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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 17, Issue 12 - Dec 2005
Volume 17, Issue 11 - Nov 2005
Volume 17, Issue 10 - Oct 2005
Volume 17, Issue 9 - Sep 2005
Volume 17, Issue 8 - Aug 2005
Volume 17, Issue 7 - Jul 2005
Volume 17, Issue 6 - Jun 2005
Volume 17, Issue 5 - May 2005
Volume 17, Issue 4 - Apr 2005
Volume 17, Issue 3 - Mar 2005
Volume 17, Issue 2 - Feb 2005
Volume 17, Issue 1 - Jan 2005
Selecting the target year
Numerical and Experimental Analysis of Design Parameters of a Slim Room Air-conditioner
Shin Jong Jin ; Lee Hee Sool ; Kim Jong Moon ; Min June Kee ; Oh Sang Kyoung ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 2, 2005, Pages 95~100
Numerical simulations and experiments were conducted to analyze the design parameters for a slim room air-conditioner. These design parameters included a fan shape, a front panel, a scroll shape, a bell mouth, a distance between a fan and a heat exchanger, etc. Each design parameter was analyzed numerically and/or experimentally in terms of the flow rate and the sound pressure level, which should be the most influential factors for developing the slim room air-conditioner. The fan with a uniform height showed a better performance than that with a linearly varying height. It is recommended to use a front grill rather than a front panel according to sound pressure levels since the front panel itself is a huge resistance to the inlet flow. A redesigned scroll shape by changing the rotational direction of a fan also contributed a lot to lowering the sound pressure level. There existed a distance between a fan and a heat exchanger, where flow rates increased effectively.
An Experimental Study on the Performance of Outdoor Heat Exchanger for Heat Pump Using
Chang Young Soo ; Lee Min Kyu ; Ahn Young San ; Kim Young Il ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 2, 2005, Pages 101~109
The purpose of this study is to investigate the performance of outdoor heat exchanger for heat pump using carbon dioxide. Two types of fin and tube heat exchangers (2 rows for type A and 3 rows for B) are tested. Both heat exchangers have counter-cross flow and 1-circuit arrangement. Test results such as heat transfer rate, pressure drop characteristics and temperature distribution in the heat exchanger are shown with respect to mass flow rate of refrigerant and frontal air velocity For cooling mode, the minimum temperature difference between air and refrigerant of type B is smaller than that of type A by
, but the pressure loss of air side is much higher for type B by
. It is found that a large temperature gradient of carbon dioxide during gas cooling Process Promotes thermal conduction through tube wall and fins which results in degradation of heat transfer performance. For heating mode operation, type B heat exchanger shows higher heat transfer performance compared to type A. However, because pressure loss of refrigerant side of type B is much greater than that of type A, the refrigerant outlet pressure of type B becomes lower than that of type A.
Characterization of Interaction between Two Particles/Bubbles Flow with Moving Object Flow Image Analyzer System
Choi Hae Man ; Monji Hideaki ; Matsui Goichi ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 2, 2005, Pages 110~116
This paper deals with interaction between two bubbles or particles and flow around them, visualized by a moving object flow image analyzer(MOFIA) consisting of a three-dimensional (3D) moving object image analyzer(MOIA) and two-dimensional particle image velocimetry(PIV). The experiments were carried out for rising bubbles or particles of various densities, sizes, and/or shapes in stagnant water in a vertical pipe. In the MOFIA employed, 3D-MOIA was used to measure particles or bubbles motion and PIV was used to measure fluid flow, The experimental results showed that the interaction was characterized by the shape, size and density of two particles or bubbles.
An Experimental Study on the Performance of Plastic Plate Heat Exchanger
Yoo Seong Yeon ; Chung Min Ho ; Kim Ki Hyung ; Lee Je Myo ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 2, 2005, Pages 117~124
Aluminum plate heat exchanger, rotary wheel heat exchanger, and heat pipe heat exchanger have been used (or ventilation heat recovery in the air-conditioning system. The purpose of this research is to develop high efficiency plastic plate heat exchanger which can substitute aluminum plate heat exchanger. Because thermal conductivity of plastic is quite small compared to that of aluminum, various heat transfer enhancement techniques are applied in the design of plastic plates. Five types of heat exchanger model are designed and manufactured, which are plate type, plate-fin type, turbulent promoter type, corrugate type, and dimple type. Thermal performance and pressure loss of each heat exchangers are measured in various operating conditions, and compared each other. Test results show that heat transfer performance of corrugate type, turbulent promoter type, and dimple type are increases about
at the equivalent fan power compared to those of plate type, respectively. On the other hand, the heat transfer performance of plate-fin type decreases
because fins can not play their own role.
