Environmental Engineering Reference
In-Depth Information
In addition to the control components essential for operation, further system com-
ponents and auxiliary devices such as valves, a manometer, security devices and
other control instruments are required.
Low-temperature range
High temperature range
Drive energy
Compressor
Vapour
Vapour
From heat source
To heat sink
Heat
(low
temperature)
Heat
(high
temperature)
Low
High
pressure of
refrigerant
To heat source
From heat sink
2-
phase
Liquid
Evaporator
Condenser
Circulating working
medium (refrigerant)
Expansion valve
Fig. 9.3
Basic heat pump flow scheme of compression heat pump
(see /9-1/)
The compressor is driven mechanically by an electric or combustion engine.
Combustion motor drives can couple the heat generated by cooling the motor with
the heating process.
The working medium circulating in the heat pump circuit is evaporated in the
evaporator at low pressure and low temperature (even below 0 °C) by adding heat.
The heat is made available by using ambient air or shallow geothermal energy via
a heat carrier intermediate circuit or directly in the case of direct evaporation. The
working medium, now gaseous after the energy withdrawal from the heat source,
is suctioned and compressed by a compressor. During that process its temperature
is increased to a level higher than the flow of the heat utilisation system (i.e. low-
temperature heating system for a residential building). Still under high pressure,
the working medium is then liquefied in the condenser, discharging heat to the
heat utilisation system. Afterwards it flows to the low-temperature section via the
expansion valve. Now the circuit starts again. Evaporator and condenser as the
heat exchanger are the interfaces of the heat pump with the rest of the system.
Sorption heat pumps.
Absorption heat pumps as important representatives of sorp-
tion heat pumps consist of an evaporator, an absorber a desorber and the con-
denser. Two expansion valves and a solvent pump are required for operation.
Whereas a mechanical compressor is used for the compression heat pump, there is
a "thermal compressor" used in the absorption heat pump. Drive energy for this
"thermal compressor" is mainly required thermally (desorber); this thermal drive
energy can be supplied e.g. by gas or oil combustion or by using (industrial) waste
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