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 refriger-
ant, 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 in-
creases 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
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 re-
trieved by the heat pump's boiler section.
G
11
Chapter 2 | The heat pump – the heart of the house
NIBE F1255
