hajdu HP-TOWER HPT200C Manuel De Mise En Service, D'opération Et D'entretien page 67

2 – fi rst heat exchanger located in the water tank
of the water heater: heat exchange between
the cooling fl uid and the sanitary water to be
heated up takes place along its surface. As
in this phase, the physical state of the warm
cooling gas changes and it condenses into liq-
uid form, while transferring its heat to the wa-
ter, this heat exchanger is defi ned as condens-
er.
3 – expansion valve: a device which lets the cool-
ing fl uid pass through itself, as soon as its
pressure and temperature decrease, there-
by perceivably following the expansion of the
liquid as a result of the increase of the pipe
cross-section above the valve.
4 – second heat exchanger located in the up-
per part of the water heater with its surface
increased by the addition of fi ns. The second
heat exchanger performs heat exchange be-
tween the cooling fl uid and the free source or
the environmental air drifted artifi cially by a
special fan in the proper way. As in this phase,
the cooling fl uid evaporates and extracts heat
from the environmental air, this heat exchang-
er is defi ned as an evaporator.
As heat energy is able to fl ow from a higher tem-
perature level to a lower temperature level exclu-
sively, the temperature of the cooling agent located in the evaporator (4) has to be low-
er than the environmental air acting as free source, and at the same time, in order to
transfer heat, the temperature of the cooling agent located in the condenser (2) has to
be higher than the water to be heated in the tank.
The temperature diff erence within the heat pump circuit is produced by the compres-
sor (1) and the expansion valve (3) located between the evaporator (4) and the con-
denser (2), due to physical characteristics of the cooling fl uid.
The effi ciency of the heat pump circuit is measured by the coeffi cient of performance
(COP). COP is the ratio of energy received by the appliance (in this case, the heat trans-
ferred to the water to be heated) and the electric power used (by the compressor and
the supporting equipment of the appliance). The COP may change, subject to the type
of the heat pump and the applicable operational conditions. Example: A value of 3 for
COP means that the heat pump transfers 3 kWh heat to the material to be heated after
every 1 kWh electricity used, from which 2 kWh is extracted from the free source. The
rated COP values of the HPT200(C) heat pump water heater are listed in table 1.1.-1
containing the technical specifi cations.
Figure 3.2.-1.
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