I am trying to model an air-to-water heat pump with Modelica. The heat pump should be able to heat water to a temperature between 20-23 °C during the whole year. A Boiler will assist the heat pump when outdoor temperature becomes too low in winter season.

Since I could not find any air-to-water heat pump model in the Modelica library that I am using, I decided to develop a simple model by myself and I am looking for performance curves. I have found this link that includes standard performance curves for heat pumps:

http://www.comnet.org/mgp/content/676-heating-systems?purpose=0#heat-pump-capacity-adjustment-curves-(CAP-FT)

If you look at the section "Electric Heat Pump Heating Efficiency Adjustment Curve" you will see that the parameter EIR_FT is function of two variables: Toadb and Tdb. Toadb is the outdoor air dr-bulb temperature, but unfortunately I cannot understand what Tdb actually refers to. In the description it says Tdb: The entering coil dry-bulb temperature.

I am trying to model an air-to-water heat pump with Modelica. The heat pump should be able to heat water to a temperature between 20-23 °C during the whole year. A Boiler will assist the heat pump when outdoor temperature becomes too low in winter season.

Since I could not find any air-to-water heat pump model in the Modelica library that I am using, I decided to develop a simple model for heating by myself and I am looking for using performance curves. curves. I have found this useful link that includes shows standard performance curves for heat pumps:pumps:

http://www.comnet.org/mgp/content/676-heating-systems?purpose=0#heat-pump-capacity-adjustment-curves-(CAP-FT)

If you look at the section "Electric Heat Pump Heating Efficiency Adjustment Curve" you will see that the parameter EIR_FT is function of two variables: Toadb and Tdb. Toadb is the outdoor air dr-bulb temperature, but unfortunately I cannot understand what Tdb actually refers to. In the description it says Tdb: The entering coil dry-bulb temperature.

I am trying to model an air-to-water heat pump for heating by using performance curves. I have found this useful link that shows standard performance curves for heat pumps:

http://www.comnet.org/mgp/content/676-heating-systems?purpose=0#heat-pump-capacity-adjustment-curves-(CAP-FT)

If you look at the section "Electric Heat Pump Heating Efficiency Adjustment Curve" you will see that the parameter EIR_FT is function of two variables: Toadb and Tdb. Toadb is the outdoor air dr-bulb temperature, but unfortunately I cannot understand what Tdb actually refers to. In the description it says Tdb: The entering coil dry-bulb temperature.