Title page for ETD etd-06192002-104041

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
  • automotive air conditioning system
  • modal analysis
  • vibration analysis
Date of Defense 2002-05-29
Availability restricted
Presently, 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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