• 한국가스학회:학술대회논문집
• /
• 한국가스학회 1998년도 추계학술발표회 논문집
• /
• pp.249-254
• /
• 1998

This paper describes the study of developing air-cooled absorption system which uses a new working solution instead of LiBr solution to improve the performance of system. The absorption chiller-heater considered was an air-cooled, double-effect, $H_2O/LiBr+HO(CH_2)_3$ system of parallel flow type. In this study, we found out the characteristic of new working solution through the cycle simulation and compared the result that of LiBr solution to evaluate. The new working fluid has a wider working range with $8\%$ higher crystallization limit at the saturated refrigerant pressure of 0.8kPa. The optimum designs and operating conditions of air-cooled absorption system were suggested based on this cycle simulation analysis. It was demonstrated that new working fluid substantially improves the performance of the absorption refrigeration machine and is expected to increase the COP by as much as $5\%$.

• Journal of Advanced Marine Engineering and Technology
• /
• 제36권6호
• /
• pp.762-767
• /
• 2012

본 연구는 실내외기가 일체화된 이동식 에어컨을 대상으로 장치 운전 중 발생되는 응축수를 응축기에 분사한 경우, 응축수가 장치의 성능특성에 미치는 영향을 파악한 연구이다. 연구 결과 응축기 입출구 냉매온도 및 출구 공기온도는 응축수를 이용하지 않는 기존방식에 비해 낮게 유입 및 유출되어 응축수에 의해 상당한 응축부하가 처리되는 것을 알 수 있었다. 또한 동일한 조건에서 장치의 냉동능력과 성능계수는 평균 약 3%, 13~16%정도 높게 나타났으며, 압축기 소비동력 또한 약 27%정도 낮게 나타나응축수를 이용한 경우가 주기적인 응축수 배출에 따른 문제점 해결 이외에도 장치의 성능향상에 크게 기여하는 결과를 얻을 수 있었다.

• 한국태양에너지학회 논문집
• /
• 제22권1호
• /
• pp.1-8
• /
• 2002

With the possibility of hot water being able to be used as a heating source in a liquid desiccant system, an experimental apparatus for regeneration of the liquid desiccant was set up and series of experiments were conducted in a climate-controlled chamber. This study was performed to ascertain the influences of experimental factors on regenerating performance and to suggest the optimal combination of factors affecting regeneration rate. Furthermore. in order to figure out the contribution ratio of the factors on regenerating performance, a multi-way factorial design among the design of experiments was adopted. According to experimental results, the most influential factor on regenerating performance was temperature of the liquid desiccant and its contribution ratio was about 79.4%. In addition. the optimal operating combination was as follows; $60^{\circ}C$ of solution temperature, $14\ell$/min of solution flow rate, and 190m3/h of air volume.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 1996년도 제23회 학술대회
• /
• pp.7-16
• /
• 1996

Rapid increase of refrigeration & air-conditioning system( r & a system ) in modern industries brings attention to the urgency of development as a core technology in the area. And it required to the compatibility problem of r & a system to alternative refrigerant for the protection of environment. Then, it is requested to research about the lubrication characteristics of refrigerant compressor which is the core thechnology in the r & a system. The study of lubrication characteristics in the critical sliding component is essential for the design of refrigerant compressor. Therefore, theoetical investigation of the lubrication characteristics of rotary compressor for r & a system is studied. And the Runge-Kutta method is used for the analysis of the behavior of rolling piston in the rotary compressor. The results show that the rotating speed of shaft and the discharge pressure have an important effect upon the angular velocity of the rolling piston. This results give important basic data for the further lubrication analysis and design of the rotary compressor.

• 대한기계학회논문집B
• /
• 제25권8호
• /
• pp.1005-1012
• /
• 2001

When vortex tubes are applied to enhance the coefficient of performance of refrigeration system, the smaller one is preferable. However, the existing vortex generator with a nozzle hole diameter of 0.5mm was not suitable due to chocking of the nozzle hole. Therefore, experimental investigation was made to find an appropriate geometry of vortex generator, which could give a comparable effect of energy separation to commercial ones without chocking problem. The tested vortex generators were tangential and spiral types, which had single inducing channel with larger cross-sectional area than that of conventional multi-hole ones. The experimental result showed that the performance of the spiral type was better than that of the tangential one. As a small size of spiral one, the diameter of cold-end orifice is proposed to an half of tube diameter for the application to refrigeration system, while cold mass fraction ratio is 0.5∼0.6 for a desirable operation.

