Optical measurement of atmospheric carbon dioxide
From PC5271 wiki
Team members
Ta Na
Cao Yuan
Gao Yihan
Qi Kaiyi
Chen Yiming
Idea
Climate change has already become one of the most important challenges humanity faces. Carbon dioxide, the major greenhouse gas, is 'heating up' the Earth's atmosphere as they have an absorption peak in infrared wavelengths.
This project aims to build a portable and accurate carbon dioxide concentration measurement device.
Possible measurement mechanisms
- Spectroscopy. Carbon dioxide has absorption peaks at 15, 4.3, 2.7 and 2 μm. With a laser/source of such wavelength and the correct filter, we could judge the concentration by absorption levels. See viasala for inspiration of a potential real-time reference design.
- Interferometry. Carbon dioxide has a slightly different refraction index for all wavelengths. By observing the change in interference patterns, we can tell if there is a change in carbon dioxide concentration due to a change in effective path length.
In the end we chose single-wavelength spectroscopy, i.e. absorbance measurement to measure the CO2 content.
Experiment Preparation
Components
- Light source:
- A thermal/blackbody radiation/light source that can emit EM radiation at 4 micrometers. Done with a 12W halogen lamp, mounted on an IKEA SVALLET lamp stand.
- Sensor:
- Thermopile detectors: G-TPCO-035 / TS418-1N426: Thermopile detector with a built-in optical bandpass filter for light around 4μm wavelength for CO2 absorption
- multimeter
- Gas chamber:
- airtight acrylic box surrounding all optical components (chosen)
- metal (stainless steel) extrusion with hollow structures sealed with transparent SiO2 cover glass (chosen)
- gas chamber with specific materials (Si/SiO2) transparent to 4 micrometer wavelength
- Power supply and micellaneous electronics:
- banana wires
- CO2 source:
- bottled CO2
- dry ice
- to look up
- extinction coefficient of CO2
Experiment Principles
The experiment is based on the varied extinction coefficient of CO2 under standard atmospheric conditions. As 4
Experiment process
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Experiment 1
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Experiment setup
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Data acquisition and analysis
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Experiment 2
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Experiment setup
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Data acquisition and analysis
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Experiment 3
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Experiment setup
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Data acquisition and analysis
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Comparative studies
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