• 한국자동차공학회논문집
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• 제6권2호
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• pp.203-211
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• 1998

The system performance of an automobile air conditioning system with variations of charging conditions has been investigated experimentally. An automobile air conditioning system was composed of laminated type evaporator, parallel flow type condenser, swash plate type com-pressor, externally equalized thermostatic expansion valve and receiver drier. The objective of this study was to quantify the influence of the refrigerant charge under the steady state operation of an automobile air conditioning system. The results indicated that a 10% undercharge caused a 10% reduction in the capacity of evaporator.

• 설비공학논문집
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• 제26권4호
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• pp.193-198
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• 2014

Heat transfer performance variation of a condenser caused by non-uniform distribution of air flow was investigated using a numerical simulation method. A heat exchanger used for a outdoor unit of a commercial heat pump system and represented by a numerical model was selected. Non-uniform profile of air-velocity was constructed by measuring the air velocity at various locations of the outdoor unit. Simulation was conducted for various refrigerant circuits and air flow conditions. Simulation results show that the heat transfer capacity was reduced depending on the air-flow rate and the refrigerant circuit configuration. It is also shown that the capacity reduction rate is increased as the average air velocity decreases.

• 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.

• 한국수소및신에너지학회논문집
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• 제31권1호
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• pp.33-40
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• 2020

As hydrogen utilization becomes more active recently, a large amount of hydrogen should be supplied safely. Among the three supply methods, liquefied hydrogen, which is an optimal method of storage and transportation convenience and high safety, has a low temperature of -253℃, which is complicated by the liquefaction process and consumes a lot of electricity, resulting in high operating costs. In order to reduce the electrical energy required for liquefaction and to raise the efficiency, hydrogen is cooled by using a mixed refrigerant in a precooling step. The electricity required for the precooling process of the mixed refrigerant can be reduced by using the cold energy of LNG. Actually, LNG cold energy is used in refrigeration warehouse and air liquefaction separation process, and a lot of power reduction is achieved. The purpose of this study is to replace the electric power by using LNG cold energy instead of the electric air-cooler to lower the temperature of the hydrogen and refrigerant that are increased due to the compression in the hydrogen liquefaction process. The required energy was obtained by simulating mixed refrigerant (MR) hydrogen liquefaction system with LNG cold heat and electric system. In addition, the power replacement rate of the electric process were obtained with the pressure, the temperature of LNG, the rate of latent heat utilization, and the hydrogen liquefaction capacity, Therefore, optimization of the hydrogen liquefaction system using LNG cold energy was carried out.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.875-879
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• 2006

Noise reduction has become a major issue of the duct air-conditioners. This paper describes the reduction of noise and vibration of rotational slim duct system. The design of slim duct system is the most important point of noise reduction in terms of the motor of 2f line noise, resonance noise between forced frequency and natural frequency of Sirocco fan, unbalance noise of motor axis and the noise induced refrigerant. The noise of duct system is mainly measured from diffuser and bottom of duct. The optimal design was implemented after measuring the effect of noise and vibration in each part which is composed of duct system. In this paper, experimental results show that the main elements in air-conditioner duct design. These elements are anti-vibration rubber of motor, axis length of motor, rubber coupler, materials of sirocco fan and control method of motor which are the most vital factors in reducing noise.

• International Journal of Air-Conditioning and Refrigeration
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• 제10권2호
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• pp.88-96
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• 2002

The present study was conducted to estimate the effect on fouling reduction in tubes of the condenser. It shows in detail how to calculate the fouling factor from the experimental results of refrigeration systems with or without the automatic cleaning system using sponge balls and to predict the variation of the factor with time. It also represents how to calculate the temperature and pressure decrease of the refrigerant vapor in the condenser and the load decrease of the compressor in the refrigeration system by fouling reduction.

