Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Mechanical Engineering

First Advisor

Howard Shapiro


Home refrigerators are the largest consumers of electricity among household appliances, consuming an estimated 7% of the total electricity used in the United States;As a result of the NAECA and Montreal Protocol, refrigerator/freezer manufacturers and researchers are presently searching for more efficient refrigerator/freezer designs which utilize non-CFC refrigerants. Recent studies show that the gasket area heat gain may account for as much as 21% of the total thermal load in refrigerator/freezer. Also, study shows that HFC-134a, the most likely replacement of CFC-12, is immiscible with mineral oil and may result in slightly higher energy consumption as a drop-in replacement;The purpose of this research was to investigate, both experimentally and theoretically, total gasket gain (gasket infiltration and conduction heat gain) and the effects of HFC-134a on energy consumption of refrigerator/freezers. This research presents the results of an extensive literature review, interviews with refrigerator/freezer and gasket manufacturers, experimental and theoretical evaluation of gasket infiltration and heat gain. This study showed that only 2% of total load in a refrigerator/freezer is due to gasket infiltration and the total load due to gasket heat gain is only 5%. These amounts are undoubtedly less significant than the amount that has been claimed by either literature or the refrigerator/freezer manufacturers;Also included is a description of the experimental evaluation of HFC-134a as a replacement for CFC-12 in a typical top mount refrigerator/freezer. Different capillary tube lengths and different HFC-134a charges were investigated. The data showed that energy consumption using HFC-134a was slightly lower relative to the CFC-12 based unit. Optimum capillary pressure drop and HFC-134a charge levels were also determined.



Digital Repository @ Iowa State University,

Copyright Owner

Majid Ghassemi



Proquest ID


File Format


File Size

95 pages