Gas exchange transient buffering systems and methods
Inventors
Johnson, Mark A. • Eckles, Robert D. • Lynch, Douglas J. • McCoy, Johnathan I. E. • Hupp, Jason
Assignees
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Publication Number
US-11719679-B2
Publication Date
2023-08-08
Expiration Date
Abstract
Gas exchange analysis methods and systems utilize a water vapor buffering component including a material configured to buffer water vapor in a flow of a gas, whereby fluctuations in the water vapor content in the flow of the gas are slowed for components downstream from the water vapor buffering component. Components downstream of the water vapor buffering component may include: a first water vapor sensor configured to receive the flow of the gas from the water vapor buffering component and configured to measure a first concentration of water vapor in the gas; a sample chamber configured to receive the gas exiting the water vapor buffering component or the first water vapor sensor and to hold a sample capable of adding or removing water vapor from the gas; and a second water vapor sensor configured to measure a second concentration of water vapor in the gas exiting the sample chamber.
Core Innovation
The invention describes gas exchange analysis systems in which ambient water vapor transients propagate into time-lag errors between a reference and a sample water vapor measurement. In open gas exchange systems and closed gas exchange systems, water vapor fluctuations in a gas flow create errors in measured water vapor content that depend on transient dynamics rather than the true sample behavior.
To address this, the invention adds a component in the gas flow path upstream from a sample chamber and from a first water vapor sensor. The component includes an amount of a water vapor selective material that absorbs water in the presence of a positive water concentration gradient and desorbs water in the presence of a negative water concentration gradient, thereby controlling a rate of fluctuations in water vapor content propagated to the first water vapor sensor and to the sample chamber without enforcing a fixed humidity.
The system uses a first water vapor sensor configured to measure a first concentration of water vapor and a second water vapor sensor configured to measure a second concentration of water vapor exiting the sample chamber. The sample chamber is configured to hold a sample capable of adding or removing water from the gas, and the water buffering component can be embodied with water-absorbing/desorbing material such as Nafion, including Nafion beads, a Nafion tube, and a flat membrane, with optional dynamic adjustment of exposed Nafion.
Claims Coverage
The partial content includes three independent claims, each centered on controlling propagation of water vapor fluctuations using a water concentration-gradient responsive water vapor selective material, with measurement architecture based on first and second water vapor sensors and a sample chamber.
Water concentration-gradient responsive water vapor buffering component in a gas exchange system
A gas exchange analysis system having a first water vapor sensor, a sample chamber configured to receive gas exiting the first water vapor sensor or receive gas from the first gas flow line, and a second water vapor sensor; and a component in the first gas flow line before the first water vapor sensor and before the sample chamber, the component including an amount of a material that absorbs water in the presence of a positive water concentration gradient and desorbs water in the presence of a negative water concentration gradient to control a rate of fluctuations in water vapor content propagated in the flow of the gas to the first water vapor sensor and to the sample chamber.
Gradient-responsive reduction of incoming airstream water vapor fluctuations for a downstream sample chamber
A method of reducing fluctuations of water content provided to a sample chamber in a gas exchange measurement system by providing an incoming airstream having a variable water vapor content; reducing water vapor content fluctuations in the incoming airstream using a component including a material that absorbs or desorbs water in the presence of a water concentration gradient, wherein the material absorbs water in the presence of a positive water concentration gradient and desorbs water in the presence of a negative water concentration gradient to thereby control a rate of fluctuations in the variable water vapor content in the incoming airstream propagated to a sample chamber downstream from the component, wherein the sample chamber holds a sample capable of adding or removing water from the airstream.
Water concentration-gradient responsive control of downstream water vapor fluctuations using a buffer component
A gas exchange analysis system having a component including an amount of a material that absorbs or desorbs water in the presence of a water concentration gradient, wherein the material absorbs water in the presence of a positive water concentration gradient and desorbs water in the presence of a negative water concentration gradient to control a rate of fluctuations in the water vapor content in the flow of the gas propagated to components downstream from the component, wherein the downstream components include a first water vapor sensor, a sample chamber configured to receive gas exiting the first water vapor sensor (or gas from the component) and to hold a sample capable of adding or removing water vapor from the gas, and a second water vapor sensor configured to measure a second concentration of water vapor in the gas exiting the sample chamber.
Across the independent claims, the central inventive concept is controlling the rate of water vapor fluctuation propagation using a component with a material that absorbs and desorbs water based on the sign of a water concentration gradient, together with a sample chamber and first and second water vapor sensors arranged so that downstream measurements reflect reduced transient artifacts.
Stated Advantages
Improved stomatal conductance measurements by reducing transient humidity artifacts.
Documented Applications
Stomatal conductance measurements using gas exchange analysis systems such as a leaf porometer with a sample chamber and water vapor sensors.
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