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The electric vehicles are not completely emission-free. The vehicles consume power and the power generation processes involve carbon emissions, resulting in indirect vehicle usage carbon emissions. A use-phase carbon emissions assessment can help electric vehicle designers and manufacturers analyze the onboard carbon footprint and mitigate vehicle-related carbon emissions through energy consumption optimization. In this article, we focus on the use-phase carbon footprint based on the energy losses in electric vehicle battery packs. A battery pack energy loss model is established to examine the carbon footprint of four main subsystems of the battery pack, including the energy storage system, thermal management system, and battery junction box. We use the proposed method to evaluate the battery pack use-phase carbon emissions in four different cities from four main continents. The results show that the highest emissions appear in Tokyo (436.2 kgCO 2) due to the relatively high greenhouse gas factor on the grid, the London has the lowest 207.5 kgCO 2 emissions due to the massive adoption of sustainable energy during power generation. With a similar high greenhouse gas factor, but Sydney shows lower emissions (347.5 kgCO 2) compared to Tokyo, which illustrates the closer the annual average temperature to the battery suitable operation range, the lower energy loss happens inside the battery pack due to the low thermal management load and resistance energy loss in the cells. This electric vehicle has the highest energy loss rate (20.8%) in New York, 343.6 kgCO 2 emissions, and the highest thermal management system energy losses show the high seasonal temperature difference causing the high thermal management load to maintain the battery temperature. The proposed method can be used for different battery pack configurations and vehicle uses, providing researchers with a robust and versatile use-phase carbon emissions assessment strategy. • A battery pack use-phase carbon footprint assessment strategy is proposed. • The carbon emissions for four battery pack subsystems are calculated. • Temperature has the greatest impact on the battery pack carbon emissions. [ABSTRACT FROM AUTHOR]

A battery pack is the main energy storage element, and directly affects the performance of an electric vehicle. Battery thermal management system research and its development for a modern electric vehicle is required. This paper selects the forced air cooling of battery pack as the research object, and uses simulation methods to research the heat dissipation performance with different structures of battery packs. The results indicate that according to the four types of transient state conditions, the rising temperature of both battery packs are significantly higher than the temperature difference, the maximum temperature rise and temperature difference of a horizontal battery pack are lower than a longitudinal battery pack. When an electric vehicle begins to decrease speed, the curves of temperature rising and temperature difference increase. This shows the internal heat is continuously rising, so even in a electric vehicle beginning to decrease speed, the fan must work. The reference basis for choosing battery pack type and an analysis of heat flow field characteristics, including fan run-time control, are offered. [ABSTRACT FROM AUTHOR]

This paper reviews the heat dissipation performance of battery pack with different structures (including: longitudinal battery pack, horizontal battery pack, and changing the position of air-inlet and air-outlet) and operation conditions (including: SOC state, charge and discharge rate, and practical operation condition), and finally arrives at the conclusions as follows: the average thermal power of 55Ah lithium-ion battery monomer decreases along with environment temperature rising, SOC state decreasing and charge and discharge rate falling; the maximum temperature rising and temperature difference of battery pack are not only relevant to the flow rate, but also related to the airflow duct structure, the battery pack with air-inlets on both sides is more conducive to the forced air cooling; the flow rate of battery pack at 70% SOC state is maximum, the maximum temperature rising and temperature difference of battery pack at 70% SOC state are minimum, and that of 90% SOC state are maximum; the flow rate and the average pressure drop between air-inlet and air-outlet both decrease along with charge and discharge rate increasing, but the maximum temperature rising and temperature difference of battery pack increase; as considering the practical operation condition of battery pack, the charge and discharge rate is between 0.5C and 0.8C, and the maximum temperature rising and maximum temperature difference of battery pack are 7.61°C and 4.29°C. Then the reference basis for heat flow field characteristic analysis and structure design of battery pack are offered. [ABSTRACT FROM AUTHOR]

Abstract: Electric vehicle cooling modes are divided into air cooling, liquid cooling and phase change material cooling, the air cooling is divided into natural air cooling and forced air cooling. This paper selects the forced air cooling as the study object, and researches the heat dissipation performance of different airflow duct modes, the results indicated that: as considering that changing the longitudinal battery pack into horizontal battery pack, it could improve the heat dissipation performance by shorting airflow path; it increases the contact area for thermal conduction by adding bottom duct, and the area of battery pack top exists natural convection, so the heat dissipation performance of bottom duct mode is more superior; for battery pack with bottom duct mode, it uses the double “U” type duct instead of double “1” type duct in order to improve the heat dissipation performance; when the heat dissipation condition is poor, it could reduce the SOC state or charge & discharge rate to satisfy the heat dissipation performance requirements; as considering the practical operation condition of battery pack with double “U” type duct, it has a large margin of high charge and discharge rate to meet the needs of electric vehicle acceleration or deceleration operation. [Copyright &y& Elsevier]

Aiming at some models of electric vehicles without battery pack cooling device recently appeared on vehicle market, a feasibility analysis on electric vehicles without battery pack cooling device is conducted in this paper by both measurement test and model simulation on an EV with lithium iron phosphate battery but no cooling device currently in operation. The analysis leads to a conclusion that at the early operation stage of EV, due to small internal resistance and large heat capacity there is not much temperature rise in battery pack so if suitable initial temperature is assured (in particular with battery pack exchange mode) the battery pack can work without cooling device; However with the aging of battery, the internal resistance of battery greatly increases resulting in significant temperature rise, the heat dissipation of battery pack should be considered. [ABSTRACT FROM AUTHOR]