Fuel-cell testing

---

More 1 2 3 4

Capabilities that deliver reliable monitoring and control, as well as offer the benefit of a flexible configuration, are critical to keep pace with evolving fuel-cell technology, according to National Instruments.

A Ballard fuel-cell stack being tested prior to shipment.

Fuel cells are one of the most promising technologies for delivering clean and efficient power for automotive and residential applications. A fuel cell directly converts the chemical energy of hydrogen and oxygen into electricity with a byproduct of pure water. Until recently, fuel cells have largely been restricted to NASA space missions and a few research labs around the world. However, with increased urgency in reducing pollution and greenhouse gas emissions, a resurgence of interest in fuel cells has occurred in the scientific community. Today, governments and large corporations are making massive investments into the development of these clean power sources. Although fuel cells hold great promise for clean, inexpensive power, they are still in their developmental infancy, and a great deal of research is necessary before they are considered viable power systems. Test capabilities that deliver reliable monitoring and control, and offer the benefit of a flexible configuration, are critical to these advances. The capabilities will permit scientists to easily tailor their systems to keep pace with evolving fuel-cell technology.

Even though several types of fuel cells exist, they all work under the same basic premise of converting hydrogen and oxygen into electrical power. Of the fuel-cell technologies, which include alkaline (AFC), molten carbonate (MC), phosphoric acid (PAFC), proton exchange membrane (PEM), and solid oxide (SOFC), PEM is gaining most of the attention in automotive applications. PEMs are popular due to their relatively low operating temperature and high efficiency. The PEM fuel cell operates by using platinum-coated membranes as a catalyst to break a hydrogen atom into a proton and an electron. The membrane is permeable to protons, but impenetrable to free electrons. These electrons are forced to travel through an electric circuit before they rejoin with free protons and oxygen molecules to form water. In this way, the anode of the fuel cell produces electricity, and the cathode creates heat and water. However, just as it took years of tests and improvements to achieve the efficiencies currently realized by internal combustion engines, many improvements are necessary before fuel cells are viable for automotive use.

Electricity generated in a Proton Exchange Membrane (PEM) fuel cell. Click to enlarge

The introduction of computer control revolutionized the internal combustion engine. It allowed engineers to monitor and control fuel rate, timing, and cooling. With the adoption of monitoring and controlling techniques such as fuel injection, oxygen sensors, knock detectors, and mass flow sensors, engine efficiencies have reached an all-time high, while pollution per engine has been greatly reduced. Engineers have learned that through computer control and careful monitoring of important variables, vehicle powerplants can be greatly improved. To develop a viable fuel cell, engineers need to accurately monitor the condition of the hydrogen stream, oxygen stream, output voltage, and current. To optimize a fuel cell, not only are the flow and pressure of the hydrogen and oxygen monitored, but also the humidity and temperature of the gas streams. Knowing the voltages of the individual membranes can enable an engineer to read the health of a fuel-cell stack and control the output resistance to map the power densities of the stacks. To improve the efficiencies of next-generation fuel cells, engineers are constantly incorporating new measurements into their tests and demanding reliable, accurate, and flexible test systems.

More 1 2 3 4