Publicité
Les langues disponibles
Les langues disponibles
2 – first heat exchanger located in the water tank
of the water heater: heat exchange between
the cooling fluid 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 liquid form, while transferring its heat to
the water, this heat exchanger is defined as
condenser.
3 – expansion valve: a device which lets the
cooling fluid pass through itself, as soon as its
pressure and temperature decrease, thereby
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 upper
part of the water heater with its surface
increased by the addition of fins. The second
heat exchanger performs heat exchange
between the cooling fluid and the free source
or the environmental air drifted artificially by a
special fan in the proper way. As in this phase,
the cooling fluid evaporates and extracts
heat from the environmental air, this heat
exchanger is defined as an evaporator.
As heat energy is able to flow from a higher
temperature level to a lower temperature level
exclusively, the temperature of the cooling agent located in the evaporator (4) has to be
lower 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 difference within the heat pump circuit is produced by the
compressor (1) and the expansion valve (3) located between the evaporator (4) and the
condenser (2), due to physical characteristics of the cooling fluid.
The efficiency of the heat pump circuit is measured by the coefficient of performance
(COP). COP is the ratio of energy received by the appliance (in this case, the heat
transferred 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 HPT300(C) heat pump water heater are listed in table 1.1.-
1 containing the technical specifications.
Figure 3.2.-1.
67
Publicité
