Heat pump function
A heat pump can use stored solar energy from rock, ground or water in order
to heat a property. The conversion of stored energy in nature to property
heating occurs in three different circuits. In the brine circuit, (1) , free heat
energy is retrieved from the surroundings and transported to the heat pump.
In the refrigerant circuit, (2) , the heat pump increases the retrieved heat's
low temperature to a high temperature. In the heating medium circuit, (3) ,
the heat is distributed around the house.
Brine circuit
In a hose, collector, an anti-freeze liquid, brine, circulates from the heat pump
out to the heat source (rock/ground/lake). The energy from the heat source is
stored by it heating the brine a few degrees, from about –3°C to about 0 °C.
A
The collector then routes the brine to the heat pump’s evaporator. Here, the
brine releases heat energy and the temperature drops a few degrees. The liquid
then returns to the heat source to retrieve energy again.
B
Refrigerant circuit
Another liquid circulates in a closed system in the heat pump, a refrigerant, which
also passes the evaporator. The refrigerant has a very low boiling point. In the
evaporator the refrigerant receives the heat energy from the brine and starts to
boil.
C
The gas that is produced during boiling is routed into an electrically powered
compressor. When the gas is compressed, the pressure increases and the gas's
temperature increases considerably, from 5°C to approx. 100 °C.
D
From the compressor, gas is forced into a heat exchanger, condenser, where it
releases heat energy to the heating system in the house, whereupon the gas is
cooled and condenses to a liquid form again.
E
As the pressure is still high, the refrigerant can pass an expansion valve, where
the pressure drops so that the refrigerant returns to its original temperature. The
refrigerant has now completed a full cycle. It is routed to the evaporator again
and the process is repeated.
F
Heat medium circuit
The heating energy that the refrigerant releases in the condenser is retrieved by
the heat pump's boiler section.
G
The heating medium circulates in a closed system and transports the heated wa-
ter's heat energy to the house water heater and radiators/heating coils.
H
The temperatures are only examples and may vary between different installations and time
of year.
9NIBE™ F1245Chapter 2 | The heat pump – the heart of the house
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