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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 18, Issue 12 - Dec 2006
Volume 18, Issue 11 - Nov 2006
Volume 18, Issue 10 - Oct 2006
Volume 18, Issue 9 - Sep 2006
Volume 18, Issue 8 - Aug 2006
Volume 18, Issue 7 - Jul 2006
Volume 18, Issue 6 - Jun 2006
Volume 18, Issue 5 - May 2006
Volume 18, Issue 4 - Apr 2006
Volume 18, Issue 3 - Mar 2006
Volume 18, Issue 2 - Feb 2006
Volume 18, Issue 1 - Jan 2006
Selecting the target year
The Experimental Study on the Heat Transfer of HFC134a for Condensation Tubes with Various Enhanced Surfaces
Park Chan-Hyoung ; Lee Young-Su ; Jeong Jin-Hee ; Kang Yong-Tae ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 8, 2006, Pages 613~619
The objectives of this paper are to study the characteristics of heat transfer for enhanced tubes (19.05 mm) used in the condenser with high saturation temperatures and to provide a guideline for optimum design of a condenser using HFC134a. Three different enhanced tubes are tested at a high saturation temperature of
(16 bar); a low-fin and three turbo-C tubes.. The refrigerant, HFC134a is condensed on the outside of the tube while the cooling water flows inside the tube. The film Reynolds number varies from 130 to 330. The wall subcooling temperature ranges from
. This study provides experimental heat transfer coefficients for condensation on the enhanced tubes. It is found that the turbo-C(2) tube provides the highest heat transfer coefficient.
The Study On the Distribution of Indoor Concentration of Microorganism in Commercial Building
Park Kyung-Su ; Choi Sang-Gon ; Hong Jin-Kwan ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 8, 2006, Pages 620~626
Recently, indoor air quality (IAQ) is one of the greatest problems in our modern societies. Although research for IAQ is made rapid progress but IAQ problems concerning in door microorganism contamination is required to be studied still more. So we have investigated the indoor microorganism concentration of a variety of department store, subway station, underground shopping center, kindergartens, library where people complain about the in-door air quality. The experiment on microorganism concentration of indoor air was carried out and the average of total microorganisms was measured. Comparing the experimental results with existing foreign criterion, the experimental results show that the ministry of environment recommendation microorganism concentration value (
) is in need of revision in the near future.
Effects of Pulsating Flow on Evaporation of Refrigerant in a Plate Heat Exchanger
Kang Byung-Ha ; Jeong Il-Kwon ; Kim Suk-Hyun ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 8, 2006, Pages 627~634
Evaporation heat transfer characteristics by pulsating flow in a plate heat exchanger have been investigated experimentally in this study. R-l34a is evaporated by receiving heat from the hot water in the plate heat exchanger. The pulsating frequency in refrigerant side of the plate heat exchanger is varied in the range of 5-25 Hz. The operating pressure of R-l34a and mass flux of hot water are also varied 0.6-0.9 MPa and
, respectively. The experimental results indicate that evaporation heat transfer coefficient of pulsating flow is improved up to 6.3% compared with that of the steady flow at 10 Hz and
. It is also found that the evaporation heat transfer enhancement ratio is decreased with an increase in mass flux of hot water, and the evaporation heat transfer enhancement is little influenced by operating pressure of R-l34a.
A Practical Approach for Optimal Design of Pipe Diameters in Pipe Network
Choi Chang-Yong ; Ko Sang-Cheol ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 8, 2006, Pages 635~640
An optimizer has been applied for the optimal design of pipe diameters in the pipe flow network problems. Pipe network flow analysis, which is developed separately, is performed within the interface for the optimization algorithm. A pipe network is chosen for the test, and optimizer GenOpt is applied with Holder-Mead-O'Niell's simplex algorithm after solving the network flow problem by the Newton-Raphson method. As a result, optimally do-signed pipe diameters are successfully obtained which minimize the total design cost. Design cost of pipe flow network can be considered as the sum of pipe installation cost and pump operation cost. In this study, a practical and efficient solution method for the pipe network optimization is presented. Test system is solved for the demonstration of the present optimization technique.
