modelWaterHeaterHeatPumpPoly
Information
A quasi steady state polynomial air source heat pump for heat pump water heating application.
Hypothesis and equations
Air to water heat pump for an external air source heat pump water heater (ASHPWH) with mantle heat exchanger including both fixed and variable speed compressor.
Polynomial model extrapolatable to various ASHPWH sizes using linear extrapolation based on manufacturer data : heating time, maximum compressor power and tank volume.
Quasi-steady state model based on air temperature, tank water temperature and compressor speed.
Built upon a detailed model neglecting :
- Oil circulation and accumulation
- Frost growth (shown to be neglegible for ASHPWHs - K. R. Deutz 2018)
- Compressor inertia (quasi-steady state heat pump)
System reference configuration :
- 200L water tank
- Maximum compressor reference power = 670W
- Heating time = 25750s
- 13cm3 variable speed compressor
- Mantle heat exchanger condenser
Bibliography
See K. R. Deutz PhD Thesis 04/2018
Modeling and Experimental Study of a Heat Pump Water Heater Cycle - Purdue Conference - K. R. Deutz 2016
Second Order Polynomial Regression for a standard Heat Pump Water Heater thermal Capacity Control Algorithm - K. R. Deutz 2017
Detailed and dynamic air source heat pump water heater model : combining a zonal tank model approach with a grey box heat pump model - Applied Energy - K. R. Deutz 2018
Instructions for use
- Take constructor catalogue and fill in the required parameters
- Couple with a tank model for the water temperature
- Couple with a weather file for the external air temperature
- Couple with boolean on/off signal with a controller model
- Couple speed with a controller model or a real constant 50Hz input if using fixed speed compressor and take inverter
Known limits / Use precautions
Guaranteed validity range :
- Air temperatures : from -5°C to 25°C
- Water temperatures : from 25°C to 55°C
- Compressor speeds : from 30Hz to 120Hz
Watch for simulation results outside the validity range and extrapolation
Validations
COP, electric power and thermal capacity validated model.
COP, electric power and thermal capacity validated experimentally on air temperatures ranging from -3°C to 20°C and compressor speeds ranging from 30Hz to 120Hz.
Validated model - Kévin Deutz 08/2017
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Licensed by EDF under a 3-clause BSD-license
Copyright © EDF 2009 - 2023
BuildSysPro version 3.6.0
Author : Kévin DEUTZ, EDF (2017)
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Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.Power | Pe_max | 670 | Maximum absorbed power by the heat pump unit at 7°C external air, 50Hz and a water temperature of 55°C [W] |
| Modelica.Units.SI.Time | t_heating | 25750 | Heat-up time at 7°C external air for 10->55°C in tank [s] |
| Modelica.Units.SI.Volume | V_tank | 0.2 | Heat-up time at 7°C external air for 10->55°C in tank [m3] |
| Real | n_inverter | 0.95 | Inverter compressor efficiency |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Blocks.Interfaces.RealInput | T_water | Water temperature [K] | |
| Modelica.Blocks.Interfaces.RealInput | T_air | External air temperature [K] | |
| Modelica.Blocks.Interfaces.RealInput | speed | Compressor speed [Hz] | |
| Modelica.Blocks.Interfaces.BooleanInput | OnOff | ||
| Modelica.Blocks.Interfaces.RealOutput | Pe_comp | Electrical power of the compressor [W] | |
| Modelica.Blocks.Interfaces.RealOutput | Pe_tot | Total electrical power [W] | |
| Modelica.Blocks.Interfaces.RealOutput | COP_comp | COP of the compressor | |
| Modelica.Blocks.Interfaces.RealOutput | COP_tot | Total COP | |
| Modelica.Blocks.Interfaces.RealOutput | Pq_cond | Heat power at the condensor [W] |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Real | Pe_fan |