The cooling tower selection is one of the most important step in designing HVAC system.

Chiller consumes around 80% of total HVAC power consumption. But the chillers performance measured in terms of COP is solely depend on the cooling tower performance. That is why selecting a best suitable cooling tower for the application is utmost important.

There are few different types of chillers, we have already seen it. You may check it here.

## Steps for cooling tower selection

- Know the heat rejection capacity of the cooling tower.
- Chiller’s heat rejection
- Condenser water flow rate
- Condenser temperature range and wet bulb temperature of the site.

- Cooling tower type – factors affecting cooling tower type as per application.
- Other factors for cooling tower selection
- CTI Certified cooling tower
- Noise level
- Drive type
- Weather conditions
- External static pressure

Now, we shall see one by one point for cooling tower selection.

**Know the heat rejection capacity of the cooling tower.**

- Know the temperature range required for condenser, delta T. Example, Entering Water temperature 37 C and leaving water temperature 32 C. So delta T is 5 C
- Cooling tower heat rejection = Chiller’s heat rejection x 30% higher.
- Example, if chiller’s heat rejection is 500kw; then select the cooling tower with 650 kw. 30% is just a widely accepted safety margin for cooling tower selection.
- The chillers capacity often indicated in tonnage, Please check how to convert it to cooling tower tonnage.
- Now you got the cooling tower kw, lets convert this into water flow rate.
- 650kw cooling tower means, 650 x 860 / (5 x 1000) = 111.8 m3/hr Water flow rate required @ 37 Entering water temperature and 32 C leaving water temperature.
- Wet bulb temperature- The WBT gives us an idea that how much temperature we can reduce by evaporative cooling. Generally, 28 C wet bulb temperature is used.
- So, we need to use 111.8 m3/hr @ 37-32/28 C ( Entering Water Temperature – Leaving Water Temperature/ Wet Bulb Temperature)