Experiment 3 Fuel Cells

Summary

Highlights

• The importance of maintaining a stable system for accurate fuel cell measurements. 📏
• How to deal with voltage drops by initiating purge cycles. 🔄
• Why monitoring hydrogen flow is essential for safety and performance tracking. 🛡️
• Insights into how system moisture and temperature variations affect efficiency. 💧
• The significance of understanding leakage rates in fuel cell systems. 🚰

Key Takeaways

• Fuel cells require careful monitoring of current and voltage to maintain optimal performance. 📈
• Moisture and temperature management is crucial for efficient fuel cell operation. 🌡️
• Fuel cell stacks have internal resistances that can cause voltage deviations. ⚡
• Proper initialization and purging processes prevent performance drops. 🔄
• Airflow and temperature settings significantly affect combustion and efficiency. 🌀

Overview

Chapters

• 00:00 - 00:30: Introduction The 'Introduction' chapter outlines the components involved in a fuel cell experiment. This includes a description of the hydrogen tank used to store hydrogen, a flow meter to measure the flow of gases, and the fuel cell stack which is integral to the experiment. It serves as a briefing for what will be encountered and utilized in the course of the experiment.
• 00:30 - 01:30: Components and Setup In this chapter, titled 'Components and Setup,' the focus is on various components involved in the process of combustion and cooling. Key elements include ventilators which supply air, multiple meters for measuring hydrogen flow, fan power, stack temperature, current, and voltage. These instruments are essential for monitoring and controlling the system's electrical load settings, thereby affecting the overall functionality of the setup.
• 01:30 - 02:30: System Initialization The chapter 'System Initialization' discusses the design and function of a fuel cell stack. It explains that the stack is a dead-ended system, meaning waste gases and moisture accumulate in the last cell, which can degrade performance. To mitigate this issue, a release system is used to maintain efficiency.
• 02:30 - 04:00: Applying Load and Purge Cycle The chapter discusses the application of a load and purge cycle within a system. It begins with the automatic operation of a valve during performance degradation of the stack, detected by the monitoring system. The chapter also covers the initial steps of starting up this system, including opening the hydrogen storage tank, switching off the electronic load, and ensuring no load is applied during the system's initialization process.
• 04:00 - 05:30: Hydrogen Flow and Voltage Measurement This chapter, titled 'Hydrogen Flow and Voltage Measurement,' describes the process of initializing a system involving hydrogen flow. It begins with an initialization phase marked by a clicking sound, which indicates that the purge valve is opened, releasing hydrogen and other gases. This process sets the stack in proper working condition and concludes with the meters being turned on, ready for further operation.
• 05:30 - 07:30: Current Stabilization The chapter discusses the procedure for stabilizing the current in an experimental setup. It involves initially applying load to the system to introduce moisture into a membrane that dried up during a long pause between experiments. The process is detailed as starting with reducing the load and then progressively increasing it in steps.
• 07:30 - 10:00: Temperature Dependency The chapter titled 'Temperature Dependency' discusses a scenario within a system where an unusual clicking sound was observed, signaling a significant voltage drop in the stack wattage. In response to this anomaly, the system initiated a purge cycle to address the issue. During this purge cycle, there's an attempt to provoke another response, particularly focusing on the hydrogen flow rate to assess any underlying concerns related to temperature dependency.

