Fault detection, Heat exchanger fault, Multi-heat pump system, Regression method
This paper presents the fault detection algorithm using regression method for plural indoor units faults of multi-heat pump system under heating mode. To develop the fault detection algorithm, experiment was performed under no fault mode. Total 65 experimental data were obtained from the experiment. Regression models for five heat exchangers which including one outdoor unit and four indoor units were developed by using these 65 data. Each regression model consists of seven inputs (inlet and outlet temperatures, pressure and mass flow rate of refrigerant, inlet and outlet temperature of air, fan RPM) and one output (heat capacity). Then based on these models, the fault detection algorithm was made. To ascertain whether the fault detection algorithm works well or not, series of faulty and no fault experiment were conducted. There are five working modes which including (1) no fault mode, (2) one of the indoor units fault mode, (3) two of the indoor units faults mode, (4) three of the indoor units faults mode and (5) all of the indoor units faults mode. Indoor unit fault was simulated by blocking the air inlet. The air flow rate was measured by a wind tunnel. Under this situation, the air flow rate was reduced by about 35% of no fault mode. The fault detection algorithm works very nicely at five working modes.