A forced-draft cooling tower is to be designed to cool water from 35°C to 15°C in a dry, cool climate where the air is at 20°C with a relative humidity of 30%. The design air mass velocity is to be  = 1.6 kg dryair/m2 s with an  value 1.25 times smaller than the maximum. For these conditions,  is estimated to be 1.5 m.

(a) Determine the maximumand actual values of  and the height of fill required.

(b) Suppose thatthe tower is built with the height calculated in part (a) but that, all of a sudden, the relative humidity of the inlet air increases to 50%, while its temperature remains the same. Assuming that  and  remain the same, determine by what percentage the water flow rate will have to decrease if itis still desired to have an outlet water temperature of 15°C.

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