Experimental analysis for reducing refrigerant-induced noise of 4-way cassette type air conditioner

Various refrigerant flow patterns can produce a range of noise types according to their cycle conditions. Consequently, the identification of flow patterns in a tube is crucial to reducing refrigerant-induced noise. Because of the obstacles involved in identifying them accurately by experiment, in this paper, these flow patterns are estimated from the flow pattern map. Working from the assumption that the refrigerant-induced noise for an air conditioner in the heating mode comes from slug flow in the condenser-outlet pipe, the reduction of refrigerant-induced noise by avoiding slug flow in a tube is examined. To fully understand the conditions under which the refrigerant-induced noise occurs, cycle simulator equipment for an outdoor unit is developed. With this cycle simulator, noise tests of 4-way cassette type indoor units are performed under the conditions that the refrigerant-induced noise occurs. Increasing the mass flux in a tube by reducing the diameter of the condenser-outlet pipe can avoid slug flow, and the refrigerant-induced noise can therefore be reduced. The results of the cycle simulator can be verified with an outdoor unit 5HP system multi air conditioner and the results are well in line with simulator results. This paper was recommended for publication in revised form by Associate Editor Yeon June Kang Hyung-Suk Han received a B.S. degree in Production and Mechanical Engineering from Pusan National University in 1996. He then went on to receive his M.S. and Ph.D. degrees from Pusan National University in 1998 and 2007, respectively. Dr. Han is currently a Senior Researcher at Defense Agency of Technology and Quality, Pusan, Korea. He is currently serving as a Co-Researcher of Noise and Vibration Analysis Laboratory in Pusan National University. Dr. Han’s research interests are in the area of the mechanical applications of noise and vibration including refrigerant-induced noise. Wei-Bong Jeong received a B.S. degree in Mechanical Engineering from Seoul National University in 1978. He then went on to receive his M.S. and Ph.D. degrees from KAIST in 1980 and from Tokyo Institute of Technology in 1990, respectively. Dr. Jeong is currently a Professor at the Mechanical Engineering at Pusan National University in Busan, Korea. He is currently serving as an Academic Director of the Korean Society for Noise and Vibration Engineering. Dr. Jeong’s research interests are in the area of the measurement and signal processing of noise and vibration, finite/boundary element programming of noise and vibration, fluid-structure interactions and acoustic-structure interactions.