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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 19, Issue 12 - Dec 2007
Volume 19, Issue 11 - Nov 2007
Volume 19, Issue 10 - Oct 2007
Volume 19, Issue 9 - Sep 2007
Volume 19, Issue 8 - Aug 2007
Volume 19, Issue 7 - Jul 2007
Volume 19, Issue 6 - Jun 2007
Volume 19, Issue 5 - May 2007
Volume 19, Issue 4 - Apr 2007
Volume 19, Issue 3 - Mar 2007
Volume 19, Issue 2 - Feb 2007
Volume 19, Issue 1 - Jan 2007
Selecting the target year
Condensation Heat Transfer Coefficients of R245fa on a Plain Tube
Shim, Yun-Bo ; Park, Ki-Jung ; Jung, Dong-Soo ; Kim, Jong-Seong ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 19, issue 8, 2007, Pages 555~562
In this study, condensation heat transfer coefficients (HTCs) of R22, R134a, R245fa and R123 are measured on a horizontal plain tube. All data are taken at the vapor temperature of
with a wall subcooling temperature
. Test results show the HTCs of newly developed alternative low vapor pressure refrigerant, R245fa, on a plain tube are 9.5% higher than those of R123 while they are 3.3% and 5.6% lower than those of R134a and R22 respectively. Nusselt's prediction equation for a plain tube underpredicts the data by 13.7% for all refrigerants while a modified equation yielded 5.9% deviation against all data. From the view point of environmental safety and condensation heat transfer, R245fa is a long term good candidate to replace R123 used in centrifugal chillers.
Prediction of Characteristics for the Air-side Particulate Fouling in Finned-Tube Heat Exchangers of Air Conditioners used in the Field
Ahn, Young-Chull ; Jung, Sung-Hak ; Hwang, Yu-Jin ; Lee, Chang-Gun ; Kim, Doo-Hyun ; Jung, Seong-Ir ; Lee, Jae-Keun ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 19, issue 8, 2007, Pages 563~568
The air-side particulate fouling in the heat exchangers of HVAC applications degrades the performances of cooling capacity, pressure drop across a heat exchanger, and indoor air quality. Indoor and outdoor air contaminants foul heat exchangers. An empirical modeling equation has been derived from the experimental results using accelerated tests and it showed good predictions of the fouling characteristics of the slitted finned tube heat exchangers. However the modeling equation predicts only the fouling characteristics of new heat exchangers and it can not predicts fouling characteristics obtained from actual field data which contains the effect of hydrophilicity deterioration. Therefore an modified modeling equation is proposed and it shows good predictions of the actual fouling characteristics of finned-tube heat exchangers.
Effect of Desiccant and Channel Geometries on the Performance of Desiccant Rotor
Chung, Jae-Dong ; Lee, Dae-Young ; Yoon, Seok-Mann ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 19, issue 8, 2007, Pages 569~576
The desiccant rotor is the most essential component of desiccant cooling system, but one of its drawbacks to spread out is rotor size. To reduce the size of rotor the analysis of rotor performance is crucial. Systematic examination on the effect of desiccant and channel geometries has been conducted based on the numerical program previously developed. Considered parameters related to channel geometries are channel shape and cross section area of channel, and parameters related to desiccant are mass fraction, heat capacity, density, maximum water uptake and separation factor of isotherm. Considerable reduction of rotor size is expected by adjusting the parameters.
Fluid Dynamic Performance in a Hot-Water Heating System with a Variable-Flow-Rate Balancing Valve
Hur, Jurn ; Lee, Suk- Jong ; Sung, Jae-Yong ; Lee, Myeong-Ho ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 19, issue 8, 2007, Pages 577~584
A variable-flow-rate balancing valve has been developed and optimized to apply to a distributor in a hot-water heating system. Fluid dynamic performance of the system was evaluated by comparing the results with the previous pressure difference control valve (PDCV) system. In view of the variations of pressure drop and flow rate according to the sequential closing of the control valves, the present system which is named "smart system distributor", is very stable without a certain flow rate concentration. The level of pressure drop variation is also low as compared with the previous system with a PDCV. In view of the occurrence of cavitation, the present system is quite superior to the previous system because the instantaneous pressures at all sections are much higher than the vapor pressure. On the other hand, the previous system has a possibility of cavitation when one or more control valves are closed.
