Trace Gas Source (MA)

Inject or extract trace gas at a constant rate

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Libraries:
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

$${\Phi }_s=\{\begin{array}{ll}{\dot{m}}_{specified}\cdot h_g\left(T_{specified}\right),\hfill & \text{if }{\dot{m}}_{specified}\ge 0\hfill \\ {\dot{m}}_{specified}\cdot h_g\left(T_s\right),\hfill & \text{if }{\dot{m}}_{specified}<0\hfill \end{array}$$

where:

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

• h_g is the trace gas specific enthalpy.

• T_specified 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.

• T_s 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.

Examples

Vehicle HVAC System

Models moist air flow in a vehicle heating, ventilation, and air conditioning (HVAC) system. The vehicle cabin is represented as a volume of moist air exchanging heat with the external environment. The moist air flows through a recirculation flap, a blower, an evaporator, a blend door, and a heater before returning to the cabin. The recirculation flap selects flow intake from the cabin or from the external environment. The blender door diverts flow around the heater to control the temperature.

Open Model

Ports

Conserving

S — Inject or extract trace gas

moist air source

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

Parameters

Rate of added trace gas — Constant mass flow rate through the source

0 kg/s (default)

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.

Added trace gas temperature specification — Select specification method for the temperature of added trace gas

Atmospheric temperature (default) | Specified temperature

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.

Temperature of added trace gas — Trace gas temperature

293.15 K (default)

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.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2018a