Water-to-Water Heat Pumps
A water-to-water or brine-to-water heat pump is a component fitted with four hydraulic connections. The calculations of heating power and absorbed power are based on a so-called “Scattered data interpolation“. This also enables unknown interpolation nodes to be omitted, which may result in less accurate results. As with air/water heat pumps start-up losses will not be considered for water/water heat pumps either. Besides the supplied amount of energy the calculated coefficient of performance takes into account only the amount of energy absorbed by the compressor.
When configuring a system care should always be taken to ensure that brine temperature at the heat-pump input (Ts) is always lower that the inlet temperature (Tv) in the heating loop.
A realistic heat pump control can be reproduced by means of the minimum operation time and the minimum idle time.
Catalog Data with Reference Points from a File
The data format for the definition of reference points in a profile file is as follows:
#Name der Heat pump;;;;
#Evaporator[°C];Condenser[°C];Heating power[W];Electrical power[W]; Cooling power[W]
-5;35;14800;3700;0
0;35;17200;3600;0…
…
Optionally, the cooling power may be also indicated. Where this is greater than 0, the internal losses of the heat pump will be taken into consideration in the simulation.
Internal losses HP = cooling power + electrical power – heating power
Two-Stage Water/Water Heat Pump
A two-stage water/water heat pump works on the same principle as a two-stage air/water heat pump.
Its operation is based on the standard water/water heat pump model.
Two-stage operation is only considered in case of heating.
In the database or in the profile file, reference points are entered for the full power; the format is the same as for a standard water/water heat pump.