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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 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
Study on Ice Making Behavior of Water Solution with Surfactant
;Hideo Inaba;Akihiko horibe;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 12, 2001, Pages 1175~1183
Recently, a great attention has been paid to the ice thermal storage system for the purpose of energy saving and reduction in peak electrical demand. In the present study, it has been investigated the freezing behavior of several kinds of water solutions with nonionic surfactant. In order to prevent ice blockage in a cooled pipe, the amount and wall adhesion behavior of ice of the test fluids were observed experimentally under different concentration of water solution with surfactant, temperature of cooled wall, and the shear velocity of test fluids. The results showed that the size of ice crystal became smaller at higher shear velocity at wall. And the lowest limit of wall adhesion of ice in water solution with surfactant was found at 230 W/
of heat flux.
Velocity Measurement in a Rectangular Duct with
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 12, 2001, Pages 1184~1195
Analysis of fluid flow in rectangular ducts has been conducted since it has a wide application. The purpose is to provide experimental data for the comparison with computational results. Velocity distributions inside a rectangular duct with
mitered elbow are measured by 5W laser doppler velocity meter for Reynolds numbers of 4,049, 8,104, and 12,186. Flow rates obtained by the integration of measured velocity profile at three cross-sections, which are inlet, middle section after the elbow, and outlet, have errors less than 0.9% among them. Turbulent fluctuation components in two directions are found to have almost similar magnitude each other at a certain location due to the isotropic characteristic of turbulence.
Perturbation Analysis of a Meandering Rivulet
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 12, 2001, Pages 1196~1204
The rivulet is a narrow stream of liquid flowing down a solid surface. When the rivulet\`s flow rate exceeds a certain limit, it tends to meander exhibiting the instability of its interface. This analysis performs a perturbation analysis of this meandering rivulet assuming an inviscid flow possessing contact angle hysteresis at the contact line. The analysis reveals that the contact angle hysteresis as well as the velocity difference across the inter-face, strongly induces the instability of the liquid interface. Moreover, when the rivulet veto-city is low, it is predicted that the axisymmetric disturbance amplifies more rapidly than the anti-axisymmetric disturbance, which explains the emergence of the droplet flow at the low velocity regime.
A Numerical Study on the Collection Characteristics of a Wide Plate-Spacing Electrostatic Precipitator
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 12, 2001, Pages 1205~1213
The electrical characteristics and particle collection efficiency of a wide-plate spacing electrostatic precipitator are numerically investigated, and the results are compared with those obtained experimentally. The electric potential and field strength near the collection plate increase with increasing the plate spacing. The electric field strength of a discharge electrode of a twisted pin type is larger than that of a rectangular type. As the roughness factor of the discharge electrode wire becomes small, or the plate spacing becomes narrow, the corona current of the precipitator increases. The numerical results agree well with those obtained from experimental method.
Effect of Diameter and Length on the Absorption Performance in a Vertical Absorber Tube
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 12, 2001, Pages 1214~1222
The present study investigated the effect of diameter and length on the absorption performance of a vertical falling film type absorber using
O solution of 60 wt%. The parameters were diameter of absorber (17.2, 23.4, 31.1 mm), length of absorber (771, 1150, 1528 mm), and film Reynolds numbers (50, 70, 90, 110, 130, 150). As the diameter of the absorber was increased, the absorption mass flux, Sherwood number, heat flux, and heat transfer coefficient were increased, in which Sherwood number and heat transfer coefficient were increased up to 13% and 30% respectively. As the length of the absorber was increased, the total absorption rate and heat transfer coefficient were increased by 37% and 35% respectively, while the absorption mass flux was decreased.
Consideration on the T-history Method for Measuring Heat of Fusion of Phase Change Materials
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 12, 2001, Pages 1223~1229
Though conventional calorimetry methods such as differential scanning calorimetry (DSC) and differential thermal analysis (DTA) are used generally in measuring heat of fusion, T-history method has the advantages of a simple experimental apparatus and no requirements of sampling process, which is particularly useful for measuring thermal properties of inhomogeneous phase change materials (PCMs) in sealed tubes. However, random criteria (a degree of supercooling) used in selecting the range of latent heat release and neglecting sensible heat during the phase change process can cause significant errors in determining the heat of fusion. In the present study, it was shown that a 40% discrepancy exists between the original T-history and the present methods when analyzing the same experimental data. As a result, a reasonable modification to the original T-history method is proposed.
An Experiment and Numerical Analysis of Mixed Convection in a Rectangular Space with Variable Partition
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 12, 2001, Pages 1230~1235
The laminar convection heat transfer in a ventilated space with various horizontal partitions was studied numerically and experimentally. The experimental results by holographic interferometer showed good agreements with the numerical results. For the numerical study, the governing equations were solved by using a finite volume method for
, Pr=0.71 and the variations of partition lengths. The isotherms and velocity vectors have been represented for various parameters. As the length of partition increases, the convection heat transfer decreases. Based on the numerical data, a correlation was obtained for the dimensionless mean Nusselt number in terms of
. In the region of
<1, the mean Nusselt number was very small, but in the region of
, the mean Nusselt number was constant.
Influence of Control Pressure and Concentration of Water Solution at Continuous Ice Making in a Tube
;;Hideo Inaba;Akihiko Horibe;Naoto haruki;Hidetoshi Miura;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 12, 2001, Pages 1236~1244
In the present study, the possibility of continuous slurry ice making using flowing water solution in a cooled tube has been investigated. The experiments were carried out at various concentration and velocity of water solution, temperature of cooled tube wall, and control pressure in a tube. As a result, four types of operating conditions, that is super-cooling, continuous ice making, intermittent ice making and ice blockage, were classified. And it was found that the critical condition for the continuous ice making was acquired as a function of these experimental parameters.
