Fuel cells in unmanned aircraft

This project investigates the implementation of a fuel cell into a small unmanned aerial vehicle. Small model aircraft are used around the world by hobbyists for pleasure and creating home videos. Currently these aircraft are a excellent solution for many commercial applications; land surveying, search and rescue, police surveillance, border control and recently in the news for the Army. However, these aircraft can only fly for a fraction of an hour, and then require a length battery recharge, or for many spare batteries to be carried. A fuel cell offers a far greater endurance than any battery whilst still maintaining low weight. It is anticipated that a fuel cell for the aircraft in this project will last for six to ten hours, and is very quick and easy to refuel, and requires no recharging at all

An electric vehicle model and validation using a Nissan Leaf: a Python-based object-oriented programming approach

Electric vehicles are becoming more and more prevalent, especially with major manufacturers announcing that they will be focusing on electric or hybrid vehicles in the future. This article describes an object-oriented approach to a vehicle model using Python 3. This approach allows for flexibility of vehicle design. The key parameters were input to define the specific vehicle for validation, in this case a Nissan Leaf. It is anticipated that this flexibility will lead to rapid exploratory design of vehicle variants, such as four-wheel drive, independent wheel drive and multiple electrical sources. The model had its objects individually validated before the whole vehicle was verified against common drive cycles and a real-world drive in the United Kingdom recorded using an On-board Diagnostics (OBD2) Bluetooth dongle

Modelling of distributed time constants in carbon based supercapacitors

Modelling of distributed time constants in carbon based supercapacitor

Testing microtubular SOFCs in unmanned air vehicles (UAVs)

Unmanned Air Vehicles (UAVs) powered by microtubular SOFCs (mSOFCs) are described for comparison with polymer fuel cells (PEFCs). Using propane as fuel, 7mm diameter mSOFCs have been tested in a 2m wingspan aircraft with a total weight of 6kg. The start-up time was 12 minutes to deliver 250W in a fuel cell/battery hybrid drive system. Tubes were YSZ cermet anode supported, with 10 µm YSZ electrolyte, 6µm SDC interlayer coated with 50µm LSCF cathode. Silver wires were used as interconnects. Pure propane fuel gas was mixed with air in a CPOX reactor using catalytic fuel processing mesh. A polymeric fuel inlet manifold gave cold sealing at the tube inlet ends which projected out of the hot box. Cathode air was provided in counterflow, preheated over an anode off-gas catalyst. The fuel utilization was 55%, output power of 250W. The fuel cell was incorporated in a hybrid electrical system with lithium polymer battery and inserted in a Skywalker X8 UAV with 500g of propane in an aluminum tank

The modelling of carbon-based supercapacitors: distributions of time constants and Pascal Equivalent Circuits

Supercapacitors are an emerging technology with applications in pulse power, motive power, and energy storage. However, their carbon electrodes show a variety of non-ideal behaviours that have so far eluded explanation. These include Voltage Decay after charging, Voltage Rebound after discharging, and Dispersed Kinetics at long times. In the present work, we establish that a vertical ladder network of RC components can reproduce all these puzzling phenomena. Both software and hardware realizations of the network are described. In general, porous carbon electrodes contain random distributions of resistance R and capacitance C, with a wider spread of log R values than log C values. To understand what this implies, a simplified model is developed in which log R is treated as a Gaussian random variable while log C is treated as a constant. From this model, a new family of equivalent circuits is developed in which the continuous distribution of log R values is replaced by a discrete set of log R values drawn from a geometric series. We call these Pascal Equivalent Circuits. Their behaviour is shown to resemble closely that of real supercapacitors. The results confirm that distributions of RC time constants dominate the behaviour of real supercapacitors

Powerpath controller for fuel cell & battery hybridisation

AbstractProton Exchange Membrane (PEM) fuel cells are a chemically fuelled power supply which generally have a higher energy density than Lithium-Polymer Battery (LIPOs) but a much lower power density. In order for PEM fuel cells to increase the endurance of an in-service battery power supply, without decreasing the peak power, it should be hybridised with a battery. It is key for the market that the overall switch to hybrid technology is low cost in terms of size, weight and money.Hybrid technology tends to be generically designed to suit any power system, using regulators to ensure voltage matching, and diodes to control the direction of electrical flow. Many electric motors are controlled by speed controllers which can regulate the thrust provided by the motor, accounting for fluctuations in voltage usually found in a depleting battery. Using diode and regulator based hybrids for electric motor applications is therefore inherently inefficient even if complicated synchronous DC–DC converters are used due to the increased cost, size and weight.This paper demonstrates the ability to use ideal diodes to control the flow of electricity through the hybrid and that voltage regulation is not needed for a motor in this case. Furthermore, this paper explores the natural balancing strategy created by duty cycling the PEM fuel cell to different points within it's polarisation curve, removing the requirement for DC–DC converters to match it to the battery voltage. The changes made improve the efficiency of the hybrid power electronics to over 97%

Fuel cell hybrid unmanned aerial vehicle

Fuel cell hybrid unmanned aerial vehicl

Powerpath controller for a fuel cell and battery

Powerpath controller for a fuel cell and batter

LU-X8SH UAS Testing

A hydrogen fuel cell is a device that converts hydrogen gas & air into electricity and water. Although these devices are much lower power density than batteries, they can pump out that power for many hours, depending on the amount of fuel you are storing. At Loughborough University, UK, we are working on a fuel cell and LiPo hybrid, to give you the oompf for take off (and go-arounds!) and the long endurance for cruise and loiter. The base aircraft is the Skywalker X8, modified to carry considerably more weight than it is designed for (currently 4.5kg all up, and pushing towards 6kg with more testing). This video briefly explains the platform setup, shows a video using ArduPilot's autonomous take-off, and concludes with a short 4.5kg flight. In the coming weeks look forward to videos of the payload approaching 6kg, and the fuel cell being connected properly and providing some of the power

Testing Micro-Tubular SOFCs in Unmanned Air Vehicles (UAVs)

This article was published in the journal, ECS Transactions [© ECS - The Electrochemical Society].Unmanned Air Vehicles (UAVs) powered by microtubular SOFCs (mSOFCs) are described for comparison with polymer fuel cells (PEFCs). Using propane as fuel, 7mm diameter mSOFCs have been tested in a 2m wingspan aircraft with a total weight of 6kg. The start-up time was 12 minutes to deliver 250W in a fuel cell/battery hybrid drive system. Tubes were YSZ cermet anode supported, with 10 µm YSZ electrolyte, 6µm SDC interlayer coated with 50µm LSCF cathode. Silver wires were used as interconnects. Pure propane fuel gas was mixed with air in a CPOX reactor using catalytic fuel processing mesh. A polymeric fuel inlet manifold gave cold sealing at the tube inlet ends which projected out of the hot box. Cathode air was provided in counterflow, preheated over an anode off-gas catalyst. The fuel utilization was 55%, output power of 250W. The fuel cell was incorporated in a hybrid electrical system with lithium polymer battery and inserted in a Skywalker X8 UAV with 500g of propane in an aluminum tank