Paper No 717 – Single Fault Impact Analysis of a Residential Heat Pump in the Cooling Mode According to the Temperature Conditions – 14th IEA Heat Pump Conference, Chicago, USA
Various faults in components of the refrigeration cycle impact on system efficiency degradation differently. In addition, since sensitive features of each fault are different, the severity of the failures varies according to the operating conditions. Therefore, impacts of residential heat pump faults according to different indoor/outdoor air conditions were analyzed. The test was implemented with R410A residential unitary split heat pump with thermostatic expansion valve (TXV). Six types of common faults were imposed individually: compressor leakage, condenser fouling, evaporator fouling, liquid line restriction, refrigerant undercharge, refrigerant overcharge. Performance parameter model using 2nd order multivariate polynomial was built based on nofault data. The rate of performance degradation according to the change in operating conditions and the change of fault level was calculated, and the effects of each fault were analyzed. For instance, in case of the temperature difference between indoor and outdoor is small, the refrigerant flow rate increases to handle the cooling load, resulting in a steep decrease in performance at condenser fouling. On the other hand, in this case, the required evaporator capacity was reduced, so the effect of evaporator fouling was small.