modelOutsideAirConvection
Cover heat exchange by convection with outside air function of wind speed
Extends from Modelica.Thermal.HeatTransfer.Interfaces.Element1D (Partial heat transfer element with two HeatPort connectors that does not store energy).
Information
The convection at the outer side of the greenhouse cover is modeled according to the experimental work of [1], who characterised the heat exchange coefficient at this saw-tooth surface as a function of the wind speed. The wind speed, being a boundary condition, is an input of the model. The main parameter is the cover tilt.
[1] G.P.A Bot. Greenhouse climate : from physical processes to a dynamic model. PhD thesis, Wageningen University, 1983.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.Area | A | floor surface | |
| Modelica.Units.SI.Angle | phi | inclination of the surface (0 if horizontal, 25 for typical cover) |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| HeatPort_a | port_a (from Element1D) | ||
| HeatPort_b | port_b (from Element1D) |
Components
| Type | Name | Default | 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.Velocity | u | 0 | Wind speed |
| Modelica.Units.SI.CoefficientOfHeatTransfer | HEC_ab | ||
| Real | alpha | ||
| Real | s | 11 | Slope of the differentiable switch function for vapour pressure differences |
| Real | alpha_a | ||
| Real | alpha_b | ||
| Real | du |