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ACRC Technical Report 102PDF


Title:Experimental Study of Mobile Air Conditioning System Transient Behavior
Author(s):Collins, C.D.; Miller, N.R.
Subject(s):mobile air conditioning systems
Abstract:An experimental study of the the transient behavior of an automobile arr conditioning system was performed. The experiments were conducted on an original equipment air conditioning system modified for laboratory investigation. Qualitative results showing a clear relationship between refrigerant charge and mean clutch cycling period, and between refrigerant charge and the transient behavior of the evaporator outlet refrigerant temperature, were obtained. A five-factor, two-level, designed experiment was performed to determine the sensitivity of the clutch cycling period of the air conditioning refrigeration system to small (8%-15%) changes in: condenser air flow rate, condenser air inlet temperature, evaporator air inlet temperature, compressor speed, and refrigerant mass. The values chosen for each factor were based on a nominal operating condition which assumed a vehicle speed of 60 mph, and an air conditioning system operating on maximum cold setting, full recirculation, and maximum evaporator speed. The test facility permitted the control of condenser and evaporator air flow rates and inlet air temperatures, compressor speed, and refrigerant charge. Evaporator fan speed was set at the same value for all tests, and all tests were run dry coil. For the range of variables studied, experimental results showed that refrigerant charge loss corresponded to a shortening of the mean clutch cycling period and a decrease in the variance of the mean clutch cycling period. Experimental results further showed that the transient behavior of the evaporator refrigerant outlet temperature, following each clutch engagement, was clearly a function of refrigerant charge. A parameter, Time to Temperature Turning, was defined which adequately describes this behavior in terms of time and temperature only. The results imply that a strong possiblity exists for the development of a real-time, on-line refrigerant charge loss diagnostic device based on temperature measurements and time.
Issue Date:1996-07
Publisher:Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign.
Series/Report:Air Conditioning and Refrigeration Center TR-102
Genre:Technical Report
Sponsor:Air Conditioning and Refrigeration Project 51
Date Available in IDEALS:2009-04-22
Identifier in Online Catalog:3942746

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