THE INFLUENCE OF NON-CONDENSABLE GASES ON THE THERMAL-ACOUSTIC BEHAVIOR OF HOUSEHOLD REFRIGERATORS
Rodolfo Espíndola1; Fernando Testoni Knabben1; claudio melo1; Arthur S. A. Marcon1
1 UFSC
doi:10.20906/CPS/COB-2015-0189
Resumo
In refrigeration systems with evaporating pressure below the atmospheric pressure, air from the external environment can infiltrate into the circuit through small leaks in the suction line. Alternatively, if any problem happens in the evacuation process on the production line, residual air might be left into the circuit. This work addresses an experimental study on the influence of non-condensable gases on the thermal-acoustic behavior of a household refrigeration system. Two methods of inserting these gases into the system were applied. The first consisted of applying different vacuum pressures before inserting refrigerant. The second consisted of injecting controlled amounts of nitrogen 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 showed that, with very small amounts of non-condensable gases, the system developed a slightly better performance. However, with large amounts, a worse performance was observed combined with large fluctuations on the flow pattern and on the acceleration readings. In addition, for all cases it was noted that the sub-cooling degree increases with the amount of non-condensable gases.
Palavras-chave: non-condensable gases; energy consumption; refrigerator