Installation manual
www.dimplex.de 129
Water-to-Water Heat Pump 4.3.2
Absorption well
The ground water cooled by the heat pump is returned to the
ground via an absorption well. The absorption well must be
drilled 10 - 15 m downstream from the extraction well in the
direction of the ground water current in order to ensure that the
flow is not "short-circuited". The absorption well must be able to
accommodate the same amount of water as the extraction well
supplies.
Because the operational reliability of the system depends on the
design and construction of the wells, this work should be carried
out by an experienced well constructor.
NOTE
A list of qualified well constructors is available at www.dimplex.de.
Fig. 4.1: Example of the integration of a water-to-water heat pump with
extraction and absorbtion wells
4.3.2 Waste heat from cooling water as the heat source
Temperature range of the waste heat 10 to 25 °C
For utilising waste heat, you must first clarify whether the cooling
water is available in suitable quality and ample amount, as well
as the extent to which the heat generated by the heat pump can
be used.
ATTENTION!
If the heat source temperature can rise to over 25°C, the temperature-
controlled mixer is required that, for temperatures over 25°C, adds the
cooling water to a partial volume flow of the cooling water outlet.
Cooling water of consistently good quality
The heat produced can be utilised with a water-to-water heat
pump, if the compatibility of the cooling water or waste water
according toTable 4.2 on p. 128 has been verified.
If the water quality is evaluated as being too poor or if the water
quality varies (i.e. in the case of a fault), a heat pump equipped
with an intermediate circuit must be installed.
Cooling water with varying or poor quality
Installing an intermediate circuit helps to protect the heat pump if
there is danger that the cooling water could corrode or clog the
heat pump's evaporator (i.e. sedimentation).
NOTE
Generally, brine-to-water heat pumps are installed in order to expand the
range of operating temperatures to lower temperatures. For water-to-
water heat pumps, the system already becomes non-operational if the
minimum outlet temperature of the heat pump falls below approx. 4°C.
For brine-to-water heat pumps, the intermediate heat transfer
circuit (heat exchanger - heat pump) must then be filled with an
antifreeze (-14 °C) because temperatures around the freezing
point could likely occur. The brine circuit should be equipped with
a circulating pump and safety valves in the same way as for
standard ground heat collectors and borehole heat exchangers.
The circulating pump should be dimensioned in a way that
ensures the intermediate heat exchanger does not freeze.
The heat exchanger is dimensioned according to the following
parameters:
Water quality
Range of operating temperatures
Cooling capacity of the heat pump type in use
Primary and secondary cycle water flow
In the simplest of cases, the heat exchanger consists of PE pipes
that are installed directly in the cooling water, thus requiring no
additional cooling water pump. This cost-efficient alternative can
be used as long as the cooling water pool is large enough.
NOTE
For the installation of a brine-to-water heat pump, the water flow in the
primary cycle must be at least 10 % above the brine flow rate of the
secondary cycle.
Fig. 4.2: Waste heat recovery using an intermediate heat exchanger with a
brine-to-water heat pump
Legend
1) Cooling water pump
2) Heat source pump
3) Manual valve
4) Heat exchanger
5) Expansion vessel
6) Pressure relief valve
7) Pressure gauge
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