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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 16, Issue 12 - Dec 2004
Volume 16, Issue 11 - Nov 2004
Volume 16, Issue 10 - Oct 2004
Volume 16, Issue 9 - Sep 2004
Volume 16, Issue 8 - Aug 2004
Volume 16, Issue 7 - Jul 2004
Volume 16, Issue 6 - Jun 2004
Volume 16, Issue 5 - May 2004
Volume 16, Issue 4 - Apr 2004
Volume 16, Issue 3 - Mar 2004
Volume 16, Issue 2 - Feb 2004
Volume 16, Issue 1 - Jan 2004
Selecting the target year
Optimal Design for Indoor Thermal Environment based on CFD Simulation and Genetic Algorithms
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 2, 2004, Pages 111~120
The optimal design method of indoor thermal environment using CFD coupled simulation and genetic algorithms (GA) is developed in this study. CFD could analyze the thermal environment considering the distribution of temperature, velocity, etc. in a room. Therefore, It would be appropriate to use CFD for the optimal design method considering their distribution. In this paper, the optimal design means the most appropriate boundary conditions of the room among the conditions where the design target of indoor therm environment is achieved. Two step optimal indoor thermal environment design method is proposed. It includes the GA for searching the optimal indoor thermal environment design. To examine the performance of this method, the optimal design of hybrid ventilation system, which uses the natural cross ventilation and the radiation-cooling panel is conducted. The optimal design which satisfies the design target (thermal comfort, minimum cooling load, minimum vertical temperature difference) is found using two step optimal design method.
Conceptual Development of a Subminiature Cool Pad Applying Sorption Cooling Effect
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 2, 2004, Pages 121~127
This paper describes conceptual development and idea-verification of a sub-miniature portable cooler which dose not necessitate any pre-cooling nor any external energy supply. The basic principle of the cooling mechanism is the vaporization of water and sub-sequent cooling due to the evaporative latent heat loss. In this work, the vaporization of the water is stimulated by desiccant material to improve the cooling effect. The evaporative cooling caused by the desiccant is modeled and analyzed considering the sorption characteristics of the desiccant. In addition, the portable cooler is fabricated in the shape of a thin pad, and its cooling characteristics are tested and compared with the analytic results.
Verification Experiment and Analysis for 6 kW Solar Water Heating System(Part 1： Verification Experiment)
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 2, 2004, Pages 128~134
In order to verify and take measures against a variety of troubles which cannot be predicted in a well-controlled laboratory, it is necessary that solar system should be experimented in an actual situation during a long period. Through this experiment it can be also understood how the load pattern and operational conditions expected in a design process become different to those in the actual running, which can be applied to a new system design. We installed 6 kW solar hot water heating system with a shower facility and operated during 7 months. As a result, average 8.3 persons took a shower a day； solar fraction is 71％ and total collector efficiency is 40％ during the periods from March to September. We confirmed several troubles encountered in the actual situation and considered practical center-measures.
An Experimental Study of Smoke Movement in Tunnel Fires with a Vertical Shaft
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 2, 2004, Pages 135~141
The present paper concerns a smoke movement in a tunnel fire with a vertical shaft. The model tunnel measured 13.4m long, 0.4m wide and 0.4m high. The cross section is 1： 20 of a full scale tunnel. Ethanol was used as a fuel. The fire size in model tests varied from 1.35 kW to 13.37 kW, which corresponds to full scale fires of 2.41 to 23.91 MW. Smoke front velocity and temperatrue were decreased due to the vertical shaft install. Temperature was reduced maximum about 2
at ceiling and about 23
at vertical position. CO concentration was reduced as the vent width widened. When vent width was more than 15 cm, CO concentration was not reached 100 ppm. Descent degree of the smoke layer was confirmed through the visualization.