A Study on the Optimum Design for the Discharge Port of a R410A Rotary Compressor
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 12, 2001, Pages 1245~1254
For a R410A-rolling piston type rotary compressor model which was modified by reducing the cylinder height and shaft eccentricity from R22-compressor version, numerical simulation has been carried out and simulation results have been found to be compared fairly well with those of measurements. EER of this first version of R410A compressor was 4.8% lower than that of R22 compressor. To improve the performance of the R410A compressor model, parametric study on the design parameters related to the discharge port system has been performed by using the numerical simulation program, and optimum conditions for the highest EER have been obtained with the aid of Taguchi method. With the optimized discharge port configuration, EER has been improved by 1.7%.
Stabilization of Fuel F1ow in a Multi-Nozzle Combustion System Burning Natural Gas
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 12, 2001, Pages 1255~1265
A numerical study has been conducted to characterize the transient flow in a utility gas turbine burning natural gas. The solution domain encompasses the supply gas pressure regulator to the combustor of the gas turbine that employs multi-nozzle fuel injectors. Some results produced for verification in the present study agree suite well with the experimental ones. It is found that the total gas flow may decrease noticeably during its combustion mode change, which would be the reason of momentary combustion upset, when a reference case of opening ratios of control valves in the system is applied. Several parameters are then varied in order to make the total gas flow stable over that period of time. Results of this study may be useful to understand the unsteady behavior of combustion system burning natural gas.
Melting of Ice Inside a Horizontal Cylinder under the Volume Change
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 12, 2001, Pages 1266~1274
Heat transfer phenomena during melting process of the phase change material (ice) was studied by numerical analysis and experiments. In a horizontal ice storage tube, the natural convection caused an increase in melting rate. However, the reduction of the heating surface area caused a decrease in melting rate. Therefore, during the melting process of ice in a horizontal cylinder, the reduction of the heating surface area should be considered. Under the same heating wall and initial water temperature condition, the melting rate became higher for
/=1.00 due to the difference in the reduction of heating surface area. A modified melting model considering the equivalent thermal conductivity of liquid phase and volume reduction was proposed. The results of the model were compared with the measured values and found to be in good agreement.
Convective Heat Transfer of a Paraffin Slurry in a Drag Reducing Carrier Fluid
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 12, 2001, Pages 1275~1281
Aqueous polymer solutions are known to have small pressure reduction. Paraffin slurries are known to have high thermal capacity. Paraffin particles are mixed into an aqueous polymer solution to make a new heat transfer fluid having high thermal capacity but low pressure reduction. The heat transfer characteristics of the new slurry was tested in a circular tube having a constant heat transfer boundary condition. The new slurry was found to have high Nusselt numbers as well as high thermal capacity and low pressure reduction in the laminar flow. The trends of the Nusselt numbers along the heating test section were studied for various heating conditions.
Natural Convection for Air-Layer between Body Skin and Clothing with Considering Coefficient of Permeability
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 12, 2001, Pages 1282~1287
This study presents the numerical analysis of natural convection of a micro- environments with air permeability in the clothing air-layer. As a numerical model the clothing air layer of shoulder and arm were adopted. Finite volume method for two-dimensional laminar flow was used for the analysis of flow and thermal characteristics of velocity, temperature and concentration in the air layer between body and clothing. As temperature boundary conditions, a body skin has a high temperature with
and the environmental temperatures are 5, 15 and
for various permeability coefficients. The distributions of concentration, temperature and velocity are shown that two large cells form at horizontal and vertical air layer, respectively. As the temperature difference between body skin and environment decreases, the heat transfer is decreased rapidly.
Fault Detection and Diagnosis for an Air-Handling Unit Using Artificial Neural Networks
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 12, 2001, Pages 1288~1296
A scheme for on-line fault detection and diagnosis of an air-handling unit is presented. The fault detection scheme uses residuals which are generated by comparing each measurement with analytical redundancies computed from the reference models. In this paper, artificial neural networks (ANNs) are used to estimate analytical redundancy and to classify faults. The Lebenburg-Marquardt algorithm is used to train feed forward ANNs that provide estimates of continuous states and diagnosis results. The simulation result demonstrated that the ANNs can effectively detect and diagnose faults in the highly non-linear and complex HVAC systems.
An Experimental Study on the Control Methods of Radiant Floor Heating Systems
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 12, 2001, Pages 1297~1305
In this study, existing control methods that are suggested or applied until now are classified by control parameters, and stability of in the room and floor surface temperatures of each control method is compared through experiments. Then, the control performance of these control methods are analyzed to evaluate the applicability to Korean apartment housing. From the result of the applicability analysis, the outdoor reset with on/off PWM control is found to be desirable for district heating systems and flux modulation is found to be applicable for decentralized heating systems. In the case of independent control systems for each room, on/off PWM control is desirable.
Simulation on Performance Characteristics of a Tip-Seal Type Scroll Compressor
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 12, 2001, Pages 1306~1318
This paper presents leakage and performance characteristics of a tip-seal type scroll compressor, The performance of a scroll compressor is strongly dependent on the leak age across the compression pockets. However, literature for leakage characteristics of the tip seal type scroll compressor is very limited due to complex sealing mechanism. In the present study, a simulation study was executed to investigate the tip-seal type scroll compressor by considering leakages passing through flank and tip clearance. As a result, the leakage phenomena of the tip seal type scroll compressor as a function of discharge pressure, tip clearance, dimension of the tip seal were analyzed. Effects of leakage on the performance of the compressor were also clarified.