8/12/2019 The Natural Ventilation System Study on Electric Vehicle

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The Natural Ventilation System Study On Electric Vehicle

Shouhao Li

School of Transportation and Vehicle Engineering

Shandong University of Technology

Zibo, China

lishouhao@163.com

AbstractThe existing ventilation structure of battery pack of

electric vehicle is studied. analyze the effects of the angel and

installation height of the guide plate at the inlet on air flow.

numerical simulation of cooling structure is made by using the

fluent software.

Keywords:Battery temperature;HEV; CFD

The effect of the temperature on the degreaseperformance is obvious to batteries of electric vehicle [1].Ithas great significance for electric vehicle that the batteryworks in the optimal temperature range. Air-cooled designoften uses for battery cooling. Serial and parallel structure

often uses in Air-cooled system [2].structure of Ventilationdesign has a big difference for the cooling effect.

I. CFD THEORETICALAccording to the fluid theory, the air flow in air duct is

three-dimension problem. Due to the backflow existing in airduct, the k - equations is used [3].

( ) 0D Vx y z

= + + =

(1)

22

22

22

( ) ( ) 1

Re

( ) ( ) 1

Re

( ) ( ) 1

Re

v pu

t x y z x

v v v pv

t x y z y

u v p

t x y z z

+ + + = +

+ + + = +

+ + + = +

(2)

Turbulence viscosity is estimated by formula(3).2

t u

ku C

= (3)

k: Turbulent motion energy : Diffusion speed

uC : constant

Turbulent motion energy and diffusion speed arecalculated by the following formula (4).

1 2

( ) ( )( )

( )( )( ) ( )

j

k

j j j

k uk k P

t x x x

u kC P C P

t x x x k

+ = +

+ = +

Constant value: 1 20.09, 1.44, 1.92UC C C = = =

II. FLOW FIELD SIMULATIONA. Location of data measurement points

The concrete location was shown in F i g .1 .

Figure 1. Schematic diagram of measurement points

Taking duct as research object , the inside dimension is

3 m 0.3 m m. There are Four 10 round hole. The air

can blow to battery box by the four round hole.

B. Grid divisionAfter the creation of a physical mode, the grid division can

be carry out F ig.2 and FIG.3.

Figure 2. Grid division1

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978-1-4577-0536-6/11/$26.00 2011 IEEE

8/12/2019 The Natural Ventilation System Study on Electric Vehicle

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Figure 3. Grid division 2

C. Ssimulation results and analysisThe simulation is conducted in a limited area. The

solution initial condition and boundary conditions should begiven.

It can be considered a not compressed gas when thevelocity less than a third .

The cooling gas imports entrance boundary conditions:

31

5

2

5 , 27 , 1.177

1.568*10

c kgmv Ts m

mvs

= = =

=

Part of cooling air are blocked by the guide plate andflow down when the cooling air import into Battery box.Another part of the cooling air continues to flow backward.The cool air into the battery box eventually outflow from thebattery box export

The simulation result is shown in FIG.3.

Figure 4. Z=0 Simulation result

The air volume will different by the opening Angle andheight differences. The smaller air volume with the openingangle and height differences.

The physical map is shown in FIG.4.

Figure 5. The physical map

III. CONCLUSIONThe angel and installation height of the guide plate at the

inlet on air flow is influenced the air volume to the Batterybox. A reasonable angel and installation height of the guideplate can make it uniformity to different Battery box. Auniformity air flow has great benefit to the temperature of thebattery of HEV. It has great significance to guarantee thebattery charging and discharging cycle efficiency andprolong the service life of the battery system has importantsignificance.

REFERENCES

[1] Li D H ,Yang K,Chen S , et al1 Thermal behavior of overchargednickel/ metal hydride batteries [ J ] 1 J Power Sources , 2008 , 184(2) :622

626.

[2] Ahmad A P1 Battery thermal models for hybrid vehicle simulations [J]1 J Power Sources ,2002 ,110 (2) :377 - 3821

[3] Klas A, Filip J. Process evaluation of all 865MWe lignite firedO2/CO2 power plant [J]. Energy Conversion and Management, 2006,47(18-19): 34873498.

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