blockCapacityWaterCooled

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(θ_e,in, θ_c,in, ff) = cap_θ(θ_e,in, θ_c,in) cap_FF(ff) cap_FFCon(ffCon) Q̇_nom

where cap_FFCon(ffCon) is the additional modifier for cooling capacity, and calculated as:

capCon_FFCon(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 ⁄ ṁCon_nom

where ṁCon is the mass flow rate at the condenser and ṁCon_nom 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

EIR_FFCon(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.

Revisions

• April 5, 2023, by Xing Lu:
  Updated class being extended from PartialCoolingCapacity to Buildings.Fluid.DXSystems.Cooling.BaseClasses.PartialCapacity.
• November 8, 2022, by Michael Wetter:
  Corrected calculation of performance which used the wrong upper bound, and which used ff instead of ffCon for calculating cap_FFCon.
  This is for issue 3146.
• October 21, 2019, by Michael Wetter:
  Ensured that transition interval for computation of corFac is non-zero.
  This is for issue 1202.
• February 17, 2017 by Yangyang Fu:
  First implementation.