Claudio Melo

THE INFLUENCE OF NON-CONDENSABLE GASES ON THE THERMAL-ACOUSTIC BEHAVIOR OF HOUSEHOLD REFRIGERATORS

In refrigeration systems with evaporating pressure below atmospheric pressure, air from the external environment can infiltrate into the circuit through small leaks in the suction line. Additionally, if a problem occurs during the evacuation process on the production line, residual air might be left inside the circuit. This paper reports an experimental study on the influence of non-condensable gases on the thermal-acoustic behavior of a household refrigeration system. Controlled amounts of nitrogen were injected into the system through a purpose-built device. Steady-state energy consumption tests were carried out for each situation. Simultaneously, acceleration signals were monitored by an accelerometer installed at the evaporator inlet and videos of the flow pattern at the capillary tube inlet were recorded. The results show that, with very small amounts of non-condensable gases, the system performance was slightly improved. However, with large amounts, a worse performance was observed combined with large fluctuations in the flow pattern and the acceleration readings. In addition, for all cases it was noted that the subcooling degree increased with the amount of non-condensable gases.