Water Volume
Control volume element of Water
Description
Equations
Variables
Connections
Parameters
See Also
The Water Volume component models a generic control volume for the lumped thermal fluid simulation of Water. In this component, the mass and energy conservation are calculated.
The calculation is changed based on parameter values of Fidelity of properties and Dynamics of mass in the Water Settings component.
Fidelity of properties = Constant and Dynamics of mass = Static
If Type of Branch is a⇒b+c+d (Branching), Mass conservation is calculated with:
NumOfRoute=∑x=b,c,d{1.0port__x on=true0.0port__x on=false
`port_x.mflow`=−1NumOfRoute⋅`port_a.mflow` if port__x on=true x=b,c,d
`port_a.p`=p
`port_x.p`=p if port__x on=true x=b,c,d
If Type of Branch is a+c+d⇒b (Confluence), Mass conservation is calculated with:
NumOfRoute=1.0+∑x=c,d{1.0port__x on=true0.0port__x on=false
`port_b.mflow`=−(`port_a.mflow`+∑x=c,d{`port_x.mflow`port__x on=true0.0port__x on=false)
p=−1NumOfRoute⋅∑x=a,c,d{`port_x.p`port__x on=true0.0port__x on=false
`port_b.p`=p
Energy conservation is calculated with:
c__p⋅M⋅ⅆTⅆt=`port_a.mflow`⋅ActualStream`port_a.hflow` +∑x=b,c,d{`port_x.mflow`⋅ActualStream`port_x.hflow`port__x on=true0.0port__x on=false+{`heat.Q_flow`useHeatPort=true0.0useHeatPort=false
State equation:
p=ρ⋅R__gas⋅T
Relationship of mass:
u=UM
M=ρ⋅V
Definition of Enthalpy:
hflow=Function__flowT
u=hflow−pρ
Port definitions:
`port_a.hflow`=hflow
`port_x.hflow`=hflow if port__x on=true x=b,c,d
`port_a.rho`=ρ
`port_x.rho`=ρ if port__x on=true x=b,c,d
`port_a.T`=T
`port_x.T`=T if port__x on=true x=b,c,d
v1=`port_a.mflow`ActualStream`port_a.rho`⋅A1
vi=`port_x.mflow`ActualStream`port_x.rho`⋅Ai if port__x on=true x=b,c,d,the order of vector is b=2,c=3,d=4
`heat.T`=T
(*) Regarding the value of properties, see more in Water Settings.
Fidelity of properties = Constant and Dynamics of mass = Dynamic
Mass conservation is calculated with:
ⅆρⅆt=`port_a.mflow`+∑x=b,c,d{`port_x.mflow`port__x on=true0.0port__x on=falseV
ⅆUⅆt=`port_a.mflow`⋅ActualStream`port_a.hflow` +∑x=b,c,d{`port_x.mflow`⋅ActualStream`port_x.hflow`port__x on=true0.0port__x on=false+{`heat.Q_flow`useHeatPort=true0.0useHeatPort=false
hflow=Function__hflowT
c__p−R__gas⋅ⅆTⅆt=ⅆUⅆtρ⋅V−U⋅ρ2⋅V
Fidelity of properties : Liquid water (Lookup table of IAPWS/IF97) and Dynamics of mass = Static
LUT__cpp,T⋅M⋅ⅆTⅆt=`port_a.mflow`⋅ActualStream`port_a.hflow` +∑x=b,c,d{`port_x.mflow`⋅ActualStream`port_x.hflow`port__x on=true0.0port__x on=false+{`heat.Q_flow`useHeatPort=true0.0useHeatPort=false
hflow=LUT__hflowp,T
Definition of Density:
ρ=LUT__ρp,T
(*) Additional information about properties is available in Water Settings.
Fidelity of properties : Liquid water (Lookup table of IAPWS/IF97) and Dynamics of mass = Dynamic
ⅆpⅆt=−ⅆUⅆ t⋅1V+ⅆhflowⅆt⋅ρ+hflow⋅ⅆρⅆt
Fidelity of properties : IAPWS/IF97 standard and Dynamics of mass = Static
Function__cpp,T⋅M⋅ⅆTⅆt=`port_a.mflow`⋅ActualStream`port_a.hflow` +∑x=b,c,d{`port_x.mflow`⋅ActualStream`port_x.hflow`port__x on=true0.0port__x on=false+{`heat.Q_flow`useHeatPort=true0.0useHeatPort=false
hflow=Function__hflowp, T
ρ=Function__ρp, T
Fidelity of properties : IAPWS/IF97 standard and Dynamics of mass = Dynamic
(*) This mode is not available in this version of the Heat Transfer Library
Symbol
Units
Modelica ID
p
Pa
Pressure
T
K
Temperature
ρ
kgm3
Density
rho
hflow
Jkg
Specific enthalpy
u
Specific energy
U
J
Energy
M
kg
Mass
mflow
kgs
Mass flow rate
NumOfRoute
−
Number of valid routes
v
ms
Velocity of flow
Name
Condition
port__a
Water Port
port_a
port__b
if port_c on is true.
port_b
port__c
if port_d on is true.
port_c
port__d
if port_b on is true.
port_d
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
heat
if Heat port is true.
Heat Port
Default
Watersimulationsettings
WaterSettings1
Specify a component of Water simulation settings
Settings
V
0.000001
m3
Volume of the node
A
Pi10000,Pi10000,Pi10000,Pi10000
m2
Flow area of each port
1 : port_a, 2 : port_b
3 : port_c, 4 : port_d
port__b on
false
If true, port_b is valid
sw_b
port__c on
If true, port_c is valid
sw_c
port__d on
If true, port_d is valid
sw_d
p__start
101325
Initial condition of Pressure
p_start
T__start
293.15
Initial condition of temperature
T_start
Internalstatesoutput
If true, the output of the internal states is valid. The breakdown list of output variables in states are the followings:
[5] : Velocity of port_a [6] : Velocity of port_b
[7] : Velocity of port_c [8] : Velocity of port_d
useStates
Heat port
If true, Heat port is valid
useHeatPort
Type ofBranch
a⇒b+c+d
Branch type setting only for Static mass flow simulation, when Dynamics of mass option of Water Settings is Static.
a⇒b+c+d :
The input flow is split into 3 ports
a+c+d⇒b :
The input flows from 3 ports are confluent
TypeOfBranch
Heat Transfer Library Overview
Water Overview
Water Basic Overview
Download Help Document