Determine the design air mass flow required to handle 12,000 litres/min of cooling water?

Water enter a cooling tower at 400C and drops 150C of temperature before exit. The tower receives atmospheric air at 200C and 40% relative humidity. The air leaves the tower at 350C and 95% relative humidity. If the atmospheric pressure is 1.01325 bar determine the design air mass flow required to handle 12,000 litres/min of cooling water?

Differential pressure calculation

Hi There, I am enclosing a figure where I have to determine the differentia pressure. Could someone let me know how to do it? As additional information, the fluid is a mixture of gas. Regards, Howard

Laplace, and wave equations

Please see the attached file. Kindly provide clear and detailed steps. Thanks