Heat pump

The heat pump can work as an Air Source Heat Pump (ASHP) or as a Ground Source Heat Pump (GSHP), visualised in the figures below. The evaporator side of an ASHP extracts it's energy from the ambient air, while a GSHP extracts its energy from the underground.

The sine wave for the GSHP can be altered to represent the underground temperature. The amount the temperature fluctuates (Amplitude) depends on the depth. The period is one year to accurately simulate the seasonal temperature difference of the underground.

The Hysopt software determines the heat flow of the heat pump using COP- and power tables. The data required for these tables can be found in the manufacturer's technical brochures.

This procedure is used to parameterize the heat pump and booster heat pump for dynamic simulation.

Image 3: Technical brochure example

Please note that some technical brochures only mention the heat flow and not the electrical power. The latter can be determined using the following formula:

Pelectrical = Qheating/COP

Hysopt requires these table values to be provided in CSV format (comma-separated values), preview tables can be downloaded from Hysopt (A = download; B = upload). 

When you open the downloaded COP table you notice that the first column represents the inflow temperature of the evaporator, the second column the outflow temperature of the condenser, and the third column the COP.  Adjusting the power table is done in a similar way as the COP table, the difference is that now the 3rd column represents the electric power. Below you can see a completed COP table and power table according to the manufacturing datasheet above.

Image 4: COP table example

Image 5: Power table example

It's also possible to input a modulating heat pump, therefore the user needs to make an extra fourth column in both CSV files named "modulation".

When the heat pump uses a modulation between one or two compressors, the user needs to adjust both CSV files with the corresponding information in the manufacturing datasheet of the heat pump. Below you can see a completed power table with modulation of 50% or 1 compressor and modulation of 100% or 2 compressors. For simulation the user needs to make an external control loop that is connected to the activation signal of the heat pump, this needs to be a signal of 0,5 (use of one compressor) or 1 (use of two compressors). 

When the heat pump has a continuous modulation between 20% and 100%, the user also needs to adjust the CSV files corresponding with the minimum and maximum modulation. Below you can see a completed power table with a continuous modulation between 20% and 100%. For simulation, the user needs to provide a continuous control signal (for example the manipulated value of a PI-controller) to the activation signal of the heat pump. Depending on the incoming signal, the COP and electrical power are interpolated between the minimum and maximum modulation.

         Image 6: Power table example with modulation with one or two compressors.                                  Image 7: Power table example with continuous modulation. 

The COP and power table is scaled with the following data:

With an ASHP for instance, the manufacturer typically gives the thermal power with the following quotation "A7/W35" which means an (A) air temperature of 7°C (evaporator side) and a (W) water temperature of 35°C (condenser side). For a GSHP on the other hand, the quotation is typical "G0/W35". With this information, the thermal power with the corresponded temperatures is implemented in the table and the remaining values in the table (with other temperatures) are scaled with the reference thermal power.

In default (without a lock), the design thermal power and design temperatures are used to scale the tables. The user can insert the manufacturer-specific thermal power and temperatures, and lock them so they won't be overwritten by the design conditions.