Abstract The compressor of a refrigerator accounts for approximately 60-80% of the total energy consumption necessary for the refrigeration cycle. This study investigates the implementation of a pre-compression system featuring a vibrating nozzle, with the goal of enhancing the efficiency of a linear compressor. By utilizing this pre-compression system, the cooling capacity and efficiency of the compressor are expected to improve. The numerical results show that the pre-compression system leads to an improvement of approximately 1.7% in cooling capacity compared to the baseline model. Furthermore, an increase of approximately 0.1 in EER was observed, confirming the feasibility of incorporating a pre-compression system with a vibrating nozzle.

냉매 오충전은 에어컨에서 빈번하게 발생하는 고장 모드 중 하나로, 적정 충전량 대비 부족 및 과충전 모두 냉방 성능의 저하를 유 발하므로 충전된 냉매량을 정확하게 판단하는 것이 중요하다. 본 연구에서는 퍼지 군집화 기법을 통한 정상상태 식별을 통해 냉매 오 충전량을 다중 분류하는 모델을 개발하였다. 정상상태 식별을 위해 에어컨 운전 데이터에 대해 이동 평균 간의 차이를 활용한 퍼지 군 집화 알고리즘을 적용하였으며, IFDR를 통해 기존 연구된 정상상태 판단 기법들과 식별 결과를 비교하였다. 이후, 시스템 내 상관성 을 고려한 mRMR을 이용해 특징을 선택하였으며, 도출된 특징을 이용해 SVM 기반의 다중 분류 모델이 생성되었다. 제안된 방법은 시험 데이터를 통해 만족할 만한 분류 정확도와 강건성을 도출하였다.

본 연구에서는 CO2 가스 배출 저감 및 선박 폐열 회수 증대를 목적으로 선박 배기로 버려지는 폐열을 전기로 변환하는 ORC(Organic Rankine Cycle) 발전에 대해 시뮬레이션을 통한 냉매별 효율을 보여주고 있다. 상대적으로 고온인 배기가스의 폐열과 상대적으로 저온인 냉각해수를 이용하여 Aspen HYSYS 11을 이용하여 시뮬레이션을 수행하였다. 해수냉각 ORC 발전시스템의 시뮬레이션 결과, 작동유체 효율은 R717 냉매가 2.86 %로 가장 높았고, 다음 순으로 R152a, R134a, R143a, R125a로 나타났다.

The new thermal management models of linear compressors have been recently reported. These models adopt the simplified transient flow effects to shorten the excessive analysis time. Among the unsteady flow effects of the linear compressor, the effect of the gap flow between the compressor housing and the body due to the body vibration on the heat transfer performance was studied in this paper. For this study, a numerical analysis for the unsteady axisymmetric flows was performed by using CFD (Computational Fluid Dynamics). The results show that the high-speed refrigerant flows occurred in the gap between the compressor housing and the body, which contribute to increasing the heat transfer from high temperature refrigerants in the housing to the outside air. In addition, as the gap decreases, the refrigerant flow rate through the gap increases and the heat transfer rate increases as well.

In this paper, we analyzed the characteristics of the mass flow rate and velocity of the refrigerant in response to a change in the number of holes and the diameter size(Type-1～4) of the valve guide refrigerant to flow from Pc to Ps when the pressure is constant. Type-1 is 40% higher mass flow flowing in the direction of Ps as compared with the Pc mass flow rate. Type-2 is 64% higher mass flow flowing in the direction of Ps as compared with the Pc mass flow rate. Type-3 is 50% higher mass flow flowing in the direction of Ps as compared with the Pc mass flow rate. Type-4 is 47% higher mass flow flowing in the direction of Ps as compared with the Pc mass flow rate.

