Numerical simulations on fault behaviors of air-conditioning systems with multi indoor coils
A series of system simulations were conducted to learn the behavior of air-conditioning systems with multi indoor coils in various fault modes. Five common faults such as overcharge, undercharge, reduced indoor coil air flow, reduced outdoor coil air flow, and superheat control were considered. Simultaneous multi-fault behaviors are also included in this study. The interactions of the indoor coils were investigated with various indoor coil size combinations. Response parameters were evaporation temperature, compressor discharge temperature, saturated condensing temperature, subcooling, indoor air side temperature drop, and outdoor air side temperature rise. It was found that the multi indoor air-conditioning systems behave very similarly to the single indoor coil unit and that the system behavior is dominated by a more crucial fault when multi-faults are imposed. Finally, simple linear fault detection models are presented for each fault as the function of the response parameters.
Keywords: Fault detection, air-conditioning, Split unit, System simulation