What is aging?
Aging is the normal prosess that occurs to fill in a cooling tower when the surface of the new PVC fill material slowly allows water te spread and form a thin film. The problem is that new PVC is essentially hydrophobic, i.e it repels water. Water will bead-up in droplets instead of forming a film on the surface increasing the surface area and also the rate of thermal heat rejection. This, of course, defeats the purpose of film type fill. The cooling capacity of the new fill will be well below that of an "aged" fill.
What is the performance difference between aged packs and unaged?
According to Brentwood industries and their findings on the matter, performance deficits of 10-25% occured, depending on the water rates(i.e unaged packs yield lower performance at low water rates) Here at Wynroete Verkoeling we conducted similar tests and our findings were very similar. So when sizing the tower and calculating the water flow it is crucial to keep these factors in mind. Luckily PVC ages relatively quickly and this shortfall disappears after the aging is complete. Other fill materials (i.e polypropylene) take much longer to age. The aging process can take up to 6 months (working months) and depends on the water flow rate.
How do we determine when the fill has aged completely?
Remove a pack. Use a squirt bottle to squirt water on a vertical side sheet of the pack. IF the water forms a film on the surface, the fill is aged. If the water still forms droplets on the surface, further aging is required.
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