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Development of a methodology to measure the rates of air infiltration into refrigerated compartments.

Number: pap. 2058

Author(s) : PEREIRA P. V., SGROTT A., BACK L. F.

Summary

The infiltration of hot and humid air through the magnetic seals – also called gaskets – of household refrigerators increases the system thermal load and accelerates the frost accumulation on the evaporator coil. The air infiltration is even more pronounced when a manufacturing deviation takes place and prevents the proper closure of the refrigerator doors. An increase in the amount of frost accumulated on the evaporator increases the power consumption and may even jeopardize the refrigerator functioning with considerable impact on the technical assistance costs. The aim of this study was to develop a methodology to measure the rates of air infiltration into refrigerated compartments based on the tracer gas dilution technique. An experimental apparatus was designed and constructed especially for this purpose. The apparatus includes a means of distributing the tracer gas uniformly into the zone, a means of ensuring a uniform concentration both in the vertical and horizontal directions, a means for obtaining the air samples and a gas analyzer to measure the gas concentration at known times. Concentration measurements were taken using the infrared photoacoustic spectroscopy technique. Tests were carried out on three distinct refrigerators, with the compressor on and off and with the concentration decay and constant concentration measurement techniques. It was observed that the tests have a high level of repeatability, with deviations of less than 5% in the air infiltration rate measurements. It was also noted that the two measurement techniques provide practically the same results. Furthermore, it was found that the air infiltration rate is approximately five times higher when the compressor is turned on due to the higher pressure difference at the gasket created by the higher temperature difference. The influence of the rate of the change in the refrigerator temperature over time on the behavior of the air infiltration was also investigated. In addition, adsorption tests were carried out and the results indicated 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. To verify that the technique developed is reliable and practical and that it represents a useful tool for the design and analysis of household refrigerators, two new refrigerators were tested. The tests were performed with different gaskets and extra seals in key regions. The results for the variation in the air infiltration were found to be reliable and the technique is practical to apply.

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Pages: 10

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Details

  • Original title: Development of a methodology to measure the rates of air infiltration into refrigerated compartments.
  • Record ID : 30018854
  • Languages: English
  • Source: 2016 Purdue Conferences. 16th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2016/07/11

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