Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Korean Journal of Air-Conditioning and Refrigeration Engineering
Journal Basic Information
Journal DOI :
The Society of Air-Conditioning and Refrigerating Engineers of Korea
Editor in Chief :
Volume & Issues
Volume 17, Issue 12 - Dec 2005
Volume 17, Issue 11 - Nov 2005
Volume 17, Issue 10 - Oct 2005
Volume 17, Issue 9 - Sep 2005
Volume 17, Issue 8 - Aug 2005
Volume 17, Issue 7 - Jul 2005
Volume 17, Issue 6 - Jun 2005
Volume 17, Issue 5 - May 2005
Volume 17, Issue 4 - Apr 2005
Volume 17, Issue 3 - Mar 2005
Volume 17, Issue 2 - Feb 2005
Volume 17, Issue 1 - Jan 2005
Selecting the target year
Numerical Analysis on the Flow Field and Heat Transfer Characteristics of Longitudinal Vortices in Turbulent Boundary Layer - On the Common Flow Down -
Yang Jang-Sik ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 9, 2005, Pages 789~798
This paper is a numerical study concerning how the interactions between a pair of the vortices effect flow field and heat transfer. The flow field (common flow down) behind a vortex generator is modeled by the information that is available from studies on a half-delta winglet. Also, the energy equation and the Reynolds-averaged Wavier-Stokes equation for three-dimensional turbulent flows, together with a two-layer turbulence model to resolve the near-wall flow, are solved by the method of AF-ADI. The present results predict that the boundary layer is thinned in the regions where the secondary flow is directed toward the wall and thickened where it Is directed away from the wall. Although some discrepancies are observed near the center of the vortex core, the overall performance of the computational model is found to be satisfactory.
Numerical Analysis on the Flow Field and Heat Transfer Characteristics of Longitudinal Vortices in Turbulent Boundary Layer - On the Common Flow Up -
Yang Jang-Sik ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 9, 2005, Pages 799~807
The flow characteristics and the heat transfer rate on a surface by the interaction of a pair of vortices are studied numerically. To analyze the common flow up produced by vortex generators in a rectangular channel flow, the pseudo-compressibility viscous method is introduced into the Reynolds-averaged Navier-Stokes equation for 3-dimensional unsteady, incompressible viscous flows. To predict turbulence characteristics, a two-layer
turbulence model is used on the flat plate 3-dimensional turbulence boundary The computational results predict accurately Reynolds stress, turbulent kinetic energy and flow field generated by the vortex generators. The numerical results, such as thermal boundary layers, skin friction characteristics and heat transfers, are also reasonably close to the experimental data.
An Analysis of the Patents for Heat Pumps
Choi Jong Min ; Kim Yongchan ; Cheon Deokwoo ; Shin Yun-Hee ; Lee Sang Hyuk ; Kwak Jae Su ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 9, 2005, Pages 808~815
A technical analysis was conducted to predict the development trends for heat pump system. This study was based on submitted patents from 1983 to 2002 in Korea, USA, and Japan. The total number of raw data from the registered database was 19,261 and the obtained data to be analyzed through the filtering process was 5,143. Japan's technical development for the heat pump system was more dominant than the other countries. Approximately
of the total patents related with the heat pump system was registered by Japan. The number of patents for the heat pump system registered by Korea was very low in 1980's, but it increased rapidly in 1990's. As a result, the number of patents applied by Korea was
of all patents. When the patent was categorized into compression, absorption/ad-sorption, and chemical type, the technology of compression type made up over
in each country. Approximately
of the patents surveyed in this study was developed for air or water source heat pumps because of easy applications compared with other heat sources. The
of all patents was applied by companies when applicants were divided into three groups of company, individual, and the others (national institute, university, and so on).
Condensing Performance Evaluation in Smooth and Micro-Fin Tubes for Natural Mixture Refrigerant (Propane/Butane)
Lee Sang-Mu ; Lee Joo-Dong ; Park Byung-Duck ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 9, 2005, Pages 816~823
This paper deals with the heat exchange performance prediction of a counter flow type double-tube condenser for natural refrigerant mixtures composed of Propane/n-Butane or Propane/i-Butane in a smooth tube and a micro-fin tube. The local characteristics of heat transfer, mass transfer and pressure drop are calculated using a prediction method developed by the authors. The total pressure drop and the overall heat transfer coefficient are also evaluated on various heat exchange conditions. The calculated results of the natural refrigerant mixtures are compared with HCFC22. In conclusion, natural refrigerant mixtures composed of Propane/n-Butane or Propane/i-Butane are appropriate candidates for alternative refrigerant from the viewpoint of heat transfer characteristics.
Study on the Performance Optimization of Commercial Metal Hydride Refrigerator Powered by Exhaust Gas from Micro Gas Turbine
Kim Hyoungsik ; Sohn Wha-seung ; Choi Kyoung-shik ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 9, 2005, Pages 824~829
MHR(Metal Hydride Refrigerator) powered by MGT exhaust gas is investigated to find out the optimum conditions corresponding to MGT operating powers. There are many factors to affect cooling capacity of MHR. In this study, the effect of switching time, flow rate of brine on cooling temperature and capacity is investigated. The present results show (1) hydrogen reaction is saturated with 25 min switching time at 25 kW MGT power, (2) cooling power shows maximum phenomenon with increasing switching time, (3) optimum switching times are 20 minutes for 15kW MGT power and 15 minutes for 20, 25kW MGT power, (4) according to increasing brine flow rate, cooling capacity shows decrease at 15 kW MGT power and changes little at above 20 kW MGT power.
