| At the same time as the high speed train travels at high speed,the train staff and passengers need a comfortable internal environment.Therefore,a reliable air conditioning system is used to regulate the temperature and air quality within the motor car to provide a comfortable ride environment.With the continuous improving of the train running speed,the aerodynamic performance of the whole train and the inside have changed,and the airflow organization has changed accordingly,which has also affected the main parameters of the air conditioning system used for the train.In research and development,it is necessary to consider the reliability factors of air conditioning system related equipment and consider its economic factors.In the operation process of high speed train,maintaining and repairing the refrigeration and air conditioning system is one of the key contents of the daily work of high speed train.Through the study of the characteristics of the air conditioning unit,especially the matching characteristics of between their different parts,combined with the existing problems,the in-depth study of the principle helps the system to be optimized the design and be facilitated the maintenance,so that its performance and economy are simultaneously optimized.Thus,studying the system characteristics of air-conditioning units for high-speed train is of great significance to the performance optimization of the entire motor-driven air-conditioning system and to energy conservation.The main works of this paper are two parts:(1)a calculation program of an high speed train air-conditioning system is coded and tested,and the characteristics of the air-conditioning system for high speed are mainly studied;(2)Through the numerical simulation,the influences caused by different operating parameters of the air conditioning system on the characteristics of the air conditioning unit are obtained,which are used as a means to optimize the design of the air conditioning system for high speed train.Through the numerical simulation method,the following main conclusions are obtained:(1)At the rated working condition,with increasing of the KF_c value of the condenser,the energy efficiency ratio EER is gradually increased and then stabilized.Therefore,simply increasing the KF_c value of the condenser does not necessarily increase the energy efficiency ratio,but wastes manpower and material resources.(2)At the rated working condition,with increasing of KF_e value of the evaporator,the trend of energy efficiency ratio EER is to increase slowly and then gradually decrease.Therefore,simply increasing the KF_e value of the evaporator does not necessarily increase the energy efficiency ratio,but is more energy-intensive.(3)At the rated working condition,with increasing of the flow area of the electronic expansion valve,the energy efficiency ratio EER of the system gradually increases and then decreases slowly.Therefore,adjusting the flow area of the electronic expansion valve within a certain range can increase the energy efficiency ratio,so that the performance of the air conditioning system can be optimized to a certain extent,thereby achieving the purpose of saving energy.(4)At the rated working condition,with increasing of the cooling capacity,the energy efficiency of the system increases gradually and then decreases.Therefore,simply increasing the cooling capacity is not necessarily beneficial to the system performance,but the cooling capacity of the air conditioner must match the other components of the system to play the maximum role.(5)At the rated working condition,with increasing of the temperature inside the high speed train,the energy efficiency of the air conditioning system increases firstly and then decreases gradually,and the reduction is small.Therefore,simply increasing the temperature inside the vehicle does not necessarily increase the energy efficiency ratio of the system.(6)At the rated working condition,with increasing of the temperature outside the high speed train,the energy efficiency ratio of the air conditioning system is slowly decreasing,and the decreasing speed is very slow.(7)At the rated working condition,if the speed of the compressor is simply increased,the energy efficiency ratio can not be improved.(8)At the rated working condition,with increasing the air flow rate of the condensing fan,the energy efficiency ratio of the air conditioner first increases and then tends to be stable.Therefore,simply increasing the air volume of the condensing fan cannot achieve the purpose of saving energy.(9)At the rated working condition,simple increasing of the air flow rate of the indoor fan,the energy efficiency ratio increases first and then decreases,but it is more energy-intensive. |
