• 한국소음진동공학회논문집
• /
• 제22권12호
• /
• pp.1184-1190
• /
• 2012

This study is focused on the experimental analysis of the noise induced by phase change of refrigerant at the entrance of capillary tube. The refrigerant is usually two-phase condition when it flowed into the capillary tube. At the entrance of capillary tube, the phase condition of refrigerant is formed by sub-cool control. If it has sufficient sub-cool temperature, all of the vapor refrigerants turned to liquid, which means there is only liquid. Otherwise, the gas is coexisted. Based on this theory, we experiment on each case by changing sub-cool temperature using refrigerant-supplying equipment. The noise level is measured for each case and compared.

• 에너지공학
• /
• 제6권1호
• /
• pp.87-95
• /
• 1997

금속염화물과 암모니아간의 가역반응을 이용한 화학열펌프는 비프레온계 냉동 냉장시스템으로서 환경규약의 제한이 없고 가스, 전기 및 산업폐열 등 다양한 구동열원을 사용할수 있으며 축열에 의한 에너지 저장이나 산업공정에서의 대용량 에너지관리 시스템 등 응용분야가 다양한 장점을 갖고 있다. 통상 소규모의 실험실 장치에서 파일롯트 플랜트(pilot plant)로 전환하는 과정에서 시스템의 성능에 대한 해석이 필요하며 화학반응기의 거동에 대한 컴퓨터 모사도 필수적이다. 따라서 본 연구에서는 작동조건에 따라 화학식 냉동기 성능계수가 어떻게 변하는지를 예측하였고 반응기 모델링에 의한 동적모사를 수행하여 반응기의 온도거동, 작동조건에 따른 전화율 변화, 반응혼합물의 제조변수가 냉동기 성능에 미치는 영향 등을 고찰하였다.

• 설비공학논문집
• /
• 제26권11호
• /
• pp.547-552
• /
• 2014

As global warming in recent years has raised ever more critical concern, refrigerants with high global warming potentials (GWP) are facing the challenge of being phased out. R410A, with a GWP of 2,088, has been widely used in residential air-conditioning and heat pump systems. A potential substitute for R410A is R32, which has a GWP of 675. The present study presents experimental results of an inverter heat pump system that uses R32 as an alternative refrigerant to R410A. Drop-in tests with R32 indicated that the energy efficiency ratio of the system increased by 5.3% in cooling standard mode, and by 4.2% in heating standard mode at the same capacity; and that the cooling and heating capacity increased by about 12% at the same compressor operating frequency, while the annual performance factor (APF) of the system increased by 5.3%.

• 소성∙가공
• /
• 제23권7호
• /
• pp.419-424
• /
• 2014

In order to improve efficiency, an outdoor unit using a refrigerant cooling method is designed into many air conditioner systems. The heat exchanger is composed of a Cu tube and an plate. The optimal design for the cold plate is very important because the efficiency of the heat transfer depends on the contact area between the Cu tube and the cold plate. The current study focused on the design of the cold plate to obtain a uniform contact between the Cu tube and the cold plate. Both FE(finite element) analysis and optimization were used in the design. The contact area between the tube and plate was predicted and improved by 16% through the press forming simulations. The springback after press forming was also reduced when the optimized design parameters were used. To verify the validity of the optimal cold plate design, a verification test was conducted. As a result, the performance of the heat exchanger improved by 34% when compared to benchmarked products.

• 설비공학논문집
• /
• 제18권11호
• /
• pp.851-858
• /
• 2006

[ $CO_2$ ] and propane mixtures, which are environmentally benign, nontoxic, low in price, and compatible with materials and lubricants, were considered as promising alternative refrigerants. A fully instrumented air-conditioning system was developed for a precise performance evaluation of pure $CO_2$ and $CO_2/propane$ mixtures. In this paper, the effect of the charging amount and circulation concentration on the cooling performance of the system using $CO_2$ and propane mixtures was tested and discussed. Pure $CO_2$ and 85/15, 75/25 and 60/40 binary blends by the charged mass percentage of $CO_2/propane$ were selected as working fluids. An optimum charging amount was proposed as a parameter instead of the degree of subcooling, which can not be well defined in the transcritical cycle, to properly compare the performance between the transcritical and subcritical cycles.

• 대한설비공학회지:설비저널
• /
• 제17권4호
• /
• pp.408-417
• /
• 1988

This study optimized the condenser dimension of heat pump system with the heat sources which are solar irradiation and ambient air. At first, the author selected the principal design factors influencing the performance of heat pump system. And the author considered the variation of condenser dimension according to the variation of the selected design factors, that is, ambient air temperature, condenser temperature, degree of superheating, degree of sub-cooling and irradiation. As a result this study, among refrigerants R12, R22 and R500, refrigerant R22 has more heating output than R12 and R500, and the coefficient of performance on this heat pump system is not greatly influenced by the degree of superheating and degree of sub cooling. The ambient air temperature is below $5^{\circ}C$ at balance point and the optimal tube length of condenser dimension is about 3.8 m. Also the author gained the optimal design diagram for the optimization of condenser dimension according to various design factors.

• 반도체디스플레이기술학회지
• /
• 제23권2호
• /
• pp.6-11
• /
• 2024

This paper presents the design and experimental analysis of a cryogenic refrigeration system for -100 ℃, primarily intended for semiconductor etching process. The refrigeration system utilizes non-flammable mixed refrigerant Joule-Thomson refrigeration cycle, incorporating a precooling stage to enhance overall performance. The selected refrigerants for the system include R1234yf for the precooling stage, and Ar, R14, R23 and R218 for the main cooling stage of the Joule-Thomson refrigeration cycle. Design results according to the system constraints and experimental results are discussed, including lowest evaporation temperature, compressor isentropic efficiency and overall pressure tendencies. The achieved refrigerant fraction from optimal design is Ar: R14: R23: R218 = 0.15: 0.4: 0.15: 0.3, indicating COP of 0.1118 at the isentropic compressor efficiency of 50%. The experimental result shows the developed system reaches steady state in approximately 3 hours.

• 설비공학논문집
• /
• 제9권4호
• /
• pp.536-544
• /
• 1997

This study presents test results of a residential window system air-conditioner using R22 and two potential alternative refrigerants, R407C and R410B. A series of performance tests was performed for the basic and liquid-suction heat exchange cycle in a psychrometric calorimeter test facility. For R407C, the same rotary compressor was used as in the R22 system. However, compressor for the R410B system was modified to provide the similar cooling capacity. The evaporator circuit was changed to get a counter-cross flow heat exchanger to take advantage of zeotropic mixture's temperature glide, and liquid-line suction-line heat exchange cycle was also considered to improve the performance of the system. Test results were compared to those for the basic R22 system.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2008년도 동계학술발표대회 논문집
• /
• pp.181-185
• /
• 2008

The new concept for liquefaction of natural gas has been designed and simulated in this paper. Conventional liquefaction cycles are usually composed with Joule-Thomson valves at lower temperature refrigerant cycle. The new concept of natural gas liquefaction is discussed. The main difference with conventional liquefaction process is the presence of the turbine at low temperature of MR (mixed refrigerant) cycle. The turbine acts as expander but also as an energy generator. This generated energy is provided to the compressor which consumes energy to pressurize refrigerants. The composition of the mixed refrigerant is investigated in this study. Components of the refrigerant are methane, propane and nitrogen. Composition for new process is traced with Aspen HYSYS software. LNG heat exchangers are analyzed for the new process. Heating and cooling curves in heat exchangers were also analyzed.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2005년도 하계학술발표대회
• /
• pp.33-33
• /
• 2005