بررسي دوبعدي انتقال حرارت و شكل محفظه هاي حاوي PCM جهت خنك كاري باتري هاي ليتيومي

چكيده انگليسي :

Two Dimensional Studies of Heat Transfer and Profile of PCM Enclosures Used for Lithium ion Battery Cooling Atefeh Baradaran Naghshine a baradarannaghshine@me iut ac ir January 21th 2013 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Ebrahim Shirani eshirani@cc iut ac ir Abstract In recent years thermal management of Lithium ion batteries has been taken into consideration due to their high heat generation rate Passive thermal management systems using Phase Change Materials PCM can control the temperature excursions and maintain temperature uniformity in Li ion batteries without using active cooling These materials are widely used for cooling electrical elements and batteries In this project the mechanism of heat transfer material properties convection coefficient and ambient temperature are studied To understand the effect of each property on cooling models with different properties this project The most effective one is conductivity When the amount of this property exceed from 1 are simulated The heat capacity the thermal heat conductivity coefficient and latent heat of PCM are studied in PCM can control the temperature during melting process After that the amount of latent heat increase the time duration of melting and absorb more energy form battery for constant volume of PCM The results of simulation with various heat capacities almost similar The results show this property is not effective as that of conductivity or latent heat adiabatic to convection coefficient equal to 30 was simulated and subsequent simulations in this For understanding the effect of air convection coefficient on cooling a model with various coefficients from work were performed using 10 The rectangular trapezius quadratic and three part quadratic profiles are tried to find the best one The criterion for choosing best profile was the maximum temperature of system Also in each simulation the percentage of liquid fraction has been considered for comparison At first one volume for PCM must be chosen and during changing the profile this amount must be fixed For rectangular profile the thickness of PCM in side edges change and subsequently the upper edge change In these simulations PCM in upper corner of enclosure melt in final moments So the trapezius profile was selected and simulations with fix volume have been performed Then the quadratic profiles were selected The results of these simulations did not produce appropriate maximum temperature So the three part quadratic profile chose for next step This profile was like trapezius one with quadratic edges These simulations had better results All of these simulations have been done for two materials with different properties It could be seen that in low conductive materials PCM must be placed monotonous around battery But for materials such as graphite composite with high conductivity it s better to place more PCM around adiabatic boundary In the end modeling of PCM with variable properties relative to temperature has been taken In this model convection heat transfer has been considered and contour of velocity density have been display Because of considering convection heat transfer this model obtains more suitable thermal performance with lower temperature Key Words Thermal management Phase Change Material PCM Suitable profile Lithium ion battery

برادران نقشينه، عاطفه

بررسي دوبعدي انتقال حرارت و شكل محفظه هاي حاوي PCM جهت خنك كاري باتري هاي ليتيومي

كنترل گرمايي , مواد با قابليت تغيير فاز , پروفيل مناسب