blockCapacityAirSource
Extends from Buildings.Fluid.DXSystems.Cooling.BaseClasses.PartialCapacity (Calculates performance curve value at given temperature and mass flow rate).
Information
This model calculates cooling capacity and EIR for air source DX coils in off-designed conditions based on performance modifers calculated in partial model Buildings.Fluid.DXSystems.Cooling.BaseClasses.PartialCapacity.
Cooling capacity
The cooling capacity modifiers are multiplied with nominal cooling capacity to obtain the cooling capacity of the coil at given inlet temperatures and mass flow rate as
Q̇(θe,in, θc,in, ff) = capθ(θe,in, θc,in) capFF(ff) Q̇nom,
where θe,in is the evaporator inlet temperature and θc,in is the condenser inlet temperature in degrees Celsius. θe,in is the dry-bulb temperature if the coil is dry, or the wet-bulb temperature if the coil is wet. capθ(θe,in, θc,in) is cooling capacity modifier as a function of temperature. capFF(ff) is cooling capacity modifier as a function of nomalized mass flowrate at the evaporator.
Energy Input Ratio (EIR)
The Energy Input Ratio (EIR) is the inverse of the Coefficient of Performance (COP). Similar to the cooling rate, the EIR of the coil is the product of a function that takes into account changes in condenser and evaporator inlet temperatures, and changes in mass flow rate. The EIR is computed as
EIR(θe,in, θc,in, ff) = EIRθ(θe,in, θc,in) EIRFF(ff) ⁄ COPnominal
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | use_mCon_flow (from PartialCapacity) | Set to true to enable connector for the condenser mass flow rate | |
| Integer | nSta (from PartialCapacity) | Number of coil stages (not counting the off stage) | |
| Buildings.Fluid.DXSystems.Cooling.AirSource.Data.Generic.BaseClasses.Stage[nSta] | sta (from PartialCapacity) | Performance data for this stage |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Blocks.Interfaces.IntegerInput | stage (from PartialCapacity) | Stage of coil, or 0/1 for variable-speed coil | |
| Modelica.Blocks.Interfaces.RealInput | TConIn (from PartialCapacity) | Temperature of air entering the condenser coil | |
| Modelica.Blocks.Interfaces.RealInput | m_flow (from PartialCapacity) | Air mass flow rate at the evaporator | |
| Modelica.Blocks.Interfaces.RealInput | TEvaIn (from PartialCapacity) | Temperature of air entering the evaporator (wet bulb for wet coil and dry bulb for dry coil) | |
| Modelica.Blocks.Interfaces.RealInput | mCon_flow (from PartialCapacity) | Water mass flow rate at the condenser | |
| Modelica.Blocks.Interfaces.RealOutput[nSta] | Q_flow (from PartialCapacity) | Total cooling capacity | |
| Modelica.Blocks.Interfaces.RealOutput[nSta] | EIR (from PartialCapacity) | Energy Input Ratio |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Real | ff (from PartialCapacity) | Air flow fraction: ratio of actual air flow rate by rated mass flow rate | |
| Real[nSta] | cap_T (from PartialCapacity) | Cooling capacity modification factor as a function of temperature | |
| Real[nSta] | cap_FF (from PartialCapacity) | Cooling capacity modification factor as a function of flow fraction | |
| Real[nSta] | EIR_T (from PartialCapacity) | EIR modification factor as a function of temperature | |
| Real[nSta] | EIR_FF (from PartialCapacity) | EIR modification factor as a function of flow fraction | |
| Real[nSta] | corFac (from PartialCapacity) | Correction factor that is one inside the valid flow fraction, and attains zero below the valid flow fraction |
Revisions
-
April 3, 2023 by Karthik Devaprasad and Xing Lu:
Updated class name fromCoolingCapacityAirCooledtoCoilCapacityAirSource, since the class is used in both heating coil and cooling coil calculations for air-source DX coils.
Updated class being extended fromPartialCoolingCapacityto Buildings.Fluid.DXSystems.Cooling.BaseClasses.PartialCapacity. -
February 17, 2017 by Yangyang Fu:
First implementation.