An empirical model for simulating the effects of refrigerant charge faults on air conditioner performance

Abstract

This article introduces a simple empirical model that can be readily implemented in building simulation programs to model the effects of refrigerant charge on air conditioner performance. Under- or over-charged refrigerant faults are relatively common and impact performance of equipment. It is important to understand their overall impacts in the context of whole building energy consumption and comfort in order to prioritize their importance relative to other building issues. This article develops an empirical model using some existing data. The model applies corrections to the rated values of cooling capacity, energy input ratio, and sensible heat ratio of existing air-conditioning equipment modeling approaches. Model predictions are compared with experimental results obtained from three air conditioners that have fixed orifices as expansion devices. The accuracy of the model is compared with a more complex empirical model and is shown to provide better accuracy for predicting cooling capacity and sensible heat ratio.