Effect on Ice Slurry Flowing in the Elbow of Various Angle
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 2, 2004, Pages 142~149
Recently, the government introduced the thermal storage system for reducing the electric power load. Especially, the ice slurry type has gained lots of interest due to its good heat transfer and flowing characteristics. This study was peformed to understand the effects of transporting ice slurry through elbows of various angle. Propylene glycol water solution was used and about 2 mm ice particles were circulated. The experiments were carried out under various conditions, such as concentration and velocity of water solution ranging between 0∼20 wt％, 1.5∼2.5 m/s, respectively. And elbows with 4 different angles of 30
. The differential pressure and IPF (ice packing factor) between the pipe entry and exit were measured. The tendency of pressure loss and outlet IPF in elbow is that the pressure loss was reduced as concentration and flow velocity of water solution is increased, and low value appeared at 10 wt％ and 2.5 m/s. The variation of outlet IPF was compared with the inlet IPF in the range of
An Experimental Study on Miscibility and Vapor Pressure of R-744/Oil Mixtures
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 2, 2004, Pages 150~157
Carbon dioxide (
, R-744) has become a very popular issue in application to refrigeration and air conditioning systems as a natural refrigerant. An experimental study has been carried out to investigate miscibility and the vapor pressure of refrigerant R-744 in the presence of lubricant oil. This is of particular interest in the selection of the lubricant oil for the compressor of a refrigeration system or an air conditioning system using the refrigerant R-744. The experimental set-up consists of the equilibrium cell, measuring devices, the vacuum pump, the constant temperature bath and relevant connecting pipes made of stainless steel. Five lubricant oils, such as mineral oil (Naphthenic), AB (Alkyl Benzene) oil, PAO (Poly Alpha Olefin) oil, PAG (Poly Alkylene Glycol) oil and POE (Polyol Ester) oil are considered in the present study. Test runs were conducted with the oil concentration range from 5 to 50 wt％, and the temperature range from -10 to 1
intervals. The miscibility results are visualized and correlated with the vapor pressure for the individual test components.
Simulation Study on the Performance Improvement of a Transcritical Carbon Dioxide Cycle
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 2, 2004, Pages 158~166
The performance of a heat pump using
is predicted and analyzed by using a cycle simulation model developed in this study. Cycle simulations are conducted by varying design parameters and operating conditions with the applications of advanced techniques to improve system performance. The applied systems in the simulations are internal heat exchanger, expander, and 2-stage compression with intercooling. As a result, the applications of advanced techniques improve the heating and cooling performances of the transcritical
cycle by 8∼26％ and 20∼30％, respectively, over the basic cycle.
Theoretical Analysis on the Heat and Mass Transfer in a Sorption Cool Pad
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 2, 2004, Pages 167~174
A sorption cool pad brings cooling effect without any pre-cooling, nor any external energy supply. It uses evaporative cooling effect stimulated by the desiccative sorption. In this paper, heat and mass transfer in the sorption cool pad are investigated theoretically. The evaporative cooling process caused by the desiccant is modeled and analyzed considering the sorption characteristics of the desiccant. Two nondimensional parameters are found to dominate the cooling process： one is related to the psychrometric characteristics and the other is to the sorption capacity of the desiccant. The former decides the time to reach the lowest temperature and the later controls the time duration of the cooling effect being sustained.
Performance Analysis of Water/Air Direct Contact Air Conditioning System
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 2, 2004, Pages 175~183
Performance of the water/air direct contact air conditioning system, in which heat and mass are directly transferred between air and water droplet, is simulated using semi-empirical method. Direct contact system improves transport efficiency compared to conventional indirect contact system. In this study, correlations for h
A / c
which represent the capacity of direct contact system are derived as a function of air and water flowrate from the experimental data. Cooling and heating performance of the water/air direct contact air conditioning system are evaluated using these correlations.ons.
Energy Performance Evaluation of VAV System through Various Operating Strategies in Office Buildings
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 2, 2004, Pages 184~193
The purpose of this study is to evaluate the performance of various control strategies in commercial buildings which have been operated by the variable air volume (VAV) system. Two buildings in Seoul were chosen for the field study. The one (D building) combined by LonWorks has the constant airflow of supply fan and the proportional control of VAV units (damper type). The other (S building) combined by DDC has the PI control mode of the supply fan and the floating control of VAV units (venturi type). In estimating thermal comfort and energy performance through control modes of PI, PID, and CAV in the supply fan, we could identify several energy efficient operating control strategies for the VAV system.
Effect of Wavy Flow of Vertical Falling Film on the Absorption Performance
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 2, 2004, Pages 194~201
In the present study, the improvement of absorption characteristics on combined heat and mass transfer process in a falling film of a vertical absorber by change of geometric parameters were studied experimentally and analytically. The energy and diffusion equations are solved simultaneously to give the temperature and concentration variations at the liquid solution-refrigerant vapor interface and at the wall. Absorption behaviors of heat and mass transfer were analyzed through falling film of the LiBr aqueous solution contacted by refrigerant vapor in the absorber. Effects of film Reynolds number, geometric parameters by insert device (spring) and flow pattern on heat and mass transfer performances have been also investigated. Especially, effects of the flow pattern by geometric parameters have been considered to observe the total heat and mass transfer rates through falling film along the absorber. As a numerical and experimental result, maximum absorption rate was shown at the wave-flow by insert device (spring). The error ranges between experiment and analysis were from 5.8 to 12％ at Re