Investigation of the Variability in the Measurement of Cyclic Degradation Coefficient of Air Conditioning Systems

Abstract The variation in the cyclic performance of air conditioning systems (conforming with the latest rating standards) is investigated. Two code testers of very different sizes but meeting the standards’ requirements are used to evaluate the cyclic degradation coefficient (Cd) for the same air conditioner. The measured Cd from the two code testers shows a deviation of about 20%. A validated Modelica model is used to analyze the code testers’ thermal inertia as it is suspected to be a significant contributor. A new parameter called “thermal inertia factor” is defined to account for these thermal inertia effects on the measured Cd. However, all the deviations in Cd are not resolved at this point. The measurement uncertainty is simulated with the Monte Carlo method and discovered to be a critical contributor to the Cd deviation. The current study is the first of its kind and is expected to facilitate improved test procedures by accounting for the variations arising from differences in code tester designs at different laboratories.