modelElectricWaterHeater_constProp_L4
Temperature and Heat flow rate based model of a stratified thermal storage with finite volume discretisation (1=top, n=bottom) no thermodynamic property computation
Extends from TransiEnt.Basics.Icons.Model (Icon for models), TransiEnt.Basics.Icons.ThermalStorageBasic (Icon for thermal storage model).
Information
1. Purpose of model
Hot water storage with spatial discretisation. Thermodynamic properties are not calculated in dependance of the temperature.
2. Level of detail, physical effects considered, and physical insight
(Purely technical component without physical modeling.)
3. Limits of validity
(Purely technical component without physical modeling.)
4. Interfaces
m_flow: output for mass flow rate in [kg/s]( drawn water is assumed to be replaced by cold water)
Tamb_input: input for ambient in temperature in [K]
u[N_heaters]: BooleanInput (control input for heating element 1)
epp: active power port
5. Nomenclature
(no elements)
6. Governing Equations
(no equations)
7. Remarks for Usage
(no remarks)
8. Validation
(no remarks)
9. References
(no remarks)
10. Version History
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| SI.Length | dx | h/n | |
| Real | a | k/(rho*c) | |
| SI.Mass | m_i | m/n | |
| SI.MassFlowRate | m_flow_cf | m_i/d*v_cf | |
| Integer | i_minturb_1 | min(i_heatingZone_1) | |
| Integer | i_minturb_2 | min(i_heatingZone_2) | |
| Geometry | |||
| SI.Area | A_top | 0.3 | top tank area |
| SI.Area | A_bottom | A_top | bottom tank area |
| SI.Area | A_wall | 0.0097 | outside tank area |
| SI.Length | d | 0.01 | diameter of tank |
| SI.Length | h | 1 | height of tank |
| Heating Units | |||
| Integer | N_heaters | 2 | |
| SI.Power | P_0 | 4.5e3 | |
| SI.Efficiency | eta | 1 | |
| Integer[N_heaters] | i_heater | {integer(floor(0.2*n)), n - 1} | Index of control volume containing heater (1=bottom, n=top) |
| Integer | N_mix | 3 | Number of control volumes around heater position directly affected by the heater |
| Integer[N_mix] | i_heatingZone_1 | integer(linspace(i_heater[1] - N_mix/2 + 1, i_heater[1] + N_mix/2, N_mix)) | |
| Integer[N_mix] | i_heatingZone_2 | integer(linspace(i_heater[2] - N_mix/2 + 1, i_heater[2] + N_mix/2, N_mix)) | |
| Thermodynamics | |||
| SI.Mass | m | 300 | mass inside tank |
| SI.Temperature[n] | T_start | linspace(273.15 + 40, 273.15 + 60, n) | Temperatures at initalization |
| SI.Temperature | Tamb | 273.15 + 20 | Constant ambient temperature, if isTambConst=true |
| SI.Temperature | T_inflow | 273.15 + 35 | Temperature of water inflow |
| SI.Temperature | T_max | 273.15 + 95 | Maximum temperature used for computation of SOC |
| SI.ThermalConductivity | k | 0.6 | Thermal conductivity of fluid in storage |
| SI.Density | rho | 1e3 | Density of fluid in storage |
| SI.SpecificHeatCapacity | c | 4.185e3 | Heat capacity of fluid in storage |
| Modelica.Units.SI.CoefficientOfHeatTransfer | U | 0.5 | Coefficient of heat transfer to ambient (side, top and bottom walls) |
| SI.Velocity | v_cf | 0.05 | Empiric parameter for modeling of turbulence induced by internal heaters |
| Numerical parameters | |||
| Integer | n | 100 | Number of control volumes |
| Boolean | isTambConst | false | False, Ambient temperature through input connector |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| TransiEnt.Basics.Interfaces.General.MassFlowRateIn | m_flow | Drawn water is assumed to be replaced by cold water | |
| TransiEnt.Basics.Interfaces.General.TemperatureIn | Tamb_input | Input for ambient temperature in [K] | |
| Modelica.Blocks.Interfaces.BooleanInput[N_heaters] | u | control input for heating element n | |
| TransiEnt.Basics.Interfaces.Electrical.ActivePowerPort | epp |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| SI.Temperature[n] | T | ||
| SI.TemperatureSlope[n] | dTdt_diff | ||
| SI.TemperatureSlope[n] | dTdt_plug | ||
| SI.TemperatureSlope[n] | dTdt_loss | ||
| SI.TemperatureSlope[n] | dTdt_heater | ||
| SI.TemperatureSlope[n] | dTdt_turb | ||
| SI.Energy | E_stor | m*c*(sum(T)/n - T_inflow) | |
| Real | SOC | E_stor/(m*c*(T_max - T_inflow)) | |
| SI.Temperature | T_mean | sum(T)/n | |
| SI.Temperature | T_outflow | T[n] | |
| SI.HeatFlowRate | Q_flow_out | m_flow*c*(T_inflow - T_outflow) | |
| SI.HeatFlowRate | Q_heater_1 | if u[1] then P_0*eta else 0 | |
| SI.HeatFlowRate | Q_heater_2 | if u[2] then P_0*eta else 0 | |
| SI.Power | P_el_heater_1 | if u[1] then P_0 else 0 | |
| SI.Power | P_el_heater_2 | if u[2] then P_0 else 0 | |
| SI.HeatFlowRate | Q_heater | Q_heater_1 + Q_heater_2 |