Fuel Cell VOC Filtration Monitoring System

Fuel cells exist as an alternative and cleaner power source option to fossil fuels, but as a product they tend to be a delicate mix of expensive, hard to replace, and easy to break. One of the ways they’re most susceptible to damage is airborne contaminants, with things like smoke, exhaust, and solid particles in the air being able to make a single fuel cell completely useless via irreversible internal damage. To prevent this kind of damage, adequate filters are needed to keep the internals of the fuel cell protected, but testing said filters is a roadblock on its own. Currently, it costs our client around $5,000 per test per filter to test the effectiveness of various air filters when it comes to safeguarding their fuel cells. Our team’s test stand design would negate those costs almost entirely and make testing easy and efficient in terms of both time and cost, as our design includes easy access to the filter housing so multiple filters can be swapped in and out for individual tests without the need of separate setups, as well as integrated data collection and readout to allow faster and easier-to-understand results.

Background
Hyster - Yale is a company that builds forklifts and in these forklifts they are beginning to working with Nuvera fuel cell stacks. Forklifts are often used in places such as shops, warehouses, and factories. In these locations there are high amounts of volatile organic compounds such as: toluene, isopropyl alcohol, and benzene. When the fuel stacks are exposed to these types of compounds it detroys the interior of the fuel cell and they must be replaced, however fuel stacks are expensive so they must remian intact and useful for as long as possible. To do this filters are used to protect the fuel cells and filter the air so a very little amount of VOCs reach the fuel cells. The filters needed to be tested to ensure that they are adquate for the task at hand, however testing these filters is not an easy task. The current cost of one test per filter is about 5000 dollars and the filters must be sent away for testing. This test stand will allow Hyster - Yale for efficient and less costly in house testing.

This project has been worked on previously for the past two years. The previous test stand implemented two air quality sensors to test the filters absorbance of the VOCS, and was powered with an ATX power source and Arduino Mega.

The photo also shown how the old test stand functioned with labels showing the different components.

=Specifications= The filtration test stand needs to meet several design specifications in order to be both usable and reliable for testing filters for fuel cells. The test stand will utilize low cost air quality sensors and a gas injection system.

Must be able to measure:
 * Mass air flow
 * Inlet and outlet air temperature
 * Inlet and outlet gas concentraion

Test stand will inlcude: Working with Hyster - Yale and advisors Hevel developed the following product requirements and the tests for the requirements to be validated. The tables below will show the requirements and validations.
 * A primary air mover
 * Applicable flow control
 * Appropriate ducting
 * Gas injection system
 * Testing of multiple filters
 * Data acquisiton system

=Design Developments=

Test Stand Operation
With the previous design in mind and using the old documentation Hevel figured out how the test stand operated. The inital design did test provided data from the sensors however Hyster - Yale would like Hevel to continue devloping the stand.

This is the Piping and Instrumentation diagram of the final design of the system, inlcuding the basics of the electrical components and how it will work. The system starts with inlet air and an ambient air quality sensors, then gas containments will be injected into the system using VOC impinging jets, following this there is an air sensor to measure the amount of contaminents introduced into the system, the air will then flow into the expansion chamber, then the air will flow through the filter and an air sensor will measure the air quality after the filter. There is also a mass air flow sensor to measure the air flow and ensure that we are getting an adequate amount of constant air provided by the exhaust fans.



Initial Designs and Project Expectations
Hevel was given an inital test stand with the code, with the product requirements given by Hyster - Yale.

Final Test Stand Overview
In the models of the test stand shown the electrical components and impinging gas system are not shown. This model shows the main components of the test stand with arrows showing what everything is and will it will be placed. The test stand will have three air quality sensorsand the filter housing allows for quick filter swapping. The expansion chamber is to allow contaminated air to reach the entirety of the filter which is will make it more like on site conditions.

Test Stand Including Enclosure
The test stand will inlcude a wooden enclosure made of plywood and will be easy to remove so components inside the test stand will be easy to reach or swap. The enlcosure will be laser cut. There will be cut outs for impinging gas system, filter housing, and injection site. The electrical components will be stored in a panel attached to the enclosure.

The laser cut enclosure was cut in panels and wood glued together. For the operators to have access all the components of the test stand one of the panels is on hinges and acts as a door. The enclosure is light and easy to remove. All of the photos are labeled and show the different components of the test stand.

Impinging Gas Injection System
The orginal team came up with a design for an impinging gas system, so we rebuilt the orignal design. The final design will include two modules for multiple contaminants can be introduced into the system. We chose to continue with this designs because there is no heating or pressurized canisters, however we will be including altimeters in the modules to monitor the pressure. The modules rely on quasi-passive evaporation into the influent airstream. There will be a place for the modules to sit inside of the enclosure. The following pictures show the models of the modules with their different components and how and where they will located on the test stand.

These photos show the impinging gas modules that we rebuild and how they sit in the stand. These modules worked effectively with our testing and the design was simple and easy to create. We used PVC components to build the modules and used a sealent to ensure that they worked properly.





Instrumentation
Hevel will be using two types of air quality sensors, we will be using the SGP30 and the BME680. Both of these sensors are from Adafruit, they are both low cost and have the features we need for this type of test stand. SGP30: BME280:
 * On Board Functions for TVOC, CO2eq, Ethanol, and H2 readings. Metal Oxide Sensor
 * TVOC signal between 0 ppb to 60000 ppb. Hoping to run between 10ppm to 30ppm, within 32 ppb, max sampling rate 1 Hz
 * Drift Behavior Given: 2.5 % of measured value at 30 ppm after 200 hours.
 * Relative Humidity readings within 32 to 140 F are within 4%
 * Temperature readings within 32 to 149 F are within 1.0 C, max sampling rate 1 Hz

There will be three of each types of the sensors that are in three different locations. The model before shows where air sensors two and three are placed on the test stand. For the air sensor to get a proper reading they must be placed correctly in the test stand. The sensors have to be placed so they are able to get a good reading, to do this we designed sensor mounts and 3D printed them out of nylon, so that they will not melt when exposed to the contaminents during testing. The mounts are slide into the caps and the sensors are secured into place with screws.
 * Air sensors number one will be placed with the electrical components for testing the air quality of the ambient air for creating a baseline.
 * Air sensors number two will be placed after the impinging gas nozzles to measure the contaminants in produced by what is being placed into the system.
 * Air sensors number three is after the filter and before the exhaust fan to determine how well the filter worked.

Filter Adapters
On the test stand the same filter housing will be used to connect the expansion chamber to the mass air flow sensor and fans. However, multiple types of filters will be used for testing, so we designed two types of filter adapters, one for cylindrical filters and one for rectangular filters. These will be placed inside of the expansion chamber.



User Interface
The final design will include an easy to use user interface with a screen, D-pad, and MicroSD Card Reader to extract data. All of the electrical components will be intergrated to work as one system. The data will be stored on the Arduino and will be able to be exported.

The screen will include a Manual and Automated test options. Automated Test:
 * Select test time
 * The fan speed for the test
 * The live differential of the test, select to output data to flash drive, automatic shut off after test.

Manual Screen:
 * Change fan speed
 * See live differential
 * Output stored data

All of the electrical components will be placed inside of a laser cutted wood box. The top of the box will come off for easy access to all of the components.



=Standard Testing Procedure= The flow chart shown show the standard testing procedure of the test stand. Hevel will be following the ISO 11155-2 testing standards.

=Team Members=

=Additional Documentation=

Project Schedule

Meeting Minutes

Budget