Computational investigations of battery thermal management system with environmental effects employing a combination of phase change materials and forced air cooling

ABSTRACT

The thermal management system of battery pack was investigated based on the combination of two different phase change materials OM35 and Paraffin wax coupled with forced air cooling to maintain the thermal distribution in the battery pack at a discharge rate of 1C. Numerical investigations were carried out by computational fluid dynamics (CFD) to understand the effects of battery thermal characteristics on environmental conditions in different cities of India. Furthermore, the thermal behavior of the system in an active and passive cooling was analyzed. The result indicates that active cooling can reduce the temperature rise in the battery pack by 2.8°C in the discharge cycle. The above studies identified active cooling not always required when the vehicle speed increases above 40 km/h. Environmental conditions during summer have a significant impact on the temperature rise in the battery pack.

KEYWORDS:

• Environmental effects
• air cooling
• phase change material
• active cooling
• passive cooling

Nomenclature

D	=	Hydraulic diameter
H	=	Specific enthalpy pf the PCM
$k_{\rho }$	=	Thermal conductivity of the PCM.
Qconv	=	Heat convected per unit volume, W/m3
Qgen	=	Heat generated in the battery per unit volume, W/m3
Qskin	=	Heat dissipated from the battery skin per unit volume, W/m3
Re	=	Reynolds Number
Tref	=	Reference temperature, oC
U	=	Air flow velocity
$U_{max}$	=	Maximum velocity
y	=	Distance to the near wall
Greek symbols	=
$\mu$	=	Dynamic viscosity, Pa.s
${\rho }_p$	=	Density of the PCM
${\rho }_f$	=	Density of the fluid
$\rho$	=	Density, kg/m3
${\mu }_f$	=	Dynamic viscosity of the fluid
$\overrightarrow{u}$	=	Velocity vector, m/s
$\mathrm{\nabla }$	=	Operator
$\vartheta$	=	Local kinematic viscosity,
${\tau }_w$	=	Wall shear stress
Subscripts	=
conv	=	Convective
gen	=	Generation
f	=	Fluid
max	=	maximum
ᵖ	=	Phase change material
ref	=	Reference
Skin	=	Battery skin of the cell
w	=	Wall
Acronyms	=
CLOUD	=	Cloud cover, tenths
ELEV	=	Elevation of Target above Sea Level, Meters
PAIR	=	Barometric Pressure, Millibars
RHUM	=	Relative Humidity in, %
TAIR	=	Air Temperature, °C
WIND DIR	=	Wind Direction (from North to East), Degrees
WIND SPD	=	Wind Speed, Knots
Abbreviations	=
BTMS	=	Battery Thermal Management System
BMS	=	Battery Management System
CFD	=	Computational Fluid Dynamics
CPCM	=	Composite Phase Change Material
ECM	=	Equivalent Circuit Model
EG	=	Expanded Graphite
EV	=	Electric Vehicle
HEV	=	Hybrid Electric Vehicle
LDPE	=	Low-Density Polyethylene
OCV	=	Open Circuit Voltage
PCM	=	Phase Change Material
SOC	=	State of Charge