METHANE BIFOCAL MODELING
Description
Bifocal modeling is an instructional and analytical approach that connects two complementary "views" of the same phenomenon: (1) directly measurable macroscopic behavior, and (2) a simplified mechanistic model that explains why that behavior occurs. In the methane greenhouse effect experiment, bifocal modeling links real-time environmental data from a small enclosed space with a conceptual model of infrared absorption and heat trapping by CH₄. This conceptual model refers to molecular vibration of CH₄ that consist of asymetric stretching and bending which active interaction with IR but symteric stretching and doubly degenerate bending are not active with IR In this setup, an Arduino microcontroller serves as the data acquisition unit. Methane concentration is monitored using an MQ-4 gas sensor, while temperature is measured using a DHT22 sensor. The space is exposed to a controlled heat source (a lamp), and the Arduino continuously records the sensor readings at fixed intervals. The macroscopic "focus" view is represented by data showing methane levels (in ppm) along with temperature increases and approaches to steady state. This view allows the user to identify patterns such as faster warming rates, higher peak temperatures, or slower cooling as methane levels increase.
Files
Steps to reproduce
1. Build the physical greenhouse-effect model (hardware) - Construct a transparent sealed box (acrylic or clear plastic) following the provided design dimensions and layout. - Prepare mounting points for the Arduino, MQ-4 sensor (gas inlet exposed to chamber air), and DHT22 sensor (placed away from direct heat). - Ensure cable routing is neat and that the box can be opened/closed for setup while remaining as airtight as practical during operation. 2. Download and save the Arduino IDE installer - Download the Arduino IDE installer from the official Arduino website. - Save the installer file to your computer (e.g., Downloads folder or a dedicated project folder). 3. Install the Arduino IDE - Run the installer and complete the installation steps. - Launch Arduino IDE to confirm it opens correctly. 4. Download the Arduino sketch (CH4.ino) - Download the file CH4.ino - Save it in a project directory on your computer. 5. Connect the hardware to the computer - Wire the MQ-4 and DHT22 to the Arduino according to the circuit diagram. - Connect the Arduino to the computer via USB. 6. Upload and run the program - Open CH4.ino in Arduino IDE. - Select Tools → Board and choose the correct Arduino board model (Arduino UNO). - Select Tools → Port and choose the port corresponding to your Arduino. - Click Upload to compile and upload the sketch to the Arduino. 7. Verify sensor data via Serial Monitor - Open Tools → Serial Monitor. - Confirm that CH₄ readings (ppm or sensor output) and temperature values appear and update consistently. Once the data is displayed correctly, close the Serial Monitor and Arduino IDE 8. First-time sensor warm-up requirement (MQ-4) - For first-time use, allow the MQ-4 sensor to operate for at least 2 hours before sealing/closing the chamber. This warm-up helps stabilize sensor behavior prior to running a closed-box measurement. 9. Download and launch the simulator application - Download CH4simulator.rar to your computer. - Extract the archive (e.g., right-click → Extract). - Open the extracted folder and run the CH4Simulator.exe file. - This file is a pre-built Unity-based application. 10. Confirm the bifocal display in the simulator - On the simulator interface, verify that it displays CH₄ ppm and temperature values. - Observe the methane vibration animation inside the box, which provides the conceptual/molecular-level visualization aligned with the measured data.
Institutions
- Indonesia University of EducationWest Java, Bandung