Environmental Engineering Reference
In-Depth Information
enough domestic hot water can be supplied even at times of peak demand. Ad-
ditionally, higher water temperatures can be generated short-term to avoid le-
gionella.
6.5
6.5
6
6
35 °C cond.
outelt temp.
Air-to-water heat pump
5.5
5.5
5
5
4.5
4.5
35 °C cond.
outlet temp.
4
4
3.5
50 °C cond.
outlet temp.
3.5
3
3
2.5
2.5
Brine-to-water heat pump
50 °C cond.
outlet temp.
2
2
1.5
1.5
-20
-15 -10
-5
0
5
10
-10
-5
0
5
10
15
20
Fig. 9.18
Influence of the heat source temperature level and the space heating inlet tem-
perature on the heat pump Coefficient of Performance (COP) (brine with 25 % antifreeze
compound; temp. temperature, cond. condenser see /9-18/)
Air temperature in °C
Brine temperature in °C
−
Space heating and domestic hot water. A joint generation of domestic hot water
and space heat using the heat pump with a heat exchanger does generally not
make sense due to the normally higher temperature level of the domestic hot
water and the resulting lower SPFs for the entire system. It is therefore useful
to separate the generation of domestic hot water and space heating. For that
purpose, domestic hot water can be generated with a separate heat pump or an
electrically heated domestic hot water store respectively. A cheaper alternative
option is the supply of heat to domestic hot water and space heating using the
same heat pump. Together with the heat exchanger for the heating system a
second heat exchanger for the domestic hot water supply is installed in the con-
denser part of the heat pump. If the generated heat is discharged into the
heating circuit, a lower condenser temperature is required than if it is dis-
charged to the domestic hot water circuit. The heat pump can thus be run under
the individual optimum conditions with a COP that is as high as possible. A
further possibility to combine the generation of space heating and domestic hot
water is the utilisation of the heat that is released at high temperatures after the
compressor up to the condensation point when desuperheating the refrigerant,
down to the point of condensation in a separate heat exchanger for domestic
hot water generation. The condensation itself is used to warm up the space
heating water.
−
Further uses. Apart from the supply of space and domestic hot water heating,
heat pump systems can also be used for space cooling, as the operation of the
heat pump is generally reversible. In those countries where space cooling is a
Search WWH ::
Custom Search