Research On Heat Transfer Of Battery Stack Of Electric Underwater Vehicle

Intelligent Unmanned Underwater Vehicles (UUVs) have taken on a number of roles in thenavies around the world, including hydrographic reconnaissance, mine countermeasures, andoceanographic survey etc., which are highly dependent on a quiet, reliable, low-cost andhigh-performance power supply. Fortunately, Lithium/thionyl chloride batteries can be used toprovide the propulsion power for UUVs to perform undersea or surface operations due to theirlarge capacity, high power output, etc. However, it is possible to cause thermorunawaybecause of Joule effect if a mass battery stack discharges several hours at a high current. Thispotential risk seriously restricts the wide applications of Lithium/thionyl chloride batteries inthe field of underwater vehicles. In this work, it is studied effects of heat transferenhancement solutions and discharging currents on characteristics of temperature and velocityof Lithium/thionyl chloride battery stack inside the underwater vehicle in detail. It mainlyincludes a couple of aspects as follows.(1) It is studied effects of discharging current and convective heat transfer coefficient ontemperature characteristics of ER48660Li/SOCl2battery in computational and experimentalmethods, in order to obtain a relationship of discharging current and temperaturecharacteristics of the battery.(2) Effects of discharging current on characteristics of temperature and velocity inside thebattery stack are investigated thoroughly based on heat transfer enhancement solutions ofABS/PPS battery frameworks in the computational and experimental methods, which is aimedto explore bottlenecks blocking fast heat transfer.(3) On the basis of heat transfer enhancement solutions of aluminum-based ABS/PPS batteryframeworks, ABS/PPS grid exchangers and heat bridges, which are designed to enhance heattransfer along Z direction, heat transfer among batteries as well as heat transfer betweenbattery stack and the shell of underwater vehicle, respectively, the methods of numericalsimulation and experiment are applied to research temperature and velocity responses todifferent discharging currents of the battery stack.(4) It is studied how heat pipes enhance heat transfer occurring in the battery stack, as well ashow discharging current affects temperature and velocity distributions inside the battery stackbased on a heat transfer enhancement solution of heat pipes. In addition, temperaturedifference among batteries is also concerned.(5) A phase change material (PCM), RT48paraffin, is filled into the battery stack to raise itsequivalent thermal conductivity. In this case, computational research work is implemented toprobe into effects of discharging current on the characteristics of temperature and velocity.(6) Regarding a high volume fraction of air inside the circular battery stack, a compacthexagonal battery stack is designed to raise equivalent thermal conductivity and power output.In addition, numerical simulations are conducted over the hexagonal battery stack based onheat transfer enhancement solution of ABS/PPS battery frameworks to capture features oftemperature and velocity distributed inside the battery stack while it carries out dischargingprocesses at different currents. (7) In similar, RT48paraffin is also filled into the hexagonal battery stack to enhance its heattransfer. Consequently, an expecting temperature drop is represented due to phase change ofRT48paraffin when the discharging processes are implemented over the hexagonal batterystack at diverse currents.In general, it is indicated that the heat transfer enhancement solution on the basis of RT48paraffin phase change takes on an apparent temperature drop as well as relevant temperatureuniformity over the battery stack compared to the heat transfer enhancement solutions byusing ABS/PPS, aluminum-based ABS/PPS battery frameworks, heat bridges, heat pipes,ABS/PPS/aluminum/copper grid exchangers, etc. In addition, the hexagonal battery stackshows inspiring advantages, e.g., lower temperature, higher power output etc., when thecircular battery stack is mentioned for contrast.