Direct cooling by a closed cooling tower and its economic analysis

Puts forward the energy saving scheme using evaporative cooling where the closed cooling tower serves for air conditioning systems directly without operation of refrigerating machines when the outdoor wet-bulb temperature is 3~5 ℃ lower than the required chilled water temperature in transition seasons even the whole year. Obtains the condition of the system shifting to the direct cooling operating mode by using logarithmic mean temperature difference method. The case analysis result indicates that the effect of energy saving is obvious when the direct cooling mode is adopted under the condition without operating the refrigerating machine, and that the additional equipment investment can be recovered in less than two years, with a better economic benefit.