Field Measurement And Energy-Saving Analysis Of Evaporative Condensing Air Conditioning System In Subway Station

The ventilation and air-conditioning system of the subway station consumes a lot of energy and has a large energy-saving potential.How to improve energy efficiency has become the focus of scholars at home and abroad.However,at present,most domestic subway stations use traditional water-cooled air conditioning and ventilation systems.Due to the need to install a cooling tower to cool the cooling water,the layout and operation of the cooling tower consumes a large amount of water while increasing the floor space.There are still many deficiencies in areas such as land.Therefore,this paper adopts a new type of direct expansion evaporative condensing air conditioning and ventilation system for subway and applies it to the actual project,and has carried out three years of continuous field measurement research on the system.The purpose is to study the actual operation of the system and its energy conservationIn this paper,a subway station(station A)with direct expansion evaporative condensing air conditioning and ventilation system in Beijing was taken as the research object to measure it in the air conditioning season of 2016-2018.The ventilation and air conditioning system of station A was composed of two A and B systems that use direct expansion evaporative condensing air conditioning and ventilation systems.Among the air-conditioning equipment,the equipment that consumes the most energy was the compressor,which can account for 53.07%～66.09%of the total energy consumption of the system,followed by the main blower and main exhaust fan,which could account for 24.02%～37.35%of the total energy consumption of the system.The actual operating state of the air-conditioning system has a greater impact on the performance of the air-conditioning system.The total average COP of the compressor under high-efficiency and low-efficiency conditions was 3.99/2.96,that was,the COP value under high-efficiency conditions was about 25.8%.As the air distribution of the evaporative condenser increases,the heat exchange capacity of the evaporative condenser gradually increases,while the COP increases first and then decreases.The maximum COP was 4.24,and the calculated optimal air speed of the evaporative condenser was 3.18 m/s.With the increase of the wet bulb temperature of the air at the inlet of the evaporative condenser,the heat exchange amount and COP of the evaporative condensation gradually increase.With the increase of the wet bulb temperature of the air at the inlet of the evaporative condenser,the heat exchange amount and COP of the evaporative condensation gradually increase.This paper selects station B,which was similar to station A in station area,structure and total design load,and uses traditional water-cooled air conditioning and ventilation systems as a comparison Station,the two stations were measured at the same time.The analysis showed that the COP of the direct expansion evaporative condensing refrigeration system was about 12.39%higher than that of the traditional water-cooled refrigeration system,and the energy consumption of the direct expansion evaporative condensing refrigeration system was about 38.13%lower than the total energy consumption of the traditional water-cooled system.The system simulation model was established and its correctness was verified.Fit the simulation data to get the mathematical relationship between the best air distribution of the evaporative condenser and the efficiency of the refrigeration system.In addition,the effects of the air distribution and inlet wet bulb temperature of the evaporative condenser on the power of the air conditioning refrigeration system and the compressor were analyzed and simulated.It was obtained that with the increase of the air distribution of the evaporative condenser,the refrigeration system COP increases first and then decreases.When the air distribution was130727.52 m~3/h,that was,the oncoming wind speed was 3.08 m/s,the refrigeration system was in the best operating state.The research results in this paper could provide some theoretical support for the application of evaporative condensing air conditioning systems in subway stations,and have certain practical application value.