• 소음진동
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• 제3권2호
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• pp.163-167
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• 1993

Suction and discharge valves of special type refrigerant compressor are designed by finite element method for effective valve design development procedure. It is well known that valve dynamic characteristics, for example, the natural frequencies and vibration modes, are necessary for the computer simulation of compressor valve dynamics, the analysis of flow patterns, noise, impact stresses and their propagation phenomena. This paper has analysed the natural frequencies and vibration modes for the first three orders under the given special boundary conditions and the experiments are conducted by laser holography. And also stress distribution is analysed and experiment by strain gage is followed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.673-678
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• 2014

In a compressor, highly impulsive pressure fluctuations induced by a reciprocating piston and valves cause noise and vibration to be so critical issues that low noise requirement always challenges engineers developing it. A muffler is frequently used for reducing these impulsive noise components, but has adverse effects on compressor's performance due to additional pressure drop and heat transfer of refrigerant when it pass through the muffler. In this study, compressible full 3-dimensional CFD simulations are performed to investigate both of flow and acoustic performances of a muffler in use for compressors. On a basis of the analysis results, a parametric study using design factors introduced to improve flow and acoustic performances of the existing muffler is carried out. Finally, improved designs are suggested to confirm the current results.

• Journal of Advanced Marine Engineering and Technology
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• 제30권6호
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• pp.702-708
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• 2006

This study shows the experimental characteristics of the double pipe inserted liquid pipe with small diameter in the gas pipe with large diameter for circulating of a liquid of high temperature, pressure and a gas of low temperature, pressure at the same time. So the functions of pipe and pipe's expansion and heat transfer are presented simultaneously. In the result, the temperature of gas refrigerant at the inlet of compressor increased about $5^{\circ}C$ by the heat transfer with liquid refrigerant in case of the double pipe. And liquid gas refrigerant which the temperature at the inlet of evaporator decreased about $3^{\circ}C$ comparing with the existing type flows into an evaporator COP of the double pipe increased about $7{\sim}10%$ comparing with that of the conventional pipe. And the noise of the double pipe at capillary tube is less than that of the conventional type about 3dB. Consequently. it is convinced the superiority of the double pipe in the heat loss and soundproofing aspect.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.93-98
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• 2010

One of the most effective key factors to improve performance of automotive reciprocating compressor is the design of suction and discharge reed valves. Reed valves are also the major sources of compressor noise. Valve motion is highly coupled with refrigerant flow. In this study, a process of fluid-structure interaction analysis was developed to predict the cylinder inner flow and the dynamic behavior of valve simultaneously. Interface programs computational structural dynamics code. The full cycle simulations of compressor were performed using FSI analysis was alidated by comparing the simulation results with the experimental results.

• 소음진동
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• 제6권4호
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• pp.513-519
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• 1996

This paper is concerned with the bubble sound at the accumulator which is generated by the difference of the high pressure side and the low pressure side in the cycle of the refrigerator. The causes of the bubble sound generation are verified by the visualized test of the operating refrigerant flow at the accumulator and the measurements of the temperature and pressure. Two cases were tested, one with the accumulator has a orifice and the other with the accumulator hasn't a orifice. So that, it is presented the comparison of the bubble sound levels and spectrums in each cases. To predict the bubble sizes when they are generated, the linearized equation driven by Strasberg is used.

• 설비공학논문집
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• 제21권2호
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• pp.87-93
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• 2009

Slim telecommunication cabinet cooler, equipped with parallel flow heat exchangers and operating with R-22, is developed. The performance is compared with imported one, equipped with fin-tube heat exchangers and operating with R-134a. Test results show that the newly-developed cooler increases the cooling capacity by 6% and EER by 33%. The refrigerant charge for the developed cooler is 500g compared with 1250g for the imported one. The adoption of parallel flow heat exchanger appears to have reduced the refrigerant charge. In addition, it is shown that the reduced air flow rates through parallel heat exchangers as compared with those through fin-tube heat exchangers are beneficial to the reduction of the equipment noise.

• Smart Structures and Systems
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• 제23권1호
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• pp.71-79
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• 2019

In general, it may be advantageous to measure the pressure pulsation near a valve to detect a valve defect in a linear compressor. However, the acceleration signals are more advantageous for rapid classification in a mass-production line. This paper deals with the performance improvement of fault classification using only the compressor-shell acceleration signal based on the relation between the refrigerant pressure pulsation and the shell acceleration of the compressor. A transfer function was estimated experimentally to take into account the signal noise ratio between the pressure pulsation of the refrigerant in the suction pipe and the shell acceleration. The shell acceleration signal of the compressor was modified using this transfer function to improve the defect classification performance. The defect classification of the modified signal was evaluated in the acceleration signal in the frequency domain using Fisher's discriminant ratio (FDR). The defect classification method was validated by experimental data. By using the method presented, the classification of valve defects can be performed rapidly and efficiently during mass production.

• 한국유체기계학회 논문집
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• 제7권3호
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• pp.7-13
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• 2004

In this paper, we identify the noise source and the path of a chiller. This chiller is newly developed for R-l34a refrigerant and 250 RT cooling capacity. The measured overall SPL of the developed turbo-chiller is about 100 dBA. Due to the high rotating speed of the centrifugal impeller, the nun noise source of the chiller is the blade passing frequency and its higher harmonics of the centrifugal impeller. This generated soundpropagates through the duct, and then transmits and radiates to the outer field. From the experiment, it is found that the high frequency noise is mostlytransmitted and radiated through the elbow duct, but the low frequency noise is transmitted and vadiated through the condenser wall. Therefore applying the absorbing material is an effective way of reducing the high and low frequency noise simultaneously. Measurement results show that the application of the sound absorbing material to the elbow duct reduced the overall sound pressure level by 4 dB compared to the 9 dBA reduction for the case of full enclosure. In order to control the generated noise, a dissipativetype silencer is also designed and tested. The silencer reduced the radiated noise about 7.5 dBA.

• 한국소음진동공학회논문집
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• 제19권12호
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• pp.1237-1243
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• 2009

A computational procedure to estimate the noise radiated from a discharge valve system in a linear compressor was discussed and established. This procedure was composed of three steps. As the first step, the dynamic behavior of the valve system was estimated taking into consideration of fluid-valve-piston interactions. As the second step, the flow characteristics of refrigerant in the discharge valve system were estimated through computational fluid dynamics applying the behaviors of the valves as moving boundary conditions. The variations of pressures and velocities of fluid were converted to quadrupole noise sources. As the final step, the boundary element method based on Helmholtz equation was applied to predict the radiated acoustic pressure. The computational results by the presented procedure were experimentally validated.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.771-772
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• 2014

In this paper, the integrated design method of suction muffler in compressor was studied. There are three things to consider when designing this. First, the transmission loss was maximized to consider the noise reduction. Second, dissipation energy of fluid flow was minimized for energy efficiency. Finally, acoustical resonance frequency of suction muffler was controlled because energy efficiency can be increased by supercharging of refrigerant. Therefore, suction muffler was designed to have the specific resonance frequency. The input impedance was used for designing target acoustical resonance frequency. Topology optimization was used for optimization method.