Controlled Moisture Source (MA)
Adding or removing moisture at a constant or variable flow rate.
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Description
The Moisture Source (MA) unit is a constant or time-varying moisture source or absorber for a connected humid air volume.
A positive or negative mass flow rate results in an increase or decrease of the moisture level respectively.
Moisture can be added in the form of water vapour or water.
For water vapour, the energy associated with the addition or removal of moisture is equal to
,
where:
-
- is the mass flow rate of water vapour given by the input scalar signal at the M port or by the Rate of added moisture parameter.
-
- is the specific enthalpy of water vapour.
-
- is the temperature of added water vapour, given by the input scalar signal at port T or parameter Temperature of added moisture. The unit uses this value to estimate the specific enthalpy of added moisture only. The specific enthalpy of removed moisture is determined from the temperature of the connected humid air volume.
-
- is the temperature at the S port, which is equal to the temperature of the connected volume with humid air.
For water, the energy associated with the addition or removal of moisture is equal to
,
where:
-
- is the specific enthalpy of vaporisation of water.
Ports
Non-directional
S - moisture addition or removal
moisture and gas impurity
Humid Air Source Port. Connect this port to the S port of a humid air final volume unit to add or remove moisture using the Moisture Source (MA) unit.
Input
M - mass flow rate reference signal, kg/sec
scalar
Input port that defines the mass flow rate of moisture through the source.
Dependencies
To use this port, select the Controlled source checkbox.
T - temperature reference signal, K
scalar
Input port that defines the temperature of the added moisture. The unit uses this value to estimate the specific enthalpy of the added moisture only. The specific enthalpy of removed moisture is determined from the temperature of the connected moist air volume.
Dependencies
To use this port, select the Controlled source checkbox.
Parameters
Controlled source - whether the moisture flow rate and temperature are set by the input signal
On (by default) | Off
Defines how the flow rate and moisture temperature will be set:
-
`On' - flow rate and moisture temperature are set by input signals M and T.
-
`Off' - constant flow rate and moisture temperature using the Rate of added moisture and Added moisture temperature specification parameters respectively.
Moisture added or removed - add or remove moisture in the form of water vapour or water
Vapor (By default) | Liquid.
Select whether the source adds or removes moisture as water vapour or water:
-
Vapor- the enthalpy of moisture added or removed corresponds to the enthalpy of water vapour, which is greater than the enthalpy of water. -
Liquid- the enthalpy of moisture added or removed corresponds to the enthalpy of water, which is less than the enthalpy of water vapour.
Rate of added moisture - constant mass flow rate through the source
0 (By default).
Mass flow rate of moisture through the source.
A positive value adds moisture to the connected volume with humid air. A negative value removes moisture from this volume.
Dependencies
Used if the Controlled source checkbox is not selected.
Added moisture temperature specification - moisture temperature specification method
Atmospheric temperature (by default) | Specified temperature.
Selects the moisture temperature specification method:
-
`Atmospheric temperature' - uses the atmospheric temperature set by the Moist Air Properties (MA) unit connected to the loop.
-
Specified temperature- the value is set using the Temperature of added moisture parameter.
Dependencies
It is used if the Controlled source checkbox is not selected.
Temperature of added moisture - moisture temperature
`293.15 K (by default).
Moisture Temperature. This temperature remains constant during the simulation. The unit uses this value only to estimate the specific enthalpy of added moisture. The specific enthalpy of removed moisture is determined based on the temperature of the connected humid air volume.
Dependencies
Used when Added moisture temperature specification is set to Specified temperature.