Environmental Engineering Reference
In-Depth Information
guaranteed to sink below the defrosting temperature between 14 and 16 °C in
an air register.
Refrigeration mode 1
(cold recovery)
Heat mode
(cold storage)
Refrigeration mode 2
(heat storage)
Cooling system
Heating system
Cooling system
Heat pump
(cooling machine)
Heat pump
Ground probe
storage
Winter
Ground probe
storage
Ground probe
storage
Summer
Summer
Fig. 9.16
Ground-coupled heat pump for heating and cooling /9-16/
−
In refrigeration mode 2 (Fig. 9.16) the heat pump operates as a refrigerating
machine. Space air is cooled by the heat pump evaporator and the generated
heat is transferred into the subsoil. In this operational mode each operational
condition (including air dehumidification) can be achieved - like in a conven-
tional refrigerating system. The saving of drive energy is an advantage com-
pared to conventional refrigerating machines releasing condenser heat to the
ambient air.
Split system air conditioners for space heating and cooling.
Split system air-
conditioners are air-to-air heat pumps with an indoor and an outdoor unit con-
nected by two tubes of the refrigeration cycle. They cover 70 % of the total mar-
ket for room air-conditioners (RACs), which constitute a growing electrical end-
use in the European Union. RACs may be used in households and can be bought
or ordered directly by their occupants and as such they can be classified as domes-
tic appliances. However, the same appliances are also commonly used in offices,
hotels and small shops. Quite often, split system equipment is also used for manu-
facturing and process cooling applications. The widespread use of split systems
(about one million plants were sold in Europe already in 1996, and the market has
constantly grown since then) is an affirmation of their advantages /9-17/.
In the cooling mode the indoor unit comprises the evaporator and its fan and a
water drain. The outdoor unit consists of compressor, condenser (including fan),
expansion device (often only a capillary tube) and the filter dryer unit. In most
modern commercial applications, the compressor and the condenser are combined
into a single piece of equipment called condensing unit (for the cooling applica-
tion).
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