# Is a cooling tower a worthwhile investment? (part 3)

Now let’s see how we calculate the size of the tower with the available data:

Let’s suppose that the water flow rate is 15 – 20 – 25 m3/ (m2h), hence we have the size (top view)of the tower. We also have the market price and, hence, the price of the tower.

For the cost of fan power, let’s assume an air velocity of 3.5 m/s. We therefore know the air flow rate to the fan and let’s assume the yield value of the impeller at 70%. It’s now possible to calculate the power absorbed in kW that will be useful to determine the fan power cost.

Using the same method we can also calculate the power absorbed by the pump for the water circulation.

The cost of the installation is calculated to be as much as the cost of the tower.

 Calculations of the cost for the installation of a cooling tower m2 tower (20 m3/h m2 approx.) 1.26 Cost of the tower 7,536,000 Cost for installation 7.536,000 Total cost 15,072,000
 Calculation of the cost for the power of the system with tower Energy Consumed motor fan motor kW 1.05 air flow rate 13,565 prevalence mm CA 20 motorfan yield 70% pump motor for the movement of water 5.42 water flow rate 25,12 prevalence m AC supply 30 yield of the pump 70% Total kW for circuit tower kW / year 12,413 Cost of electricity per year 1,241,281 Cost for the make-up water calculated to 5% m3 / h 1.3 Cost of make-up water 2,411,520 Cost bleed-off water (= make-up / 2 x cost of water purge) 602,880 Cost of maintenance of the tower 5% of the installation cost 753,600 Total operative costs 2,597,761
 Costs Evaluation Cost with aqueduct water in one year 36,172,800 Operating cost of the system with tower 2,597,761 Savings in one year 33,575,039 Savings each month 2,797,920 Total cost of the tower 15,072,000 The investment return (ROI) in MONTHS 5,4

Here we can see that the ROI payback period for the tower installation is only 5 and a half months. Because of the small entity involved, financial costs were not taken into account.