Application of Series/Parallel connection of DMFC? (Direct Methanol Fuel Cell)

In summary, series connection of Direct Methanol Fuel Cells provides increased voltage and output in a shorter amount of time, while parallel connection results in increased current output.
  • #1
0Rion
6
0
Hello,

Just as the title asks, what sort of applications would series and parallel connections of Direct Methanol Fuel Cell suit the best? Based from my understanding of Fuel Cells and experimental results, one cell is not enough to power anything, hence they are used in stacks, in addition series connection provided more voltage, whereas parallel gave more current. Moreover, power density peak was reached in a shorter amount of time in parallel connection vs. series, where it took longer (polarization curve). Any ideas where one connection might be preferable to another? (DMFCs are typically used in commercial sectors I believe).

Thanks!
 
  • #3
Hello,

To anyone still interested in this topic, even though I haven't gotten any replies associated with the above said question and to correct previous assessments,
Series Connection of the DMFC resulted in increased voltage and reaching maximum power output in a much shorter period of time. Series connection then, would play a significant role in charging and running smaller types of electronics and amplifiers. Parallel Connection on the other hand resulted in increased current output, taking more time in reaching the maximum power level when compared to the series connection. Parallel connection would then suit appliances such as motors and actuators (forklifts, airport tug-vehicles, pneumatic and piezoelectric actuators, relays, thermal bi-morphs). Hope anyone still finds this information useful.
 
  • #4
Hi Orion!
I've actually recently been starting to build a micro-DMFC stack for portable electronics of my own.

From my understanding, each cell, when no current is moving through an external circuit, produces a given OCP (Open Circuit Potential) that is a little less than its theoretical (usually about 0.6-0.8 V) potential due to catalyst kinetics, methanol crossover, proton resistance through the membrane and such.

When you hook the cell up to a given potential drop, say a battery or DC-DC converter, if the potential drop is less than the OCP (say 0.5V) then the extra over potential will drive more reaction and raise the current density of the cell, hence the polarisation curve.

So, let's say that you're trying to power something with 4V of potential, you could hypothetically hook up 6 cells in series (Call the OCP of the cells 0.7 V) and they would together supply 4.2 V at OCP. That 0.2V of over potential is essentially distributed through the cells to drive more reaction, leading to an increase in current density. So now, on the polarisation curve, each cell is actually making 0.66 V at whatever current density the polarisation curve gives.

Normally, in these sorts of situations, the voltage is set by arranging that many cells in series or whatnot and the current density varies based on it.

Hope this clears all that up. I'm still a tiny bit sketchy on these counterintuitive polarisation curves myself.

Feel free to shoot me a message some time regarding research into DMFCs (michael-james.olsen@students.mq.edu.au). It's a lonely world right now.
 

1. What is a DMFC and how does it work?

A Direct Methanol Fuel Cell (DMFC) is an electrochemical device that converts the chemical energy of methanol into electrical energy. It works by using a proton exchange membrane to separate the anode and cathode compartments, where the methanol is oxidized at the anode to produce protons and electrons. The electrons flow through an external circuit, generating electricity, while the protons are transported through the membrane to the cathode, where they combine with oxygen to form water.

2. What are the advantages of using series/parallel connection in DMFC?

The series/parallel connection of DMFC allows for increased power output and efficiency. Connecting multiple DMFCs in series increases the voltage, while connecting them in parallel increases the current. This results in a higher overall power output compared to using a single DMFC. Additionally, this configuration allows for better utilization of the methanol fuel, as it is evenly distributed among the cells.

3. How is the performance of a DMFC affected by the series/parallel connection?

The performance of a DMFC is greatly influenced by the series/parallel connection. In series connection, the voltage increases, but the current remains the same for each cell. This can lead to a decrease in performance due to higher internal resistance and lower fuel utilization. In parallel connection, the current increases, but the voltage remains the same for each cell. This can result in better performance due to lower internal resistance and higher fuel utilization.

4. Are there any limitations to using series/parallel connection in DMFC?

Yes, there are some limitations to using series/parallel connection in DMFC. One limitation is the increase in complexity and cost of the system, as it requires additional components such as current collectors and interconnectors. Another limitation is the potential for uneven fuel distribution among the cells, which can lead to performance variations. Furthermore, the series/parallel connection may not be suitable for all types of DMFCs, as it depends on the design and operating conditions of the cells.

5. What are the potential applications of series/parallel connection in DMFC?

The series/parallel connection of DMFC has various potential applications, including portable power sources for electronic devices, backup power systems, and distributed power generation for residential and commercial buildings. It can also be used in hybrid systems, where the DMFC is combined with other energy sources such as solar panels or batteries to provide a more reliable and sustainable power supply. In the future, it may also have applications in transportation, such as powering electric vehicles.

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