Initial Parametrization

The tutorial provided in TESPy’s documentation for simulating heat pumps has been followed to develop the first design calculation, available in the ‘Parametrization_NominalData.py’ file. While the tutorial provides a detailed explanation of the complete parametrization of the model, only the most relevant parameters are discussed here.

The data obtained from the manufacturer’s datasheet corresponding to the nominal operating point is shown in table below.

Nominal operating point data

Parameter	Value	Units
Condenser inlet temperature	30	°C
Condenser outlet temperature	35	°C
Source air temperature	7	°C
Temperature difference for air in evaporator	5	°C
Heating capacity	32.5	kW
Electrical Power	8.56	kW
Refrigerant	R448A	–

This data has been used to set the parameters of the corresponding components and connections as described in the tutorial. Since the refrigerant R448A is not available in TESPy, R404A has been used due to the similarity in their properties (reference).

TESPy uses the isentropic efficiency of the compressor to calculate the power consumption as shown in equation below.

Since the isentropic efficiency of the compressor (‘eta_s’) is not available in the datasheet, the value has been changed on a trial-and-error basis to match the power consumption calculated by the model to that mentioned in the datasheet.

Note

For heat pumps having two stages of compression, like the one in this example, in addition to the isentropic efficiency, the pressure ratio (‘pr’) for the second stage is also a required parameter.

This has to be adjusted on a trial and error basis as well, so that it works for the different range of operating conditions of the heat pump. This could be checked, by choosing data points from the edges of the operation range, and following the same procedure as done for nominal operating point data.