Refrigerant circuit with expansion valve — AUDI

Refrigerant circuit with expansion valve
HP – High-pressure side of refrigerant circuit (HD in illustration)
LP – Low-pressure side of refrigerant circuit (ND in illustration)
Component
State of refrigerant
Pressure (bar)
Temperature in degrees centigrade
1
Evaporator, from inlet to outlet
Vapour
approx. 1.2 bar
Remark
1
approx. -7 °C
Remark
2
2
Expansion valve
Liquid, expanded to vapour
approx. 14 bar
approx. +55 °C (high-pressure side), reduced to -7 °C (low-pressure side)
3
High-pressure switch / high-pressure sender
Liquid
approx. 14 bar
approx. +55 ℃
4
Service connection (high-pressure side)
and
5
Receiver
Liquid
approx. 14 bar
approx. +55 ℃
6
Condenser
From gas (at inlet) via vapour to liquid (at outlet)
approx. 14 bar
From approx. +65 °C (at inlet) to approx. +55 °C (at outlet)
7
High-pressure safety valve
and
8
Air conditioner compressor (HP side)
Gas
approx. 14 bar
approx. +65 ℃
9
Air conditioner compressor (low-pressure side)
Gas
approx. 1.2 bar
Remark
1
approx. -1 ℃
Remark
2
10
Damping chamber (not fitted on all vehicles) and
11
Service connection (low-pressure side)
Gas
approx. 1.2 bar
Remark
1
approx. -1 °C
Remark
2
1 - The pressure in a refrigerant circuit with a regulating air conditioner compressor is maintained at approx. 2 bar absolute (corresponding to approx. 1 bar gauge) despite varying heat transfer and fluctuating engine speeds. This however only applies within the output range of the air conditioner compressor. If the output limits of the air conditioner compressor are exceeded, the pressure will increase
Chapter
.
2 - The temperature in a refrigerant circuit with a regulating air conditioner compressor is maintained within the regulating range of the air conditioner compressor despite varying heat transfer and fluctuating engine speeds. This however only applies within the output range of the air conditioner compressor. If the output limits of the air conditioner compressor are exceeded, the temperature will increase
Chapter
.
Note
Non self-regulating air conditioner compressors are switched off by the relevant control unit via the
air conditioner compressor regulating valve
N280
at evaporator temperatures below 0 °C.
On vehicles with
air conditioner compressor regulating valve
N280
the pressure on the low pressure side is altered by actuating the valve.
On vehicles with two evaporators and two expansion valves, the temperature and the pressure in the refrigerant circuit correspond to those on vehicles with only one evaporator and one expansion valve (parallel connection).
Depending on the design of the refrigerant circuit, a component with an internal heat exchanger may be fitted (e.g. on the Audi A4 2008 > and the Audi A5 Coupé 2008 > a refrigerant line with an internal heat exchanger). In the internal heat exchanger, the hot refrigerant (liquid) flowing through the high-pressure side gives off energy to the cold refrigerant (gaseous or vaporous) flowing through the low-pressure side, thus enhancing the efficiency of the air conditioner
Chapter
.
Arrows show direction of refrigerant flow.
HP – High-pressure side of refrigerant circuit (HD in illustration)
LP – Low-pressure side of refrigerant circuit (ND in illustration)
Evaporator
Expansion valve
High-pressure switch / high-pressure sender
Different versions depending on vehicle
Service connection (high-pressure side)
Receiver
Different versions depending on vehicle
Condenser
High-pressure safety valve
Air conditioner compressor (high-pressure side)
Air conditioner compressor (low-pressure side)
Damping chamber
Not fitted on all vehicles
Service connection (low-pressure side)