Test-Bench for Measurement of Leak-Flow Rate of MAC Compressors 2001-01-0794
The Centre for Energy Studies, with a financial support by ADEME (French Agency for Environment and Energy Management), has realized a test bench for the measurement of R-134a leak flow rates of Mobile Air-Conditioning) MAC components.
The test bench is equiped with an infrared spectrophotometer permitting thorough and fast measurements. The measurement principle is simple. R-134a pressure is generated in gas phase in the component to be tested (in the study, the compressor). This component is located in a leak tight control volume at atmospheric pressure. The control volume is filled in recomposed air as to prevent any external pollution.
The control volume is swept by a continuous flow permitting continuous measurement of the R-134a concentration in the measurement cell. Knowing the concentration increase, the control volume and the time, the concentration measure permits the calculation of the leak flow rate.
One of the advantages of the measurement protocol is the continuous measure, which permits both the verification of the leak flow rate consistency and the accuracy improvement by longer measurement time. However first acceptable values can be obtained after 10 minutes and ± 10 % accuracy after two hours.
The test bench was designed for the leak flow rate measurement of compressors both idle and rotating. The learning process led to design an additional cooling system of the control cell when the compressor is driven by the motor located in the control cell.
Tests indicated very high resistant torques, in particular when the compressor is cold. This limited the maximum testing speed at 2500 rpm. However a series of key results have been obtained and are presented in this paper.