HFC-134a is currently used as a refrigerant in automotive air conditioning system replacing the ozone depleting CFC-12 refrigerant. This paper was experimentally studied on the performance characteristics of an automotive air conditioning system with variations of charging refrigerant and compressor speed. An air conditioning system was composed of laminated type evaporator, parallel flow type condenser, vane rotary type compressor, externally equalized thermostatic expansion valve and receiver drier with specifications of Hyundai Sonata Ⅱ vehicle. And the automatic measuring system of air conditioner used KTE-1000BA developed by a KT ENG Co., Ltd.. of Korea. The optimum conditions which were tested as available parameters for better performance are indicated charging refrigerant 800 g and compressor speed 1700 rpm.

본 연구는 에어컨의 적정냉매충전량 진단을 위한 자료를 제공하기 위하여 수행하였다. 공기 온도 33∼35℃, 습도 55∼57%RH로 조절되는 실내에서 SONATA III(Hyundai motor Co., Korea)자동차의 에어컨시스템을 대상으로 냉매충전 및 성능시험장치를 구성하고 냉매충전량 변화에 따른 냉매라인의 측정량으로 각 지점 온도와 고압 및 저압을 측정하고 분석하였다. 냉매라인의 측정온도는 압축기, 응축기, 리시버드라이어 및 증발기의 입구와 출구 파이프표면온도와 응축기와 증발기벤트 입구와 출구의 송풍공기온도이다. 이들 각 온도와 압력은 정도의 차이는 있으나 모두 냉매충전량(Wr)에 따른 영향을 받으며, 이들을 측정하여 냉매충전 정도를 진단할 수 있는 것으로 나타났다. 엔진회전속도 2,000 rpm과 1,500 rpm에 따른 각 측정량의 변화양상은 차이가 나타나지 않아 에너지사용량이 낮은 1500 rpm이 시험 회전수로 적당할 것으로 판단된다. 냉매충전량에 가장 큰 영향을 입는 측정량은 증발기벤트 입출구온도차(Td)이며, 그 다음이 냉매라인 고압측의 압력(P1)으로 나타났다. 1,500 rpm에서 Wr이 350 g까지 증가함에 따라 Td는 급격히 증가하다가 350g에서 700g까지는 12.8℃에서 16.7℃로 완만하게 증가하였고, 700g을 초과하면서 완만하게 감소하였다. P1은 Wr이 400 g까지 증가함에 따라 급격히 증가하다가 400 g에서 700 g까지는 14.3 kgf/cm2에서 16.0 kgf/cm2으로 완만하게 증가하였고 700 g을 초과하면 급격하게 상승하였다. 에어컨사용설명서에 제시된 냉매충전량이 720 g인 것을 고려하면 1,500 rpm에서 적정냉매충전량 진단은 5%오차범위에서 증발기벤트 입출구 공기온도차가 15℃, 고압측압력 15 kgf/cm2일 때로 추정된다. 에어컨상태가 정상인 진단은 Td가 12℃이상과 P1이 14 kgf/cm²에서 16 kgf/cm² 사이일 때로 판단된다.

The purpose of this study is analyzing the performance of sea water cooling system under various refrigerant pipe length. In sea water cooling system, the increase of refrigerant pipe length cause increases of pressure drops. These pressure drops cause fresh gas in liquid pipe and increase specific volume in gas pipe outlet, so sea water cooling system capacity is decreased by decrease of refrigerant mass flow rate. Sea water cooling system capacity in refrigerant pipe length 70m is decreased more than 30% when compared with pipe length 10m and the decrease of the coefficient of performance is nearly 20%.

