blockCapacityWaterCooled
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 at off-designed conditions for water source DX coils. The difference between air source and water source DX coils is that water source DX coils require two additional modifer curves for total cooling capacity and EIR as a function of water mass flowrate at the condensers.
Total Cooling Capacity
The total cooling capacity at off-designed conditions for water source DX coils is calculated as:
Q̇(θe,in, θc,in, ff) = capθ(θe,in, θc,in) capFF(ff) capFFCon(ffCon) Q̇nom
where capFFCon(ffCon) is the additional modifier for cooling capacity, and calculated as:
capConFFCon(ffCon) = b1 + b2 ffCon + b3 ffCon2 + b4ffCon3 + ...
where the variable ffCon is the nomalized mass flow rate at the condenser, and calculated as:
ffCon = ṁCon ⁄ ṁConnom
where ṁCon is the mass flow rate at the condenser and ṁConnom is the nominal mass flow rate at the condenser.
Energy Input Ratio (EIR)
The Energy Input Ratio (EIR) is the inverse of the Coefficient of Performance (COP). Similar to the cooling capacity modifiers, the change in EIR due to change in water mass flow rate at the condenser is
EIRFFCon(ffCon) = b1 + b2 ffCon + b3 ffCon2 + b4ffCon3 + ...
where the six coefficients are obtained from the coil performance data record. See Buildings.Fluid.DXSystems.Cooling.BaseClasses.PartialCapacity for more information.
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 5, 2023, by Xing Lu:
Updated class being extended fromPartialCoolingCapacityto Buildings.Fluid.DXSystems.Cooling.BaseClasses.PartialCapacity. -
November 8, 2022, by Michael Wetter:
Corrected calculation of performance which used the wrong upper bound, and which usedffinstead offfConfor calculatingcap_FFCon.
This is for issue 3146. -
October 21, 2019, by Michael Wetter:
Ensured that transition interval for computation ofcorFacis non-zero.
This is for issue 1202. -
February 17, 2017 by Yangyang Fu:
First implementation.