Research On Heat Transfer Of Nanofluid In The Power Battery Cooling System

The environmental protection and energy saving is one of key factors of the sustainable development of modern industry.The electric vehicles has become the mainstream trend due to reasons of energy saving,environmental protection and other characteristics.The pack of battery as the main power source of electric vehicle,and it is easy to cause large heat due to the high energy demand.Study on the cooling system of high heat transfer characteristics,to improve the performance of power batteries and electric cars.Nanofluid is a new type of heat transfer medium by adding nanoparticles in base fluid.The heat transfer performance of liquid and efficient cooling target can be improved by introduction of nanofluid.This paper intends to research the flow and heat transfer characteristics of ethylene glycol water based nanofluid in the battery cooling system,and analyze the value of ethylene glycol water based nanofluid in improving the cooling efficiency of high temperature battery.The main research work in this paper is outline as follows:1.The thermal model of cell is established based on the mechanism of heat generation and transfer.The heat generation and heat transfer mechanism of the battery are analyzed based on the structure of power battery,and the three-dimensional thermal model of the battery is established.The cell specific heat capacity and thermal conductivity are analyzed and summarized.Based on the working characteristics of the power cell,the low concentration Al2O3-glycol water nanofluid are prepared,and the suspension stability is analyzed.2.The mathematical model of flow and heat transfer of ethylene glycol water based nanofluid is established,according to the application of typical glow around a cell and pipe flow.The partial differential governing equations are transformed into a system of nonlinear ordinary differential equations via suitable mathematical transformation and then solved numerically using Keller-box method and shooting method respectively.Besides,the influences of significant physical parameters on the distributions of the velocity,temperature,as well as the law of the nanofluid flow and heat transfer are researched.3.The heat transfer enhancement of ethylene glycol water-based nanofluid is studied in the case of high temperature square cell with short circuit under impact extrusion.The new structure of cooling plate channel is designed based on the temperature characteristics of square battery,and then the influence of the coolant flow rate and temperature to the battery maximum temperature and mean temperature are analyzed.The flow and heat transfer characteristics of ethylene glycol water based nanofluid in high temperature cell with impact extrusion are analyzed.4.The heat transfer enhancement of ethylene glycol water-based nanofluid is reseached based on cylindrical battery group with single thermal runaway.The temperature characteristics of the thermal runaway cell are analyzed,and the effect of thermal runaway battery on the whole battery pack is studied.The influence of ethylene glycol water-based nanofluid and nanoparticle concentration to the heat dissipation are analyzed.The innovative of this paper is introducing nanofluid with high heat conductivity to the typical structure of battery cooling system for electrical car.The temperature characteristics of large area of high temperature battery and a single thermal runaway battery are analyzed,and the flow and heat transfer of nanofluid in the battery cooling system is studied to enhance the cooling effect and ensure the safety of batteries.