Air infiltration, Gasket, Tracer gas, Household refrigerator, Frost accumulation
This work focuses on the development of a methodology for measuring the air infiltration rates into refrigerated compartments based on the tracer gas technique. To this end an experimental apparatus was designed and constructed. The apparatus is comprised of a device to supply the tracer gas uniformly into the zone, a device to ensure a uniform concentration both in the vertical and horizontal directions, a device to collect the air samples and a gas analyzer to measure the gas concentration according to the infrared photoacoustic spectroscopy technique. Tests were carried out with three distinct refrigerators, with the compressor on and off, using both the concentration decay and constant concentration measurement techniques. A high level of repeatability in the air infiltration rate measurements has been found, with deviations always lower than 5%. It was also noted that the two measurement techniques provide practically the same results. Furthermore, it was observed that the air infiltration rate is approximately five times higher when the compressor is turned on due to the higher pressure difference created by the higher temperature difference. Adsorption tests were also carried out indicating that the adsorption of the tracer gas by the refrigerator materials and gasket is insignificant when compared to the concentration variations caused by air infiltration. Manufacturing deviations were also simulated and it was found that they greatly increase the air infiltration rate through the gasket. The developed technique is reliable and practical and can become a useful tool for the design and analysis of household refrigerators.