Simulation Study on the Performance Improvement of a
System Applying a Two-stage Phase-separate Cycle
Ryu Chang-Gi ; Lee Ho-Seong ; Kim Yong-Chan ; Cho Hong-Hyun ; Cho Sung-Wook ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 8, 2006, Pages 641~648
In this study, a two-stage phase-separate cycle was investigated analytically to improve the performance of the
system in the cooling mode. The simulation results were verified with the measured data. The predictions using the simulation model were consistent with the measured data within
deviations. The performance of the modified
system with the two-stage phase-separated cycle was analyzed with the variations of outdoor temperature and EEV opening. The cooling COP decreased with the increase of compressor frequency. The highest COP was 2.7 at compressor frequencies of 30 Hz and 30 Hz for the first and second compressors, respectively. In addition, the cooling COP increased by 9.3% with an application of optimum control of the first and second-stage EEV openings.
The Effect on Indoor Air Quality Improvement by Ventilation Rate in Newly Built Apartment
Choi Seok-Yong ; Kim Sang-Hee ; Yee Jung-Jae ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 8, 2006, Pages 649~655
The recent indoor air quality problem in a newly-built apartment house is resulted from the improvement of airtightness performance and the use of the building material contained harmful chemical substances. As a result, these cause indoor air quality gradually to become worse and the harmful effect on occupant health called Sick House Syndrome. The most effective solution to improve the indoor air quality is to encourage the use of green building material. However, if the house is built with general building material, ventilation with outdoor air is alternative to dilute the pollutant concentration. The purpose of this re-search is to find optimum ventilation time in a newly-built apartment house at which the ventilatoris installed. It is found that the HCHO and toluene concentrations are remarkably decreased with the elapse of ventilation time and the concentration reduction rate is increased with increment of air change rate after one hour after operating the ventilator.
The Convective Heat Transfer for the Flow Perpendicular to the Tube Array
Jeon Yong-Han ; Kim Jong-Yoon ; Kim Nam-Jin ; Kim Chong-Bo ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 8, 2006, Pages 656~663
The convective heat transfer on the outer surface of tube arrays perpendicular to the flow direction was experimentally investigated. The test sections which include the aligned and staggered arrangements were made and the local heat transfer coefficients on the outer surface of the tube were measured after the flow has been fully developed. The results showed that the local heat transfer coefficients of the staggered arrangement, which has transverse pitch of 0.075 m and longitudinal pitch of 0.08 m, were about 15% greater than that of the aligned arrangement. Also, the overall mean Nusselt number of the former was greater than that of the latter. It is verified that the results obtained by using the simulation show the same tendency with those of experiment.
Evaluation of Spreading Thermal Resistance in Symmetrical Four-Heat Generating Electronic Components
Kim Yun-Ho ; Kim Seo-Young ; Rhee Gwang-Hoon ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 8, 2006, Pages 664~671
We propose the correlation to predict the spreading thermal resistance on a plate with symmetrical four heat sources. The correlation transforms four heat sources to a single equivalent heat source and then the spreading thermal resistance can be obtained with the existing equation for a single heat source. When the four heat sources are mounted on a square base plate, the correlation is expressed as a function of the heat source size, the length of base plate, the plate thermal conductivity and the distance between heat sources. Compared to the results of three-dimensional numerical analysis, the spreading thermal resistance by the proposed correlation is in good agreement within 10 percent accuracy.
Thermal Analysis of a Cryochamber for an Infrared Detector Considering a Radiation Shield
Kim Young-Min ; Kang Byung-Ha ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 8, 2006, Pages 672~677
The steady cooling characteristics of a cryochamber for infrared (IR) detector have been investigated analytically, considering radiation shields. The thermal modeling considers the conduction heat transfer through cold finger, the gaseous conduction due to out-gassing, and the radiation heat transfer. The cooling load of the cryochamber is obtained by using a fin equation. The results obtained indicate that the gaseous conduction plays an important role in determining the steady cooling load. The steady cooling load is increased as the gas pressure is increased. It is also found that the cooling load is substantially decreased with a radiation shield. The most thermal load of a cryochamber occurs through the cold finger.
Analysis of Heat Transfer and Drying Characteristics in the Dryer Using the Refraction of Radiation
Lee Kong-Hoon ; Hong Yong-Ju ; Kim Ook-Joong ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 8, 2006, Pages 678~685
Analysis of drying characteristics has been carried out with one-dimensional model in the dryer using the principle of the refraction of radiation. The dryer is composed of hot water tank, plastic film conveyer belt, drying material, etc. The model considers the con-duction and radiation within the plastic film and drying material. The film is semitransparent to radiation and the drying material is assumed to be semitransparent or opaque to radiation. The results show that the effect of radiative transfer on the drying rate is relatively large when the thickness of drying material is small and the water temperature is high. When the material is thin, the drying rate due to conduction is also enhanced and the drying time can considerably be reduced.