Coil:Cooling:WaterToAirHeatPump:EquationFit
Coil:Cooling:WaterToAirHeatPump:ParameterEstimation
Used in:
- Zone Water To Air Heat Pump
- Unitary Water To Air Heat Pump AHU
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Coil:Cooling:WaterToAirHeatPump:EquationFit Coil:Cooling:WaterToAirHeatPump:ParameterEstimation |
Used in:
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The Water to Air Heat Pump Cooling Coil provides access to the EnergyPlus Equation fit and Parameter Estimation models.
Equation Fit: The Equation Fit Water to Air heat pump Cooling coil is a simple curve-fit model that requires coefficients generated from heat pump catalog data to model performance. The model resembles a black box with no use of heat transfer equations. A detailed description of the equation-fit model is available in the following reference: Tang,C. C. 2005. Modeling Packaged Heat Pumps in Quasi-Steady State Energy Simulation Program. M.S. Thesis. Department of Mechanical and Aerospace Engineering, Oklahoma State University. It is also downloadable from www.hvac.okstate.edu.
DesignBuilder v2026.1 and later only: Parameter Estimation: The Parameter Estimation Water to Air heat pump Cooling coil is a deterministic model that requires parameters to describe the operating conditions of the heat pump’s components. The parameters are generated from the manufacturer catalog data using multi-variable optimisation method. The parameters required for WatertoAirHP cooling coil are similar to WatertoAirHP heating except the source side outside heat transfer coefficient parameter is not required for heating.
A unique auto-assigned name identifying name for the coil. Any reference to this coil by another object (typically a Zone Water To Air Heat Pump or a Unitary Water To Air Heat Pump AHU) will use this name.
Two types of coil are available:
1-Equation Fit - a simple curve-fit model that requires coefficients generated from heat pump catalog data to model performance.
2-Parameter Estimation - a deterministic model that requires parameters to describe the operating conditions of the heat pump’s components. The parameters are generated from the manufacturer catalog data using multi-variable optimisation method.
Note: The Coil type selected here must match the setting on the paired Water-to-Air Heat Pump Heating Coil.
This numeric field contains the rated volumetric air flow rate on the load side of the heat pump (in m3/s or ft3). This field is autosizable.
This numeric field contains the rated volumetric water flow rate on the source side of the heat pump (in m3/s or gal/min). This field is autosizable.
This numeric field contains the gross rated total cooling capacity of the heat pump (in W or Btu/hr). This field is autosizable.The gross rated total cooling capacity should be within 20% of the gross rated heating capacity, otherwise a warning message is issued. The gross rated total cooling capacity shouldnot account for the effect of supply air fan heat.
This numeric field contains the gross rated sensible capacity of the heat pump (in W or Btu/hr). This field is autosizable. The gross rated sensible cooling capacity shouldnot account for the effect of supply air fan heat.
This numeric field contains the rated cooling coefficient of performance of the heat pump.
This numeric field contains the entering water temperature (in °C or °F) at which the coil capacity, COP and power are rated at. As such, the coil’s COP should be entered at this temperature. The default value is 30°C (rating temperature for water loop water-to-air heat pumps in ISO-13256-1-1998).
This numeric field contains the entering air dry-bulb temperature (in °C or °F) at which the coil capacity, COP and power are rated at. As such, the coil’s COP should be entered at this temperature. The default value is 27°C (rated temperature for water loop water-to-air heat pumps in ISO-13256-1-1998).
This numeric field contains the entering air wet-bulb temperature (in °C or °F) at which the coil capacity, COP and power are rated at. As such, the coil’s COP should be entered at this temperature. The default value is 19°C (rated temperature for water loop water-to-air heat pumps in ISO-13256-1-1998).
Select a Quad Linear Performance Curve for the heat pump total cooling capacity. The Single Speed Equation-Fit Model for Unitary Water-To-Air Heat Pump under the Air System Compound Component Groups in the Engineering Reference document includes an explanation of the curve coefficients.
Select a Quint Linear Performance Curve for the heat pump power consumption. The Single Speed Equation-Fit Model for Unitary Water-To-Air Heat Pump under the Air System Compound Component Groups in the Engineering Reference document includes an explanation of the curve coefficients.
Select a Quad Linear Performance Curve for the heat pump power consumption. The Single Speed Equation-Fit Model for Unitary Water-To-Air Heat Pump under the Air System Compound Component Groups in the Engineering Reference document includes an explanation of the curve coefficients.
This numeric field defines the nominal time (in seconds) after startup for condensate to begin leaving the coil’s condensate drain line at the coil’s rated airflow and temperature conditions, starting with a dry coil. Nominal time is equal to the ratio of the energy of the coil’s maximum condensate holding capacity (J) to the coil’s steady-state latent capacity (W). Suggested value is 1000. A zero value means the latent degradation model is disabled. The default value for this field is zero.
This numeric field defines ratio of the initial moisture evaporation rate from the cooling coil (when the compressor first turns off, in Watts) and the coil’s steady-state latent capacity (Watts) at rated airflow and temperature conditions. Suggested value is 1.5. A zero value means the latent degradation model is disabled. The default value for this field is zero.
The following settings are required when the Coil type is set to 1-Parameter Estimation. DesignBuilder v2026.1 and later only.