Cooling System Energy-Saving Diagnosis And Analysis Of Subway Station In Chongqing

With the rapid development of the rail transit industry in recent years,it has also brought about increasingly serious energy consumption problems.In the actual energy consumption of subway stations,the energy consumption of the ventilation and air conditioning system consumes a relatively large amount of energy,while the cold source system accounts for more than 60% of the ventilation and air conditioning system's energy consumption.Therefore,the energy saving of the station's cold source system should not be underestimated.Compared with ordinary public buildings,subway stations have the characteristics of unstable load change and inconsistent passenger capacity planning in different periods.Thence,the design,operation and energy consumption characteristics of the cold source system have certain special characteristics.In order to promote the effective implementation of energy saving work in subway stations,this paper starts with real data.Influencing factors and existing problems of the cold station system in the subway station,such as design characteristics,actual operation conditions and energy consumption are diagnosed in detail.According to the existing problems,this paper compares the energy consumption difference of station cold source system under different design conditions,and proposes corresponding solutions to guide the energy~saving design of the cold source system in new station.This paper conducts field research on several Chongqing subway stations in different lines.The parameters of the cold source system of the 58 underground subway stations,including the design parameters of the chillers,chilled water pumps,cooling water pumps and cooling towers,equipment connection relationship and proportioning scheme,were analyzed.And summed up the problems in the design and operation of the cold source system.To verify the results of the field research,12 representative underground subway stations were selected to measure the indoor environment and cold source system performance and operation status.Through the analysis of the design parameters of the cold source system and the actual measurement,the following problems are found: the indoor environment of the underground station in Chongqing is generally low,and the actual environmental parameters and design values of different regions are different.The water system parameters of different stations are not reasonable,and the supply and return water temperature distribution ranges are wide and far higher than the design value.The chillers are all configured according to the "initial + forward" load,and partial load demand is not considered.The energy consumption of the ordinary water~cooled cold source system is too high,and the energy consumption of the transmission and distribution system in the evaporative condensation type cold source system is significantly smaller as a result of no cooling tower.Although the measured results show that the return water temperature of the chilled water in the form of "Large and small systems use cold sources separately " is consistent,and the performance coefficient of the cold machine is higher.However,most of the new stations still use the traditional design method of “Large and small systems use cold sources together”.The advantages and disadvantages of different systems in the industry are still being explored.The existence of these problems is a key factor affecting the performance and energy consumption of cold source systems.Therefore,for the related problems diagnosed by the survey and the actual measurement,the combination of the mathematical model of the chiller and the DeST numerical simulation is used to analyze the influence of parameter changes on the energy consumption of the chiller during the actual operation of the station's cold source system.Meanwhile,the effects of different cold source configurations,different system forms and pump mode settings on the energy consumption of the cold source system are simulated.The following conclusions are drawn: the effluent temperature of the variable cooling water is more obvious than the effluent temperature of the chilled water to the energy consumption and performance of the chiller.When the load rate is high,changing the effluent temperature of chilled water and cooling water has more obvious impact on the energy consumption and performance of the chiller.Comparing with the configuration scheme of two chillers used in subway station,the station can save 5%~6% of power consumption by configurate three chillers of same tape according to long-term,the station can save 12%~15% of power consumption by configurate two chillers of diffierent tapes according to “initial+long” term.For the simulated station,the difference between the form of “Large and small systems use cold sources together” and “Large and small systems use cold sources separately” is not obvious.When the water pump in the transmission and distribution system is frequency~converted,the chilled water pump can save 41.8%,36.7%,30.7% of electricity in the initial,near~term and long~term operation of the station respectively.At the same time,the cooling water pump can save 37.5%,33.4% and 26.5% of electricity in the initial,short~term and long~term operation of the station respectively.The research results of this study provide a reference for the design of the cold source system and energy~saving operation of the subway station.