Numerical Analysis of Melting Process in a Water Tank for Fuel-cell Vehicles
Kim, Hark-Koo ; Jeong, Si-Young ; Hur, Nahm-Keon ; Lim, Tae-Won ; Park, Yong-Sun ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 19, issue 8, 2007, Pages 585~592
Good cold start characteristics are essential for satisfactory operation of fuel cell vehicles. In this study, the melting process has been numerically investigated for a water tank used in fuel cell vehicles. The 2-D model of the tank containing ice and plate heaters was assumed and the unsteady melting process of the ice was calculated. The enthalpy method was used for the description of the melting process, and a FVM code was used to solve the problem. The feasibility study compared with other experiment showed that the developed program was able to describe the melting process well. From the numerical analysis carried out for different wall temperatures of the pate heaters, some important design factors could be found such as local overheating and pressurization in the tank.
A Study on the Measuring Method of Ice Slurry Viscosity Using the Falling Sphere Viscometer
Kim, Myoung-Jun ; Yu, Jik-Su ; Lim, Jae-Keun ; Choe, Soon-Youl ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 19, issue 8, 2007, Pages 593~598
The present study has dealt with the measuring method of ice slurry viscosity using falling sphere viscometer. The experimental apparatus was composed by test section and high-speed video system. And the spheres used in this study were alumina and glass. The main parameters were ice packing factor (IPF) and falling velocity of sphere so the acquired results were discussed for these parameters. The viscosity of ice slurry was calculated by using measured falling velocity and moving distance at instantaneous time and the Stokes hypothesis was used for this calculation. It was clarified that possible measuring range was
of this type of measuring device and measuring method. In addition, it was clarified that the viscosity of ice slurry increased to increase of ice packing factor (IPF) of ice slurry.
A Real Time Measurement of Ice Concentration of Ice Slurry in Pipe
Jung, Hae-Won ; Peck, Jong-Hyeon ; Kim, Yong-Chan ; Kang, Chae-Dong ; Hong, Hi-Ki ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 19, issue 8, 2007, Pages 599~606
An experimental study was performed to measure a ice concentration of ice slurry flowing in a pipe in a real time. In the present paper, we suggested a measuring method by a refractive index and compared it to other methods by a freezing point and a density. To measure the refractive index of the solution, ice particles in the ice slurry should be completely removed and a hydro-cyclone was introduced instead of a mesh. The measuring method through the refractive index coincided with the density method using the real-time solution density within
error range, having the error range less than the other two methods. In the other hand, the measuring method through the density has a good resolution, but the result using the initial density of the solution was different more than 10% error from that using the real-time density. And it has an error range 1.5 times greater than the method through the refractive index.
The Effect of Ice Adhesion according to Functional Group and Chemical Structure of Additive
Chung, Dong-Yeol ; Peck, Jong-Hyeon ; Kang, Chae-Dong ; Hong, Hi-Ki ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 19, issue 8, 2007, Pages 607~614
This paper investigated that the functional group and chemical structure of additives affect ice adhesion in aqueous solutions cooling with stirring. In order to compare the effect on the ice adhesion in aqueous solutions, the functional group like carboxyl (-COOH), hydroxyl(-OH) or amine(
) one were compared each other. Among the functional group, the strength of the hydrogen bonding force order is amine, hydroxyl and carboxyl one. It supports that ethylene diamine 7 mass% solution including amine group was effective to suppress the ice adhesion, though it is corrosive. Also, the ice adhesion were effectively resisted and formed lots of ice slurries in cooling experiment of 7 mass% solution of 1, 2-and 1, 3-propanediol which is different molecular structure but equal molecular weight each other.