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.
The temperatures below are only examples and may vary between dif-
ferent installations and times of year.
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 approx. 5ｰC to approx. 100
ｰ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 tem-
perature. 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
water's heat energy to the house water heater and radiators/heating coils.
H
Passive cooling
NIBE F1255PC
BEChapter 2 | The heat pump – the heart of the house10