• International Journal of Air-Conditioning and Refrigeration
• /
• 제6권
• /
• pp.104-112
• /
• 1998

Ammonia has been used as refrigerant for more than 100 years in absorption as well as in compression systems. Due to its poisonous and inflammable properties, however, its use has been mainly on heavy industrial plants in which regular maintenance is available. For these systems, condensers are generally water∼cooled. This is suitable for large systems over 20RT but is not suitable for small systems. In order to apply ammonia for a small system, it is important to adopt an air-cooled condenser. In this study, simple numerical analysis of an air-cooled condenser for an ammonia refrigeration system has been carried out. The condenser is designed as horizontal tubes with plate fins attached at the outer surface to enhance the air-side heat transfer rate. Effect of fin shape and arrangement are studied in detail. Since the local heat transfer coefficient is highest at the leading edge, heat flux is highest at the edge and decreases along the distance. Conditions of inlet air are also varied in the study and condenser length that is required for full condensation is calculated. The results show that it is important to enhance both the air-side and internal heat transfer coefficients.

• 설비공학논문집
• /
• 제17권8호
• /
• pp.772-779
• /
• 2005

An efficiency of a refrigeration cycle and a reliability of a compressor can be reduced if a refrigerant including excessive lubricating oil is exhausted from the compressor. Thus, the analysis of the oil behavior inside the compressor is required to prevent the problem. A tested rotary compressor with visualization windows has been manufactured in this study to investigate the oil behavior using developed visualization techniques. The oil behaviors at various operating conditions have been quantified to obtain the relationship with the outlet pressure inside the compressor. Also, the effect of the operating conditions on the quantity of the exhausted oil from the rotary compressor has been investigated using a manufactured test model.

• 설비공학논문집
• /
• 제21권5호
• /
• pp.305-310
• /
• 2009

The amount of heat loss of a refrigerator through the gasket is nearly 30% of total refrigerator heat loss. In this paper, quantitative evaluation analysis of heat loss through gasket is established with numerical heat transfer analysis. Extending the gasket shape to protect the heat loss from the gasket, power consumption is measured by using real refrigerator in a temperature and humidity chamber and suggest the gasket shape to reduce the heat loss. From the present result of the numerical simulation of heat transfer and experiment with varying gasket shape, we are able to reduce the heat loss about 20-40% by using extended gasket and the power consumption can be reduced about 5%.

• 한국수소및신에너지학회논문집
• /
• 제23권5호
• /
• pp.521-529
• /
• 2012

Since the energy demand for refrigeration and air-conditioning has greatly increased all over the world, thermally activated refrigeration cycle has attracted much attention. This study carries out a performance analysis of a vapor compression cycle (VCC) driven by organic Rankine cycle (ORC) utilizing low-temperature heat source in the form of sensible heat. The ORC is assumed to produce minimum net work which is required to drive the VCC without generating an excess electricity. Effects of important system parameters such as turbine inlet pressure, condensing temperature, and evaporating temperature on the system variables such as mass flow ratio, net work production, and coefficient of performance (COP) are thoroughly investigated. The effect of choice of working fluid on COP is also considered. Results show that net work production and COP increase with increasing turbine inlet pressure or decreasing condensing temperature. Out of the five kinds of organic fluids considered $C_4H_{10}$ gives a relatively high COP in the range of low turbine inlet pressure.

• 한국식품영양학회지
• /
• 제35권2호
• /
• pp.88-95
• /
• 2022

The antioxidant effects by pre-treatment of Hutgae fruit water and ethanol (30°, Soju) extract on refrigerated eels were analyzed. The antioxidant activities were measured through DPPH and ABTS scavenging effect, values of acidity, peroxide, carbonyl, and TBA. The peroxide prevention effects of linoleic acid and eel oil were also assessed. Regarding DPPH radical scavenging, Hutgae ethanol extract presented higher scavenging effects than vitamin C 5 mM solution (p<0.05). The eel's peroxidation degree was measured through 21 days of refrigeration after cleaning and immersion into the extract solution for one hour. Upon measuring the values of four different peroxide indicators, those of eels pre-treated with Hutgae extracts were lower than those of eels untreated. The POV of Hutgae ethanol extract, vitamin C 5 mM, and the control was 11.1, 11.3, 15.5 meq/kg, respectively. Hutgae ethanol extract showed higher antioxidant activities in TBA value, and carbonyl value than other samples. In linoleic acid or eel oil, Hutgae extract was as superiorly effective in preventing peroxide generation of refrigerated eels as vitamin C 10 mM solution. In conclusion, pre-application of Hutgae water and ethanol (30°, Soju) extract on eels was proved to be competent in stopping peroxidation of eel in refrigeration.