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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 19, Issue 12 - Dec 2007
Volume 19, Issue 11 - Nov 2007
Volume 19, Issue 10 - Oct 2007
Volume 19, Issue 9 - Sep 2007
Volume 19, Issue 8 - Aug 2007
Volume 19, Issue 7 - Jul 2007
Volume 19, Issue 6 - Jun 2007
Volume 19, Issue 5 - May 2007
Volume 19, Issue 4 - Apr 2007
Volume 19, Issue 3 - Mar 2007
Volume 19, Issue 2 - Feb 2007
Volume 19, Issue 1 - Jan 2007
Selecting the target year
A Study for Optimal Design of the AIG to Improve the Performance of DeNOx Facilities Installed in Combined Cycle Plant
Kim, Kwang-Chu ; Park, Man-Heung ; Yoon, Jun-Kyu ; Lim, Jong-Han ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 19, issue 12, 2007, Pages 811~820
A Study on the optimal design of the AIG(Ammonia Injection Grid) to improve the performance of DeNOx facilities in the HRSG(Heat Recovery Steam Generator) was performed using the CFD analysis. On the basis of the flow analysis results in the case that the AIG in the HRSG was not installed, the numerical analyses according to the positions of AIG, injection angles of nozzle and the control of ammonia injection quantity were carried out. The standard deviation according to factors was calculated for quantitative comparison. As the results, the AIG in the HRSG should be installed in the position that the uniform flow field shows through the exact flow analysis in the previous of the AIG design and installation. In the case the AIG has already been installed and non uniform flow distribution shows, it is recommended that flow correction device or KoNOx catalyst should be used. Otherwise, the control of ammonia injection angle or the ammonia injection quantity using the velocity profile analysis is demanded to accomplish the optimal performance.
Experimental and Numerical Analysis in the Surroundings of Impingement Baffle Plate of the Extracting Nozzle for Disclosing Shell Wall Thinning of a Feedwater Heater
Jung, Sun-Hee ; Kim, Kyung-Hoon ; Hwang, Kyeung-Mo ; Song, Seock-Yoon ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 19, issue 12, 2007, Pages 821~830
Feedwater heaters of many nuclear power plants have recently experienced severe wall thinning damage, which will increase as operating time progresses. Several nuclear power plants in Korea have experienced wall thinning damage in the area around the impingement baffle-installed downstream of the high pressure turbine extraction steam line- inside number 5A and 5B feedwater heaters. At that point, the extracted steam from the high pressure turbine is two phase fluid at high temperature, high pressure, and high speed. Since it flows in reverse direction after impinging the impingement baffle, the shell wall of the number 5 high pressure feedwater heater may be affected by flow-accelerated corrosion. This paper describes the comparisons between the numerical results using the FLUENT code and the down scale experimental data on effect of geometry of the impingement baffle plate on the shell wall thinning. Additionally, a new type impingement baffle plate was installed above the impingement baffle plate in the feedwater heater and then the numerical and experimental study were performed in the same progress.
Prediction of Stratified Turbulent Channel Flows with an Second Moment Model Using the Elliptic Equations
Shin, Jong-Keun ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 19, issue 12, 2007, Pages 831~841
This work is to extend the elliptic operator, which has been already adopted in turbulent stress model, to fully developed turbulent buoyant channel flows with changing the orientation of the buoyancy vector to be perpendicular to the channel walls. The turbulent heat flux models based on the elliptic concept are employed and closely linked to the elliptic blending second moment closure which is used for the prediction of Reynolds stresses. In order to reflect the stable or unstable stratification conditions, the present model introduces the gradient Richardson number into the thermal to mechanical time scale ratio and model coefficients. The present model has been applied for the computation of stably and unstably stratified turbulent channel flows and the prediction results are directly compared to the DNS data.
Solubility Consideration in Performance Analysis of a
Twin Rotary Compressor
Kim, Woo-Young ; Ahn, Jong-Min ; Kim, Hyun-Jin ; Cho, Sung-Oug ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 19, issue 12, 2007, Pages 842~849
two-stage twin rotary compressor used for heat pump water heater system, changes of
solubility in PAG oil were investigated along the gas passages from the first stage suction to final discharge. Only slight changes in solubility took place in suction chambers for both of the first and second stages, but for compression chambers, solubility variation ranged from 0.115 to 0.136, and from 0.133 to 0.182, respectively for the first and second stages. Calculation of gas flashing in parts of leakage oil flows and of oil contained in control volumes due to solubility changes was conducted and included in gas pressure calculation. For the second stage, gas flashing amounts to around
for most leakage flows. Cooling capacity, compressor input, and COP obtained by calculation were well compared to the experimental results. Effects of operation speed on the compressor performance was also studied: as the shaft speed increased, adiabatic efficiency decreased rapidly due to increased over-compression loss.
