Application Of Ground Source Heat Pump Technology In Subway Stations Of Middle Latitude Valley City

Urban rail transit system has the characteristics of large carrying capacity,fast transportation speed and less pollution,and has been developed rapidly in recent years.As of the end of 2016,China's urban rail transit operations have reached 4252.8 km,of which 3168.7 km subway,accounting for 76.3% of the total operating lines.As the length of the subway line grows year by year,its total energy consumption is increasing year by year.At present,China's per capita energy consumption is significantly lower than the world average.In the future development,China will consume more energy,and the lack of energy supply will restrict China's economic development.In the subway energy consumption composition,traction subway vehicles running power consumption accounted for the main part,followed by environmental control air conditioning system running power consumption,accounting for about 30% of total power consumption,with great energy saving potential.The ground source heat pump system is a heat pump air conditioning system that transfers low-level thermal energy from soil,groundwater or surface water to high heat by using a small amount of electrical energy.If the use of ground source heat pump system in the subway station,will produce significant environmental benefits and economic benefits.This paper chooses the typical subway station A in the mid-latitude valley city-Lanzhou as the research object,and discusses the subway station A public area ventilation and air conditioning system load composition and calculation method.and uses TRNSYS TRNBuild to build a load calculation model to calculate the time-dependent cooling load in the long-term(2041)refrigeration season.Subway station public area ventilation and air conditioning is characterized by only a single season in the summer cooling,no heat in winter.At the same time,Lanzhou is a mid-latitude valley city of the Yellow River through it,subway Line 1 along the Yellow River along the east and west across the central city.According to the above characteristics,the Yellow River water is selected as the low heat source of the ground source heat pump system,and the heat exchange between the plate heat exchanger and the Yellow River water is used.The water source heat pump screw chiller is established,and the Yellow River water source heat pump system is run in the refrigeration season.Based on the equipment parameters of the Yellow River water source heat pump system,TRNSYS Simulation Studio is used to simulate the system.In this paper,the changes of cooling water temperature and the change of chilled water temperature on the side of the subway station(load)are analyzed in detail.According to the simulation results of the heat pump system,this paper determines the energy efficiency and time-consuming power consumption of the Yellow River water source heat pump system and the water source heat pump screw chillers.Finally,this paper compares the economic and environmental benefits of the Yellow River water source heat pump system with the ground source heat pump system,the cooling tower-chiller.This paper calculates the initial investment,follow-up costs,relative payback period,thermal economics cost,and pollutant emissions during the three systems.According to the calculation results,the Yellow River water source heat pump system has significant advantages both in economic and environmental benefits.Through the research and analysis of this paper,the Yellow River water source heat pump system is applied to the middle latitude valley city subway station to provide technical support and case.