When Not to Use Evaporative Cooling？

Evaporative cooling should not be used when the ambient wet-bulb temperature is excessively high. The core principle of evaporative cooling relies on the temperature difference between the dry-bulb and wet-bulb temperatures of air for heat transfer; the larger this difference, the higher the cooling efficiency.

In regions with hot and humid climates-such as the plum rain season in coastal southern China or tropical rainforest zones in Southeast Asia-the ambient wet-bulb temperature approaches the target cooling temperature, significantly weakening the driving force for water vapor evaporation.

This not only fails to achieve the desired cooling effect but also forces the cooling system to operate continuously at full load, increasing the risk of equipment failure. For instance, in environments where the wet-bulb temperature exceeds 24°C, using evaporative cooling to lower industrial circulating water to below 28°C results in a much lower energy efficiency ratio compared to water chillers, rendering it entirely economically unviable.

Evaporative cooling should be avoided when the cooling medium requires stringent water quality standards. During the evaporative cooling process, circulating water becomes increasingly concentrated, leading to elevated levels of impurities such as calcium and magnesium ions and suspended solids, which easily form scale and biological slime on heat exchange surfaces.

Additionally, open-type evaporative cooling systems directly introduce dust and pollutants from the air, causing contamination of the medium. For process cooling in industries such as precision manufacturing, electronic chip production, and pharmaceuticals-where cooling media demand high purity and low impurity content-adopting evaporative cooling would raise medium purification costs and may even trigger equipment blockages or product quality defects. Furthermore, if the cooling medium is a corrosive or flammable and explosive liquid, the open or semi-open structure of evaporative cooling systems poses risks of medium leakage and safety accidents.

Evaporative cooling is unsuitable for scenarios where processes demand extremely high outlet temperature stability. The cooling effect of evaporative cooling is highly susceptible to fluctuations in ambient temperature and humidity; minor changes in external climate conditions can cause fluctuations in the outlet temperature of the cooling medium.

For example, precision instrument temperature control and precise temperature regulation in chemical reactors typically require temperature stability within a tolerance of ±1°C. this accuracy requirement, and forced application may lead to serious consequences such as reaction runaway or instrument measurement errors.

Evaporative cooling should be restricted in water-scarce areas or regions with strict environmental regulations. Evaporative cooling is accompanied by substantial water loss: take industrial closed cooling towers as an example, their water make-up rate generally ranges from 1% to 3% of the circulating water volume, and large-scale application consumes enormous amounts of water resources.

In arid northwestern China or industrial parks with tight water quotas, this water-consuming characteristic conflicts with water conservation policies. Meanwhile, the circulating wastewater generated by evaporative cooling contains high concentrations of salts, fungicides, and other substances. In regions with strict environmental requirements and inadequate wastewater treatment systems, such wastewater can contaminate soil and water bodies, exposing users to the risk of heavy environmental penalties.