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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 Comparison of Performance Characteristics in Refrigeration System using
Ha Ok-Nam ; Lee Kyu-Tae ; Ha Kyung-Soo ; Jeong Song-Tae ; Kim Jin-Hyun ; Hong Seong-In ; Yun Kab-Sig ; Kim Yang-Hyun ; Kwon Il-Wook ; Lee Jong-In ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 5, 2006, Pages 377~383
Recently, production and use of Freon substances are restrained due to destruction of ozone layer and grobal warming. In this aspect of environmental problems, the best solution is to use the natural refrigerant such as ammonia. Thus, this study apply the
and R22 to study the performance characteristic from the superheat control and compare the energy efficiency of two refrigerants from the high performance. The condensing pressure of refrigeration system is increased from 1,500 kPa to 1,600 kPa and degree of superheat is increased from 0 to
at each condensing pressure. As the result of experiment, when comparing the each COP, we knew the
is suitable as the alternative refrigerant of the R22.
Two-Phase Two-Component Loop Thermosyphon with Nanofluid
Rhi Seok-Ho ; Park Jong-Chan ; Cha Kyeong-Il ; Lim Taek-Kyu ; Lee Chung-Gu ; Shin Dong-Ryun ; Park Gi-Ho ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 5, 2006, Pages 384~392
Reported are the heat transfer characteristics of a two-phase loop thermosyphon (TLT) with nanofluids consisted of nano-size silver particles and distilled water as the working fluid. The nanofluids used in the present study are dispersed solutions with various amount of silver nanoparticle in distilled water. It is seen from the present study that the heat transfer performance of the test TLT with nanofluids increased as much as about 2 times higher than that of a TLT with pure water as the working fluid based on same heat flux. The study also showed that there was no deterioration of the TLT performance with time, up to a period of 8 days of continuous operation which implies that there was no coagulation of nanoparticles within the working nanofluid during the operation of the test TLT.
Investigation on the Cooling Characteristics of a Regenerative Evaporation Water Cooler
Choi Bong-Su ; Hong Hi-Ki ; Lee Dae-Young ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 5, 2006, Pages 393~401
The regenerative evaporation water cooler is devised and analysed in this study. The regenerative evaporation water cooler is composed of a sensible heat exchanger to cool the incoming air, followed by a latent heat exchanger to cool the water evaporatively with the cooled air flowing out of the sensible heat exchanger. By linearizing psychrometric characteristics, the heat and mass transfer in the regenerative evaporation water cooler is analyzed theoretically. The results show that the water can be cooled down even lower than the wet-bulb temperature of the inlet air. When the inlet air is
and 20% in relative humidity, and the inlet temperature of the water is
, the regenerative evaporation water cooler provides a larger cooling capacity than the conventional evaporation water cooler if the effectiveness of the latent heat exchanger is higher than 0.6 and that of the sensible heat exchanger is higher than 0.5.
Optimization of Nozzle Arrangement in a Liquid Direct Contact Cooling System : Constant Inlet Flowrate Analysis
Kim Won-Nyun ; Kim Seo-Young ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 5, 2006, Pages 402~409
For the design of a liquid direct contact cooling system, thermal and hydraulic analysis has been carried out. Well-known Zukauskas correlations are used to estimate the Nusselt number between the liquid refrigerant columns and the inlet airflow. The inlet air velocity is set at a typical value used in an actual showcase. For a constant column number, the best nozzle arrangement is determined for the maximum heat transfer. Heat transfer increases as the transverse pitch of the refrigerant column decreases. Among all the cases dealt with in the present study, the staggered arrangement with 140-columns of
shows the best thermal peformance and the expected temperature drop is
. The effect of downstream refrigerant columns on the overall thermal performance is investigated as well.
Effect of the Flow Rate of Coolant on the Absorption Peformance of a Vertical Absorber
Kim Jung-Kuk ; Cho Keum-Nam ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 5, 2006, Pages 410~417
The present study predicted the effect of the flow rate of coolant on the absorption performance of a vertical falling film type absorber Heat and mass transfer peformances were numerically investigated. The exit temperatures of solution and coolant were decreased as the flow rate of the coolant was increased at the film Reynolds number of 100. The absorption mass flux was increased and then decreased as the distance from the inlet of the absorber was increased. The distance showing the maximum absorption mass flux was ranged from 0.3 to 0.5m. The heat flux and the absorption mass flux were increased and then slowly decreased as the flow rate of the coolant was increased. The maximum values were obtained at the flow rate of coolant of 2.0L/min.