• 설비공학논문집
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• 제13권6호
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• pp.482-489
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• 2001

The present study was conducted to estimate the effect on fouling reduction in tubes of the condenser. It shows in detail how to calculate the fouling factor from the experimental results of refrigeration systems with or without the automatic cleaning system using sponge balls and to predict the variation of the factor with time. It also represents how to calculate the temperature and pressure decrease of the refrigerant vapor in the condenser and the load decrease of the compressor in the refrigeration system by fouling reduction.

• 자원ㆍ환경경제연구
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• 제31권4호
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• pp.777-799
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• 2022

본 연구는 지구온난화잠재력(GWP)이 매우 큰 냉매가스에 대한 EU의 최신 규제 강화 동향을 살펴보고 탄소중립에의 시사점을 도출하였다. EU집행위는 최근 F-가스 규정(Regulation)을 대폭 강화하는 개정안을 공개하였다. 본 연구는 개정안의 냉매 관련 주요 내용의 의미를 현행 규정과 비교해 제시하였다. 개정안의 주요 내용은 시장출시 허용 HFC 최대량 대폭 축소, HFC 할당 관련 규정 강화, 고GWP 냉매 사용 제품 및 장비의 시장출시 금지 대상 추가, 규제대상 F-가스 추가 및 기존 가스의 GWP 업데이트, 그 외에도 보다 촘촘해지고 강화된 규제설계등이다. EU의 이러한 움직임은 미국, 일본 등 선진국의 정책기조에 영향을 미칠 것이며, 우리나라의 정책도 더욱 강화될 것이다. 따라서 관련 산업계에서는 차세대 냉매가스로의 변경이 불가피한 상황이 될 것이다. 한편, 본 연구는 기존의 냉매 및 F-가스 관련 연구에서는 주목하지 않았던 과불화화합물(PFAS) 규제와 관련된 최신 정책 동향에 대해서도 분석하였다. 유럽 5개국의 추진하고 있는 PFAS의 REACH(EU의 화학물질 등록, 평가, 승인 및 제한 제도) 제한물질 등록이 이뤄지게 된다면, 냉매가스와 관련해서는 산업계에 매우 큰 파장을 불러일으킬 것이다. 또한, 냉매를 비롯한 F-가스 물질과 관련된 각국의 온실가스 감축 전략도 전면 재검토가 불가피해질 것이다.

• 한국소음진동공학회논문집
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• 제20권2호
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• pp.153-159
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• 2010

This work focuses on finding a method to reduce the noise of a hermetic reciprocating compressor during start-up using an acoustical analysis. The noise of compressor during start-up, which is a higher level than that of a normal operating condition, has transient and non-stationary characteristics. The acoustical analysis of compressor cavity is performed to find an effective method to reduce the noise level. In the acoustical analysis, the shape variations of frequency response function in the neighborhood of resonances are tested for three parameters: the height of remained oil, the suction position of refrigerant and the position of driving part. As a conclusion of this result, to reduce the emission noise of compressor during start-up, the height of remained oil should be kept at 16 mm, the refrigerant should be sucked at the cross point of nodal lines of X and Y directional cavity modes, and the driving part should be positioned in the center of cavity.

• 설비공학논문집
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• 제17권3호
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• pp.216-222
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• 2005

An experimental investigation was executed to determine the capacity degradation due to fin conduction and non-uniform refrigerant distribution in a multi-path evaporator with cross-counter flow. The finned-tube evaporator, which had a three-path and three-depth-row, was tested by controlling inlet quality, exit pressure, and exit superheat for each refrigerant path. The capacity reduction due to superheat unbalance between each path was as much as $25\%$ for non-cutting evaporator, even when the overall evaporator superheat was kept at a target value of $5.6^{\circ}C$. It indicates that the internal heat transfer within the evaporator assembly causes the partial capacity drop. The capacity of cutting-evaporator with respect to non-cutting evaporator was enhanced according to the increment of air flow rate when superheat or superheat unbalance increased.