The Effects of Additives on the Cooling Characteristic of a Clathrate Compound
Kim Jin Heung ; Chung Nak Kyu ; Kim Suk Hyun ; Kim Chang Oh ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 2, 2005, Pages 125~130
This study was peformed to investigate the phase change temperature, the supercooling, the maintenance time of liquid phase and the change rate of volume of TMA 30
clathrate compound with additives. TMA 30
clathrate compound with additive was cooled at heat source temperature of
. The additives are ethylene glycol and chloroform. Their concentration are 0.1
respectively. The experimental results showed that the phase change temperature was not affected by additives and this was average
. Also the supercooling and the maintenance time of liquid phase were decreased by additives. Especially, the average value of supercooling showed by
and the maintenance time of liquid phase was by 19 minutes in the case of chloroform 0.1
. Additionally, the average change rate of volume showed by
according to additives and the volume was decreased by the phase change from liquid to solid.
A Study on the Performance of Boiling Heat Transfer of Two-Phase Closed Thermosyphons with Various Helical Grooves
Han Kyu Il ; Cho Dong Hyun ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 2, 2005, Pages 131~139
This study concerns the performance of boiling heat transfer in two-phase closed thermosyphons with various helical grooves. Distilled water, methanol, ethanol have been used as the working fluids. In the present work, a copper tube of the length of 1200 mm and 14.28 mm of inside diameter is used as the container of the thermosyphon. Each of the evaporator and the condenser section has a length of 550 mm, while the remaining part of the thermosyphon tube is adiabatic section. A experimental study was carried out for analyzing the Performances of having 50, 60, 70, 80 and 50 helical grooves. A Plain thermosyphon having the same inner and outer diameter as the grooved thermosyphons is also tested for comparison. The type of working fluid and the numbers of grooves of the thermosyphons with various helical grooves have been used as the experimental parameters. The experimental results have been assessed and compared with existing theories. The results show that the number of grooves and the type of working fluids are very important factors for the operation of thermosyphons. The helical grooved thermosyphons having 50 to 60 grooves in water, 60 to 70 grooves in methanol and ethanol shows the best heat boiling heat transfer coefficient.
On-line Optimal Control Technology for Central Heating System
Ahn Byung Cheon ; Choi Sang Gon ; Cho Sung Hwan ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 2, 2005, Pages 140~146
The on-line optimal control algorithm for central heating system has been researched for minimizing energy consumption while maintaining the comfort of indoor thermal environment in terms of the environmental variables such as indoor heating load and outdoor temperature variation. This study has been done by using TRNSYS Program in order to analyze the central heating system. The optimal control algorithm shows good energy Performances in comparison with the conventional one.
A Cascade Control Algorithm for the CO Level Control of a Long Road Tunnel
Han Do Young ; Yoon Jin Won ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 2, 2005, Pages 147~155
For a long road tunnel, a tunnel ventilation system may be used in order to reduce the pollution level below the required level. To control the tunnel pollution level, a closed loop control algorithm may be used. The cascade control algorithm, which composed of a jet fan control algorithm and an air velocity setpoint algorithm, was developed to regulate the CO level in a tunnel. The verification of control algorithms was carried out by dynamic models developed from real tunnel data sets. The simulation results showed that control algorithms developed for this study were effective to control the tunnel ventilation system.
The Operation Characteristics and Cost Analysis of an Ice Thermal Storage System
Ahn Young Hwan ; Kang Byung Ha ; Kim Suk Hyun ; Lee Dae Young ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 2, 2005, Pages 156~164
A comparative analysis of an ice storage system has been performed on the operation cost for the four control strategies, i.e., chiller priority and chiller downstream, chiller priority and chiller upstream, storage priority and chiller upstream, storage priority and chiller downstream. Main components of the ice storage system are an ice-on-coil storage tank and a screw compressor chiller. With the simulation program, the operation cost has been evaluated from the economics of an ice storage system. It is found that the operation cost of the ice storage system is strongly dependent on the control strategy, i.e., chiller priority or storage priority, but less affected by the arrangement method, i.e., chiller upstream or chiller downstream. In case of the maximum load day, the control strategy with chiller priority and chiller upstream is supposed to obtain the reduction of operation cost. However, it is found that the control strategy with storage priority and chiller downstream is the best economical operation for most summer seasons except the maximum load day.
