Performance Investigation On The Evaporative Cooling System For Pump Station With High Waste Heat At Typical Cities In Summer

Amidst the exacerbation of global warming and urban heat island issues,high-temperature weather conditions have become increasingly frequent.With the rise of electromechanical and digital technologies,the energy consumption of traditional ventilation and cooling methods for the high cooling load caused by electrical equipment has correspondingly increased.This paper focuses on the optimization project of the ventilation and cooling system of an unattended water supply pump station in Shanghai,investigating the energy efficiency differences between direct evaporative cooling technology and indirect-direct two-stage evaporative cooling technology under different climates.Theoretical calculations and energy consumption simulations were used to propose optimization solutions for high waste heat reduction in multiple climatic zones of such water supply pump stations.The main research work is summarized as follows:Firstly,the cooling performance of the two-stage evaporative cooling system was simulated.The simulation results demonstrated that using mechanical ventilation cooling can reduce indoor cooling load by 62% to 87% during the period from June to September.However,maintaining the indoor dry-bulb temperature below 35℃ is challenging for five months throughout the year.Increasing the air flow rate of the unit can augment cooling capacity,but it can also result in a surge in energy consumption and a decline in evaporative efficiency,leading to a rise of up to10% in outlet dry-bulb temperature.By utilizing indirect evaporative cooling for treating the fresh air,the maximum air supply volume is reduced by up to 22%,while the cooling capacity is increased by 10%,there remains a portion of waste heat that needs to be further investigated in order to explore measures for supplementary cooling capacity.Subsequently,the trend of indoor residual heat with respect to outdoor parameters was discovered based on the distribution characteristics of various outdoor parameters in different cities.The smaller the temperature difference between dry and wet-bulbs or the higher the outdoor dry-bulb temperature,the more obvious the situation in which the cooling load cannot be met,resulting in an increase in indoor dry-bulb temperature and an increase in indoor cooling load.Therefore,the applicability and energy efficiency of equipment cannot be evaluated solely based on the cooling capacity.After conducting a comprehensive analysis of various indoor and outdoor parameters,a scheme was proposed to combine the direct evaporative cooling air cooler with the two-stage evaporative cooling system.Simulation results under different climatic conditions indicated that this scheme had high applicability and mechanical refrigeration energysaving rate of up to 75%.Subsequently,the difference in the impact of dry-bulb temperature and wet-bulb temperature on the energy consumption of the evaporative cooler was investigated.The results showed that when the wet-bulb temperature remained unchanged,the input power could be reduced by 1.4 kW-1.5 kW for each 1℃ decrease in the dry-bulb temperature.When the drybulb temperature remained unchanged,the input power could be reduced by 0.5 kW-0.8 kW for each 1℃ decrease in the wet-bulb temperature.Finally,the simulation results were validated by actual engineering tests and network monitoring data.The simulation results showed that under the same outdoor parameters,using indirect-direct evaporative cooling technology can improve the outlet wet-bulb efficiency by40%-60% and lower the outlet temperature by up to 16%.The combined operation strategy can meet the indoor cooling load demand under actual meteorological conditions,and the air supply volume is less than that of the direct evaporative cooling system during the morning and evening periods,achieving the goal of maintaining a comfortable indoor thermal and humid environment while saving energy.