• Energy Research

Abstract Recent advancement in the micro-scale and nano-scale electronics systems, the demand of an innovative solution for the thermal management to dissipate the high amount of heat flux generated have become more rigorous to ensure good reliability of the devices. Micro-channel heat sink has been introduced to dissipate the heat flux with capacity of 10 MW m−2, which providing an ideal solution in the thermal management technology. Researches have been done experimentally or numerically to investigate effect of different geometric designs of micro-channel heat sinks to promote better heat transfer between micro-channel walls and cooling fluid. Other than micro-channel geometric design, type of cooling fluids and two-phase flow boiling are important issues in the micro-channel based thermal management system. In addition, applications of nano-fluids in the micro-channel heat sink are also highlighted which helps in improving the thermal conductivity of the coolant and leads to better heat dissipation rate. In addition, applications of micro-channel in the engineering sector such as solar cell, fuel cell and medical devices are reviewed. For the literature, implementation of micro-channel in the electronic devices as a thermal management solution is highly recommended due to its ability to protect and prolong the lifespan of electronic devices.

Abstract Electric vehicle (EV) has been steadily gaining attention and as a viable alternative to mitigate pressing global energy crisis and environmental issues caused by conventional internal combustion engine vehicles. Nonetheless, the dynamic operation of EV encompassing high charging and discharging currents generated from regenerative braking and acceleration, respectively, may adversely affect the cycle life of the conventional energy storage system. Hence, incorporation of supercapacitors into the energy storage system is recommended in view of its superior cycle efficiency and high power density, which aids in relieving the battery’s stress and thus extends its cycle life. In this study, a hybrid energy storage system (HESS) comprising Li-ion batteries and supercapacitors are modeled to evaluate its electrical and thermal performances under different driving cycles. The results obtained reveal that the dynamic stress, peak power demand and thermal performance of the battery have been significantly improved by incorporating supercapacitors into the battery pack in HESS. In comparison with the conventional battery energy storage system, the peak current demands of the battery in HESS for UDDS and US06 cycles have been reduced by 63%, 72.9% and 71.7%, respectively. This approach has shown to be effective in extending the battery’s lifespan and is able to improve the safety and reliability of the conventional battery energy storage system.

Abstract Temperature is one of the factors which affect the power availability, driveability and durability of the battery pack. Folded fin and serpentine channel are commonly used to provide cooling for the battery pack. During the cooling process, fluid absorbed the heat generated along the flow direction and caused the reduction of the cooling capacity. Hence, downstream temperature is always higher than the upstream temperature. Inconsistent cooling effect will lead to high variation of temperature distribution and shorten the life expectancy of the battery pack. In this study, a battery module consists of three pieces of LiFePO4 pouch cell arranged side by side, and aluminium foam is sandwiched between two heat spreaders to form a cooling plate. Aluminium foams with different porosity and pores density were modelled to investigate the thermal performance and flow field numerically. Correlation of Nusselt number, permeability and resistance loss coefficient from the literature was extracted and used in the CFD simulation. From the simulation results, it is shown that 10 PPI aluminium foam with 0.918 porosity offered the highest thermal performance and lowest flow resistance. Hence, the optimized aluminium foam cooling plate can be used as a new type of cooling system for the battery pack.

Abstract This piece of research presents the capability of active and passive cool roof systems, which is designed to reduce the heat transmission into an attic through the metal deck roofing for industrial buildings in Malaysia. In this study, an ideal cool roof system focusing on utilizing solar energy, cavity ventilation and thermal reflective coating (TRC) were employed and investigated. This technique is one of the most innovative and sustainable practices at reducing the energy consumption that provide buildings with comfortable indoor conditions through natural means. The four cool roof models were designed and built in active and passive systems to examine the effect of attic temperature reduction. Application of TRC can significantly reduce the heat absorption of the metal roof. The roof and attic temperatures of the roof models were measured to determine the performance of cool roof system. The roof design (d) results indicate a great reduction at about 15 °C in the attic air temperature compared to normal roof. The outstanding performance is due to the cool roof system that integrated TRC, improved moving air cavity (MAC)-solar powered fans and opened attic inlet comprise the ability to reflect the sunlight and circulate the hot air efficiently.