Experimental Study of Phase Change Cooling System’s Performance of Traction Convertor for High Speed Train
|School||Lanzhou Jiaotong University|
|Course||Thermal Power Engineering|
|Keywords||High speed train IGBT Phase change cooling heat transfer Experimentalstudy|
Since the21st century, rail transit industry developed rapidly in China, the speedinessand security of the trains have become the mainstream, high-speed trains which use AC astraction transmission way occupy an important position. In AC traction transmission system,the traction convertor plays an important role. As the core component of traction transmission,IGBT switches constantly during the operation so a lot of heat is produced at the moment ofturning on and off. As the switching frequency of IGBT increasing, the quantity of heat risesrapidly. If the heat can not be sent out effectively and quickly, severe thermal fatigue willoccur within the IGBT, even burn out because of overheating. So it not only has effects on thenormal work of traction convertor, but also endangers the security and stability of trainoperation. So the key problem is how to removing the heat from IGBT in the tractionconvertor more effectively and promptly.The article takes the cooling system of the traction convertor on CRH2as example,analyzes the power loss of IGBT, contrasts advantages and disadvantages of different kinds ofheat dissipating method and determines the cooling scheme of IGBT in traction convertersand the structure of cooling them. The parts’ structures of phase change cooling system aredrawn by CAD and the models are built by using Solid Works. The various instruments, thenecessary equipment and the refrigerant used in the experiment involved in the phasechange cooling system are described in detail. Finally, the cooling physical models areestablished, test bench of IGBT power component’s phase change cooling system is built,also the hot resistance of the system is analyzed in detail.In the experiment, cooling performance of the tube radiator which is filled withrefrigerant and installed in small groove forms of cooling substrates is tested under thecondition of different heating power and wind conditions. The outlet pressure, import andexport of duct air temperature, flow velocity in the duct, the temperature on the tube wall, theinternal pressure of main specimen boiling pool and maximum temperature on the surface ofdifferent structure of the cold plate tube radiator are measured. Also, the methods ofcalculating the temperature at import and export, the temperature at the surface of the coldplate and the flow velocity in the duct are given, Boiling heat transfer coefficients andCondensation heat transfer coefficients which are under different working conditions areobtained, so the temperature variations of the under the surface of cold plates are given out. Itproved the affect of boiling surface structure to the boiling heat transfer intensity. Heattransfer law of the phase change cooling system is studied, the relevant parameters of the heattransfer and fluid flows through the tube radiator are calculate and it also gives out variationsof duct air forced convection heat transfer, Nu and friction factor f of wind speed. Through the experiment of measurement of each node temperature, in the cooling system of phase changethermal resistance of different heat transfer process are calculated. Thermal resistancechanges under the conditions of different heating power are analyzed as well as the effects ofsystem filling rate to boiling heat transfer, thermal resistance, and condensation heat transferin thermal resistance, boiling heat transfer and condensation heat exchanger total thermalresistance as well as average boiling heat transfer coefficient. The paper provides design ideasfor the design of phase change cooling system and a research basis for the mechanism ofrefrigerant phase change.