Effect of Pressurization and Cooling Rate on Dissolution of a Stationary Supercooled Aqueous Solution
Kim, Byung-Seon ; Peck, Jong-Hyun ; Hong, Hi-Ki ; Kang, Chae-Dong ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 19, issue 12, 2007, Pages 850~856
In a supercooled or capsule type ice storage system, aqueous solution (or water) may have trouble with non-uniform dissolution though the system contributes to the simplicity of system and ecological improvement. The non-uniform dissolution increases the instability of the system because it may cause an ice blockage in pipe or cooling part. In order to observe the supercooled state, a cooling experiment was performed with pressurization to an ethylene glycol(EG) 3 mass% solution in stationary state. Also, the effect of the pressurization from 101 to 505 kPa to the dissolution of supercooled aqueous solution was measured with the dissolution time of the supercooled aqueous solution at a fixed cooling rate of brine. At results, the dissolution of supercooled point decreased as the pressure of the aqueous solution in the vessel increased. Moreover, the dissolution point increased as the heat flux for cooling increased.
A Study on the Performance Evaluation of Recirculation System for Individual Hot Water Supply System in Residential Buildings
Cha, Min-Chul ; Yeo, Myoung-Souk ; Seok, Ho-Tae ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 19, issue 12, 2007, Pages 857~864
In the current residential building, hot water supply system consumes the second largest energy in order to make the thermal comport condition of residential space. The more residential environment improves the more the demand for hot water and water consumption is increasing gradually. So this study examines the possibility of applying the recirculation for individual hot water supply system compared with the existing method for waiting time for hot water, wasted water and energy consumption. The results are as follows. (1) In case of recirculation system method the waiting time for hot water can be reduced up to
in spring and fall period and so dose up to
in winter period. (2) The total wasted water has a little change compared with the existing method which can make the total wasted water reduced about
. (3) The efficiency of hot water supply system can be improved, if the method which blocks the inflow of cold water is applied, when return pump is operated to recirculate hot water in recirculation system.
A Field Survey of Indoor Air Environment of Schools
Chung, Min-Hee ; Jung, Sun-Mi ; Kim, Mi-Yeon ; Kim, Gun-Woo ; Park, Jin-Chul ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 19, issue 12, 2007, Pages 865~873
Recently there has been more apprehensions about health and environment. Since the concern has been increased, it is realized that students need to study in comfort and clean environment, and plan to study in environmental friendly facilities. Hence it is needed for both indoor air quality performance evaluation and greening facilities in order to plan environmental friendly schools. Accordingly, this study analyzes the indoor air quality throughout field survey of schools to provide preliminary data to develop environmental friendly education facilities. This paper investigates and analyzes indoor environment standards and performances in schools. There will be included 15 existing schools and 5 newly built schools for survey in Seoul and Gyeonggi. Additionally, environmental problems are also investigated and analyzed by occupants' questionnaires through surveys.
Effects of a Guide Fin Blade on the Flow Characteristics in a Ventilating Axial Fan
Park, Hong-Kwang ; Lee, Jee-Keun ; Rho, Byung-Joon ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 19, issue 12, 2007, Pages 874~882
The effects of a guide fin blade on the flow characteristics in a ventilating axial fan were investigated experimentally. The guide fins were setup onto the pressure surface of the blade, and their effects on the flowrate were evaluated. Two types of the guide fin blade were designed. One is the stem fin blade, and the other is the radial fin blade. The stem fin is designed normal to the circumference of a circle, and the radial fin is designed along the circumference of a circle. The results from the guide fin blade fans are compared with that of the blade without guide fins. The position and the geometry of the radial fin setting up on the blade have an effect on the increase of flowrate with the minor sacrifice of rotational speed of the blades. The radial fin positioning at 0.84 times blade diameter shows highest performance in the flowrate. The increase of the blade weight resulting from applying the guide fins shows minor effect on the variation of rotational speed of the blades.
Study on the Melting Point of Ar by Molecular Dynamic Simulation
Chung, Jae-Dong ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 19, issue 12, 2007, Pages 883~888
As a starting point of investigating what molecular dynamic simulations can reveal about the nature of atomic level of heating and cooling process, argon described by the LJ potential is considered. Stepwise heating and cooling of constant rates are simulated in the NPT (constant number, pressure and temperature) ensemble. Hysteresis is found due to the superheating and supercooling. Drastic change of volume and energy is involved with phase change, but the melting point can not be obtained by simply observing the changes of these quantities. Since liquid and solid phases can co-exist at the same temperature, Gibbs free energy should be calculated to find the temperature where the Gibbs free energy of liquid is equal to that of the solid since the equilibrium state is the state of minimum Gibbs free energy. The obtained melting temperature,
, is close to that of the experiment with only 2% error.