Evaluation of Dual Side Cooling System for Prismatic Batteries for Vehicle Aplications

Today lithium-ion stands out among the various battery technologies in vehicle applications thanks to their good energy density, low self-discharge and the absence of the memory effect. Nevertheless, lithium-ion batteries pose many challenges such as driving range, lifespan, safety issues and also the charging time which is still significant. In order to reduce the charging time, it is necessary to inject a very high current into the battery which may drastically raise its temperature and thus reduce its lifespan. Today, in most cases, the battery pack of an electric vehicle is cooled through flat cooling plates, mounted either by the lateral or the bottom surfaces. These cooling plates can also be used to warm up the battery in cold weather. But during the fast charge, this configuration poses some problems and can be not efficient enough to cool or heat the batteries. In this study, a battery module is thermally managed not only by the bottom cooling plate but also by a second cooling plate placed on the busbars. According to simulations and experimental tests regarding one case study, this configuration makes it possible to not only cool the module more quickly by reducing the thermal time constant by 47% but also reduces the battery maximum pick temperature reached with a conventional cooling system by 6°C. It stands out that the top cooling plate acts like a thermal bridge which unifies the temperature inside the battery module and thus support the equal ageing process of the batteries

Temperature Sensor Based on Periodically Tapered Optical Fibers

In this paper, the fabrication and characterization of a temperature sensor based on periodically tapered optical fibers (PTOF) are presented. The relation between the geometry of the sensors and sensing ability was investigated in order to find the relatively simple structure of a sensor. Four types of PTOF structures with two, four, six and eight waists were manufactured with the fusion splicer. For each PTOF type, the theoretical free spectral range (FSR) was calculated and compared with measurements. The experiments were conducted for a temperature range of 20–70 °C. The results proved that the number of the tapered regions in PTOF is crucial, because some of the investigated structures did not exhibit the temperature response. The interference occurring inside the structures with two and four waists was found be too weak and, therefore, the transmission dip was hardly visible. We proved that sensors with a low number of tapered regions cannot be considered as a temperature sensor. Sufficiently more valuable results were obtained for the last two types of PTOF, where the sensor’s sensitivity was equal to 0.07 dB/°C with an excellent linear fitting (R2 > 0.99). The transmission dip shift can be described by a linear function (R2 > 0.97) with a slope α > 0.39 nm/°C

Temperature Sensor Based on Periodically Tapered Optical Fibers

In this paper, the fabrication and characterization of a temperature sensor based on periodically tapered optical fibers (PTOF) are presented. The relation between the geometry of the sensors and sensing ability was investigated in order to find the relatively simple structure of a sensor. Four types of PTOF structures with two, four, six and eight waists were manufactured with the fusion splicer. For each PTOF type, the theoretical free spectral range (FSR) was calculated and compared with measurements. The experiments were conducted for a temperature range of 20–70 °C. The results proved that the number of the tapered regions in PTOF is crucial, because some of the investigated structures did not exhibit the temperature response. The interference occurring inside the structures with two and four waists was found be too weak and, therefore, the transmission dip was hardly visible. We proved that sensors with a low number of tapered regions cannot be considered as a temperature sensor. Sufficiently more valuable results were obtained for the last two types of PTOF, where the sensor’s sensitivity was equal to 0.07 dB/°C with an excellent linear fitting (R2 > 0.99). The transmission dip shift can be described by a linear function (R2 > 0.97) with a slope α > 0.39 nm/°C