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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 18, Issue 12 - Dec 2006
Volume 18, Issue 11 - Nov 2006
Volume 18, Issue 10 - Oct 2006
Volume 18, Issue 9 - Sep 2006
Volume 18, Issue 8 - Aug 2006
Volume 18, Issue 7 - Jul 2006
Volume 18, Issue 6 - Jun 2006
Volume 18, Issue 5 - May 2006
Volume 18, Issue 4 - Apr 2006
Volume 18, Issue 3 - Mar 2006
Volume 18, Issue 2 - Feb 2006
Volume 18, Issue 1 - Jan 2006
Selecting the target year
A Study on the Optimal Control Strategy of Air-Conditioning System with Slab Thermal Storage - The Difference by the Presence of Radiant Heat as a Criterion Factor -
Jung Jae-Hoon ; Shin Young-Gy ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 4, 2006, Pages 287~296
In this paper, optimal control strategy of the air-conditioning system with slab thermal storage was investigated based on the optimal control theory. An optimal heat output to the plenum chamber and the air-conditioned room was determined based on two kinds of criterion functions. The first one requires small deviation in room air temperature from a set-point value and low energy consumption. It is shown that the optimized control is to store heat through the whole storage time and to increase storage rate gradually with time. As the second case, a criterion that both a deviation of operative temperature from a set-point temperature and the energy consumption should be minimized was adopted. The room air temperature was a little high and the cooling load during storage time was reduced, compared with the results when a criterion function considering only the room air temperature is used.
Experimental Study on the Characteristics of the Heat Transfer and the Pressure Drop inside the Small Diameter Tube with the Heat Transfer Enhancing Geometry
Park Chan-Woo ; Chin Sung-Min ; Jurng Jong-Soo ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 4, 2006, Pages 297~303
Friction and heat transfer coefficients were measured inside the corrugated tube using water as the working fluid. The test is performed for 16 tubes which outer diameter of tubes are 12.7 mm. These specifications are 4 indentation depths and 4 indentation pitches, respectively. The range of the water velocity inside the tube is from 0.5 to 3.0 m/s (8,500
Characteristics on Spray Cooling Performance on the Micro-Porous Coated Surfaces
Kim Yoon-Ho ; Choi Chi-Hwan ; Lee Kyu-Jung ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 4, 2006, Pages 304~311
Experiments on evaporative spray cooling on the square plate heaters with plain or micro-porous coated surfaces were performed in this study. Micro-porous coated surfaces were made by using DOM [Diamond particle, Omegabond 101, Methyl-Ethyl-Keton] method. In case of purely air-jet cooling, the micro-porous coating doesn't affect the cooling capacity. In spray cooling three different flow patterns (complete wetting, evaporative wetting, dryout) are observed on both plain and micro-porous coated surfaces. The effects of various operating conditions, such as water flow rate, particle size, and coating thickness were investigated on the micro-porous coated surfaces. It is found that the level of surface wetting is an important factor to determine the performance of spray cooling. It depends on the balance between absorbed liquid amount by capillary force over porosity and the evaporative amount. The micro-porous coated surface has largest cooling capacity, especially in the evaporative wetting zone. It is found that the effects of liquid flow rate and coating thickness are significant in evaporative wetting zone, but are not in complete wetting and dryout zones.
Performance of HCFC22 Alternatives R1270, R290, R1270/R290, R290/HFC152a, R1270/R290/RE170 Refrigerants for Air-conditioning and Heat Pump Applications
Hwang Ji-Hwan ; Baek In-Cheol ; Jung Dong-Soo ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 4, 2006, Pages 312~319
In this study, performance of 2 pure hydrocarbons and 7 mixtures was measured in an attempt to substitute HCFC22 used in air-conditioners and heat pumps. The mixtures were composed of R1270 (propylene), R290 (propane), HFC152a, and RE170 (Dimethyl ether, DME). The pure and mixed refrigerants tested have GWPs of
as compared to that of
and the mixtures are all near-azeotropic showing the gliding temperature difference (GTD) of less than
. Thermodynamic cycle analysis was carried out to determine the optimum compositions and actual tests were performed in a laboratory heat pump test bench at the evaporation and condensation temperatures of 7.5 and
respectively. Test results show that the coefficient of performance (COP) of these mixtures is up to 5.7% higher than that of HCFC22. While propane showed 11.5% reduction in capacity, most of the fluids tested had the similar capacity to that of HCFC22. Compressor discharge temperatures were reduced by
with these fluids. There was no problem with mineral oil since the mixtures were mainly composed of hydrocarbons. The amount of charge was reduced up to 55% as compared to HCFC22. Overall, these fluids provide good performance with reasonable energy savings without any environmental problem and thus can be used as long term alternatives for. residential air-conditioning and heat pumping application.
Influence of NCG Charging Mass on the Heat Transport Capacity of Variable Conductance Heat Pipe
Suh Jeong-Se ; Park Young-Sik ; Chung Kyung-Taek ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 4, 2006, Pages 320~327
Numerical analysis and experimental study are performed to investigate the effect of heat load and operating temperature on the thermal performance of several variable conductance heat pipe (VCHP) with screen meshed wick. The heat pipe is designed in 200 screen meshes, 500 mm length and 12.7 mm outer diameter tube of copper, water (4.8 g) is used as working fluid and nitrogen as non-condensible gas (NCG). Heat pipe used in this study has evaporator, condenser and adiabatic section, respectively. Analysis values and experimental data of wall temperature distribution along axial length are presented for heat transport capacity, condenser cooling water temperature change, degrees of an inclination angle and operating temperature. These analysis and experiment give the follow findings: For the same charging mass of working fluid, the operating temperature of heat pipe becomes to be high with the increasing of charging mass of NCG. When the heat flux at the evaporator section increases, the vapor pressure in the pipe rises and consequently compresses the NCG to the condenser end part and increases the active length of the condenser. From previous process, it is found out we can control the operating temperature effectively and also the analysis and experimental results are relatively coincided well.
