• 한국CDE학회논문집
• /
• 제22권1호
• /
• pp.59-69
• /
• 2017

Internal capacity of a refrigerator is an important indicator for design and purchasing criteria. The components facing the internal space may have holes or gaps between parts. In traditional way, design engineers manually remodeled the parts to fill the holes and the gaps for enclosed boundary of the internal space. Then they calculated internal volume by subtracting the assembly of parts from its enclosing volume. However, filling holes and gaps is not an automated process requiring a plenty of labor and time. In this research, we have developed a voxel-based method to estimate the internal volume of a refrigerator automatically. It starts transforming all components facing the interior space into voxels and fills all holes and gaps automatically by the developed hole-filling algorithm to form a completely closed boundary of the assembly. Then, it identifies the boundary voxels that are facing to the internal voxels with any part of the component. After getting the intersection points between the boundary voxels and the surfaces of components, it generates the boundary surface of triangular facets with the intersection points. Finally, it estimates the internal volume by adding volume of each tetrahedron composed of a triangle of boundary surface and an arbitrary point.

• 자원리싸이클링
• /
• 제22권4호
• /
• pp.70-80
• /
• 2013

냉장고는 폐 전기전자제품(WEEE)에서 가장 많은 양이 처리되고 있는 품목이며 또한 가장 재활용이 복잡한 공정이다. 이는 가전제품 중 부피와 중량이 가장 크며 철, 비철금속, 플라스틱(PP, PS, ABS)등으로 이루어진 다양한 부품과 소재를 사용하고 있기 때문이다. 특히 최근에는 대용량 양문형 냉장고나 스탠드형 김치냉장고 등의 새로운 모델 출시와 더불어 다양한 혼합 재질의 사용으로 인해 폐 냉장고 재활용 공정의 어려움이 더욱 증가되고 있다. 뿐만 아니라 국내외 WEEE 재활용 관련 입법의 도입으로 폐 냉장고의 재활용 및 재자원화는 필수이고 관련 자원순환기술개발은 국가 기술경쟁력의 강화 및 국제 환경규제 대응 측면에서도 매우 중요하다고 할 수 있다. 따라서 현재 우리나라의 폐 냉장고 재활용 처리 및 기술개발 현황을 분석하고 선진국의 재활용 기술을 비교 분석하고자 한다.

• 한국초전도ㆍ저온공학회논문지
• /
• 제14권4호
• /
• pp.50-53
• /
• 2012

This paper describes experimental study on GM-type pulse tube refrigerator (PTR). In a PTR, the pulse tube is only filled with working gas and there exists secondary flow due to a large temperature difference between cold-end and warm-end. The stability of secondary flow is affected by orientation of cold-head and thus, the cooling performance is deteriorated by gas mixing due to secondary flow. In this study, a single stage GM-type pulse tube refrigerator is fabricated and tested. The cooing performance of the fabricated PTR is measured as varying cold-head orientation angle and the results are used as reference data. Then, we divided interior space of pulse tube into three segments, and fixed the various size of screen mesh at interface of each segment to suppress the performance degradation due to secondary flow. For various configuration of pulse tube, no-load test and heat load test are carried out with the fixed experimental condition of charging pressure, operating frequency and orifice valve turns. From experimental results, the fine screen mesh shows the effective suppression of performance degradation for the large orientation angle, but the use of screen mesh cause the loss of cooling capacity rather than the case of no insertion into pulse tube. It should be compromised whether the use of screen mesh in consideration of the installation limitation of a GM-type pulse tube refrigerator.

• 설비공학논문집
• /
• 제8권1호
• /
• pp.110-119
• /
• 1996

A numerical of thermoacoustic refrigerators has been developed. Effects of heat transfer and viscosity on pressure and velocity distributions in resonators and heat exchangers were considered. Predictions of cooling capacity and COP agreed well with previous experimental results. Effects of important design parameters, such as pressure ratio, spacing between the plates in the stack and stack length, on the performance of thermoacoustic refrigerators were shown.

• KEPCO Journal on Electric Power and Energy
• /
• 제2권2호
• /
• pp.299-305
• /
• 2016

초전도 전력 케이블의 상용화 노력에 따라 점차 장선화 되면서, 단위 냉각 시스템당 냉각용량이 큰 대용량 냉동기의 필요성이 증가하고 있다. 국내에서는 극저온 냉동기에 대한 기술 부족으로 인해 현재 극저온 냉동기는 해외 선진사로부터 고가의 비용으로 수입되고 있다. 초전도 전력 케이블의 상용화를 위해서는 대용량 브레이튼 냉동기의 국내 개발이 시급하다. 대용량 브레이튼 냉동기의 구성은 복열식 열교환기, 압축기, 극저온 터보 팽창기로 구성되어 있으며, 냉동기 효율과 가장 직접적인 연관이 있는 것은 극저온 터보 팽창기이다. 극저온 터보 팽창기는 극저온에서 고속으로 회전하면서 고압의 헬륨 혹은 네온 가스를 팽창시켜 온도를 낮추는 역할을 한다. 본 논문에서는 역브레이튼 냉동 사이클을 설계하고, 이에 적합한 극저온 터보 팽창기를 설계하였다.

