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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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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 13, Issue 12 - Dec 2001
Volume 13, Issue 11 - Nov 2001
Volume 13, Issue 10 - Oct 2001
Volume 13, Issue 9 - Sep 2001
Volume 13, Issue 8 - Aug 2001
Volume 13, Issue 7 - Jul 2001
Volume 13, Issue 6 - Jun 2001
Volume 13, Issue 5 - May 2001
Volume 13, Issue 4 - Apr 2001
Volume 13, Issue 3 - Mar 2001
Volume 13, Issue 2 - Feb 2001
Volume 13, Issue 1 - Jan 2001
Selecting the target year
A Study on Heat Flow Characteristics during Hot Water Extraction Process
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 7, 2001, Pages 549~556
Heat flow characteristics during hot water extraction process was studied experimentally. Data were taken at various outlet port type for the fixed inlet port type, inlet-outlet temperature differences and mass flow rates. In this study, the temperature distribution in a storage tank and an outlet temperature were measured to predict a flow pattern in the storage tank, and a hot water extraction efficiency was analysed with respect to the variables dominating a extraction process. Experimental results show that the extraction efficiency is high in a low flow rate in case of using modified distributor I(MDI) as a outlet port type.
The Study on Absorption Performance of a Plate-Fin Type Absorber
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 7, 2001, Pages 557~563
Small capacity gas absorption systems for cooling and heating have been favorably considered to reduce the seasonal imbalance of electrical loads and LNG consumption recently. A multifunctional plate-fin heat exchanger was adopted as an absorber and the performance was tested and analyzed to reduce the size and weight of the absorption heat pump. The test was performed using breadboard type ammonia absorption machine. The performance was compared with the plate type absorber and there was little difference in heat and mass transfer characteristics. The heat and mass transfer performance was a function of poor solution and vapor flow rates and the mass transfer was dependent on vapor flow rate more than heat transfer.
Study on the Performance of the Cascade System Using Alternative Refrigerants
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 7, 2001, Pages 564~571
The present study investigated the effect of key parameters on the performance of a cascade system using R-22 and R-23 refrigerants. Experimental data for the cascade system have been compared with simulation results using thermodynamic analysis. The cascade system tested at the evaporating temperature of
and the condensing temperature of
. The key experimental parameters were the evaporating temperature of the HTC(-35, -30, -25, -20,
) and mass flux of the HTC(200, 250, 300kg/
s). As the evaporating temperature and the mass flux of the HTC were increased respectively, the COP and the refrigerating efficiency were increased and then decreased while the volume flow rate per unit refrigeration capacity showed the opposite trend. The maximum COP and refrigerating efficiency were obtained at the evaporating temperature of the HTC of
and the mass flux of 250 kg/
A Study on the Collection Characteristics of Submicron Particles in an Electrostatic Precipitator - I. Electrical Characteristics
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 7, 2001, Pages 572~578
This study conducts a laboratory measurement on a cylindrical electrostatic precipitator(ESP) with a 30mm-diameter cylinder. Several kinds of test aerosols are generated with an atomizer and a diffusion dryer. The effects of applied voltage, flow state, gas velocity, and gas temperature on the electrical characteristics of the precipitator and onset of corona are experimentally investigated. The corona onset voltage is decreased, as diameter of discharge electrode wire becomes small or temperature of the precipitator increases. As the fluid velocity or particle load in the precipitator increases, the corona current is decreased.
A Study on the Collection Characteristics of Submicron Particles in an Electrostatic Precipitator - II. Collection Efficiency Characteristics
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 7, 2001, Pages 579~587
This study investigates particle collection characteristics of a cylindrical electrostatic precipitator. Experimental work has been made for the submicron particles. The effects of polarity of discharge electrode wire, particle diameter, gas velocity, gas temperature, and specific corona power on the particle collection efficiency are investigated. The efficiency of negative corona is higher than that of positive corona. as the particle diameter increases, the efficiency is decreased when the diameter is in the range of 0.02-0.6 micron, but is increased for the nanometer particles with diameter smaller than 0.02 micron. The efficiency is increased with increase of specific corona power. As the gas temperature increases, overall collection efficiency is increased for a negative corona, but is deceased for a positive corona.
