Regarding the chilled water return issue
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Gentlemen, I have a question: when looking at the flow diagrams of refrigeration units, in some cases the return water from the chilled water system first goes back to the chilled water tank before reaching the refrigeration unit, while in other cases it goes directly to the refrigeration unit. What is the difference between these two approaches?
There isn’t much difference; the design is reasonable in both cases
One is different in size from the other, right? Small devices don’t need a water tank; the tank built into the freezer is sufficient for the cooling unit. For larger sizes, an intermediate tank is required; the internal circulation takes place between the unit and the water tank, while the external circulation occurs between the water tank and the cooling unit. The larger the equipment, the more auxiliary facilities are needed in terms of details
If there are a large number of devices such as chillers that use chilled water, and the operating conditions are complex, it is advisable to install an inlet chilled water tank in order to stabilize the temperature of the chilled water entering the chiller unit; this also enhances the system’s ability to withstand fluctuations. Additionally, when the return water temperature is too high, it is also possible to send a small portion of the chilled water back to the inlet chilled water tank via a bypass in order to maintain an appropriate inlet water temperature for the chiller unit.
It’s best to send it directly back to the chiller unit; a expansion tank should be installed in the bypass line to compensate for thermal expansion and contraction.
If the usage is steady, there is no need for a water tank; however, if the usage varies greatly, a water tank buffer is necessary to prevent frequent startup of the equipment and to store a certain amount of cold energy