Effects of Flow Resonance on Heat Transfer Enhancement and Pressure Drop in a Plate Heat Exchanger
Han Sang Kyu ; Kang Byung Ha ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 2, 2005, Pages 165~172
Heat transfer enhancement of three types of brazed plate heat exchangers has been evaluated experimentally. The effects of flow resonance in a plate heat exchanger on the heat transfer rate and pressure drop have been investigated in a wide range of mass flow rates in detail. The problem is of particular interest in the innovative design of a plate heat exchanger by flow resonance. The results obtained indicate that both heat transfer coefficient and pressure drop are increased as mass flow rate is increased, as expected. It is also found that the heat transfer enhancement is increased with an increase in the plate pitch, while the heat transfer is decreased with a decrease in the chevron angle. Pressure drop also increased with an increase in the plate pitch and with a decrease in the chevron angle. Heat transfer enhancement in the plate heat exchangers is maximized by flow resonance and the resonance frequency of the present plate heat exchangers is found to be in the range of
Evaluation of Thermal Conductivity for Grout/Soil Formation Using Thermal Response Test and Parameter Estimation Models
Sohn Byong Hu ; Shin Hyun Jun ; An Hyung Jun ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 2, 2005, Pages 173~182
The Performance of U-tube ground heat exchanger for geothermal heat Pump systems depends on the thermal properties of the soil, as well as grout or backfill materials in the borehole. In-situ tests provide a means of estimating some of these properties. In this study, in-situ thermal response tests were completed on two vertical boreholes, 130 m deep with 62 mm diameter high density polyethylene U-tubes. The tests were conducted by adding a monitored amount of heat to water over a
hour period for each vertical boreholes. By monitoring the water temperatures entering and exiting the loop and heat load, overall thermal conductivity values of grout/soil formation were determined. Two parameter estimation models for evaluation of thermal response test data were compared when applied on the same temperature response data. One model is based on line-source theory and the other is a numerical one-dimensional finite difference model. The average thermal conductivity deviation between measured data and these models is of the magnitude
Effect on the Adhesion of Ice Slurry by the Characteristic of Cooling Surface
Seung Hyun ; Hong Hi Ki ; Kang Chae Dong ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 2, 2005, Pages 183~190
In the process of ice-slurry making, ice adhesion on cooling wall or in narrow flow Path disturbs continuous ice formation. In this study, the effect on the ice adhesion to cooling surface by some freezing experiments was investigated, quantitatively. Three types of solutions were frozen in various coating vessels with stirring. In the experiment, the ice adhesion between cooling wall and Ice-slurry was evaluated by measuring stirring power. From the result, the stirring power of slurry mixture in PTFE-coating vessel was smaller than those in PE-coating, PFA-coating and bare SUS vessel. Especially, in EG H PG 1.S/ HD 1.5 mass
solution, the stirring power in the PE-coating vessel was smaller than that in the PFA-coating or SUS vessel.
Numerical Analysis of Optimum Air-Layer Thickness in a Double Glazing Window
Hwang Ho June ; Choi Hyoung Gwon ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 2, 2005, Pages 191~199
Double pane window system, in which an air layer with a finite width is filled between glasses, is used in order to increase the insulation efficiency. In the present study, a conjugate heat transfer problem of a double pane window system has been studied numerically in order to investigate the effect of an air layer on the heat transmittance of the double pane window system using a finite element method based on P2P1 basis function. In this study on the conjugate heat transfer of a double pane window system, numerically predicted Nusselt numbers with or without conjugate heat transfer effect have been compared with an available existing empirical formula. It has been found that a Nusselt number from an existing formula for an enclosed space is different from that obtained from the present conjugate heat transfer analysis mainly due to the effects of a very high aspect ratio and conjugate heat transfer mechanism. Furthermore, it has been shown that the numerically estimated optimal air thickness of the double pane window system with conjugate heat transfer effect is a little bit longer than that obtained without considering conjugate heat transfer effect.