Service Instructions; The Heat Pump; General Function Description - Danfoss DHP-AL Installation And Service Instructions Manual

Service instructions

11

The heat pump

11.1

General function description

A heat pump utilises the free solar energy found in a natural heat source, such as rock, ground, ground water or air.. The heat pump can be
compared to a reversed refrigerator. In a refrigerator, heat is transferred from the inside of the refrigerator to the outside. In a heat pump
the heat that is stored in a heat source is transferred to the inside of the house. The heat pump uses the energy in the heat source and
gives back three to four times more heat energy than what it uses in electrical energy. The heat pump is, therefore, a very environmentally
friendly and economical way of heating a house.
In order for the heat pump to be able to retrieve heating energy from the heat source and transfer it to the heating system of the house,
three separate fluid circuits are required.
The circuit that retrieves the heating energy from the heat source is called the brine circuit and it maintains a low outgoing temperature to
be heated by the heat source.
The next circuit is called the refrigerant circuit and is a closed circuit which, through compression and expansion, takes the retrieved heat-
ing energy and transfers it to the last circuit, the heat transfer fluid circuit.
The heat transfer fluid circuit holds the fluid that circulates in the heating system of the house and in the heat pump's water heater.
The figure below shows how the different circuits work together in the transfer of heating energy.
Expansion valve/
pressure drop
1 A hose filled with fluid (brine) is routed to a heat source. The brine obtains energy from the heat source by the fluid temperature in the
hose being heated a few degrees by the surrounding heat source. The fluid filled hose is also known as a collector.
2 The brine is routed into the first of the heat pump's heat exchangers (evaporator). The enclosed refrigerant in the refrigerant circuit is
forced to boil as the pressure in the expansion valve drops and later evaporates to a gas in the evaporator. The energy produced during
this process is released by the slightly heated brine.
3 The refrigerant that now contains a large quantity of energy in the form of heat is transferred to the compressor, which both increases
its temperature and pressure.
4 The refrigerant then continues into the second heat exchanger (condenser). When condensing, the refrigerant supplies its heat energy
to the heat transfer fluid circuit. The refrigerant's temperature decreases and returns to a liquid state.
5 The heat transfer fluid circuit transports the heat energy out to the radiators, under floor heating or the fan convector system, which heat up.
6 The refrigerant is then transported through the expansion valve where the pressure drops and the refrigerant starts to boil and then
the process starts again.
Heating system and water heater
Condenser
Enclosed
refrigerant
Evaporator
Brine
Rock, ground, ground
water or air
Figure 43: Function principles of a heat pump.
Heat transfer fluid circuit – is the circuit that contains
the water that transports the heat/energy to the heating
system and the water heater.
Refrigerant circuit – is the circuit that contains a chlorine
and freon free refrigerant which, inside the heat pump,
transfers the energy retrieved from the brine circuit
Compressor/
through evaporation, compression and condensation, and
pressure
supplies it to the heat transfer fluid circuit.
increasing
Brine circuit – is the circuit that contains an antifreeze
water based mix that obtains and transports energy from
the heat source to the heat pump. This circuit is also
known as the collector.
VMBME102
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