modelHeatRecoverySystem
Information
This model describes a sensible heat recovery system with two streams of moist air where the exit temperature is calculated over a user set parameter. The model is valid only for equal mass flow rates of the two air streams.
If the maximum possible temperature at the outlet overshoots the set temperature for the supply air, it will be reduced to the set temperature for heating case. In summer it will be vice versa.
Main equations
The temperature of the outgoing outdoor air is defined as:TairOutOda = ε * (TairInEta - TairInOda) + TairInOda
Implementation
This model uses inputs that need to be set by models that extend or instantiate this model. The following inputs need to be assigned:
- ε, parameter to calculate exit temperature.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Real | effOn | 0.85 | efficiency of the heat recovery system (0...1) if it is used |
| Real | effOff | 0.1 | efficiency of the heat recovery system (0...1) if it is bypassed |
| Advanced | |||
| Modelica.Units.SI.SpecificHeatCapacity | cpAir | 1005 | specific heat capacity of dry air |
| Modelica.Units.SI.SpecificHeatCapacity | cpSteam | 1860 | specific heat capacity of steam |
| Modelica.Units.SI.Density | rhoAir | 1.2 | Density of air |
| Nominal conditions | |||
| Modelica.Units.SI.MassFlowRate | m_flow_nominal | nominal mass flow rate | |
| Modelica.Units.SI.PressureDifference | dp_nominal | pressure drop at nominal mass flow rate | |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Blocks.Interfaces.RealInput | mAirInEta_flow | mass flow rate of incoming exhaust air | |
| Modelica.Blocks.Interfaces.RealInput | TAirInEta | temperature of incoming exhaust air | |
| Modelica.Blocks.Interfaces.RealInput | XAirInEta | absolute humidity of incoming exhaust air | |
| Modelica.Blocks.Interfaces.RealInput | mAirInOda_flow | mass flow rate of incoming outdoor air | |
| Modelica.Blocks.Interfaces.RealInput | TAirInOda | temperature of incoming otudoor air | |
| Modelica.Blocks.Interfaces.RealInput | XAirInOda | absolute humidity of incoming outdoor air | |
| Modelica.Blocks.Interfaces.RealOutput | mAirOutEta_flow | mass flow rate of outgoing exhaust air | |
| Modelica.Blocks.Interfaces.RealOutput | TAirOutEta | temperature of outgoing exhaust air | |
| Modelica.Blocks.Interfaces.RealOutput | XAirOutEta | absolute humidity of outgoing exhaust air | |
| Modelica.Blocks.Interfaces.RealOutput | mAirOutOda_flow | mass flow rate of outgoing outdoor air | |
| Modelica.Blocks.Interfaces.RealOutput | TAirOutOda | temperature of outgoing outdoor air | |
| Modelica.Blocks.Interfaces.RealOutput | XAirOutOda | absolute humidity of outgoing outdoor air | |
| Modelica.Blocks.Interfaces.RealInput | bypOpe | bypass opening (1: fully opened, 0: fully closed) | |
| Modelica.Blocks.Interfaces.RealOutput | dpOda | pressure difference of outdoor air side | |
| Modelica.Blocks.Interfaces.RealOutput | dpEta | pressure difference of exhaust air side |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.MassFlowRate | mDryAirInOda_flow | mass flow rate of incoming dry outdoor air | |
| Modelica.Units.SI.MassFlowRate | mDryAirInEta_flow | mass flow rate of incoming dry exhaust air | |
| Modelica.Units.SI.MassFlowRate | mDryAirOutOda_flow | mass flow rate of outgoing dry outdoor air | |
| Modelica.Units.SI.MassFlowRate | mDryAirOutEta_flow | mass flow rate of outgoing dry exhaust air | |
| Modelica.Units.SI.SpecificEnthalpy | hAirInOda | specific enthalpy of incoming outdoor air | |
| Modelica.Units.SI.SpecificEnthalpy | hAirOutOda | specific enthalpy of outgoing outdoor air | |
| Modelica.Units.SI.SpecificEnthalpy | hAirInEta | specific enthalpy of incoming exhaust air | |
| Modelica.Units.SI.SpecificEnthalpy | hAirOutEta | specific enthalpy of outgoing exhaust air | |
| Modelica.Units.SI.Temperature | TAirOutOdaMax | maximum temperature of outdoor air outlet if HRS is used | |
| Modelica.Units.SI.Temperature | TAirOutOdaMin | minimum temperature of outdoor air outlet if HRS is bypassed | |
| Modelica.Units.SI.HeatFlowRate | Q_flow | heat flow | |
| PartialPressureDrop | partialPressureDropOda | ||
| PartialPressureDrop | partialPressureDropEta |
Contents
| Name | Description |
|---|---|
| PartialPressureDrop |
Revisions
- May 2019, by Ervin Lejlic:
First implementation. - May 2019, by Martin Kremer:
Changed variable names for naming convention. - August 2019, by Martin Kremer:
Added limitation for temperature at outdoor outlet. - April 2020, by Martin Kremer:
Added efficiency for bypassed HRS. Changed limitation of temperature at outdoor outlet.