The energy generated by an electric vehicle battery (EV) will determine its overall driving performance as well as its accelerating rate. The charging and discharging cycle rate of the battery will be one of the main factors in determining the efficiency of the electric vehicle. Upon engagement in the “Green Mobility Challenge”, Universiti Malaysia Perlishas been striving on maximizing the performance of the EV’s battery, specifically on the Battery Thermal Management System (BTMS). The optimum range of battery operating temperature (lithium-ion) is between 25 ~ 35 ˚C. The increase of battery temperature during operation would significantly reduce the performance coefficient and cycle lifetime of the battery and lead to an increase in running costs of the electric vehicle. To maintain battery operation within the recommended temperature range, a cost effective and high efficiency cooling system (i.e. liquid cooling system that uses either base fluid or nanofluid) must be used at the battery compartment. This cooling system is essential in improving heat dissipation loads from the battery to the surrounding.Nanofluids, with diameter less than 100 nm) are engineered as a colloidal suspension of nanoparticles in base fluid. Stability of nanofluids is the main factor in improvingperformance of the cooling system by homogeneously suspending nanoparticles in the base fluid. In this study, a two-step technique is used to produce nanofluids. Due to safety reasons, the original battery cannot be used because the possibilities of happing electric shock are high. Therefore, a hot water tank that has similar heat load and surface temperature as the battery are used to simulate the heat transfer process in the one battery compartment to the heat exchanger. The surface temperature and heat load during the experiments were set to 40 °C and is 82 W respectively. The heat exchanger consists of two helical tubes made from copper and seven loops for each tube. With the aim to maintain the battery surface temperature at a safe range, this study analyses the influence of base fluid (deionized water) and nanofluid (CuO/deionized water and Al₂O₃/deionized water) in improving the heat transfer performance between the hot water tank and heat exchanger. The battery surface temperature showed greater improvement with nanofluid as working fluid, compared to deionized water under fully developed laminar conditions (Re < 2300) and constant surface heat flux boundary condition. In addition, this study also focuses on the comparison of thermophysical properties between nanofluids with different concentration and surfactant against the deionized water. The influence of theworking fluids’ flow rate (0.5, 0.8 and 1 ℓ/min) are also considered in this investigation. The nanofluids were prepared with the addition of 5 g, 10 g and 25 g of copper oxide (CuO) with 40 nm and 80 nm sizes, and also aluminum oxide (Al₂O₃) with 80 nm nanoparticle size, into 1 litre of deionized water. It has been observed that 0.40 % volume concentration of CuO (40nm) with 10 g surfactant nanofluid and 1 ℓ/min flow rate gives the highest heat transfer rate value at 53 %, 4.5 % and 6.6 % when compared to deionized water, Al₂O₃ (80 nm) with 10 g surfactant (sodium dodecyl sulfate (SDS)) nanofluid and CuO (80 nm) with 10 g surfactant nanofluid respectively. Also, 24 hours of ultra-sonication time was found to be the optimal duration in the presence of surfactant(SDS), where it provides best stability and improved thermal conductivity by reducing aggregation within the nanoparticle