냉매는 냉동사이클을 형성하고, 냉각작용을 일으키는 매체로 산업용 냉동･공조기기, 에어컨, 냉장고 등 다양한 기기에 사용된다. 냉매는 편리한 물질이지만 냉매 중 대부분은 오존층 파괴 또는 온실효과 등 환경에 영향을 끼치는 물질이다. 냉매로 많이 사용되는 물질을 예로 들면, HCFCs는 오존층 파괴와 온실효과를 일으키고, HFCs는 오존층 파괴능력은 없지만, 교토협약에서 정한 6대 온실가스 중 하나에 속한다. 그래서 사용 전후로 냉매의 적정 관리나 처리가 중요하다. 하지만 관련법의 혼합한 부분과 관계자의 부적합한 대처로 냉매의 적정 관리와 처리가 이루어지지 않고 있다. 따라서 본 연구에서는 국내 냉매 관련법과 냉매 물질흐름도를 기반으로 관련 시스템 제도를 분석하고 문제점을 파악하여 적합한 냉매 관리 시스템 및 제도의 개선 방안을 제시하고자 한다. 국내법에서 냉매 관리 및 처리에 관련된 법은 ‘대기환경보전법’, ‘오존층 보호를 위한 특정물질의 제조, 규제 등에 관한 법률’, ‘폐기물관리법’, ‘전기･전자제품 및 자동차의 자원순환에 관한 법률’ 등이 있다. 이 법들은 단계별, 물질별, 제품별로 복합하게 이루어져 있다. 각 법들의 조문을 정리하여 관리 대상 물질 및 제품, 법에 해당하는 주체나 단계를 조사하였다. 이후 생산･수입단계, 사용단계, 회수단계, 처리단계로 분류하여 정리하였다. 냉매 흐름을 파악하기 위하여 냉매의 물질흐름도를 파악하였다. 그래서 연구를 진행하며 파악된 문제점 역시 주체별, 단계별로 정리하였다. 문제점들을 극복하기 위한 개선방안도 주체별로 분류하여 제시하였다. 냉매 관리에서 주요 문제점은 냉매 물질 모니터링 부재, 회수 및 처리 기준과 주체의 모호성, 관리 대상에서 일부 냉매물질 제외 등이 있다. 그에 따른 개선 방안으로는 주체별 역할의 강화 및 개선, 폐냉매 회수 및 처리 시스템 개선, 냉매 유지보수업자 등의 냉매 전문가 등록 및 자격 검증제도 도입 등이 있다. 본 연구는 문헌조사를 바탕으로 냉매 관리와 처리 시스템을 분석하여 개선방안을 제시하였다. 본 연구의 결과는 냉매의 친환경 시스템 및 정책 마련을 위한 기초 자료로 사용될 수 있다.

Since 1987, the use of CFCs and HCFCs in various fields such as refrigerant of a refrigerator and a vehicle, a propellant for a spray, and a urethane foaming agent has been prohibited by Montreal protocol related to ozone depletion materials. Instead of the CFCs having a high ozone depletion potential (ODP), HFC-based refrigerants without a chlorine content were developed but determined as global warming materials. Therefore, to reduce greenhouse gas such as HFCs, including CFCs and HCFCs, having a global warming potential (GWP) of 150 or more, which is abandoned from the existing apparatus, it is required to develop a new eco-friendly, economic, and stable treatment technology. When the auxiliary fuel LPG was used at a flow of 1.0 kg/h with an air ratio of 1.1, the average temperature at the vertical section in the combustion chamber was 1,300 K, which is sufficient to destroy waste HFCs. In the waste refrigerant destruction test, the destruction ratio of waste HFCs was 100% when waste HFCs were injected at a flow of 2.8 kg/h.

Hydrofluorocarbons (HFCs) emerged as alternative refrigerants after chloro fluorocarbons (CFCs) and hydro-chloro fluorocarbons (HCFCs) were identified as substances requiring control by the Montreal Protocol on Substances that Deplete the Ozone Layer. However, because the Kyoto Protocol considered HFCs as greenhouse gases, and their impact on climate change has been increasing, major developed countries have been strengthening the existing level of regulations related to the use of HFCs as refrigerants. In addition, South Korea has also passed various legislations relating to refrigerant management, in the form of policies such as the Wastes Control Act, the Act on Control etc. of the Manufacture of Specific Substances for the Protection of the Ozone Layer, the Clean Air Conservation Act, and the Act on Resource Circulation of Electrical and Electronic Equipment and Vehicles. However, reports indicate that these regulations have not been followed effectively due to the lack of a specific system relating to the phased management of production, use, and disposal of refrigerant materials. In order to identify and solve the problems relating to refrigerant management in South Korea, this study investigates the current state of refrigerant management in three separate phases: production, use, and disposal of refrigerants. Outstanding refrigerant management policies are also analyzed, using those enacted in the EU, United States, and Japan as examples, and these are then compared to regulations in Korea.

