Abstract The distribution of current/voltage can be further regulated by optimising the electrical connection topology, considering a particular battery thermal management systems. This study numerically investigates a 4P6S battery module with two connection topologies: 1) a straight connection topology, where the sub-modules consist of parallel-connected cells that are serial connected in a linear configuration, and 2) a parallelogram connection topology, where the sub-modules are serial connected in a parallelogram configuration. We find that the straight topology is more advantageous, as it allows the temperature gradient to be distributed among the parallel-connected cells in the sub-modules, mitigating over(dis)charging. Consequently, it achieves a 0.8% higher effective capacity than the parallelogram topology at 1C discharge, along with a higher state of health at 80.15% compared to 80% for the parallelogram topology. Notably, the straight topology results in a maximum current maldistribution of 0.24C at 1C discharge, which is considered an acceptable trade-off.
The deployment of solar photovoltaics (PV) and electric vehicles (EVs) is continuously increasing during urban energy transition. With the increasing deployment of energy storage, the development of the energy sharing concept and the associated advanced controls, the conventional solar mobility model (i.e., solar-to-vehicles (S2V), using solar energy in a different location) and context are becoming less compatible and limited for future scenarios. For instance, energy sharing within a building cluster enables buildings to share surplus PV power generation with other buildings of insufficient PV power generation, thereby improving the overall PV power utilization and reducing the grid power dependence. However, such energy sharing techniques are not considered in the conventional solar mobility models, which limits the potential for performance improvements. Therefore, this study conducts a systematic review of solar mobility-related studies as well as the newly developed energy concepts and techniques. Based on the review, this study extends the conventional solar mobility scope from S2V to solar-to-buildings, vehicles and storage (S2BVS). A detailed modeling of each sub-system in the S2BVS model and related advanced controls are presented, and the research gaps that need future investigation for promoting solar mobility are identified. The aim is to provide an up-to-date review of the existing studies related to solar mobility to decision makers, so as to help enhance solar power utilization, reduce buildings’ and EVs’ dependence and impacts on the power grid, as well as carbon emissions.
Flat plate Loop Heat Pipes (LHPs) have emerged as an attractive battery thermal management system (BTMS) as they allow long-distance heat transfer at no power cost due to their unique porous structure. Additionally, the flat contacting surface is suitable for end cooling in cylindrical cells due to the higher axial thermal conductivity of the jelly roll structure. Previous studies on LHP BTMS have mainly focused on the cooling performance of prismatic or pouch cells, without considering cell ageing. This study instead numerically investigates the cooling performance, the resulting current distribution, and the ageing of a 6S4P 18650 battery module equipped with LHPs BTMS, comparing the performance against a natural air convection BTMS. This study has taken various thicknesses of the heat collector plate (i.e. 0.5 mm, 1 mm, 2 mm and 3 mm) and the number of LHPs (i.e. 1 or 2) into consideration. The results indicate that utilising a single LHP in conjunction with a 2 mm thick heat collector plate emerges as the optimal configuration. This design achieves a maximum average temperature of 29.7 °C and a minimal temperature gradient of 0.02 °C under a 1C discharge condition. The proposed design also significantly enhances battery lifespan, reaching up to 310 cycles with a maximum ageing gradient of 0.005, compared to the 146 cycles and 0.04 ageing gradient observed for the module with natural air convection. This study presents the potential of LHP BTMS for future electric vehicles, demonstrating its superior effectiveness in enhancing battery performance and longevity.
A combined power and cooling system is proposed for cogeneration, which integrates the ejector cooling cycle with the Rankine cycle. Low-temperature heat source such as industrial waste heat or solar energy can be used to drive the Rankine cycle. This system will provide electricity and cooling effect simultaneously without consuming primary energy. The partially expanded vapor (from low-grade energy) will be bleed off and enter into ejector's primary nozzle, which achieves cooling effect. Simulations have been carried out to analyze the effects of various working conditions on the overall system performance, on ejector entrainment ratio and turbine power output. Five different refrigerants HFE7100, HFE7000, methanol, ethanol and water have been selected, and the above three parameters were compared, respectively. The simulation results indicated that turbine expansion ratio, heat source temperature, condenser temperature and evaporator temperature play significant roles on the turbine power output, ejector entrainment ratio and the overall thermal efficiency of the system. At a heat source temperature of 120°C, evaporator temperature of 10°C and condenser temperature of 35°C, methanol showed the highest thermal efficiency (0.195), followed by ethanol and water (0.173). It is recommended that the evaporator temperature and the appropriate working fluid should be selected according to the different working cooling requirements, and the turbine power output can then be determined accordingly.
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