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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 12, Issue 12 - Dec 2000
Volume 12, Issue 11 - Nov 2000
Volume 12, Issue 10 - Oct 2000
Volume 12, Issue 9 - Sep 2000
Volume 12, Issue 8 - Aug 2000
Volume 12, Issue 7 - Jul 2000
Volume 12, Issue 6 - Jun 2000
Volume 12, Issue 5 - May 2000
Volume 12, Issue 4 - Apr 2000
Volume 12, Issue 3 - Mar 2000
Volume 12, Issue 2 - Feb 2000
Volume 12, Issue 1 - Jan 2000
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An experiment of the particle deposition on a circular cylinder in a laminar flow
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 12, issue 2, 2000, Pages 113~119
An experimental study has been carried out in order to investigate on a particle deposition on a circular cylinder surface. The present study is focused on the particulate fouling occurring in a heat exchanger for a seawater desalinization, in a laminar flow over circular cylindrical tubes. The objective is to investigate how NaCl concentration influences the
particle deposition on the surface of a glass circular cylinder. The NaCl concentration was changed from 0 g/L to 40 g/L. As the experimental results of
particle which is deposited on the glass circular cylinder surface showed, particle deposition rate per unit time increases rapidly with the increase of NaCl concentration between 0 g/L and 15 g/L. After the maximum of particle deposition rate was found at the NaCl concentration of 15 g/L, particle deposition rate remains unchanged or decreases gradually with the NaCl concentration from 15 g/L to 40 g/L. Also the
deposition rate of particles does not have serious variations with the position at present glass surface.
A study on a uniformity of flow field in a duct cooler of FGD system
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 12, issue 2, 2000, Pages 120~130
A flow uniformity in a duct cooler of duct system of FGD(Flue Gas Desulfurization) linking a reheater and a absorber has been investigated in the present study. For this purpose, the flow characteristics according to the geometry of a vertical and horizontal vane in a curved duct of the duct system has been examined with the aid of a numerical simulation. The results indicate that the vertical vane with a little deflection toward a recirculation region makes the flow distribution in the duct cooler more uniform than that without deflection, and horizontal vane does not effect the change of the flow distribution for an angle of inclination. The mean flow uniform factor shows its maximum for duct system without the vane(case NP) and its minimum for the vertical vane with a little deflection(case P-0.8-0) .
Effects of ortho-para hydrogen conversion on hydrogen liquefaction performance
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 12, issue 2, 2000, Pages 131~139
A direct hydrogen liquefaction equipment has been developed and tested, which consists of a GM refrigerator, a liquefaction vessel, a radiation shield, a cryostat, and an ortho-para converter with catalyst. The effect of ortho-para hydrogen conversion on the performance of hydrogen liquefaction has been investigated. The time needed for the hydrogen liquefaction process with hydrogen pressure charge of 4 atm was delayed to around 75 minutes, and the liquefied mass flow rate of the hydrogen was about 0.0150∼ 0.0205 g/s when the hydrogen was liquefied with the direct hydrogen liquefaction system considering ortho-para conversion. With ortho-para conversion, the liquefied mass flow rate decreased up to 20%. Considering ortho-para conversion, there were up to 30% increase in the work input per unit liquefied mass flow rate. When the ortho-para conversion was considered, FOM decreased to be about 0.031∼0.045.
Control strategy for economic operation of an ice-storage system considering cooling load variation
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 12, issue 2, 2000, Pages 140~149
A comparative analysis was peformed on the operation cost at partial loads between ice storage systems with the two conventional control strategies, i.e., storage priority and chiller priority. The storage priority control is shown to be more economic for small cooling loads, while the chiller priority control is superior when the cooling load is as large as the design value. Based on this finding, a new control strategy is devised for an ice-storage system to minimize the operation cost at any cooling load. The new control strategy is found to be comparable to the chiller priority for large cooling loads, while it is more economic for small loads compared to the conventional control strategies. The practicality of the new control strategy is also confirmed through a performance test applying the new control strategy to an existing ice-storage system.
Turbulent natural convective heat transfer charateristics in a square enclosure with control plates attached at the horifontal partition
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 12, issue 2, 2000, Pages 150~160
Turbulent natural convective flow and heat transfer in a square enclosure with horizontal partition are investigated numerically. The enclosure is composed of a lower hot and a upper cold horizontal walls and adiabatic vertical walls. Partitions carried with the upward, downward, and both control plates are attached perpendicularly to the one of the vertical insulated walls, respectively. The low Reynolds number
model is adopted to calculate the turbulent thermal convection. The governing equations are solved by using the finite element method with Galerkin method. The computations have been carried out by varying the length of partition, the position of control plates, and the Rayleigh number based on the temperature difference between two horizontal walls and the enclosure height for water(Pr=4.95). When the control plates are attached at the edge of partition, the stability of oscillating flow grows wrose with the increase of Rayleigh number and the partition length. The heat transfer rate has been reducer than that of no control plate due to the restraint of control plates with the increase of Rayleigh number.
