Design, Purpose And Principle Of Operation Of The Assemblies - Valeo CITYSPHERE Instructions De Montage Et D'entretien

Rooftop Air Conditioning System Citysphere
2.4.

Design, purpose and principle of operation of the assemblies

Condenser
The condenser (3, Fig. 2.3) consists of aluminium flat pipes and fins interconnected to form a large heat
exchanger surface.
It cools the hot refrigerant gas so that the latter liquefies and undercools. And transfers the condensation
heat to the outside air flowing through it via the fins, at the same time.
Receiver-drier
The receiver-drier (7, Fig. 2.3) is an expansion and storage reservoir for refrigerant. Its lower part contains
a granulated desiccant, which extracts and chemically binds small amounts of water from the refrigerant. In
addition it filters out particles of dirt from the refrigerant circuit which otherwise could lead to faults.
Thermostatic block valve
The thermostatic block valve (11, Fig. 2.3) with outer pressure compensation regulates the flow of
refrigerant to the evaporator in accordance with the need for refrigerant resp. the temperature in the
evaporator. The thermostatic expansion valve represents the control element between high and low-
pressure part of the refrigerant circuit.
Evaporator
The evaporator (12, Fig. 2.3) consists of copper pipes and aluminium fins interconnected to form a large
heat exchanger surface. In order to use the available space for construction best possible, the evaporator
is bent U-shaped. The refrigerant flowing through the pipe from the expansion valve changes from the liquid
to the gaseous state and superheats. The required evaporation heat is extracted from the cabin air flowing
through the fins and is transmitted through the pipe to the refrigerant. The air dries as it cools and
condensation water is drained overboard.
Pressure switch
The pressure switch (6, Fig. 2.3) includes a high-pressure and a low-pressure switch. It measures the
pressure in the high-pressure part of the refrigerant circuit and switches off both the electric motor and the
compressor if the pressure is too low (e.g. due to loss of refrigerant) or too high (e.g. due to overheating in
the condenser).
Anti-icing switch
The anti-icing switch (10, Fig. 2.3) is a temperature switch. It measures the temperature of the refrigerant
at the injection pipes of the evaporator and switches off the compressor if there is any risk of ice forming or
lack of refrigerant.
Condenser fan
The axial fan (5, Fig. 2.3) comprises a brushless DC motor, a fan wheel, a housing and a protective grille.
Once the air conditioning system is switched on, the fan will be activated by the control system via pin 3
(yellow wire) and will supply the condenser with the required outside air (no speed regulation - On/Off only).
Evaporator fan
The evaporator fan (14, Fig. 2.3) comprises a brushless DC motor and a fan wheel. It draws cabin air and
fresh air through the evaporator and the electrical heater (comfort version only), and blows the air back into
the cabin via the air-diffusor. Fan speed control by the control system is accomplished through a digital
signal (PWM-signal) via pin 3 (yellow wire). The fan speed is controlled automatically, or if desired,
manually.
Page 42