• 한국지열·수열에너지학회논문집
• /
• 제8권2호
• /
• pp.48-54
• /
• 2012

To analyze the cooling performance of fin-tube evaporator in the refrigerator truck using R744 according to frost growth, the analytical model of evaporator was developed under frost and non-frost conditions. The performance of fin-tube evaporator was investigated with frost thickness and indoor temperature. Besides, the performance of evaporator under frost condition was compared to that under non-frost condition. As a result, area of air passage and system performance were decreased as the frost thickness increased. The cooling capacity was reduced by 10%, 20%, 30% when the frost thickness was 0.7 mm, 1.1 mm, and 1.6 mm respectively. At these conditions, the block ratio was 31%, 48%, and 71%. In addition, the outlet quality of refrigerant was not over 1 when the frost thickness was 1.6 mm in spite of high indoor air temperature.

• 한국태양에너지학회:학술대회논문집
• /
• 한국태양에너지학회 2009년도 춘계학술발표대회 논문집
• /
• pp.296-301
• /
• 2009

The ice storage system uses water for low temperature latent heat storage. However, a refrigerator capacity is increased and COP is decreased due to supercooling of water in the course of phase change from solid to liquid. This study investigates the cooling characteristics of the TMA-water clathrate compound including TMA (Tri-methyl-amine, $(CH_3)_3N)$ of $20{\sim}25wt%$ as a low temperature latent heat storage material. The results showed that the phase change temperature and the specific heat is increased and the supercooling degree is decreased as the weight concentration of TMA increased. Especially, the clathrate compound containing TMA 25wt% has the average phase change temperature of $5.8^{\circ}C$, the supercooling degree of $8.0^{\circ}C$ and the specific heat of 3.499 kJ/kgK in the cooling process. This can lead to reduction of operation time of refrigerator in low temperature latent heat storage system and efficiency improvement of refrigerator COP and overall system. Therefore, energy saving and improvement of utilization efficiency are expected.

• 대한기계학회논문집B
• /
• 제32권4호
• /
• pp.307-316
• /
• 2008

The objective of this study is to provide numerical and experimental data that can be used to investigate the performance characteristics of a flat plate fin-tube evaporator in household and commercial refrigerators under frosting conditions. Computer simulations with variations of operating conditions such as air inlet temperature, relative humidity, and geometries were performed to find out optimal design parameters of a fin-tube evaporator for household and commercial refrigerators. The tube-by-tube method was used in the simulation and the frost growth model was considered under frosting conditions. The developed analytical model predicted the decreasing rates of heat transfer capacity and air flow rate ratio within ${\pm}$10% compared to the experimental results for a refrigerator under real operating conditions. As a result, the frost thickness at $3^{\circ}C$ & 80% is increased 40% than that of $-3^{\circ}C$ & 80%, and the frost thickness at $3^{\circ}C$ & 90% is increased 30% than that of $3^{\circ}C$ & 60%. Accordingly, the operating time of the evaporator in the refrigerator was reduced with the increase of the decreasing rate of air flow rate ratio at each condition.

• 한국자동차공학회논문집
• /
• 제19권6호
• /
• pp.119-125
• /
• 2011

The analysis of performance characteristics in a refrigerator truck using R404A and R744 was carried out by using theoretical method, and each performance was compared with a variation of operating conditions. The components and cycle simulation model were developed by using EES program. To investigate the performance characteristics with operating conditions, the performance of both systems was simulated according to indoor temperature, outdoor temperature, outdoor air velocity and compressor speed. As a result, the R744 system had a better COP than R404A system for given operating condition. The cooling capacity was not increased over the outdoor air velocity of 3 m/s. Besides, the performance of R404A system was more sensitive to operating conditions compared to that of R744 system.

• 설비공학논문집
• /
• 제23권11호
• /
• pp.733-740
• /
• 2011

To analyze the cooling performance in the refrigerator truck according to frost growth, the analytical model of refrigeration system was developed under frost and non-frost condition using EES. The system performance was analyzed with outdoor temperature, storage temperature, outdoor front air velocity and compressor speed in order to investigate the system performance characteristics with operating conditions. Besides, the system performance under frost condition was compared with that under non-frost condition. As a result, the frost thickness was 0.9 mm when the refrigerating capacity of frost condition was decreased by 30%. The maximum of the system COP was shown at compressor speed of 1500 rpm for non-frost and frost condition, simultaneously. The performance under frost condition was more sensitive to the operating condition compared to that under non-frost condition.