Effects of Accumulator Heat Exchanger on the Performance of a Refrigeration System
Kang Hoon ; Choi Kwang-Min ; Park Cha-Sik ; Kim Yong-Chan ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 5, 2006, Pages 418~425
An AHX (Accumulator Heat exchanger) consists of a commercial accumulator and an inner heat exchanger located inside of the accumulator. The AHX is used in multi air-conditioners to assure that liquid-phase refrigerant enters into the expansion device. This purpose is achieved by heat transfer between the refrigerant leaving the evaporator and the refrigerant leaving the condenser. In this study, the effects of AHX on the performance of a refrigeration system using R-22 were measured and the test results were analyzed. The operating characteristics of the refrigeration system with the AHX are considerably different from those without the AHX. Therefore, it is required to determine optimum refrigerant charge and optimum operating conditions when the AHX is used in the refrigeration system having a constant flow-area expansion device such as capillary tube.
A Case Study on the Building Energy Savings through HVAC System Optimization Process
Huh Jung-Ho ; Kwon Han-Sol ; Han Soo-Gon ; Ihm Pyeong-Chan ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 5, 2006, Pages 426~433
The requirements for the optimal building system design is numerous. However, most system designers do not take care of various design strategies. They often argue that the proper simulation tools are not existed to solve the implicated design requirements and the time to consider many alternatives of building systems are insufficient. The aim of this study is to develop the optimization interface program that considers various system design variables and eventually find both the optimal values of annual energy use and cost. Therefore, Doe2Opt is developed to easily perform simulation-optimization process based on DOE2 and GenOpt, and minimizes energy cost of small-to-medium sized building for 6.7% and that of large sized building for 3% with optimizing several HVAC system variables.
Performance Analysis of Scroll Expander-Compressor Unit for
Kim Hyun-Jin ; Nam Bo-Young ; Ahn Jong-Min ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 5, 2006, Pages 434~442
In a two-stage compression
transcritical cycle, application of a scroll expander-compressor unit has been considered in order to improve the cycle COP. For both expander and 1st stage compressor, scroll wrap profile which was originally designed for a R410A air-conditioning cycle mechanism was used with minor modifications: wrap height and involute end angle were adjusted for required displacement volume and built-in volume ratio. For pressure condition of 10 Mpa/3.5 MPa and expander inlet temperature of
, 25% improvement in COP was obtained by using expander-compressor unit. As evaporator pressure increased, COP improvement was lowered mainly due to decreasing compressor peformance.
Effects of Discrete Ribs on Pressure Drop in a Rotating Two-Pass Duct
Kim Kyung-Min ; Lee Dong-Hyun ; Cho Hyung-Hee ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 5, 2006, Pages 443~450
The present study has been conducted to investigate the effects of rotation on heat/mass transfer and pressure drop characteristics in a two-pass square duct with and without discrete ribs. For stationary cases, the heat/mass transfer on the surfaces with and without discrete ribs is almost the same or reduced. For rotating cases, the gap flow affects differently the heat/mass transfer on leading and trailing surfaces with discrete ribs. On the leading surface of the first pass, the heat/mass transfer is slightly enhanced due to generating strong gap flow. On the trailing surface of the first pass, however, the heat/mass transfer is much decreased because the gap flow disturbs impingement of main flow. The phenomenon, that is, the heat/mass transfer discrepancy between the leading and trailing surfaces is distinctly presented with the increment of rotation number. The friction losses on each surface with discrete ribs are reduced because the blockage ratio decreases for both non-rotating and rotating cases. Therefore, high thermal performance appears in a duct with discrete ribs.
Solid-Fluid Interface Treatment in Conjugate Heat Transfer Analysis using Unstructured Grid System
Myong Hyon-Kook ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 5, 2006, Pages 451~457
Conjugate heat transfer (CHT) is the simultaneous, coupled heat transfer within a fluid and an adjoining solid, and the interface treatment plays an important role in its analysis, particularly when using unstructured grid system. In the present paper a new solid-fluid interface treatment in CHT analysis is presented and applied to two typical CHT problems, i.e. natural convections in both concentric thick-walled cylinders and cavity with a centered solid body. The present interface treatment for unstructured mesh clearly demonstrates the same accuracy and robustness as that for typical structured mesh.