Measurement of air side heat transfer coefficient of wire-on-tube type heat exchanger
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 12, issue 2, 2000, Pages 161~169
The experiment was conducted to obtain correlation of the air side heat transfer coefficient of wire-on-tube type heat exchanger using the single layer heat exchanger. The correction factors to Zhukauskas correlation was driven from the experimental results. The numerical analysis and experiment with several wire-on-tube type condensers to validate the correction factors are also peformed. The maximum discrepancy between experimental results and the numerical results using the correction factors of this study and Zhukauskas correlation is 10.0%, while that of reference correlation is 47.5%.
Development of simulation program for TXV and capillary tube performance analysis
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 12, issue 2, 2000, Pages 170~180
The equation which is related to TXV performance was investigated. On the basis of this equation, the TXV simulation program was developed. Results of the developed TXV simulation program were proven by the experiment on the influence of pressure difference between TXV entrance and exit and equalizing pressure. Simulation results show very good agreement with experimental results, the RMS error between them was 1.83%. The capillary tube simulation program was made by the basic equation of fluid dynamics. Results of this program were proven by data which were experimented previously. The RMS error between simulation results and experimental results was 4.13% .
A study on the by-pass valve design of a scroll compressor with asymmetric wrap
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 12, issue 2, 2000, Pages 181~189
The scroll compressor used for heat pump has a wide range of operation condition. To cover both heating and cooling modes, the operating Pressure ratio ranges from 1.5 to 6.8. Since the scroll compressor, however, is a type of compressor whose pressure ratio is fixed, some loss in the compression work is caused by the operation at the pressure ratio different from the built-in pressure ratio. A way of avoiding this problem is to introduce by-Pass holes in compression chambers, so that the compressed gas of pressure higher than the discharge pressure, yet not reached to the discharge port can be released earlier through the by-Pass holes. In this paper, an optimum Positioning of the by-Pass hole and the effect of the by-pass valve on the compressor performance are studied.
Thermodynamic performance of 2-PCM latent heat thermal energy storage system
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 12, issue 2, 2000, Pages 189~199
This paper investigates the thermodynamic performance of latent heat thermal energy storage system using two phase change materials(2-PCM system). The thermodynamic merit of using 2-PCM is clear in terms of exergetic efficiency, which is substantially higher than that of 1-PCM system. Optimum phase change temperature to maximize the exergetic efficiency exists for each case. The heat transfer area ratio of high temperature storage unit, X, becomes another important parameter for 2-PCM system if the phase change temperatures of given materials are different from those of optimum conditions. It is a good approximation for X
to be 0.5 when optimum phase change temperatures are used. Otherwise X
is determined differently as a function of given phase change temperatures.res.
A study on the applicability of radiant cooling using Ondol
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 12, issue 2, 2000, Pages 200~208
The use of air-conditioning systems for cooling in residential buildings has negative effects on the environment and causes the problem in peak electric power demand in summer. The objective of this study is to demonstrate the potential of radiant cooling systems using ondol as an alternative cooling system in our residential buildings. Computer simulation has been performed for the floor radiant cooling system performance. The results of this study show that. 1) This system can control the temperature of Ondol room within comfort limits. 2) This system can be operated with a little risk of condensation but the control of latent heat will make this system more potential.
Measurement of solubility and miscibility of R-410A/POE oil mixture
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 12, issue 2, 2000, Pages 209~217
The solubility and miscibility measurement apparatus was developed and used to obtain data for refrigerant/oil mixture. The solubility and miscibility data for R-410A/68 ISO VG polyol ester (POE) oil mixture are obtained over the temperature range from -20 to
intervals and the oil concentration range from 0 to 90 wt%. Using the experimental data, an empirical model was developed to predict the solubility relations for R-410A/POE oil mixture at equilibrium. In the R-410A/Solest 68 oil mixture, the average root-mean-square deviation between measured data and calculated results from the empirical model is 3.4% and in the R-4104/EMKARATE RL 68H oil mixture, that is 2.86%. For R-410A/68 ISO VG POE oil mixture immiscibility was usually observed at the low oil concentrations(5~30 wt%) over the all experimental temperature range(
) and at the high oil concentrations(50~90 wt%) over the low experimental temperature range(
Effects of non-absorbable gases in the absorption process of water vapor Into the Lithium Bromide-water solution film on horizontal tube bank
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 12, issue 2, 2000, Pages 218~225
In the present study, the effects of film Reynolds number (60∼200) and volumetric content of non-absorbable gases (0∼10%) in water vapor on the absorption process of aqueous LiBr solution were investigated experimentally. The formation of solution film on the horizontal tubes of six rows were observed to be complete for Re>100. Transition film Reynolds number were found to exist above which the Nusselt number and Schmidt number diminishes with solution flow rate. As the concentration of non-absorbable gases increased, mass transfer rate decreased more seriously than heat transfer rate did. The degradation effects of non-absorbable gases seemed to be significant especially when small amount of non-absorbable gases were introduced to the pure water vapor.