modelTankBranch

Model of the tank branch of a storage plant

Extends from Buildings.Fluid.Interfaces.PartialFourPort (Partial model with four ports).

Information

This model is part of a storage plant. This branch has a stratified tank. This tank can potentially be charged remotely by a chiller from the district CHW network, or by a chiller that is local to the energy transfer station that contains this tank.

Parameters

Type	Name	Default	Description
Assumptions
Boolean	allowFlowReversal1 (from PartialFourPort)	true	= false to simplify equations, assuming, but not enforcing, no flow reversal for medium 1
Boolean	allowFlowReversal2 (from PartialFourPort)	true	= false to simplify equations, assuming, but not enforcing, no flow reversal for medium 2
Nominal values
Modelica.Units.SI.MassFlowRate	m_flow_nominal		Nominal mass flow rate
Modelica.Units.SI.MassFlowRate	mTan_flow_nominal		Nominal mass flow rate for CHW tank branch
Modelica.Units.SI.MassFlowRate	mChi_flow_nominal		Nominal mass flow rate for CHW chiller branch
Modelica.Units.SI.Temperature	T_CHWS_nominal	7 + 273.15	Nominal temperature of CHW supply
Modelica.Units.SI.Temperature	T_CHWR_nominal	12 + 273.15	Nominal temperature of CHW return
Tank
Modelica.Units.SI.Volume	VTan		Tank volume
Modelica.Units.SI.Length	hTan		Height of tank (without insulation)
Modelica.Units.SI.Length	dIns		Thickness of insulation
Modelica.Units.SI.ThermalConductivity	kIns	0.04	Specific heat conductivity of insulation
Integer	nSeg	5	Number of volume segments
Modelica.Units.SI.Time	tau	1	Time constant for mixing
Dynamics › Conservation equations
Modelica.Fluid.Types.Dynamics	energyDynamics	Modelica.Fluid.Types.Dynamics.FixedInitial	Formulation of energy balance
Initialization
Medium.AbsolutePressure	p_start	Medium.p_default	Start value of pressure
Medium.Temperature	T_start	T_CHWR_nominal	Start value of temperature
Modelica.Units.SI.Temperature[nSeg]	TFlu_start	T_start*ones(nSeg)	Initial temperature of the tank segments, with TFlu_start[1] being the top segment

Connectors

Type	Name	Description
Modelica.Fluid.Interfaces.FluidPort_a	port_a1 (from PartialFourPort)	Fluid connector a1 (positive design flow direction is from port_a1 to port_b1)
Modelica.Fluid.Interfaces.FluidPort_b	port_b1 (from PartialFourPort)	Fluid connector b1 (positive design flow direction is from port_a1 to port_b1)
Modelica.Fluid.Interfaces.FluidPort_a	port_a2 (from PartialFourPort)	Fluid connector a2 (positive design flow direction is from port_a2 to port_b2)
Modelica.Fluid.Interfaces.FluidPort_b	port_b2 (from PartialFourPort)	Fluid connector b2 (positive design flow direction is from port_a2 to port_b2)
Modelica.Blocks.Interfaces.RealOutput	mTan_flow	Mass flow rate of the tank
Modelica.Blocks.Interfaces.RealOutput	Ql_flow	Heat loss of tank (positive if heat flows from tank to ambient)
Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a	heaPorTop	Heat port tank top (outside insulation)
Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a	heaPorSid	Heat port tank side (outside insulation)
Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a	heaPorBot	Heat port tank bottom (outside insulation). Leave unconnected for adiabatic condition
Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a	heaPorVol	Heat port that connects to the control volumes of the tank
Modelica.Blocks.Interfaces.RealOutput[2]	TTan	Temperatures at the tank 1: top and 2: bottom

Components

Type	Name	Description
Buildings.Fluid.Storage.Stratified	tan	Tank
Buildings.Fluid.Sensors.MassFlowRate	senFlo	Flow rate sensor for the tank,
Modelica.Thermal.HeatTransfer.Sensors.TemperatureSensor	senTemTop	Temperature sensor for tank top
Modelica.Thermal.HeatTransfer.Sensors.TemperatureSensor	senTemBot	Temperature sensor for tank bottom

Name	Description
Medium	Medium package

Revisions

March 5, 2024, by Michael Wetter:
Corrected wrong use of displayUnit.
October 4, 2022 by Hongxiang Fu:
First implementation. This is for #2859.