modelPartialTap

Partial model for a (DHW) tap

Extends from IDEAS.Fluid.Interfaces.PartialTwoPortInterface.

Information

Description

Partial model of a domestic hot water (DHW) tap, including a cold water supply to have a closed system. The tap is modelled as a thermostatic mixing valve.

The model has two flowPorts and a realInput:

  • port_a: connection to the hot water source (designation: hot)
  • port_b: connection to the inlet of cold water in the hot water source (designation: cold)
  • m_flow_set: desired DHW mass flow rate, equivalent at a user defined set point temperature

The model tries to reach the given DHW flow rate at a the desired mixing temperature TSet by mixing the hot water with cold water. The resulting hot flow rate (mFloHot) will be extracted automatically from the hot source (via port_a ). This same flow rate will be injected at TCol in the production system through the connection of port_b to the hot source.

Assumptions and limitations

  1. No heat losses.
  2. If THot is smaller than TSet, there is no mixing and the supply temperature at the tap equals THot.
  3. Fixed TSet and TCol as parameters.
  4. The mixed DHW is not available as an outlet or flowPort. It is assumed to be 'consumed'.

Model use

  1. Set the parameters for cold water supply temperature TCol and the DHW setpoint temperature TSet (mixed, at the tap).
  2. Connect port_a to the hot water source.
  3. Connect port_b to the cold water inlet of the hot water source.
  4. Depending on the implementation: fill out the table or provide a realInput for m_flow_set.
  5. Thanks to the use of an IdealSource in this model, it is NOT required to add additional pumps, ambients or AbsolutePressure to the DHW circuit.

Examples

An example of this model is given in IDEAS.Fluid.Taps.Examples.DHW_example.

Parameters

TypeNameDefaultDescription
Modelica.Units.SI.TemperatureTSet318.15Temperature setpoint of DHW at the tap
Modelica.Units.SI.TemperatureTCol283.15Temperature of cold supply water

Components

TypeNameDefaultDescription
IDEAS.Fluid.Interfaces.IdealSourcemFloSouHotIdeal mass flow source to model the hot water offtake from the system
IDEAS.Fluid.Sources.Boundary_pTbouHotSink to model the hot water offtake from the system
Modelica.Blocks.Sources.RealExpressionTCol_inTemperature of the cold water injected into the system
IDEAS.Fluid.Sources.Boundary_pTbouColSupply to model the cold water injection into the system
IDEAS.Fluid.Interfaces.IdealSourcemFloSouColIdeal mass flow source to model the cold water injection into the system
Modelica.Blocks.Sources.RealExpressionmFloHotRequired flow rate from the hot water source
IDEAS.Fluid.Sensors.TemperatureTwoPortTHotTemperature sensor
Modelica.Blocks.Logical.GreaterEqualThresholdcomBlock operator to check whether there is DHW comfort or not. True = comfort, false = discomfort.
Modelica.Blocks.Interfaces.BooleanOutputDHWComBoolean output signal to indicate whether there is DHW comfort (true) or discomfort (false)

Revisions

  • March 26, 2024, by Lucas Verleyen:
    Major refactoring.
    See #1287 for more information.
  • June, 2013, by Roel De Coninck:
    Documentation.
  • September, 2012, by Roel De Coninck:
    simplification of equations.
  • August, 2012, by Roel De Coninck:
    Initial implementation.