modelGasConvection

Model for heat convection through gas in a window assembly

Extends from Modelica.Thermal.HeatTransfer.Interfaces.Element1D (Partial heat transfer element with two HeatPort connectors that does not store energy), Buildings.BaseClasses.BaseIcon (Base icon).

Information

Model for convective heat tranfer in a single layer of window gas. Currently, the model only implements equations for vertical windows and for horizontal windows. The computation is according to TARCOG 2006, except that this implementation computes the convection coefficient as a function that is differentiable in the temperatures.

To use this model, set the parameter til to a value defined in Buildings.Types.Tilt.

If the parameter linearize is set to true, then all equations are linearized.

References

TARCOG 2006: Carli, Inc., TARCOG: Mathematical models for calculation of thermal performance of glazing systems with our without shading devices, Technical Report, Oct. 17, 2006.

Parameters

Type	Name	Default	Description
Boolean	homotopyInitialization	true	= true, use homotopy method
Buildings.HeatTransfer.Data.Gases.Generic	gas		Thermophysical properties of gas fill
Modelica.Units.SI.Area	A		Heat transfer area
Modelica.Units.SI.Area	h	sqrt(A)	Height of window
Modelica.Units.SI.Angle	til		Surface tilt (only 0, 90 and 180 degrees are implemented)
Boolean	linearize	false	Set to true to linearize emissive power
Modelica.Units.SI.Temperature	T0	293.15	Temperature used to compute thermophysical properties

Connectors

Type	Name	Description
HeatPort_a	port_a (from Element1D)
HeatPort_b	port_b (from Element1D)
Modelica.Blocks.Interfaces.RealInput	u	Input connector, used to scale the surface area to take into account an operable shading device

Components

Type	Name	Description
SI.HeatFlowRate	Q_flow (from Element1D)	Heat flow rate from port_a -> port_b
SI.TemperatureDifference	dT (from Element1D)	port_a.T - port_b.T
Modelica.Units.SI.CoefficientOfHeatTransfer	hCon	Convective heat transfer coefficient
Modelica.Units.SI.HeatFlux	q_flow	Convective heat flux
Real	Nu	Nusselt number
Real	Ra	Rayleigh number

Revisions

April 14, 2020, by Michael Wetter:
Changed homotopyInitialization to a constant.
This is for IBPSA, #1341.
March 13, 2015, by Michael Wetter:
Added assertion as the gas layer is now by default assigned a dummy layer with negative thickness. This has been done to avoid a translation error in OpenModelica.
October 17, 2014, by Michael Wetter:
Removed duplicate initial equation section.
May 30, 2014, by Michael Wetter:
Removed undesirable annotation Evaluate=true.
April 2, 2011 by Michael Wetter:
Added homotopy operator.
August 18 2010, by Michael Wetter:
First implementation.