Browsing by Author "Chang, Yuchoung"

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Design optimization of scroll compressor applied for frictional losses evaluation
(2010-05-01)
Liu, Yangguang
;
Hung, Chinghua
;
Chang, Yuchoung
;
機械工程學系
;
Department of Mechanical Engineering
This paper develops a design optimization procedure in scroll-type compressor (STC). By integrating the verified STC simulation model with an optimum solver, a frictional losses reduced problem of bearing components has been investigated. After the optimum search, the frictional losses can be reduced in range of 14.1-18.1% at all testing conditions with specified constraints. Herein, the design modifications of crank and upper bearings are compromised between reduction of frictional losses and maintenance of hydrodynamic lubrication. In addition, the narrower and shorter design of lower bearing and smaller one of thrust bearing can reduce frictional losses too. Furthermore, wider selection of materials in all the bearings can be adopted with the satisfied strength constraint. By using this procedure, various optimum combinations of parameters can be found for different STC design considerations. (C) 2010 Elsevier Ltd and IIR. All rights reserved.
Mathematical model of bypass behaviors used in scroll compressor
(2009-04-01)
Liu, Yangguang
;
Hung, Chinghua
;
Chang, Yuchoung
;
機械工程學系
;
Department of Mechanical Engineering
This paper has constructed a bypass mechanism mathematical model in scroll-type compressor (STC) and has been integrated into a simulation package to predict the STC performance. The bypass mechanism,when added to a fixed scroll, is used to prevent over-compression and liquid slugging. Under five specified operating conditions, it was found that the STC with the bypass action increased the isentropic efficiency 2.5-10% more than the STC without the bypass action. Meanwhile, the calculated results of the developed model have been validated by a STC testing apparatus. In addition, it was found that the design of the bypass mechanism in the paper, can completely avoid over-compression and pressure discrepancy while the STC is in operation. (C) 2008 Elsevier Ltd. All rights reserved.
Performance improvements in low side scroll compressor with extended operation speeds
(2011-11-01)
Tang, Yuehju
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Hung, Chinghua
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Chang, Yuchoung
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機械工程學系
;
Department of Mechanical Engineering
Scroll-type compressors (STCs) are widely used in modern air conditioners for higher efficiency and durability. However, the internal leakage, caused during un-rating operated speed, reduces the volumetric efficiency and influences the performance of STCs. This paper has proposed an axial-compliant mechanism (ACM), composed of a suspension structure and a limiting ring, to solve the leakage problem of a low side STC running in extended speeds. The aim of this ACM design is to control the leakage by keeping optimum clearance. By integrating the verified STC performance simulation package with the internal leakage model, the optimum clearance between scroll tip and bottom plate has been investigated. After the numerical simulation, by employing suitable designs, an improved ACM prototype has been developed and tested. The experimental results show that low leakage, noise, and power consumption are achieved during compression processes even with extended operation speeds, and moreover, the overall coefficient of performance is increased from 0.61% to 13.53%. In this study, the proposed design is useful for enhancing the performance of low side type STCs. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.
Structural Design and Analysis for Leaf Spring Type Axial Compliant Mechanism of Scroll Compressor
(2009)
Tang, Yuehju
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Hung, Chinghua
;
Shen, Biende
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Chang, Yuchoung
;
Hu, Robert Yie-Zu
There are many factors can influence the efficiency of scroll compressor, and one of them is the internal leakage. However, the traditional function to avoid internal refrigerant leakage in scroll pump is designing a compliant mechanism for dynamically sealing the scroll clearance caused by the unbalance inner forces and moments in scroll compressor. As we know, that the leakage path has been determined while the scroll line length has been designed. Axial leakage would be larger than flank leakage because of its longer leakage path. This paper discussed a compliant mechanism called leaf spring type axial compliant mechanism, which could improve the volumetric efficiency and increase the cooling capacity. The compliance mechanism used on controlling the floating tolerance of fixed scroll and keeping an optimum axial leakage. For the incongruity backpressure on fixed scroll in the axial direction, more friction loss comes of the increasing force pushing on the fixed scroll to contact with the orbiting scroll and decrease the compressor efficiency. For eliminate the unnecessary loss, this paper take case study of designing an axial compliance leaf spring structure to limit the floating distance of fixed scroll and keep the tip clearance under the optimum value. From finite element analysis and prototype test, this new module of sealing function could bring lower noise and higher cooling performance.
Study on involute of circle with variable radii in a scroll compressor
(2010-11-01)
Liu, Yangguang
;
Hung, Chinghua
;
Chang, Yuchoung
;
機械工程學系
;
Department of Mechanical Engineering
A geometric model of scroll profiles, constructed from an involute of circle with variable radii, has been developed by using the theorem of planar orbiting mechanisms. Parametric studies have also been investigated in this study. When compared to the conventional scroll profile with the same suction volume, volume ratio and housing size, this new model demonstrates better reliability and efficiency because of a lower wrap height. Alternatively, a scroll type compressor with a more compact housing size can be achieved by using this new profile but keeping its wrap height the same as the conventional one. Furthermore, arc and line modifications have been built to provide wider design varieties. These are used to avoid interference at the center of the scroll pair and to boost the volume ratio of this new scroll profile. (c) 2010 Elsevier Ltd. All rights reserved.