Testing facilities and measuring systems of TWK and the CO₂-Testzentrum

Fig 1.

Testing facility for a/c units using CO₂ for vehicles

Fig 2.

Evaporator testing facility for a/c units for vehicles

The evaporator testing facilities illustrated in Figures 1 and 2 can be used for so-called Zargenmessungen or for the measuring of original HVACs (front or rear modules).

The refrigeration capacity is determined by two independent measuring methods:

• On the air side, i. e. the temperature difference between the evaporator inlet and outlet as well as the determined condensate quantity of the evaporator
• On the refrigerant side, i. e. by means of a refrigerant flow meter

The testing facilities provide the following possibilities:

• Determination of the capacity
• Measuring of the pressure drop
• Examination of the temperature distribution
• Examinations of the oil transport
• Dynamic measurings
• Testing of the stability

Bild 5.

Testing facility for compressors

Bild 6.

Efficiency characteristics of different compressors

The capacity testing facility for compressors shown in Figure 5 is designed according to the principle of indirect cooling and uses a water-cooled condenser.

The following measurings can be performed:

• Uncontrolled, internally or externally controlled a/c compressors for passenger cars
• Open compressors
• Electrically operated compressors
• Single- or two-stage compressors (economizer operation)

This testing facility can also be used for endurance tests, e. g. according to VDA (Association of German Automobile Manufacturers) or special complexes of load acting on a component.

Fig 7.

System testing facility for a/c units in vehicles

Fig 8.

Influence of the amount of oil on the refrigeration capacity

This testing facility shown in Figure 7 enables system tests of a/c units in vehicles. The original components are installed according to their position in the vehicle, thus there are no artificial disturbance variables.

The evaporator is directly integrated in the HVAC in order to determine the real air flow and temperature distribution. The HVAC enables the simulation of pull-down tests, since it can be adjusted to the interior conditions of the passenger compartment. The integrated humidifier, the heater coils and the continuously adjustable high-pressure air blower ensure a high variability with regard to the evaporator load.

Fig 9.

Capacity testing facility for a/c units in vehicles

Fig 10.

Buffer effect of a condenser

The testing facility shown in Figure 9 is used for stationary capacity measurings of original a/c units.

The testing facility enables the following measurings:

• Evaporator measurings
  • Capacity measuring
  • Pressure drop
  • Temperature distribution
  • Oil transport
• Condenser measurings
  • Capacity measuring
  • Pressure drop
  • Air outlet temperature distribution
  • Measuring of the filling levels
• Examinations of liquid separators
  • Separation behavior
  • Pressure drop
  • Amount of buffer
  • Oil transport

Fig 11.

Testing facility for CO₂ components

Fig 12.

Separation behavior of an accumulator

Fig 13.

Effect of the internal heat exchanger in the p, h

The testing facility shown in Figure 11 enables the component testings for CO₂ a/c units.

The testing facility enables the following measurings:

• Examination of liquid separators
  • Separation behavior
  • Pressure drop
  • Buffer behavior
  • Oil transport
• Measuring of internal heat exchangers
  • Heat exchange capacity
  • Exchange level
  • Pressure drop
  • Comparative tests
• Testing of further components
  • Control valves
  • Flexible hoses

Fig 14.

Compressor testing facility (gas cycle)

Properties and possibilities of the compressor testing facility shown in Figure 14:

• According to the principle of the gas cycle
• Refrigeration capacity of the compressor > 3 kW
• Speed range for open compressors: 500 - 4 000 min-^-1
• Performance of endurance tests
• Optimitation of the oil cycle
• Determination of the compressor application limits
• Creation of indicator diagrams
• Failure analysis

Fig 15.

Pressure drop measurings

Fig 17.

Capacity measuring of expansion valves

The testing facility shown in Figure 15 is used for a wide range of component testings.

The testing facility provides the following possibilities:

• Capacity measurings of expansion valves
• Determination of the characteristic curve of thermostatic expansion valves
• Pressure drop measurings of
  • Lines
  • Connecting pieces
  • Hoses
  • Containers

Fig 16.

Pressure drops in suction lines

Fig 18.

Filling levels of condensers

• Measurement of the evaporator performance according to the calorimetry method
• Zargenmessung of condensers
• Determination of the filling amount in evaporators and condensers

Fig 20.

Climatic chamber

• Temperature range from -20 to +60 °C
• k x A measuring of thermally insulated housings
• Ageing tests of refrigerator and freezer housings
• Effect of the propellant on the k x A value of expanded insulating materials
• Energy consumption and efficiency measurings of a/c units
• Measuring and testing of devices at low and high ambient temperatures