Air Volume

Control volume element of Air

 Description The Air Volume component models a generic control volume for the lumped thermal fluid simulation of Air. This component calculates mainly the mass and energy conservation.

Equations

The calculation is changed based on parameter values of Fidelity of properties and Dynamics of mass in the Air Settings component.

 Fidelity of properties = Constant and Dynamics of mass = Static If Type of Branch is (Branching), Mass conservation is calculated with:   $\left(x=\left\{b,c,d\right\}\right)$ $\mathrm{port_a.p}=p$ $\mathrm{port_x.p}=p$  $\left(x=\left\{b,c,d\right\}\right)$ If Type of Branch is (Confluence), Mass conservation is calculated with:   $\mathrm{port_a.p}=p$ $\mathrm{port_b.p}=p$ Energy conservation is calculated with: State equation: $p=\mathrm{ρ}\cdot \mathrm{R__gas}\cdot T$ Relationship of mass: $u=\frac{U}{M}$ $M=\mathrm{ρ}\cdot V$ Definition of Enthalpy: $\mathrm{hflow}=\mathrm{Function__hflow}\left(T\right)$ $u=\mathrm{hflow}-\frac{p}{\mathrm{ρ}}$ Port definitions: $\mathrm{port_a.hflow}=\mathrm{hflow}$ $\mathrm{port_x.hflow}=\mathrm{hflow}$  $\left(x=\left\{b,c,d\right\}\right)$ $\mathrm{port_a.rho}=\mathrm{ρ}$ $\mathrm{port_x.rho}=\mathrm{ρ}$  $\left(x=\left\{b,c,d\right\}\right)$ $\mathrm{port_a.T}=T$ $\mathrm{port_x.T}=T$  $\left(x=\left\{b,c,d\right\}\right)$ $v\left[1\right]=\frac{\mathrm{port_a.mflow}}{\mathrm{ActualStream}\left(\mathrm{port_a.rho}\right)\cdot A\left[1\right]}$ $v\left[i\right]=\frac{\mathrm{port_x.mflow}}{\mathrm{ActualStream}\left(\mathrm{port_x.rho}\right)\cdot A\left[i\right]}$   $\mathrm{heat.T}=T$ (*) Regarding the value of properties, see more details in Air Settings.
 Fidelity of properties = Constant and Dynamics of mass = Dynamic Mass conservation is calculated with: $\mathrm{port_a.p}=p$ $\mathrm{port_x.p}=p$  $\left(x=\left\{b,c,d\right\}\right)$ Energy conservation is calculated with: State equation: $p=\mathrm{ρ}\cdot \mathrm{R__gas}\cdot T$ Relationship of mass: $u=\frac{U}{M}$ $M=\mathrm{ρ}\cdot V$ Definition of Enthalpy: $\mathrm{hflow}=\mathrm{Function__hflow}\left(T\right)$ Port definitions: $\mathrm{port_a.hflow}=\mathrm{hflow}$ $\mathrm{port_x.hflow}=\mathrm{hflow}$  $\left(x=\left\{b,c,d\right\}\right)$ $\mathrm{port_a.rho}=\mathrm{ρ}$ $\mathrm{port_x.rho}=\mathrm{ρ}$  $\left(x=\left\{b,c,d\right\}\right)$ $\mathrm{port_a.T}=T$ $\mathrm{port_x.T}=T$  $\left(x=\left\{b,c,d\right\}\right)$ $v\left[1\right]=\frac{\mathrm{port_a.mflow}}{\mathrm{ActualStream}\left(\mathrm{port_a.rho}\right)\cdot A\left[1\right]}$ $v\left[i\right]=\frac{\mathrm{port_x.mflow}}{\mathrm{ActualStream}\left(\mathrm{port_x.rho}\right)\cdot A\left[i\right]}$   $\mathrm{heat.T}=T$ (*) Regarding the values and equations of properties, see more details in Air Settings.
 Fidelity of properties: Ideal Gas (NASA Polynomial) and Dynamics of mass = Static If Type of Branch is (Branching), Mass conservation is calculated with:   $\left(x=\left\{b,c,d\right\}\right)$ $\mathrm{port_a.p}=p$ $\mathrm{port_x.p}=p$  $\left(x=\left\{b,c,d\right\}\right)$ If Type of Branch is (Confluence), Mass conservation is calculated with:   $\mathrm{port_a.p}=p$ $\mathrm{port_b.p}=p$ Energy conservation is calculated with: State equation: $p=\mathrm{ρ}\cdot \mathrm{R__gas}\cdot T$ Relationship of mass: $u=\frac{U}{M}$ $M=\mathrm{ρ}\cdot V$ Definition of Enthalpy: $\mathrm{hflow}=\mathrm{Function__hflow}\left(T\right)$ $u=\mathrm{hflow}-\frac{p}{\mathrm{ρ}}$ Port definitions: $\mathrm{port_a.hflow}=\mathrm{hflow}$ $\mathrm{port_x.hflow}=\mathrm{hflow}$  $\left(x=\left\{b,c,d\right\}\right)$ $\mathrm{port_a.rho}=\mathrm{ρ}$ $\mathrm{port_x.rho}=\mathrm{ρ}$  $\left(x=\left\{b,c,d\right\}\right)$ $\mathrm{port_a.T}=T$ $\mathrm{port_x.T}=T$  $\left(x=\left\{b,c,d\right\}\right)$ $v\left[1\right]=\frac{\mathrm{port_a.mflow}}{\mathrm{ActualStream}\left(\mathrm{port_a.rho}\right)\cdot A\left[1\right]}$ $v\left[i\right]=\frac{\mathrm{port_x.mflow}}{\mathrm{ActualStream}\left(\mathrm{port_x.rho}\right)\cdot A\left[i\right]}$   $\mathrm{heat.T}=T$ (*) The properties are defined with NASA polynomials and coefficients. For details, see Air Settings.
 Fidelity of properties: Ideal Gas (NASA Polynomial) and Dynamics of mass = Dynamic Mass conservation is calculated with: $\mathrm{port_a.p}=p$ $\mathrm{port_x.p}=p$  $\left(x=\left\{b,c,d\right\}\right)$ Energy conservation is calculated with: State equation: $p=\mathrm{ρ}\cdot \mathrm{R__gas}\cdot T$ Relationship of mass: $u=\frac{U}{M}$ $M=\mathrm{ρ}\cdot V$ Definition of Enthalpy: $\mathrm{hflow}=\mathrm{Function__hflow}\left(T\right)$ Port definitions: $\mathrm{port_a.hflow}=\mathrm{hflow}$ $\mathrm{port_x.hflow}=\mathrm{hflow}$  $\left(x=\left\{b,c,d\right\}\right)$ $\mathrm{port_a.rho}=\mathrm{ρ}$ $\mathrm{port_x.rho}=\mathrm{ρ}$  $\left(x=\left\{b,c,d\right\}\right)$ $\mathrm{port_a.T}=T$ $\mathrm{port_x.T}=T$  $\left(x=\left\{b,c,d\right\}\right)$ $v\left[1\right]=\frac{\mathrm{port_a.mflow}}{\mathrm{ActualStream}\left(\mathrm{port_a.rho}\right)\cdot A\left[1\right]}$ $v\left[i\right]=\frac{\mathrm{port_x.mflow}}{\mathrm{ActualStream}\left(\mathrm{port_x.rho}\right)\cdot A\left[i\right]}$   $\mathrm{heat.T}=T$ (*) The properties are defined with NASA polynomials and coefficients. For details, see Air Settings.