Study on the Optimization of Absorption Performance of the Vertical Tube Absorber with Falling Film
Kim, Jung-Kuk ; Cho, Keum-Nam ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 9, 2005, Pages 830~838
The present study investigated the optimization of the absorption performance of the vertical absorber tube with falling film by considering heat and mass transfer simultaneously. Effects of film Reynolds number, geometric parameters by insert device (spring) and flow pattern on heat and mass transfer performances have been also investigated. Especially, effects of coolant flow rate and the flow pattern by geometric parameters has been observed for the total heat and mass transfer rates through both numerical and experimental studies. Based on both predicted values, the optimal coolant flow rate was predicted as 1.98 L/min. The maximum absorption rate of the spring inserted tube was increased by the maximum of
than those for uniform film of bare tube. Average Sherwood numbers and Nusselt numbers were increased as Reynolds numbers increased under the dynamic and geometric conditions showing the maximum absorption performance.
A Study on the Factors Affecting the Performance of Plastic Plate Heat Exchanger
Yoo Seong-Yeon ; Chung Min-Ho ; Lee Yong-Moon ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 9, 2005, Pages 839~848
Plastic plate heat exchangers have many advantages over the conventional heat exchangers such as aluminum plate heat exchangers, rotary wheel heat exchangers and heat pipe heat exchangers which have been used for ventilation heat recovery in the air-conditioning systems. In the present study, pressure drop and heat transfer characteristics of plastic plate heat exchangers are investigated for various design parameters and operating conditions which affect the performance of the plastic plate heat exchangers. In flat plate type heat exchanger, material thickness and channel height of heat exchanger are considered, and corrugate size and heat transfer area are considered in case of corrugate type heat exchanger. Pressure drop and effectiveness of the corrugate type heat exchanger increase as the corrugate size decreases.
Cooling Performance of a Microchannel Heat Sink with Nanofluids
Jang, Seok-Pil ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 9, 2005, Pages 849~854
In this paper, the cooling performance of a microchannel heat sink with nano-particle-fluid suspensions ('nanofluids') is numerically investigated. By using theoretical models of thermal conductivity and viscosity of nanofluids that account for the fundamental role of Brownian motion respectively, we investigate the temperature contours and thermal resistance of a microchannel heat sink with nanofluids such as 6nm copper-in-water and 2nm diamond-in-water. The results show that a microchannel heat sink with nanofluids has high cooling performance compared with the cooling performance of that with water, the classical coolant. Nanofluids reduce both the thermal resistance and the temperature difference between the heated microchannel wall and the coolant.
Pressure Loss and Forced Convective Heat Transfer in an Annulus Filled with Aluminum Foam
Noh Joo-Suk ; Lee Kye-Bock ; Lee Chung-Gu ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 9, 2005, Pages 855~862
An experimental investigation has been carried out for aluminum foam heat sink inserted into the annulus to examine the feasibility as a heat sink for high performance forced water cooling in the annulus. The local wall temperature distribution, inlet and outlet pressures and temperatures, and heat transfer coefficients were measured for heat flux of 13.6, 18.9, 25.1, 31.4
and Reynolds number ranged from 120 to 2000. Experimental results show that the friction factor is higher than clear annulus without aluminum foam, while the significant augmentation in Nu is obtained. This technique can be used for the compactness of the heat exchanger.
Evaluation of Indoor Environment Characteristics through Field Measurement in Large-sized Discount Stores
Park Byung-Yoon ; Jung Yong-Ho ; Ham Heung Don ; Sohn Jang-Yeul ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 9, 2005, Pages 863~872
It is important to control indoor environment for influence on health and comfort of occupants in large-sized discount stores. On the other hand large-sized discount stores have a large number of visitors, vestibules, open spaces, high energy consumption and increasing of outside air intake. This study aims to offer the design data of building services system that can save energy and control environment through field measurement selecting two large-sized discount stores. Indoor environment factors such as temperature, relative humidity, air velocity and concentrations of
, CO gas and TSP were measured and evaluated. In each case of
, and CO gas, its maximum values were 2,800 ppm and 20 ppm. So proper strategy for the indoor air quality is indispensable in this type of building. Dry bulb temperature varies from
according to a measuring point and time. From this results, it is inferred these buildings had excessive equipment capacity. In terms of economical and environmental points, these data will be utilized to the design of HVAC system of retail facilities.
An Experimental Study on the Application of Polypropylene Capillary Tube Cooling System
Lee Young-Ju ; Jin Wu-feng ; Yeo Myoung-Souk ; Kim Kwang-Woo ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 9, 2005, Pages 873~881
In this study, we made RFC, RCC and NCC according to the method by which polypropylene capillary tube was adopted, and evaluated cooling performance of each system through model experiments. We also investigated an applicability of the combined use of radiant cooling and dehumidification system. The results are as follows: In case of normal cooling load, RFC and RCC maintained set temperature without a condensation. But, in case of peak cooling load, RFC and RCC resulted in the lack of cooling performance and caused a condensation at the radiation surface. Consequently, the only use of polypropylene capillary tube is considered not to be enough for cooling in real application. Using the combination of a dehumidification and radiant cooling system maintained the set temperature without a condensation. NCC kept the set temperature at anytime without a condensation. It is more economic than packaged air-conditioner system due to the cooling effect of the floor surface.