Numerical Analysis of Heat Transfer Characteristics in Corrugated Plate Type Heat Exchanger Channel
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 7, 2001, Pages 588~594
The purpose of this study is to investigate the thermal and hydrodynamic characteristics of the channel in corrugated plate type heat exchangers numerically. Numerical work has been conducted using the Reynolds Stress Model(RSM) by utilizing the commercial finite-volume code, FLUENT. Based on this model, the dependence of heat transfer and friction factor on geometrical parameters have been investigated. It is found that larger corrugation angle give higher values of heat transfer coefficients and friction factors. As the reynolds number increases, the heat transfer coefficient also increases. It is also observed that the heat transfer coefficient reaches maximum while the friction factor stays relatively low at same corrugation angle. Through the analysis, it is found that the optimum corrugation angle for the heat exchanger performance exists. It is noted that the flow repulsions at the contact point of the two fluid streams make the low mixing more active for larger corrugation angle and high reynolds number.
Measurement of Flow Field through a Staggered Tube Bundle using Particle Image Velocimetry
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 7, 2001, Pages 595~601
We applied PIV method to obtain instantaneous and ensemble averaged velocity fields from the first row to the fifth row of a staggered tube bundle. The Reynolds number based on the tube diameter and the maximum velocity was set to be 4,000. Remarkably different natures are observed in the developing bundle flow. Such differences are depicted in the mean recirculating bubble length and the vorticity distributions. The jet-like flow seems to be a dominant feature after the second row and usually skew. However, the ensemble averaged fields show symmetric profiles and the flow characteristics between the third and fourth measuring planes are not so different. comparison between the PIV data and the RANS simulation yields severe disagreement in spite of the same Reynolds number. It can be explained that the distinct jet-like unsteady motions are not to be accounted in th steady numerical analysis.
Experiments on Condensation Heat Transfer Characteristics and Flow Regime Inside Microfin Tubes
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 7, 2001, Pages 602~611
Experiments on the condensation heat transfer characteristics inside a smooth and a microfin tube with R410A/R22 are performed in this study. The test tubes 7/9.52 mm in outside diameters and 3m in length are used. Varying the mass flux of the refrigerant and the condensation temperatures, the average heat transfer coefficients and pressure drop are investigated. Most flows in this study are in the annular and/or wavy flow regime. It is shown that the heat transfer is enhanced and the pressure drops are larger in the microfin tube than the smooth tube. From the heat transfer enhancement coefficients and the pressure drops, it is found that the high heat transfer enhancement factors are obtained in the range of small mass flux while the penalty factors are almost equal. Experiments results show that average heat transfer coefficients of R410A is larger than that of R22 and pressure drop of R410A is less than R22.
Optimum Design of a Compact Heat Exchanger with Foam Metal Insertion
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 7, 2001, Pages 612~620
The optimum design of a heat exchanger with porous media insertion is studied in this paper. It is considered that the aluminum foam metal is inserted in a flat plate channel and air flows through it. The influence of the microstructure of the foam metal on the pressure drop and heat transfer is investigated utilizing previous analytical results and existing correlation equations. Design parameters are identified as the unit-cell size and the ligament thickness of the porous medium, and their effects are examined. The results show that there exists optimum microstructure of the porous media maximizing heat transfer with a constant pressure drop. When the increase in the pressure drop is within a practically acceptable range, the increase in the heat transfer is dominated by the increase in the heat transfer area due to the porous medium insertion. Consequently, among the porous media with a constant pressure drop, the heat transfer is maximized with a microstructure with maximum specific surface area.
