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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 24, Issue 12 - Dec 2012
Volume 24, Issue 11 - Nov 2012
Volume 24, Issue 10 - Oct 2012
Volume 24, Issue 9 - Sep 2012
Volume 24, Issue 8 - Aug 2012
Volume 24, Issue 7 - Jul 2012
Volume 24, Issue 6 - Jun 2012
Volume 24, Issue 5 - May 2012
Volume 24, Issue 4 - Apr 2012
Volume 24, Issue 3 - Mar 2012
Volume 24, Issue 2 - Feb 2012
Volume 24, Issue 1 - Jan 2012
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Heating Performance Characteristics of a Heat Pump with a Variable Speed Injection Scroll Compressor
Ko, Suk-Bin ; Heo, Jae-Hyeok ; Cho, Il-Yong ; Kim, Yong-Chan ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 5, 2012, Pages 377~384
DOI : 10.6110/KJACR.2012.24.5.377
Vapor injection technique has been applied to prevent performance degrdation of a heat pump at low ambient temperatures. In this study, the heating performance of a heat pump with a variable speed injection scroll compressor using R-410A was investigated by applying sub-cooler vapor injection(SCVI) and flash tank vapor injection(FTVI). The heating performance of the heat pump was measured by varying compressor frequency and outdoor temperature. The heating capacity of the FTVI system was 8~10% higher than that of the SCVI system at all operating conditions. On the other hand, the heating performance improvement with the increase in the compressor frequency was more prominent in the SCVI system than in the FTVI system.
Development of a Compact Refrigeration Compressor and the Study of Basic Performance for Portable Refrigerator
Jang, Jun-Young ; Kim, Young-Jun ; Nam, Yeon-Woo ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 5, 2012, Pages 385~390
DOI : 10.6110/KJACR.2012.24.5.385
This paper discusses the applicability of a compact rolling piston refrigeration compressor to portable refrigerators. The capacity of this compressor is 1 cc. Using a 12 V BLDC motor, the compressor is driven from 2500 rpm to 6000 rpm. The height of the compression module and motor is approximately 56 mm, and their weight is approximately 374 g. We confirmed the effective operation of the compressor components by evaluating their compression and cooling performance.
Performance of HFC32/HFC152a Mixture for Water-source Heat Pumps
Kang, Dong-Gyu ; Kim, Wook-Jin ; Jung, Dong-Soo ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 5, 2012, Pages 391~400
DOI : 10.6110/KJACR.2012.24.5.391
In this study, performance of HFC32/HFC152a mixture is measured in the composition range of 20 to 50% R32 with an interval of 10% for the comparison with the conventional HCFC22 in water-source heat pumps. Tests are carried out under the same capacity in a heat pump bench tester equipped with a variable speed compressor at the evaporation and condensation temperatures of 7/
for summer and winter conditions, respectively. Test results show that the compressor power of the HFC32/HFC152a mixture is 13.7% lower than that of HCFC22 while the coefficient of performance(COP) the HFC32/HFC152a mixture is 15.8% higher than that of HCFC22. Hence, from the view point of energy efficiency, the HFC32/HFC152a mixture is excellent as compared to HCFC22. Compressor discharge temperatures of HFC32/HFC152a mixture are increased up to
as compared to that of HCFC22. The amount of charge for HFC32/HFC152 mixture decrease up to 27% as compared to that of HCFC22. Overall, HFC32/ HFC152a mixture is an excellent long term candidate to replace HCFC22 in water-source heat pumps.
Mass Transfer Characteristics of the Carbon Dioxide-Water Slug Flow in Vertical Small-Bore Tubes
Lee, Kyung-Jae ; Kim, Dong-Seon ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 5, 2012, Pages 401~408
DOI : 10.6110/KJACR.2012.24.5.401
Volumetric mass transfer coefficient was measured with carbon dioxide and deionized water for the gas-liquid cocurrent slug flow in 2, 5 and 8 mm tubes. Measurement was repeated with and without a vertical section in an experimental setup and entrance effect was found greater for smaller tubes. Volumetric mass transfer coefficient in the vertical section was found generally a strong function of gas- and liquid-phase superficial velocities. 5 mm- and 8 mm-tube data are highly consistent each other but not with 2 mm tube.
Optimization of Thermoelectric Elements for Thermoelectric Coolers
Jeong, Eun-Soo ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 5, 2012, Pages 409~414
DOI : 10.6110/KJACR.2012.24.5.409
A theoretical investigation to optimize thermoelectric elements for thermoelectric coolers was performed using a new one-dimensional analytic model. Mathematical expressions for the optimum current and the optimum length of a thermoelectric element, which maximize the coefficient of performance of thermoelectric coolers, were obtained. The optimum current is expressed in terms of the cooling load for a thermoelectric element, the hot and cold side temperatures and thermoelectric properties, but not the length of a thermoelectric element. The optimum current is proportional to the cooling load and decreases as the temperature difference between the hot and cold sides decreases. It is also shown that the optimum length of a thermoelectric element decreases as the cooling load increases.
Performance Characteristics of a Regenerative Heat Exchanger Depending on Its Porous Structure
Shin, Myung-Chul ; Ahn, Joon ; Kang, Byung-Ha ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 5, 2012, Pages 415~421
DOI : 10.6110/KJACR.2012.24.5.415
Stirling engine is an external combustion engine, whose efficiency approaches that of Carnot engine with the help of a regenerator. The regenerator is a heat exchanger composed of porous medium, whose performance is dependent on the pore structure. Three types of pore structures are considered in the present study. They are wire screen, random wire and composite structure, i.e. a combination of wire screens with different hydraulic diameters. The porosity more highly affects the performance of a regenerator compared to the hydraulic diameter. The random wire can yield high effectiveness even at a high porosity. The composite mesh gives better performance when the hydraulic diameter decreases in the direction from hot side to cold side.
