Utilisation of Ambient Air and Shallow Geothermal Energy - Renewable Energy: Technology, Economics and Environment - page 390

in the English speaking area as defined in Table 9.1 are used. The main parame-
ters are explained in more detail in the following.

Coefficient of performance (COP). The COP for electrically driven heat pumps is
defined as the ratio of the discharged utilisable heat flow in the condenser to the
electric drive power of the compressor, for specific heat source and heat sink tem-
peratures. Thus it can be compared with the efficiency of conventional heating
systems. It is dependent on the operational conditions of the systems. In this case
only the amount of energy is considered as "energy input" that is used to drive the
heat pump (e.g. the electrical energy used to drive the electric heat pump) (Equa-

tion (9.3)). ε describes the efficiency rate, Q . Evap. the heat flow to the evaporator,

P Drive. the compressor drive power and Q . Cond. the condenser heat flow.

Table 9.1 Parameters of heat pumps (German phrases in brackets for the definitions of
German speaking countries)

Symbol Calculation Comments

Efficiency rate
(Leistungszahl)

ε Heating capacity/

electrical drive
power

Only for certain operational conditions
characterises electrically driven compres-
sion heat pump

Work rate
(Arbeitszahl)

β Heating work/ /

electrical drive work

Also annual work rate (β a ),
characterises electrically driven compres-
sion heat pump

Heat rate
(Heizzahl)

ζ Heating capacity /

Energy content of
the end energy car-
rier

Only for certain operational conditions for
absorption and combustion motor heat
pumps

Annual heat rate
(Jahresheizzahl)

ζ a Heating work /

Energy content of
the end energy car-
rier input

For absorption and combustion motor
heat pumps

Input rate (Auf-
wandszahl)

Drive power/
Heating capacity

To replace efficiency rate
(e.g. VDI 4650)

Annual input
rate (Jahresauf-
wandszahl)

Drive work/
heating work

To replace work rate
(e.g. VDI 4650)

Coefficient of
Performance

COP Heating capacity/

power input

English-speaking area, combines effi-
ciency rate ε and heating rate ζ

Seasonal Per-
formance Factor

SPF Heating work /

work input

English-speaking area, combines annual
work rate β a and ann ual heating rate ζ a

& &

&

QP + Q

Q Evap. Drive Evap.

ε=

Cond .

= = + 1

(9.3)

P P P

Drive Drive Drive