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4 Posts authored by: howroyd

Hydrogen Fuel Cell Bench Test Rig

 

Background:

Hydrogen Fuel Cells!

Hydrogen Fuel Cell Controller Demonstration

Hydrogen Fuel Cell Polarisation Curve

You may have seen some previous posts (above) about my developmental test rig for hydrogen fuel cells.  Well I am pleased to say it has now finished the final stage of prototyping!

 

I have released the code on github and have tried to make it as user friendly as possible, however I would really appreciate some feedback! Even if you do not have a fuel cell, you can still run the code with an AdcPiV2 and a PiFaceDigitalIO; although it won't do a lot but you can check out the user interface!!  All code is in Python3 so pretty easy to work with.

 

Obviously this is a very specific project which many people cannot replicate however I thought it would be cool to show the hobbyist community that the rPi is being used in research as such an awesome solution to the rapid prototyping of electronics and control. In my opinion, the reason that the rPi is more popular in my area that BB and the like is the community support. If we can't figure out how to do something then the forums are awash with people wanting to help.  Many thanks to all of you!

 

Graphs:

Among the millions of graphs I have, here are a couple of ones that illustrate some stuff you may find interesting:

1. On the left, the profile is the "power demand." As you can see the fuel cell is slow to respond to demand, which is expected. More interestingly, the green "Raspi" line is the attopilot90 current and voltage sensor hooked up to an AdcPiV2, and the load bank is a `mucho expensivo' calibrated research device.  Looking pretty good for the rPi!

2. On the right is a similar graph but with mass flow rate of hydrogen.  This is calculated from a 0-5v analogue signal from a sensor, being fed into an Arduino 2560, which is then connected to the rPi over I2C.  I have also included a dynamic purge controller, hence the quicker reaction time.

6-hot2.pngFC Non regular use.png

 

Rig:

Here is the messy entanglement of wires which is the prototype rig.  Soon to be condensed down into a single rPi board which will plop straight onto the GPIO header.

2014-08-22 10.56.40.jpg2014-08-22 10.56.46.jpg

 

 

Hope you found this interesting and a bit different!

 

Simon

________________________________

Low Carbon Technologies Group

Aeronautical & Automotive Engineering

Loughborough University

United Kingdom

Hi all,

 

The latest update on my project for the chemical engineering nerds out there, how to get a polarisation curve from my fuel cell using a raspberryPi controller.

 

Unlike batteries, fuel cells do not lose voltage with time because you can keep feeding it fuel. Much like a car engine keeps working until the fuel is completely gone, whereas a battery has a gradual reduction in it's output with respect to it's state of charge (SOC). However, the voltage does vary with load, and this relationship is captured in a polarisation curve.

 

Hope you find the video interesting and inspiring, if so please click LIKE!

 

Regards,

 

Simon

 

Hi all,

 

The latest update on my project; using the raspberryPi as a controller for a hydrogen fuel cell with the intent on powering a remote controlled plane.

 

Hope you find the video interesting and inspiring, if so please click LIKE!

 

Regards,

 

Simon

 

howroyd

Hydrogen Fuel Cells!

Posted by howroyd Dec 2, 2013

Hydrogen fuel cells (in particular PEMFCs) are an exciting technology which has been around for a while now. Unfortunately, they haven't really take off (excuse the pun) due to their high cost, poor lifetime and slow transient performance.

 

1. So why are people still interested?

 

Well, firstly you have the good old "clean & green" argument. In operation, the take in oxygen (from the air) and hydrogen (the fuel), and give out heat, water and electricity. No carbon dioxide, monoxide, sulfides and other nasty things.

Secondly, they're not dependent on fossil fuels to run, and are currently the most promising energy generation technology that is independent of the elements (wind, solar, etc).

Hydrogen has a superb energy density, meaning not much weight gives you a huge endurance.

Fuel cells tend to have no moving parts, unless the have a cooling fan or air supply fan, so they are mechanically very simple.


2. So why aren't we using them?

 

They require platinum as a catalyst so make the chemical reactions work. Platinum is incredibly expensive, and more annoyingly it tends to be washed away over time which reduces the fuel cells lifespan.

They are slow to respond, so cruising along at 10% power, then suddenly demanding a full 100% may take anything from seconds, to minutes, to hours, depending on the type of fuel cell. This proves a big challenge in mechanical transport, such as planes, and cars.

Hydrogen is a pain in the rear, generally. To produce the high quantities we need, we can only do it (cost-effectively) by burning fossil fuels. Of course it can be generated using renewables (wind, solar, etc), but this is far too expensive at the moment for the industry to consider.

Hydrogen also is a pain to store. Because there are so few molecules in such a large amount of space (low density), you have to store it at tremendous pressures to get a usable quantity, which requires huge storage tanks. Not particularly practical in transport applications. There are other methods, but cost and practicality is still a huge issue.

 

3. Where do I fit in?

 

To start I am not a chemical engineer. However, I am a PhD researcher for the Hydrogen Fuel Cells & their Applications Doctoral Training Centre (DTC) in the United Kingdom, so I know a fair amount about it. By trade I am a autonomous control engineer, specialising in unmanned aerial vehicles (UAVs).

Given all the problems outlined above, even the suggestion of putting a fuel cell on a small UAV, which is essentially a modified off the shelf remote controlled hobby plane, seems crazy. But it is do-able, and has been done. The advantages for flight aren't the clean & green approach currently dominating the selling point of fuel cells, but that key word "endurance". To fly for 10 hours, a UAV would have too many batteries to float, let alone fly, but with hydrogen's energy density this may well be possible. That's what I'm going to find out.

 

4. So that's nearly 500 words with no raspberryPi?

 

Haha, hopefully I have set the scene now. Let's talk about the electronics!

The fuel cell is a dumb system. It's just a contained and continuous chemical reaction. But it can be controlled through the hydrogen supply, the load and the temperature. I can overcome the poor transient performance if I know that "soon" I will need full power; I can simply crank the fuel cell up, dump the excess power, then when the time comes, 100% is there to give. Sounds wasteful, but it turns this fuel cell into something useful. To control the logic we need a computer. On a small UAV the raspberryPi is ideal, in terms of size, power (in & out), flexibility and functionality.

Running a Real Time Operating System (RTOS) is a seriously useful tool, which I could not do on my work last year (using Arduino). I can programme in any language, use other peoples software (eg the camera) and share my code with the world (and myself for backup!) on GitHub.

So far I am using several add-ons including the MATLAB/SIMULINK support (to help the academics!), rPi Camera, delta-sigma-pi I2C ADC, piFace SPI Digital IO, TMP102 I2C temperature sensors and have the whole lot connected to an onboard UAV autopilot.

 

At risk of making this essay any longer, I'll wrap up now. I hope this is something that tickles your interest, and keep tuned for some videos, pictures tutorials and demos in the coming weeks. In the meantime, if you are interested in the plane the check out my page on diydrones.

 

Simon

_________________________________

S HOWROYD MEng (Hons) RAFVR(T)

Academic Researcher

Fuel Cells in Unmanned Vehicles

Autonomous Systems Specialist

Aeronautical & Automotive Engineering

Loughborough University

 

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