Experiment 3 Fuel Cells Transcription

• 00:00 - 00:30 welcome to experiment number three fuel cells this is the test scent you would be using during the experiment and well let me explain the main components over here we have the hydrogen tank where we have stored the hydrogen for the experiment then we have a flow meter over here the fuel cell stack itself and
• 00:30 - 01:00 some ventilators that will provide the air for the combustion and cooling we have several meters over here one flow meter for the hydrogen flow one meter for the fan power one for the stack temperature a current and voltage of the stack and below we have an electronic load module where we can set different electronic loads leading to different
• 01:00 - 01:30 currents which we will apply to the fuel cell stack as you can see the fuel cell stack is designed as a dead-ended system so waste gases and moisture will accumulate in the last cell of the stack and then the performance of the fuel cell stack would draw to prevent this loss in performance we have a release
• 01:30 - 02:00 valve here which will be automatically opened during the measurement when the monitoring system detects a drop in performance of the stack okay first let's start up the system we need to open up the hydrogen storage tank we will switch off the electronic load and make sure that we have no load applied during the initialization of the system
• 02:00 - 02:30 then we will stop the system and the system starts initializing you might have heard this clicking sound that is the purge valve which has been opened and then some of the hydrogen and the Vice gasses have been released so now the stack is in perfect working condition initialization has finished the meters have turned on and now we will apply
• 02:30 - 03:00 some load to the to the stack at a higher current so that we can get some moisture to the membrane because it dried up during the long period between experiments ok to apply the we will first turn down the load now we will stepwise increase and there was once
• 03:00 - 03:30 more this clicking sound the system observed an extreme voltage drop of the stack wattage and therefore it decided to initiate a purge cycle during the purge cycle I will try to provoke one more you see that the hydrogen flow rate
• 03:30 - 04:00 increases dramatically and it's obvious that measurements should not be taken during this time if a purge cycle occurs normally you should wait for at least well 20 seconds until the values have become stable once more while looking at the stack voltage you can see that at constant current the voltage is slowly increasing so the membrane is getting
• 04:00 - 04:30 more moist and temperatures also increasing both leads to a better diffusion of oxygen and hydrogen and therefore the performance of the steak increases we will wait some minutes until the system has stabilized well okay now the system has heated up in the meantime and the system was ready for the measurement if
• 04:30 - 05:00 you are looking closely at the flow meter and up here you will see that although we have applied zero current and no load condition we would still have a small hydrogen flow this is the leakage rate of the system which we will have to take as an offset into account it's quite small for our experiment then you might wonder why and the measurement tables there are two voltages mentioned we have the stack voltage shown here on
• 05:00 - 05:30 this meter it's the voltage measured directly across the electrodes of the fuel cell stack and we have a second meter which is connected to the terminal of the fuel cell module which is measuring the terminal voltage in no load condition both voltages should be the same while increasing the load current the deviation will increase due to internal
• 05:30 - 06:00 resistances of the fuel cell module but at the moment we are reading nine point zero six as the second and nine point zero zero for the terminal voltage so we have a also a slight offset here please take that into account during the measurement now we will increase the current the next nominal current we want to achieve is 0.2 amps we will switch on the electronic load module and now we
• 06:00 - 06:30 will increase the current until we get a reading of approximately 0.2 amps quite difficult to regulate you see the values are not stable yet that's why you have two columns one for the nominal current and one for the actual current because it's almost impossible to exactly set the desired current at
• 06:30 - 07:00 low at low load the load levels okay now we are waiting for the stabilization of the system and after that we will increase the current stepwise and I will provide you the measurement data later now we are operating the stack at a current of 8.5 adds that the purge cycle will be initiated very often just take
• 07:00 - 07:30 yeah because meetings the SEC is now delivering a call at approximately 36 months which was such a small stake is quite good performance and now I will set the last step I will try to achieve the tally of 10 hands
• 07:30 - 08:00 and as you can yeah the system goes constantly into potential touch mode def while we were there the small rock around we closed the valve manually but the readings are getting unstable
• 08:00 - 08:30 well we've got stable readings at around eight point eight amps so I will provide you those data for the tenon measurement you okay for the next part of the experiment
• 08:30 - 09:00 we want to determine the temperature dependency as you can see we want to operate the stack at the temperature of approximately 44 degrees Celsius and automatic and power to reach the temperature of 44 degree will stay at a high carbon and manually reduce the airflow to approximately 34% 35% this will lead to a quick heating up of the
• 09:00 - 09:30 fuel cell stack you can see the temperatures already rising very quick and I will wait until we have stable temperature settings about 42 degree and then I will be back okay well the fuel cell stack has heated up in the mean time to 42 degrees I turned off the electronic load and have set the fan power regulation to automatic settings once more we have
• 09:30 - 10:00 leakage now of approximately three milliliters and we will continue just like before we will take the readings then set the next current wait until the current has stabilized and so on you
• 10:00 - 10:30 okay for the last part of the experiment we will have to operate the fuel cell stack at a temperature between 40 and 50 degrees Celsius and we will obstruct the the airflow by reducing the fan power manually to 6% well the rest of the experiment stays the same like before we will apply different load currents and
• 10:30 - 11:00 we will take the readings and you would see that due to the low fan power there will be some obstruction to the combustion due to a lack of oxygen you