modelEnthalpyFlow
Extends from BuildSysPro.BaseClasses.HeatTransfer.Interfaces.Element1D (Partial heat transfer element with two HeatPort connectors that does not store energy).
Information
Enthalpy flow due to air ventilation and infiltration
Hypothesis and equations
This model calculates an enthalpy flow between two rooms at different temperatures, assuming that the mass balance is met. Only one enthalpy exchange, oriented from upstream to downstream, is modelled.
The volume flow rate can be prescribed or fixed throughout the simulation.
The enthalpy flux between thermal zone and outside is defined as follows:
The main assumptions are:
- Variations in potential and kinetic energies of the air are neglected
and 
- mechanical work exchanged with the solid walls is zero
- the air temperature is uniform throughout the room: Tair uniforme
- the air specific heat is considered constant and uniform: Cp = constant
- the density of an air zone is constant and uniform: rho = constant
The model represents a quantity of air in zone A (upstream) at port_a.T temperature and at rho density moving to zone B (downstream). The enthalpy variation is only due to the temperature difference between these areas.
Bibliography
CLIM2000 : étude du renouvellement d'air, C. Rogari , Rapport de stage 3ème année ESIP-EDF. Juin1990.
model TF 101 from CLIM2000. 02/2002
Instructions for use
The conservation of mass in a thermal zone is imperative and is left to the user's care, otherwise the transfered work (PdV) can not be equal to zero.
By construction, this model can not ensure it. For example, for a thermal zone exchanging air with outdoor environment, two head-to-toe models should be used.
Similarly, this model can not be used alone for a single zone.
For more information refer to the user manual TF101 of CLIM2000.
Known limits / Use precautions
Use this type of model only for temperature differences lower than 5°C. Beyond, prefer pressure and temperature models, which provide a more accurate modeling.
Caution related to the conservation of mass.
Validations
Model validated - Gilles Plessis 02/2012
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Licensed by EDF under a 3-clause BSD-license
Copyright © EDF 2009 - 2023
BuildSysPro version 3.6.0
Author : Gilles PLESSIS, EDF (2012)
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Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Ventilation/infiltration | |||
| Boolean | use_Qv_in | false | Prescribed volume flow rate |
| Real | Qv | 0 | Constant volume flow rate for ventilation and/or infiltrations [m3/h] |
| Air properties | |||
| Modelica.Units.SI.Density | rhoair | 1.24 | Air density |
| Modelica.Units.SI.SpecificHeatCapacity | Cp | 1005 | Air specific heat capacity |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| HeatPort_a | port_a (from Element1D) | ||
| HeatPort_b | port_b (from Element1D) | ||
| Modelica.Blocks.Interfaces.RealInput | Qv_in | Prescribed air flow rate[m3/h] |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.HeatFlowRate | Q_flow (from Element1D) | Heat flow rate from port_a -> port_b | |
| Modelica.Units.SI.TemperatureDifference | dT (from Element1D) | port_a.T - port_b.T |
Revisions
Gilles Plessis 10/2011 : Suppresion du paramètre V volume de la zone d'air amont par rapport au modèle CLIM2000.
Gilles Plessis 02/2012 : Modification du modèle pour permettre un scénario de ventilation fixe ou commandé.