Variables

 Symbol Units Description Modelica ID $p$ $\mathrm{Pa}$ Pressure p $T$ $K$ Temperature T $\mathrm{ρ}$ $\frac{\mathrm{kg}}{{m}^{3}}$ Density rho $\mathrm{hflow}$ $\frac{J}{\mathrm{kg}}$ Specific enthalpy hflow $u$ $\frac{J}{\mathrm{kg}}$ Specific energy u $U$ $J$ Energy u $M$ $\mathrm{kg}$ Mass M $\mathrm{mflow}$ $\frac{\mathrm{kg}}{s}$ Mass flow rate mflow $\mathrm{NumOfRoute}$ $-$ Number of valid routes NumOfRoute $v$ $\frac{m}{s}$ Velocity of flow v

Connections

 Name Units Condition Description Modelica ID $\mathrm{port__a}$  Air Port $\mathrm{port_a}$ $\mathrm{port__b}$  if port_c on is true. Air Port $\mathrm{port_b}$ $\mathrm{port__c}$  if port_d on is true. Air Port $\mathrm{port_c}$ $\mathrm{port__d}$  if port_b on is true. Air Port $\mathrm{port_d}$ $\mathrm{states}$  if Internal states output is true. Internal states output. The breakdown list of output variables in states are the followings:  [1] : Pressure     [2] : Temperature  [3] : Density       [4] : Specific enthalpy  [5] : Velocity of port_a  [6] : Velocity of port_b  [7] : Velocity of port_c  [8] : Velocity of port_d $\mathrm{states}$ $\mathrm{heat}$  if Heat port is true. Heat Port $\mathrm{heat}$

Parameters

 Symbol Default Units Description Modelica ID $\mathrm{AirSettings1}$ $-$ Specify a component of Air simulation settings Settings $V$ $0.001$ ${m}^{3}$ Volume of the node V $A$ $\left[\frac{\mathrm{Pi}}{400},\frac{\mathrm{Pi}}{400},\frac{\mathrm{Pi}}{400},\frac{\mathrm{Pi}}{400}\right]$ ${m}^{2}$ Flow area of each port  1 : port_a,    2 : port_b  3 : port_c,    4 : port_d A $\mathrm{false}$ $-$ If true, port_b is valid sw_b $\mathrm{false}$ $-$ If true, port_c is valid sw_c $\mathrm{false}$ $-$ If true, port_d is valid sw_d $\mathrm{p__start}$ $101325$ $\mathrm{Pa}$ Initial condition of Pressure p_start $\mathrm{T__start}$ $293.15$ $K$ Initial condition of temperature T_start $\mathrm{Internal}\phantom{\rule[-0.0ex]{0.0em}{0.0ex}}\mathrm{states}\phantom{\rule[-0.0ex]{0.0em}{0.0ex}}\mathrm{output}$ $\mathrm{false}$ $-$ If true, the output of the internal states is valid. The breakdown list of output variables in states are the followings:  [1] : Pressure                [2] : Temperature  [3] : Density                  [4] : Specific enthalpy  [5] : Velocity of port_a  [6] : Velocity of port_b  [7] : Velocity of port_c  [8] : Velocity of port_d useStates $\mathrm{false}$ $-$ If true, Heat port is valid useHeatPort $a⇒b+c+d$ $-$ Branch type setting only for Static mass flow simulation, when Dynamics of mass option of Air Setting is Static.  $a⇒b+c+d$     The input flow is split into 3 ports  $a+c+d⇒b$     The input flows from 3 ports is confluent TypeOfBranch