Effect of Inlet Diffuser-Angle for Flow Uniformity of Industrial Electrostatic Precipitators
Kwon Hyun-Goo ; Park Suk-Hwan ; Cho Hyung-Hee ; Park Ki-Seo ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 4, 2006, Pages 328~334
Industrial electrostatic precipitators require a highly uniform velocity distribution in the collecting chamber. Increasing divergence angle of a diffuser makes a non-uniformity flow distribution characteristics on the diffuser exit. This paper provides CFD results of optimum positions and opening rates of perforated plates which were installed in the electrostatic precipitator. The considered divergence angels were 60 degree and 90 degree. In 90 degree diffuser, a blanking method was used.
The Impact of Bake-Out Method on the Reduction of Pollutant Concentration in New Apartments
Pang Seung-Ki ; Park Byung-Yoon ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 4, 2006, Pages 335~343
Indoor air pollution has been significantly aggravated due to hazardous pollutants emitted from petrochemical finishing materials in new apartments. Pollutants emitted into indoor environment have significant effects on the health of occupants, causing undesirable symptoms related to sick building syndrome such as headache, dizziness, difficulty in concentration, etc. Therefore, this paper attempted to investigate the reduction effect of bake out on VOCs emission in new apartments. Experiments were carried out in three households, one of which was naturally ventilated. The naturally ventilated showed the lowest indoor pollutant concentration and also showed the highest reduction rate by the use of bake out. The most desirable result was observed when the household was naturally ventilated after bake out. More detailed experiments are expected to be carried out afterwards on the prediction of reduction rate of each pollutant.
Numerical Prediction of Smoke Concentration in a Compartment Fire by Using the Modified Volumetric Heat Source Model
Kim Sung-Chan ; Lee Seong-Hyuk ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 4, 2006, Pages 344~350
The present study investigates the characteristics of fire-driven heat flows and gas concentration in a compartment fire by using the modified VHS model (MVHS). The main idea of this model is to add some source terms for combustion products and oxygen consumption to the original VHS model for providing more accurate and useful information on gas concentration distributions as well as thermal fields. It is found that the present MVHS model shows fairly good agreement with the experimental data and the eddy breakup combustion model. The tilting angle of fire plume calculated by MVHS is larger than that of EBU model because the fire source of VHS is affected by ventilating flow less than EBU. However, this discrepancy is apparently reduced in the downstream region of fire source.
Analytical Study on the Performance of a Rotary Vane Compressor
Kim Hyun-Jin ; Nam Bo-Young ; Lee Gyeong-Yong ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 4, 2006, Pages 351~358
This paper presents analytical results of a rotary vane compressor performance when the compressor is used for air supply from underwater. Compression characteristics such as pressure and temperature in a compression chamber are analyzed. Volumetric and adiabatic efficiencies are calculated. Vane dynamics are also performed to give reaction forces on the vane from the cylinder inner surface and from vane slots. Compressor efficiency is about 34.9%, and about 55% of the compressor loss is produced by the friction between the vane nose and the cylinder wall. Volumetric efficiency is about 79.5%, and indicated efficiency is about 77.1%, which are comparable to other displacement type compressors. When roller was introduced between housing inner wall and vane tips, mechanical efficiency could be improved by as much as 24.9%, depending on the roller friction.
A Numerical Study on the Flow Characteristics of Kitchen Hood System
Lim Kyung-Bin ; Lee Kwang-Sub ; Lee Chang-Hee ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 4, 2006, Pages 359~369
This study aims deriving analysis the flow characteristic of kitchen hood system with using 3-D numerical analysis method and improving the system to expel pollutes more efficiently. This system is applied with
turbulent model and using incompressibility viscosity flow range and boundary condition which are related to Bossinesq approximation following density variation in control volume. To understand the flow characteristics of four models, this study only focuses on velocity field, temperature field, and concentration field varying with followings whether separation plate is set or not and the shapes of separation plates. The quantity of air, speed of exhaust fan and temperature and concentration of heating source are concerned as constant values.
A Study on the Flow of Drilling Fluids in Slim hole Annuli
Seo Byung-Taek ; Woo Nam-Sub ; Hwang Young-Kyu ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 18, issue 4, 2006, Pages 370~376
The paper concerns an experimental study of fully developed laminar flow of a Newtonian and non-Newtonian liquid in concentric annuli with combined bulk axial flow and inner cylinder rotation. Pressure losses and skin friction coefficients have been measured for Newtonian fluid, water and non-Newtonian fluids, 0.2% aqueous of sodium carboxymethyl cellulose (CMC) and 5% bentonite solutions, when the inner cylinder rotates at the speed of
rpm. The influences of rotation, radius ratio and working fluid on the annular flow field are investigated. And the new correlations among the skin friction coefficient, the Reynolds number and the Rossby number are presented with reasonable limits of accuracy in laminar flow regime.