Humidity & Trace Gas Sensor (MA)
Measurement of humidity and the amount of gas impurities in a network of humid air.
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Description
The Humidity & Trace Gas Sensor (MA) unit measures humidity and the amount of gas impurities in a humid air network. There is no mass or energy flow through the sensor.
The W/Tw and G ports output measurements on the A port of humidity and trace gas quantity, respectively. The Tw port is used when `Wet-bulb temperature' is selected as the Measured moisture specification parameter.
The sensor readings correspond to the humidity and amount of gas impurities upstream of the node being measured. For example, if port A of the Humidity & Trace Gas Sensor (MA) unit is connected to a node between pipe 1 and pipe 2 and moist air flows from pipe 1 to pipe 2, the humidity and amount of gas impurities measured at port A characterise the volume of moist air in pipe 1. If then the air flow changes direction and flows from pipe 2 to pipe 1, then humidity and amount of gas impurities measured at port A characterise the volume of moist air in pipe 2. If the humidity and the amount of gas impurities in the two volumes of moist air are different, the measured values change when the flow direction is changed. If two or more upward flows merge at a node, the measurement of humidity and the amount of gas impurities at the node represents a weighted average value based on perfect mixing of the flows.
Ports
Output
W - humidity
scalar
Output signal port for moisture measurement. The measurement method is set by the Measured moisture specification parameter.
Dependencies
To use this port, select the Moisture checkbox and set the Measured moisture specification to one of the following values
-
Relative humidity -
Specific humidity -
`Mole fraction
-
`Humidity ratio
Tw is the temperature of a wet thermometer
scalar
Output signal port for measuring the wet thermometer temperature reading, which characterises humidity.
Dependencies
To use this port, select the Moisture checkbox and set the Measured moisture specification parameter to `Wet-bulb temperature'.
G is the gas impurity level
scalar
Signal output port for measuring the amount of gas impurities. Measurement method is set by the parameter Measured trace gas specification.
Dependencies
To use this port, select the Trace gas checkbox.
Parameters
Moisture - Enable or disable the output port for humidity measurement
Enabled (by default)| Disabled
Checking this box enables the W or Tw output port to measure the quantity specified by the Measured moisture specification.
Measured moisture specification - the way in which moisture is measured
Relative humidity (By default) | Specific humidity | Water vapor mole fraction | Humidity ratio | Wet-bulb temperature
Sets the method of measurement:
-
Relative humidity- the signal on the W port is relative humidity. -
Specific humidity- the signal on the W port is equal to specific humidity. -
Water vapor mole fraction- signal on the W port is equal to molar fraction of water vapour. -
Humidity ratio- signal on the W port equals water vapour content. -
Wet-bulb temperature- signal on the Tw port equals the wet-bulb temperature.
Trace gas - enable or disable the output port for measuring the amount of gas impurities
On (By default) | Off
When checked, the G output port is enabled to measure the quantity specified by the Measured trace gas specification.
The Measured trace gas specification is the method of measuring the amount of gas impurities
Mass fraction (by default) | Mole fraction.
Sets the measurement method:
-
Mass fraction- signal on the G port is equal to the mass fraction of gas impurities. -
Mole fraction- the signal on the G port is equal to the molar fraction of gas impurities.