Research On Heat Control System For Vehicular Power Battery Pack Based On Heat Pipe Technology

To solve the environment pollution and energy shortage, electric vehicles are used moreand more widely. As a source of electric vehicles, lithium-ion battery has become a researchfocus for its high voltage, high energy density and long cycle life. However the thermal safetyof lithium-ion battery is one of the main factors restricting its outreach.In order to keep good performance of the battery, extend its service life, and eliminatepotential dangers, battery temperature needs to be controlled within the normal operatingrange. Furthermore, the inhomogeneity of the single cells within the battery pack should alsobe reduced. In this paper, the thermal characteristics of lithium-ion batteries were analyzed bycombining numerical simulation methods and experiments. Based on the forced convectioncooling theory, heat pipes and aluminum fins were applied for the lithium-ion batteriescooling project. The main research content of this paper is presented as follows.(1) The necessity of lithium-ion battery to manage thermal was analyzed. Some basicconcepts, including the development of various heat dissipation, working principle andapplication of heat pipe, was introduced.(2) The working principles and heating mechanism of the Li-ion battery in detail werediscussed. The temperature influences on the battery’s performance were analyzed, includingcharge, discharge, internal resistance, cycle life and so on.(3) The thermal properties of lithium-ion batteries were studied. Experiments were takento measure single battery’s thermal parameters. The functions of current intensity, equivalentspecial capacity and heat generation of a single battery were acquired through the experimentresult. Besides, the orthotropic conductivities of the battery were calculated on the principleof series and parallel thermal resistance in heat transfer.(4) A heat cooling module which consisted of aluminum fins and heat pipe was designed.The experimental comparison was done by adding or decreasing the air cooling process. Thedischarge processes were done at the rate of2.5C in an airtight insulating situation.(5) By using the commercial software Icepak, the power battery thermal model was built.The initial and boundary conditions were also ascertained in the model. The temperaturedistribution of the battery was obtained from the heat generation model. The simulation resultwas also compared with experimental results in the paper.(6) The structures of battery casing and fins were designed and optimized. Theoptimization result was applied to the thermal simulation of battery pack. The distribution oftemperature was also discussed in this part.