A Study on Relationship Insulation Thickness and Infiltration Load by Window
Choi, Jeong-Min ; Cho, Sung-Woo ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 5, 2012, Pages 422~427
DOI : 10.6110/KJACR.2012.24.5.422
This study investigates on the relationship between total load which is caused by infiltration and insulation thickness against compensation effect. As the result of experiment, the PVC(Synthetic resins sash) window frame in airtightness is superior to the AL(Aluminum sash) window frame. In this study, as the increasing of insulation thickness in reference building does not reduce significantly cooling load, the compensation effect due to airtightness against infiltration is very small. But the compensation effect against infiltration can be closely related with heating load. Therefore, the proper thermal insulation thickness can be needed respect to cooling and heating load.
A Study on the Optimal Design of Confluent Pipe for Waste Collection Piping System
Sung, Sun-Kyung ; Park, Jun-Gil ; Suh, Sang-Ho ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 5, 2012, Pages 428~432
DOI : 10.6110/KJACR.2012.24.5.428
In the waste collection system, living waste is collected through the piping network. There are many confluent pipes in a piping network. These confluent pipes were often clogged up with waste. The optimal configuration of the confluent pipes has been defined by the design guide. However, nobody know how this design guide were determined. Therefore, in this paper, we found the design data for the confluent pipe configuration in order to avoid the waste clogging in a piping network. The distance between connected point on the confluent pipes should be longer than the previous design guide.
Analyses on Daylight Variations for Optimum Controls of Daylight Dimming Systems in a Small Office
Yoon, Youn-Ju ; Baik, Yong-Kyu ; Kim, Soo-Young ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 5, 2012, Pages 433~442
DOI : 10.6110/KJACR.2012.24.5.433
The influence of outdoor sky conditions on photosensor signals were examined to determine an appropriate index that is effectively used for optimum illuminance fluctuation when a daylight dimming system is used for a small office. Field measurements were conducted under various sky conditions. Results indicate that the outdoor global and vertical illuminance fluctuated within narrow ranges under clear and overcast sky conditions. The fluctuation of sky ratio under partly-cloudy sky caused wide ranges of illumnance fluctuation. A partially-shielded photosensor at backwall produced 56% of light output from fixtures controlled by a photosensor at ceiling. This implies that the photosensor at backwall does not always guarantee target illuminance due to the less output. The fluctuation of light output from fixtures were insignificant under clear and overcast sky. The fluctuation range of photosensor illuminance under partly-cloudy sky caused wide fluctuation ranges of light output. Regression result implies that the outdoor vertical illuminance was recommended for an effective index that is used for control of light output.
Variation of Spatial Cognition According to Visual Perception and Psychological Responses for Lighting Environments in Rest Space
Kim, Jae-Sang ; Lee, Ji-Hyun ; Kim, Soo-Young ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 5, 2012, Pages 443~453
DOI : 10.6110/KJACR.2012.24.5.443
This study examines visual perception and spatial satisfaction according to lighting conditions. Field measurements and surveys were performed in three rest space of university buildings where various lighting conditions were employed. Results indicate that overall impression of space improved when low color temperature, such as 3,000 K governed overall lighting environment and accent lighting was used for wall surfaces. Lighting conditions that kept uniform illuminance levels using area light sources containing fluorescent lamps with 6,500 K failed to keep favorable spatial satisfaction for space. High color temperature was not recommended for lighting in rest space. Asymmetrical illuminance levels formed by low color temperature such as 3000 K is recommended to keep positive mood and improve spatial satisfaction in rest space. Overall impression of the space was influenced by visual comfort, color temperature, spatial satisfaction and brightness. Spatial satisfaction for space was effectively impacted by psychological comfort, color temperature and overall impression for lighting conditions. Psychological comfort in space was influenced by color temperature, spatial satisfaction and visual annoyance from reflected light.
A Study on the Positively Charged Filter for Removing Fine Particles in Water
Jung, Sung-Hak ; Kim, Jong-Won ; Kim, Sang-Hee ; Jeon, Byung-Heon ; Lee, Seung-Gap ; Lee, Jae-Keun ; Ahn, Young-Chull ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 5, 2012, Pages 454~460
DOI : 10.6110/KJACR.2012.24.5.454
The purpose of the present work is to investigate the removal characteristics of positively charged filters for capturing negatively charged particles such as bacteria and virus in water. In order to reduce the pressure drop and increase the filtration efficiency, the filter media, modified by charge modifier having positive functional groups, is developed and evaluated. Improved liquid filters have been developed with the modified surface charge to capture and adsorb particles by electrokinetic interaction between the filter surface and particles contained in an aqueous liquid. The positively charged filter media is composed of glass fiber, cellulose and poly-ethylenimine resin for positively charging with the variation of volume ratio. The zeta potential value of the positively charged filter is +37.92 mV at the glass fiber and cellulose content ratio of 50 : 50 with resin content of 100%, while that of the PSL test particle is -23.5 mV at pH 7. The removal efficiency of the electro-positively charged filter is 98% for PSL particles of 0.11
, while that of the negatively charged filter is 7%. The positively charged filter media showed the potential to be an effective method for removing fine particles from the contaminated water for liquid filtration.