Buildings.Fluid.HeatExchangers.DXCoils.AirCooled.Data.Generic
Package with generic performance curves
Information
This package contains performance curves for the cooling capacity and the EIR of air-cooled DX cooling coils. For performance data of specific air-cooled DX cooling coils, see the packages Buildings.Fluid.HeatExchangers.DXCoils.AirCooled.Data.SingleSpeed and Buildings.Fluid.HeatExchangers.DXCoils.AirCooled.Data.DoubleSpeed.
The data are described in Buildings.Fluid.HeatExchangers.DXCoils.AirCooled.Data.Generic.DXCoil.
Extends from Modelica.Icons.MaterialPropertiesPackage (Icon for package containing property classes).
Package Content
Name | Description |
---|---|
DXCoil | Performance record for a DX Cooling Coil with one or multiple stages |
BaseClasses | Package with base classes for performance data |
Buildings.Fluid.HeatExchangers.DXCoils.AirCooled.Data.Generic.DXCoil
Performance record for a DX Cooling Coil with one or multiple stages
Information
This record declares the performance data for the air-cooled DX cooling coil model. The performance data are structured as follows:
nSta - Number of stages. Set to 1 for single speed coil, 2 for dual-speed (or dual stage coils), etc. minSpeRat - Minimum speed ratio, used only for variable speed coils. sta - Array of records with one performance curve for each stage, as described below.
Each element of the array per
has the following data.
spe - Rotational speed for the respective stage. (This is only used for variable speed coils to interpolate for intermediate speeds). nomVal - Nominal performance values for the respective stage. Data of the nomVal record are Q_flow_nominal - Total rate of cooling at nominal conditions. COP_nominal - Coefficient of performance at nominal conditions. SHR_nominal - Sensible heat ratio at nominal conditions. m_flow_nominal - Evaporator air mass flow rate at nominal conditions. TEvaIn_nominal - Evaporator air inlet wet-bulb temperature at nominal conditions. TConIn_nominal - Condenser air inlet temperature at nominal conditions (for evaporative coils, use wet bulb, otherwise use dry bulb temperature). phiIn_nominal - Relative humidity at evaporator inlet at nominal conditions. p_nominal - Atmospheric pressure at nominal conditions. tWet - Time until moisture drips from coil when coil is switched on gamma - Ratio of evaporation heat transfer divided by latent heat transfer at nominal condition. per - Array of records with one performance curve for the respective stage of the coil. That is, the performance curves will be used in conjunction with the nominal values defined in the record spe. capFunT - Coefficients of biquadratic polynomial for cooling capacity as a function of temperature. capFunFF - Polynomial coefficients for cooling capacity as a function of the mass flow fraction. EIRFunT - Coefficients of biquadratic polynomial for EIR as a function of temperature. EIRFunFF - Polynomial coefficients for EIR as a function of the mass flow fraction. TConInRan - Minimum and maximum condenser air inlet temperatures for which the performance curves are valid. Outside this range, they will be linearly extrapolated. TEvaInRan - Minimum and maximum evaporator air inlet temperatures for which the performance curves are valid. Outside this range, they will be linearly extrapolated. ffRan - Minimum and maximum air mass flow fraction (relative to m_flow_nominal) for which the performance curves are valid. Outside this range, they will be linearly extrapolated.
The data used to develop the performance curves
capFunT
and
EIRFunT
should represent performance when the
cooling coil is wet, i.e., the coil providing sensible cooling and at least some dehumidification.
Performance data when the cooling coil is dry
(i.e., not providing any dehumidification) should not be included when developing these modifier curves.
The DX coil model automatically detects and adjusts for dry coil conditions by evaluating
the performance curves for the wet bulb and dry bulb temperatures at the evaporator inlet,
and then selecting the corresponding performance.
The selection of the corresponding performance is described and implemented
in
Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.DryWetSelector.
The parameters tWet
and gamma
characterize the amount of
moisture that evaporates from the coil surface into the air stream when the coil is
wet and switched off. For an examplanation of the parameters, see
Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.Evaporation.
There can be an arbitrary number of polynomial coefficients for the record
capFunFF
and EIRFunFF
.
However, if a coil has multiple stages, then each stage must declare the
same amount of polynomial coefficients. For example, if a
quadratic function is used for stage one, then stage two must also use
a quadratic function.
Extends from Modelica.Icons.Record (Icon for records).
Parameters
Type | Name | Default | Description |
---|---|---|---|
Integer | nSta | nSta( ... | Number of stages |
Real | minSpeRat | 0.2 | Minimum speed ratio |
Stage | sta[nSta] | redeclare parameter Building... | Data record for coil performance at each stage |
Minimum conditions | |||
MassFlowRate | m_flow_small | 0.0001*sta[nSta].nomVal.m_fl... | Small mass flow rate for regularization near zero flow [kg/s] |