.Buildings.Fluid.DXSystems.BaseClasses.CapacityAirSource

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

where θ_e,in is the evaporator inlet temperature and θ_c,in is the condenser inlet temperature in degrees Celsius. θ_e,in is the dry-bulb temperature if the coil is dry, or the wet-bulb temperature if the coil is wet. cap_θ(θ_e,in, θ_c,in) is cooling capacity modifier as a function of temperature. cap_FF(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(θ_e,in, θ_c,in, ff) = EIR_θ(θ_e,in, θ_c,in) EIR_FF(ff) ⁄ COP_nominal

Revisions

• April 3, 2023 by Karthik Devaprasad and Xing Lu:
  Updated class name from CoolingCapacityAirCooled to CoilCapacityAirSource, since the class is used in both heating coil and cooling coil calculations for air-source DX coils.
  Updated class being extended from PartialCoolingCapacity to Buildings.Fluid.DXSystems.Cooling.BaseClasses.PartialCapacity.
• February 17, 2017 by Yangyang Fu:
  First implementation.