Sensible and Latent Cooling
Depending on the entering air and water temperatures, the water may be cooled by sensible and latent cooling of the air, or simply by latent cooling of the air. In either case, latent, i.e. evaporative, cooling is dominant. For example, consider the case in which the air enters at a lower temperature than the water (Figure 3a). The air will leave completely saturated and the cooling is part sensible and part latent. The sensible portion occurs as the air temperature increases by absorbing heat from the water. The latent portion occurs as some of the water evaporates, which draws energy out of the water.
If the air enters at the same wet bulb temperature as before, but at a higher dry-bulb temperature than the water, then the air will cool as it saturates (Figure 3b). Thus, the sensible cooling component is negative, and the all the cooling is due to evaporation. In general, cooling is dominated by latent cooling.