# Trace Gas Source (MA)

Inject or extract trace gas at a constant rate

• Library:
• Simscape / Foundation Library / Moist Air / Sources / Moisture & Trace Gas Sources

## Description

The Trace Gas Source (MA) block represents a constant source or sink of trace gas for the connected moist air volume. A positive or negative trace gas mass flow rate causes trace gas levels to increase or decrease, respectively.

The energy associated with the added or removed trace gas is

where:

• ${\stackrel{˙}{m}}_{specified}$ is the trace gas mass flow rate specified by the Trace gas mass flow rate parameter.

• hg is the trace gas specific enthalpy.

• Tspecified is the temperature of added trace gas, as specified by the block parameters. The block uses this value to evaluate the specific enthalpy of the added trace gas only. The specific enthalpy of removed trace gas is based on the temperature of the connected moist air volume.

• Ts is the temperature at port S, which is the same as the temperature of the connected moist air volume.

Port S is a moist air source conserving port. Connect this port to port S of a block with finite moist air volume to add or remove trace gas through that block. For more information, see Using Moisture and Trace Gas Sources.

## Ports

### Conserving

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Connect this port to port S of a block with finite moist air volume to add or remove trace gas through that block.

## Parameters

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Trace gas mass flow rate through the source. A positive value adds trace gas to the connected moist air volume. A negative value extracts trace gas from that volume.

Select a specification method for the trace gas temperature:

• `Atmospheric temperature` — Use the atmospheric temperature, specified by the Moist Air Properties (MA) block connected to the circuit.

• `Specified temperature` — Specify a value by using the Temperature of added trace gas parameter.

Enter the desired temperature of added trace gas. This temperature remains constant during simulation. The block uses this value to evaluate the specific enthalpy of the added trace gas only. The specific enthalpy of removed trace gas is based on the temperature of the connected moist air volume.

#### Dependencies

Enabled when the Added trace gas temperature specification parameter is set to ```Specified temperature```.