• Korea lubricating oil industries association bulletin
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• no.31
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• pp.7-14
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• 1988

• Tribology and Lubricants
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• v.12 no.2
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• pp.1-7
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• 1996

최근까지 개발되어진 대체냉매는 매우 다양한데, 실제 적용되고 있고 또한 적용이 고려되고 있는 대체냉매는 주로 기존의 냉매와 열역학적인 특성이 유사하여 기존의 냉동시스템의 구조변경 없이 사용될 수 있는 것들이 주류를 이루고 있으며, 현재 오존층 파괴 효과가 없는 HFC(Hydrofuorocarbon)계통의 냉매가 많이 개발되고 있다. 대체냉매의 적용에는 냉매의 열역학적인 성질 뿐만 아니라 ㅎ 화학적 안정성, 윤활유와의 혼합성, 연소성 등 많은 문제를 고려해야 한다. 본 해설에서는 대체냉매를 적용한 공조시스템의 개발 동향 및 문제점에 관해서 간단히 서술하였으며, 비록 제한적이기는 하나 주로 삼성전자에서 생산되고 있는 냉장고와 에어콘을 모델로 하여 설명하였다.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.23 no.4
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• pp.198-203
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• 1987

The basis of all approaches to improve reliability of marine engines exists in analyzing the field data of troubles and failures on marine engines. This paper analyses the data of troubles and failures on marine engines by Principal Component Analysis Method, one of Multivariate Data Analysis Method. The total number of data investigated is 211 and the observation period is 9 years. The analyzed factors are categorized among five groups respectively; electric.automatic control equipments, auxiliary machinery, pipings, refrigerators.air conditioners, and main engine. The failures in main engine are discovered by a definite fact of disorder, on the contrary, the failures in auxiliary machinery, refrigerators and air conditioners are discovered by sensible judgement of the operators.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.2
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• pp.108-113
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• 2017

The performance of refrigerant oil at the thrust bearing and at the journal bearing of a scroll compressor is a significant factor. This paper presents the friction and anti-wear characteristics of nano-fluid with a mixture of a refrigerant oil and nano powders. The particle size distribution and oxidation stability of nano powders prepared by the electrical explosion method were analyzed by TEM and BET. It was found that the nanoparticles showed a spherical morphology with sizes ranging of 40-60 nm and were covered with graphite layers of 2-4 nm. The thermal conductivity of POE oil was 0.1-0.5W/mk higher than that of POE oil. The coefficient of friction of Cu-POE was found to be 0.1 higher than that of Al2O3. The cooling capacity of the heat pump with nanofluid increased to 3.67%, and the performance was improved by 5.83%.

• Tribology and Lubricants
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• v.35 no.4
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• pp.206-214
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• 2019

This study investigates alternative refrigerants and refrigerant oils as well as the tendency of protecting the global environment in view of automobile air-conditioning systems. Since decades, the R12 refrigerant is not used in automobile air-conditioners because of the ozone depletion potential (ODP) problem, and for the last 20 years, the ODP-free R134a refrigerant is leading the new automotive air-conditioning market. However, owing to its high global warming potential (GWP), the R134a refrigerant use in automobile air-conditioning system is also prohibited by law, and alternative refrigerants with a low GWP need to be proposed. Therefore, recently, the application of R1234yf, R152a, or other alternative refrigerants has started worldwide. By contrast, natural refrigerant R744 was introduced in the market several years ago by VDA (Verband Der Automobilindustrie), which is a German association in the automotive industry. This study also deals with refrigerant oils. For a long time, polyalkylene glycol (PAG) oil has been traditionally used with automobile air-conditioners, and polyolester (POE) oil is suitable for HEV, PHEV, and EV air-conditioning systems, where it is used by the electrically driven compressor owing to its excellent electrical insulation properties. Finally, PAG is an excellent lubricant for all the R134a, R152a, R1234yf, and R744 refrigerants, and has the advantage that it can be applied rapidly to alternative refrigerant air-conditioning systems.