modelHADryCoil

Sensible convective heat transfer model for air to water coil

Extends from Modelica.Blocks.Icons.Block (Basic graphical layout of input/output block).

Information

Model for sensible convective heat transfer coefficients for an air to water coil.

This model computes the convective heat transfer coefficient for an air to water coil. The parameters allow a user to enable or disable, individually for each medium, the mass flow and/or the temperature dependence of the convective heat transfer coefficients. For a detailed explanation of the equation, see the references below.

References

Wetter Michael, Simulation model finned water-air-coil without condensation, LBNL-42355, Lawrence Berkeley National Laboratory, Berkeley, CA, 1999.
Wetter Michael, Simulation model air-to-air plate heat exchanger, LBNL-42354, Lawrence Berkeley National Laboratory, Berkeley, CA, 1999.

Parameters

Type	Name	Default	Description
Real	n_w	0.85	Water-side exponent for convective heat transfer coefficient, h~m_flow^n
Real	n_a	0.8	Air-side exponent for convective heat transfer coefficient, h~m_flow^n
General › Nominal condition
Modelica.Units.SI.ThermalConductance	UA_nominal		Thermal conductance at nominal flow
Modelica.Units.SI.MassFlowRate	m_flow_nominal_w		Water mass flow rate
Modelica.Units.SI.MassFlowRate	m_flow_nominal_a		Air mass flow rate
Real	r_nominal	0.5	Ratio between air-side and water-side convective heat transfer coefficient
Modelica.Units.SI.ThermalConductance	hA_nominal_w	UA_nominal*(r_nominal + 1)/r_nominal	Water side convective heat transfer coefficient
Modelica.Units.SI.ThermalConductance	hA_nominal_a	r_nominal*hA_nominal_w	Air side convective heat transfer coefficient, including fin resistance
Modelica.Units.SI.Temperature	T0_w	Modelica.Units.Conversions.from_degC(20)	Water temperature
Modelica.Units.SI.Temperature	T0_a	Modelica.Units.Conversions.from_degC(20)	Air temperature
Advanced › Modeling detail
Boolean	waterSideFlowDependent	true	Set to false to make water-side hA independent of mass flow rate
Boolean	airSideFlowDependent	true	Set to false to make air-side hA independent of mass flow rate
Boolean	waterSideTemperatureDependent	true	Set to false to make water-side hA independent of temperature
Boolean	airSideTemperatureDependent	true	Set to false to make air-side hA independent of temperature

Connectors

Type	Name	Description
Modelica.Blocks.Interfaces.RealInput	m1_flow	Mass flow rate medium 1
Modelica.Blocks.Interfaces.RealInput	m2_flow	Mass flow rate medium 2
Modelica.Blocks.Interfaces.RealInput	T_1	Temperature medium 1
Modelica.Blocks.Interfaces.RealInput	T_2	Temperature medium 2
Modelica.Blocks.Interfaces.RealOutput	hA_1	Convective heat transfer medium 1
Modelica.Blocks.Interfaces.RealOutput	hA_2	Convective heat transfer medium 2

Revisions

April 9, 2017, by Michael Wetter:
Corrected coefficient in Taylor expansion of x_a.
This is for #698.
June 8, 2010, by Michael Wetter:
Fixed bug in computation of s_w. The old implementation used the current inlet water temperature instead of the design condition that corresponds to UA_nominal.
April 16, 2008, by Michael Wetter:
First implementation.