blockPartialSurfaceCondition

Partial block for apparatus dew and dry point calculation

Extends from Modelica.Blocks.Icons.Block (Basic graphical layout of input/output block), Buildings.Fluid.DXSystems.Cooling.BaseClasses.EssentialParameters (A partial block for essential parameters for cooling DX coils).

Information

This partial block is the base class for Buildings.Fluid.DXSystems.Cooling.BaseClasses.ApparatusDewPoint and Buildings.Fluid.DXSystems.Cooling.BaseClasses.ApparatusDryPoint.

This block calculates the UA/c_p value, the bypass factor and the enthalpy difference across the coil. It uses the function Buildings.Fluid.DXSystems.Cooling.BaseClasses.Functions.speedShift for intermediate compressor speeds.

Implementation

For coils that only have discrete compressor speeds, this block does not do an interpolation for intermediate speeds. For coils with variable speed compressors, the computations are also done if the coil is off, as this ensures that the derivatives are continuous near the off conditions.

Parameters

Type	Name	Default	Description
Buildings.Fluid.DXSystems.Cooling.AirSource.Data.Generic.DXCoil	datCoi (from EssentialParameters)		Performance data
Boolean	variableSpeedCoil		Flag, set to true to interpolate data
Modelica.Units.SI.MassFlowRate	m_flow_small	datCoi.m_flow_small	Small mass flow rate for the evaporator, used for regularization
Modelica.Units.SI.AngularVelocity	maxSpe	datCoi.sta[nSta].spe	Maximum rotational speed

Connectors

Type	Name	Description
Modelica.Blocks.Interfaces.RealInput	speRat	Speed index
Modelica.Blocks.Interfaces.RealInput	Q_flow	Cooling capacity of the coil
Modelica.Blocks.Interfaces.RealInput	m_flow	Evaporator air mass flow rate
Modelica.Blocks.Interfaces.RealInput	p	Evaporator air static pressure
Modelica.Blocks.Interfaces.RealInput	XEvaIn	Evaporator inlet air mass fraction
Modelica.Blocks.Interfaces.RealInput	hEvaIn	Evaporator air inlet specific enthalpy
Modelica.Blocks.Interfaces.IntegerInput	stage	Stage of coil, or 0/1 for variable-speed coil

Components

Type	Name	Description
Real	bypass	Bypass factor
Modelica.Units.SI.AngularVelocity	spe	Rotational speed
Buildings.Fluid.DXSystems.Cooling.BaseClasses.UACp[nSta]	uacp	Calculates UA/Cp of the coil

Name	Description
Medium	Medium model

Revisions

June 26, 2018, by Michael Wetter:
Replaced algorithm with equation.
October 9, 2013 by Michael Wetter:
Corrected invalid Modelica syntax.
September 24, 2012 by Michael Wetter:
Revised implementation.
August 24, 2012, by Michael Wetter:
Moved function from Buildings.Fluid.DXSystems.BaseClasses to Buildings.Fluid.DXSystems.Cooling.BaseClasses.Functions because the package Buildings.Fluid.DXSystems.BaseClasses already contains a block called SpeedShift which gives a clash in file names on file systems that do not distinguish between upper and lower case letters.
August 1, 2012 by Kaustubh Phalak:
First implementation.