Type of Document Master's Thesis Author Stasiunas, Eric Carl URN etd-06192002-104041 Title Using Vibration Analysis to Determine Refrigerant Levels In an Automotive Air Conditioning System Degree Master of Science Department Mechanical Engineering Advisory Committee
Advisor Name Title Kasarda, Mary E. F. Committee Chair Kirk, R. Gordon Committee Member Wicks, Alfred L. Committee Member Keywords
- automotive air conditioning system
- modal analysis
- vibration analysis
Date of Defense 2002-05-29 Availability restricted AbstractPresently, auto manufacturers do not have do not have efficient or accurate methods to
determine the amount of refrigerant (R-134a) in an air conditioning system of an
automobile. In the research presented, vibration analysis is examined as a possible
method to determine this R-134a amount. Initial laboratory tests were completed and
experimental modal analysis methods were investigated. This approach is based on the
hypothesis that the natural frequency of the accumulator bottle is a function of the mass
of refrigerant in the system. Applying this theory to a working automotive air
conditioning bench test rig involved using the roving hammer method—forcing the
structure with an impact hammer at many different points and measuring the resulting
acceleration at one point on the structure. The measurements focused on finding the
natural frequency at the accumulator bottle of the air condition system with running and
non-running compressor scenarios. The experimental frequency response function (FRF)
results indicate distinct trends in the change of measured cylindrical natural frequencies
as a function of refrigerant level. Using the proposed modal analysis method, the R-134a
measurement accuracy is estimated at + or -3 oz of refrigerant in the running laboratory
system and an accuracy of + or -1 oz in the non-running laboratory system.
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