9
Aquarea air / water heat pump – design handbook 07 / 2014
Introduction
Coefficient of Performance and performance factor
Ambient heat is brought up to a higher temperature level in a cyclical
process. To do this, an environmentally compatible refrigerant undergoes
four steps:
• The refrigerant boils inside the evaporator where it is transformed
from a liquid into the gas state. During this step, heat is extracted
from the surrounding air (figure 1 on the previous page).
• Inside the compressor the pressure of the gaseous refrigerant is
greatly increased. The temperature increases accordingly. This step
occurs with the supply of electric energy (figure 2 on the previous
page).
• In the condenser, the gaseous refrigerant condenses and dissipates
the latent heat of condensation to the heating water, whereby it cools
down at the same time (figure 3 on the previous page).
• The pressure of the liquid coolant drops suddenly when it passes
through the expansion valve, causing its temperature to drop heavily
and thus allowing it to once more absorb heat from the ambient envi-
ronment (figure 5 on the previous page).
This process is a continuous cycle and can be controlled by the
inverter-plus technology of the Aquarea heat pump so that the current
heat re quirement is catered for.
Reversing the cycle process causes the unit to act like a refrigerator .
This allows Aquarea heat pumps to be used also for air conditioning.
The Coefficient of Performance (COP) of a heat pump is defined as the
ratio of heat power output to the electrical power input and says some-
thing about the efficiency of the heat pump at a certain moment.
Depending upon the outside temperature and the temperature of the
generated heat, the COP of heat pumps will differ. It is generally the
case that the coefficient of performance decreases in proportion with
an increasing temperature difference between the outside temperature
and the temperature of the heat generated. A comparison of the efficiency
of different heat pumps is only possible at the same temperatures.
COPs for air / water heat pumps are normally measured at the following
temperatures:
Outside temperature
Output flow temperature
A-15
W35
A-7
W35
A7
W35
A2
W55
(
A
stands for Air,
W
stands for Water)
1.2 Coefficient of Performance and performance factor
