No abstract

Recently, quadrotor-based drones have attracted a lot of attention because of their versatility, which makes them an ideal medium for a variety of applications, e.g., personal photography, surveillance, and the delivery of lightweight packages. The flight duration of a drone is limited by its battery capacity. Increasing the payload capacity of a drone requires more current to be supplied by the battery onboard a drone. Elevated currents through a Li-ion battery can increase the battery temperature, thus posing a significant risk of fire or explosion. Li-ion batteries are suited for drone applications, due to their high energy density. There have been attempts to use hydrogen fuel cells onboard drones. Fuel cell stacks and fuel tank assemblies can have a high energy to weight ratio. So, they may be able to power long duration drone flights, but such fuel cell stacks and associated systems, are usually extremely expensive. Hence, this work proposes the novel use of a less expensive, low capacity, metal hydride fuel stick-powered fuel cell stack as an auxiliary power supply onboard a drone. A primary advantage of this is that the fuel sticks can be used to cool the batteries, and a side effect is that this slightly reduces the burden on the onboard Li-ion battery and provides a small increment in flight time. This work presents the results of an experimental study which shows the primary effect (i.e., decrease in battery temperature) and the secondary side effect (i.e., a small increment in flight time) obtained by using a fuel cell stack. In this work, a metal hydride fuel stick powered hydrogen fuel cell is used along with a Li-ion battery onboard a drone.

This study aims to develop several different models of heatsinks, designed to cool a vertical take-off and landing unmanned aerial vehicle (UAV) battery, through topology optimization, aimed at being manufactured through selective laser melting (SLM) technology. A battery’s temperature must be properly managed for a safe and efficient operation. The methodology developed was with the support of software to carry out several simulations which, starting from several scenarios and restrictions imposed by the small space available to accommodate these small batteries in this type of aircraft. The conception resulted in several battery thermal management systems (BTMS) models, with different applications and efficiency degrees. A relevant aspect is the topology optimization being coupled to computational thermal analysis to reduce the mass of the heatsink whilst ensuring a maximum battery temperature threshold. Together with the use of topology optimization, the SLM process was selected to manufacture the heat sinks, under conditions of geometric freedom, using several high thermal conductivity metal alloys, such as, aluminium and copper to obtain the designed models.