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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
Selecting the target year
Development of a 200 W Portable PEM Fuel Cell System
Han, Hun-Sik ; Kim, Yun-Ho ; Cho, Chang-Hwan ; Kim, Seo-Young ; Hyun, Jae-Min ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 2, 2012, Pages 91~101
DOI : 10.6110/KJACR.2012.24.2.091
A 200 W portable polymer electrolyte membrane fuel cell (PEMFC) system is developed. The PEMFC system consists of an air-cooled fuel cell stack module, a fuel supply subsystem, a power management subsystem, and a control electronics subsystem. The control logic is designed for the stable system operation. The system-level performance evaluation discloses that the present PEMFC system provides a rated power output of 200.5 W at 13.4 V with the maximum balance-of-plant (BOP) efficiency of 72%, and maximum system efficiency based on lower heating value (LHV) is 37% at 120.7 W system power output.
Performance Optimization of a Hybrid Ground Source Heat Pump According to Secondary Flow Distribution Ratio between the Ground and the Supplemental Loop
Lee, Joo-Seong ; Park, Hong-Hee ; Kim, Won-Uk ; Kim, Yong-Chan ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 2, 2012, Pages 102~110
DOI : 10.6110/KJACR.2012.24.2.102
The objective of this study is to improve the performance of a hybrid ground source heat pump (HGSHP) by optimizing the flow distribution ratio of secondary fluid flow rate between a ground loop and a supplemental loop. Initially, a conventional ground source heat pump (GSHP) was tested to determine an optimum flow rate of the secondary fluid. Based on the selected optimum value, the HGSHP was also tested by varying the flow distribution ratio of the secondary fluid flow rate between the ground loop and the supplemental loop, such as 9:1, 7:3, 5:5, and 3:7. The results showed that the optimum flow distribution ratio of the secondary fluid flow rate was 7:3. The COP of the HGSHP was improved by 19% over the GSHP at a flow distribution ratio of 7:3 and an entering water temperature of
Analysis for Seasonal Operation Performance of Multistory Facade
Im, Hye-Jin ; Cho, Soo ; Sung, Uk-Ju ; Lim, Sang-Hun ; Haan, Chan-Hun ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 2, 2012, