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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 14, Issue 12 - Dec 2002
Volume 14, Issue 11 - Nov 2002
Volume 14, Issue 10 - Oct 2002
Volume 14, Issue 9 - Sep 2002
Volume 14, Issue 8 - Aug 2002
Volume 14, Issue 7 - Jul 2002
Volume 14, Issue 6 - Jun 2002
Volume 14, Issue 5 - May 2002
Volume 14, Issue 4 - Apr 2002
Volume 14, Issue 3 - Mar 2002
Volume 14, Issue 2 - Feb 2002
Volume 14, Issue 1 - Jan 2002
Selecting the target year
Off-Design Performance Analysis of a Counterflow-Type Cooling Tower
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 3, 2002, Pages 191~198
Cooling tower design procedure was set up using conventional Merkel theory, The design data could be different depending on the characteristic curve that the engineer chose. It reveals that the consistent and reasonable criteria are required based on the exact information of the cooling tower Performance. In this study, an off-design performance analysis program for a counterflow-type cooling tower was developed and verified by comparing with experimental data. Also, the off-design performance with various operating conditions was analyzed.
Optimization of the Channel of a Plate Heat Exchanger wits Ribs
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 3, 2002, Pages 199~205
In this paper, the optimum shape and arrangement of ribs in the channel of a plate heat exchanger are studied. The following dimensionless geometric parameters of ribs are selected as design variables: rib height (
), angle of attack (
), rib pitch (
), rib distance (L) and aspect ratio of rib (AR). The optimization is performed by minimizing the objective function consisting of the Nusselt number and the friction factor. The optimal values of design variables are as follows:
=3.142, L: 3.954, AR=0.342. The pressure drop and the heat transfer of the optimum model, compared to those of the reference model, are increased by 15.1% and 41.6%, respectively
Prediction of the Flow Characteristics of Jet Fan in a Confined Space
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 3, 2002, Pages 206~213
In this paper, the flow characteristics of an axial fan spraying isothermal compact jet in a confined space were investigated by the experimental methods, the numerical method, and the free jet theory According to the results, the numerical result and the experimental result are agreed well qualitatively and different quantitatively within
for the centerline velocity, the entrainment ratio, and the maximum throw. However, the free jet theory can reasonably predict the centerline velocity except the entrainment ratio and the maximum throw. In other words, the entrainment ratio and the maximum throw by 1.he free jet theory are hard to estimate the characteristics of jet because of restriction of c confined space.
Cooling Characteristics at Hot Side of the Thermoelectric Module for an Air Conditioner
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 3, 2002, Pages 214~220
A small air conditioner using thermoelectric module has been designed and built. Three types of cooling methods, such as air cooling, closed-loop water cooling, and evaporative cooling, for hot side of thermoelectric module have been investigated. Among three types of cooling method, the evaporative cooling method is seen to be the most effective to achieve the steady state operation of a thermoelectric air conditioner The system performance with evaporative cooling method are also studied in detail for several oprating parameters, such as input power to the thermoelectric module, water or air flow rate at the hot side, and air flow rate at the cold side. The results obtained indicate that the cooling capacity of a system is increased with an increase in the input power to the thermoelectric module while the system COP is decreased. It is also found that the optimal air flow rate as well as water flow rate at the hot side is needed for the best system performance at a liven operating condition. Both the system COP and cooling capacity are increased as the air flow rate at cold side is increased.
In-situ Performance Test and Prediction of a 10 RT Air Source Heat Pump
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 3, 2002, Pages 221~230
In this study, in-situ performance test of an air source heat pump which has a arted capacity of 10 RT is carried out. Since test conditions, such as indoor and outdoor air conditions cannot be controlled to satisfy the standard test conditions, experiments are done with the inlet air conditions as they exist. To estimate the performance for other conditions, he heat pump is modeled with a small number of selected parameters. The values of the parameters are determined from the few measurements measured on-site during normal operation. A simulation program is developed to calculate cooling capacity and power consumption t any other operating conditions. The simulation results are in good agreement with the experiment. This study provides a method of an on-site performance diagnosis of an air source heat pump.
Experiments on Single Phase Cooling Heat Transfer and Pressure Drop Characteristics in Microfin Tubes
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 3, 2002, Pages 231~239
Experiments on the single phase cooling heat transfer and pressure drop with microfin tubes were performed using water as a test fluid. Experimental data were obtained in the range of Reynolds number 3000 ~40000 and Prandtl number 4-6. The data of microfin tubes presented the characteristics of rough surface tube in pressure drop and heat transfer Experimental data were compared with the heat transfer and friction factor correlations of smooth tubes. Heat transfer enhancements of microfin tubes were lower than pressure drop penalty factors. The helix angle is more significant parameter in both of the pressure drop and heat transfer than the relative roughness. The correlations of Nusselt number and friction factor were suggested for the tested microfin tubes. Maximum deviations between correlations and experimental data were within
% for Nusselt number and
% for friction factor
The Characteristics of a Bypass Air Conditioning System for Load Variation
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 3, 2002, Pages 240~246
Bypass air conditioning systems are divided into three types; an outdoor air bypass, a mixed air bypass and a return air bypass system. What makes the return air by pass system more effective is that it directs all of moist outdoor air through the cooling coil. The bypass air conditioning system can maintain indoor R.H (Relative Humidity) less than a conventional CAV (Constant Air Volume) air conditioning system by adjusting face and bypass dampers at part load. When a design sensible load (the ratio of sensible load to total sensible load) is 70 percent (at this time, RSHF (Room Sensible Heat Factor) . 0.7), indoor R.H was maintained 59 percent by the return air bypass system, but 65 percent by the conventional CAV air conditioning system (valve control system). The bypass air conditioning system can also improve IAQ (Indoor Air Quality) in many buildings where the number of air change is high.
An Experimental Study of Smoke Movement in Tunnel Fires with Natural Ventilation
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 3, 2002, Pages 247~253
In this study, reduced-scale experiments were conducted to analyze smoke movement in tunnel fire with roof vent. The 1/20 scale experiments were carried out under the Froude scaling using gasoline pool fire ranging from 7.3 to 15.4 cm in diameter with total heat release rate from 1.0 to 8.46kw. In case of 1 m high vent, smoke front reached to the tunnel exit at about 16 sec delayed with ventilation. The delay time grew longer with the vent height. The temperature after the vent was lower than that without the vent. The exit temperature declined maximum of
after passing the vent. It was confirmed that the thickness of smoke layer was maintained uniformly under the 25% height of the tunnel through the visualized smoke now by a laser sheet and the digital camcorder.
Analysis of Laminar Flow Through Internally Finned Tube
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 3, 2002, Pages 254~260
There have been many studies for the flow through internally finned tube, since the heat exchangers with fin device derive much attention in heat transfer enhance cent. In this study, analysis of laminar flow through the circular tube with longitudinal fins are investigated. The height and the number of fins are arbitrary. The flow field is assumed to be laminar and conformal mapping is used to obtain analytic solution. From the analytic solution, equi-velocity lines are shown, and the flow rate through the finned tube is calculated for various fin heights and numbers of fins. Darcy friction factor for this finned tube and shear stress distributions on the wall and fin are also considered.
Numerical Model for the Analysis of Frosting Behavior
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 3, 2002, Pages 261~267
The integral boundary layer equation for the air side and the diffusion equation for the frost layer are numerically analyzed in order to predict the behavior of frost layer growth. The thickness and density of the frost layer obtained from the present study agree well with those of previous numerical results and experimental data with a maximum error of 13%. The characteristics of heat and mass transfer within the frost layer and the frost layer growth along the flow direction are investigated by performing numerical analysis. The effects of operating conditions on the frost layer growth are also examined.