Portable Calorimeter for Fire Experiments

Our project is sponsored by Dr. Richard Emberley to design a portable oxygen consumption calorimeter. This type of calorimeter works by measuring the byproducts of a fire to calculate the heat release rate. Current oxygen consumption calorimeters are immobile due to their size and are very expensive. Our goal was to design a less expensive oxygen consumption calorimeter that can be used both in the field and within a lab.

Our Team

Chris chen

Hardware and management lead

  • Kept track of the team’s timeline and progress
  • Researched and selected components to meet design requirements

kara hewson

software and design lead

  • Created the CAD model of our system
  • Developed and wrote code for our GUI

joel keddie

testing and safety lead

  • Performed Risk Assessment and Failure Mode Effect Analysis
  • Wrote Testing Procedures

kayla collins

manufacturing and budget lead

  •  Manufactured all custom components
  • Assembled the device
  • Kept track of costs for each component

Acknowledgements

Our team would like to thank our lab instructor Dr. Peter Schuster for supporting us throughout this project. We would also like to thank Dr. Richard Emberley for his sponsorship and guidance throughout the year.

Our Project Videos

Our Project's Digital Poster

Problem Statement

Design and build a portable calorimeter for use in the Combustion Lab at Cal Poly and out in the field. The device must show how the heat release rate of a burning substance changes over time.

Design Constraints

  • Must be portable
  • Must accurately output heat release rate of burning substance

Background

The heat release rate (or HRR) of a substance is very useful in fire protection engineering. There are many types of calorimeters, however an oxygen consumption calorimeter made the most sense for this application. An oxygen consumption calorimeter uses sensors to collect data on the amount of carbon monoxide (CO), carbon dioxide (CO2), and oxygen (O2) in the smoke from the burning substance. These concentrations can be used to calculate the heat release rate, shown by the equation below:

Design Concept and Process

Similar existing products were researched and the major necessary components were determined to be:

  • CO, CO2, O2 sensors for detecting concentrations
  • Pump for directing smoke from exhaust duct to sensors
  • Power supply for sensors and pump
  • Graphical user interface for collecting data
  • Aspect of portability/containment of components

These components were sourced with size, cost, and quality in mind.

Figure 1: Isometric view of our CAD model design.
Early base plate design verification
Figure 2: Early prototype of fixturing base plate to determine a size considered "portable".

Portable Calorimeter for Fire Experiments

May 2020

Final Design

Specifications
Weight – 12 lbs
Dimensions – 18″ x 14″ x 6″
Total Cost – $1355

Figure 3: Isometric view of our final build.

Software

This device requires two programs in order to run:
  • Crestline (sensor manufacturer) software to communicate with the sensor and initiate data collection, provided by company
  • Matlab App for processing sensor data and displaying the HRR value as a function of time. Also saves the collected data to an Excel file for further analysis
      • The team created this app by modifying base codes provided by Matlab App Designer
Figure 4: Initial testing of interfacing with the Crestline software and ensuring the sensor works properly.
Figure 5: Example output of Matlab App. The table displays the current values of the concentrations, HRR, and time. Run and Stop buttons are intuitive.

Manufacturing Process and Components

Manufacturing for this project was minimal. It involved laser cutting and drilling holes into an 18″x14″x1/4″ acrylic sheet that acts as the baseplate for fixturing components to. The holes in the acrylic are for securing its rubber feet, securing handles, and attaching the base plate to the briefcase that houses the components.

Components:

  • Acrylic Sheet – for fixturing base plate, rigid but light
  • Pump – 12V, low flow vacuum pump for air
  • Bioenno Battery – 12V, rechargeable
  • Crestline CO/CO2 Sensor – detects both gas concentrations, small scale, and comes with breakout board 
  • Ao2 Citicel O2 Sensor – connects to Crestline sensor, small
  • HEPA Vent filter – connect in-line, easily replaceable, keeps system clear
  • Briefcase – contains all components with base plate, lightweight
  • Other – tubing (1/8″ ID, 1/4″ ID), fittings, fasteners (bolts, velcro, and thumbscrews)

Testing

Testing is required to verify the device’s design.  Four of the most important tests that will need to be carried out are:

  •  Calibration – the sensors must be calibrated using known concentration values of gases
  • Compare to Known Heat Release Rate – a substance with a known heat release rate will be burned and compared to the heat release measurements our device takes.
  • Flowrate – must be between 0.5 L/min and  1.5 L/min for Crestline sensor to work properly, a flowmeter will be used
  • Usability – students and faculty must be able to use device with only the help of the operator manual, user experience will be tested by allowing test subjects to attempt to use the device without guidance and then surveying them on their experience

Future Work

Current events (COVID-19) have prevented the team from carrying out the necessary calibration and testing, as well as completing manufacturing. These tests will need to be completed by the sponsor once he can access the Combustion Lab.

The remaining manufacturing involves adding connections to the Combustion Lab’s exhaust duct so that the calorimeter’s hoses may attach to it.

Calibration and performance testing of the device also needs to be carried out.  The device should to be tested with experimental data. 

Figure 6: Isometric view of exhaust duct connections that will be machined once the Combustion Lab is open.

Have a Question About this Senior Project?

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