To carry out the Montreal Protocol, South Korea has completely prohibited the use of CFC which is a main refrigerant since 2010, and the use of HCFC is planned to be prohibited from 2040. Therefore, it is expected that dependency on HFC as an alternate substance of HCFC will be increased. Since HFC which is one of main substances causing global warming phenomenon may have a harmful influence on climate change, legal and institutional measures for totally managing HCFC and HFC are required. Therefore, in this study, the refrigerant management systems in EU, USA and Japan have been considered in three aspects, such as the legal system for refrigerant management, the management and regulation limits for products using refrigerant, and the reduction policies and trends, centering on HCFC and HFC which are international regulation and reduction objects. EU environmental law regulates over the entire process for ozone depletion substances, such as production, import, export, use, market release, recovery, landfill and decomposition thereof. The united states regulates forming agents, labeling agents or the like, pursuant to Article 608 of the Federal Clean Air Act (air conditioning and automobiles), and in the case of the state of California, PFC and SF6 including HFC are defined as high GWP, and separately classified and managed. Unlike EU and USA, Japan is characterized by applying the Freon recovery and decomposition law for totally managing the Freon-based gas such as CFC, HCFC and HFC, and regulations on the refrigerant recovery and decomposition for each product are also specified in separate law related to the recovery of End-Of-Life (EOL) home appliances and vehicles.

Considering the high potential of the widely-used halogenated hydrocarbons on the global warming and ozone depletion, the development of effective thermal destruction methods of these compounds are quite urgent and indispensible. As part of the research efforts of this area, the destruction of CCl4 and flame characteristics have been investigated numerically by the co-firing CCl4 with CH4 in an industrial LNG-fired combustor as a function of molar ratio of the CCl4 to CH4 using a commercial code of STAR-CCM+. Considering a broad range of Damkohler number associated with the process of intensive CHCs (Chlorinated hydrocarbons) combustion with auxiliary fuel together with the inhibition reaction especially near flammability limits, a proper combustion modeling of CCl4 thermal destruction is quite desirable. In this study, however, after careful review of the literature about the flame characteristics of halogenated hydrocarbon together with the previous study about the modeling of the CCl4 flame based on the data of burning velocity, the eddy breakup turbulent combustion model was employed since it is quite reasonably assumed that chain branching reaction looks dominant in most flame region over the halogenated inhibition effect in strong turbulent reacting flows. One of the most useful results based on this study is that; without any incorporation of flame inhibition effect, the length of co-fired flame increases steadily as the ratio of CCl4 to CH4 (R) increases from 0.0, 0.1, 0.2 to 0.5, and 1.0 together with the increase of the maximum flame and exit gas temperature. The reason of the increase of the flame length with the increase of flame temperature can be explained by the presence of the additional CCl4 fuel with low heating value. Further a detailed discussion has been made on the thermal destruction of CCl4 together with the Cl2 concentration by Deacon reaction.

This paper addresses the fugitive emission factors of showcase at use-phase and disposal-phase. The residual quantities of Korean-made fifty- two waste showcase were weighed, using a commercial recover of refrigerants to determine the emission factors at the disposal-phase. On the other hand, the emission factors at use-phase were estimated from the residual quantities and operating times. The average residual rate of fifty two scarp showcase is determined to be 75.6 ± 5.3%. The emission factor at the use-phase is estimated to be 2.8 ± 0.7%/yr in the case of using average age of 11.1 years and the average residual rate determined here. The emission factor at the disposal-phase, refrigerant is accomplished has not recycled, the residual rate was assumed that the emission factor. We estimate 7.8 g/yr for the average emission quantity of refrigerant per operating showcase, while 234.4 g for that per waste showcase. Since the chemical compositions of refrigerant of waste showcase were the same as those of new refrigerant, it is expected that the refrigerant recovered from waste showcase can be reused for refrigerant.