total load remains unchanged; of course, the volume of chilled water increases, and the increase ratio is 7/5 = 1.4, which means a 40% increase in the volume of chilled water. The advantage, though, is that you can choose a smaller size for your equipment, such as the heat exchanger! ! ! !
Is the density really increasing? The density difference between water at 7 degrees and water at 28 degrees shouldn’t be very large, right?
I just want to give it a try; I don’t know yet how large the temperature difference is I hope it will be possible to reduce water consumption, as the diameter of the cold water pipes after the modification is smaller than before (due to financial constraints); I’m not sure if that will work.
What software was used to calculate it? By changing from cooling water to chilled water, if the original heat transfer temperature difference on the cold side is maintained unchanged, the flow rate of the chilled water will change and decrease, mainly due to changes in its physical properties