Flow Induced Noise Characteristics of the Cross Flow Fan with Uniform/Random Pitch Blades
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 7, 2001, Pages 621~626
The flow induced noise of the cross-flow fan with uniform/random pitch blades is predicted by computational methods. With the time dependent surface pressure data obtained by solving the incompressible Navier-Stokes equations in moving coordinates, the acoustic pressure is predicted by the Ffowcs Williams-Hawkings equation. The positions of the blade noise source are identified through an investigation of the acoustic pressure history induced by one blade, and it is confirmed that the dominant noise source is near the stabilizer. Since the acoustic pressure of the random pitch fan fluctuates according to the blade passin, the dominant BPF noise of the uniform pitch fan is modulated into some reduced discrete noises which have multiples of a 50Hz difference from BPF.
Mathematical Modeling and Analysis on the Behavior of VOC in an Indoor Environment
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 7, 2001, Pages 627~636
This paper presents a numerical analysis of the emission process of volatile organic compound(VOC) from building material and its diffusion in a room. A polypropylene styrene-butadiene rubber(SBR) floor plate is chosen as the emission source of VOC. This study investigates spatial concentration distributions and time history of room-averaged VOC concentration for both with and without flushing. The results of this study show that for calculation based on ten-days period the room averaged VOC concentrations with and without flushing are quite different. the results thus suggest the need of flushing for new buildings.
A Numerical Analysis of the Abatement of VOC with Photocatalytic Reaction in a Flow Reactor
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 7, 2001, Pages 637~646
VOC(Volatile Organic Compound) removal characteristics in continuous flow reactors have been numerically investigated. The photocatalytic reaction have been simulated with the binding constant and the reaction rate constant obtained from experimental data for the constant-volume batch reactor, and then VOC abatement in continuous flow reactors with the same conditions as those of batch reactor has been analyzed. The standard
model and mass conservation equation have been employed for numerical calculation, and heterogeneous reaction rate has been used in terms of the boundary condition of the conservation equation. in the case of the continuous flow reactor, reaction characteristics have been estimated with various inlet velocities and with different number of baffles. The result shows that the concentration distribution and flow patterns are strongly affected by the inlet velocity, and that with the increased inlet velocity, VOC removal rate is increased, while removal efficiency is decreased. This result may be useful in the design of reactors with improved VOC removal efficiency.
Evaluation of Thermal Comfort in Task Area with Personal Air-Conditioning System(PACS) b PMV Index
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 7, 2001, Pages 647~652
The thermal comfort of indoor spaces is very important factor in our life. Regions, cultures, climates and individual difference for establishing thermally comfortable environments should be considered carefully because these factors have a large influence on the thermal comfort doing some complicated interactions with environmental, psychological and physical elements. Recently, predicted mean vote(PMV) based on the heat transfer theory between environmental factors and human bodies has evaluated by many researchers and widely used nowadays. The objective of this study is to evaluate the thermal comfort in workspaces with personal air conditioning system using the measurements of environmental comfort parameters and the questionnaire survey of occupant's thermal senses with response to the environment.
The Characteristics of Pulsating Flow in a Hydraulic Pipe
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 7, 2001, Pages 653~665
The characteristics of the pulsating flow in a hydraulic pipe have been investigated. It is necessary to study the power control of the power transmission system in the landing gear system of aircraft and the design of robots. In this system, the power transmission pipeline is composed of a hydraulic system, and the operating flow is unsteady flow. The wave equation varying with frequency is analyzed in order to investigate the characteristics of unsteady flow in such a pipe. This wave equation involves the propagation coefficient in terns of frequency and viscosity. The theoretical result of this wave equation are compared with experimental result. Each wave equation, varying with the propagation coefficient, is analyzed theoretically. then, a sinusoidal wave generator is built in order to make better sinusoidal waves, and a rectifier is built to eliminate the noise from the hydraulic pump. The theoretical results of the wave equation in the flow of viscous fluid agree well with experimental results.