modelSimpleHouse6

Free cooling model

Extends from SimpleHouse5.

Information

For this last exercise, we first increase the window size from 2 m2 to 6 m2.

We will add a ventilation model that allows to perform free cooling using outside air when solar irradiation heats up the room too much. The system consists of a fan, a damper, a controller with an air temperature setpoint between 23°C and 25°C, and a heat recovery unit with a constant effectiveness of 85%. The damper and fan have a nominal pressure drop/raise of 200 Pa. The heat recovery unit has a nominal pressure drop of 10 Pa at both sides. The nominal mass flow rate of the ventilation system is 0.1 kg/s.

Required models

Connection instructions

Connect the components such that they exchange mass (and therefore also energy) with the MixingVolume representing the zone air. Add a boundary_pT to draw air from the environment. Enable its temperature input and connect it to the TDryBul variable in the weather data reader. Also reconsider the nominal mass flow rate parameter value in the MixingVolume given the flow rate information of the ventilation system. Finally, make sure that the fan is only active when the damper is open.

Reference result

The figures below show the results.

Air temperature as function of time.

Ventilation control signal as function of time.

Parameters

TypeNameDefaultDescription
Modelica.Units.SI.PressureDifferencedpAir_nominal200Pressure drop at nominal mass flow rate for air loop

Components

TypeNameDefaultDescription
Buildings.Fluid.Actuators.Dampers.ExponentialvavDamDamper
Buildings.Fluid.Movers.Preconfigured.FlowControlled_dpfanConstant head fan
Buildings.Fluid.HeatExchangers.ConstantEffectivenesshexRecHeat exchanger for heat recuperation
Buildings.Fluid.Sources.Boundary_pTbouAirAir boundary with constant temperature
Modelica.Blocks.Logical.HysteresishysAirHysteresis controller for damper
Modelica.Blocks.Math.BooleanToRealbooRea2Boolean to real
Modelica.Blocks.Math.BooleanToRealbooRea3Boolean to real
Buildings.Fluid.Sensors.TemperatureTwoPortTFanInTemperature at fan inlet
Buildings.Fluid.Sensors.TemperatureTwoPortTFanOutTemperature at fan outlet

Revisions

  • August 5, 2024, by Hongxiang Fu:
    Added two-port temperature sensors to replace sta_*.T in reference results. This is for IBPSA #1913.
  • September 4, 2023, by Jelger Jansen:
    First implementation.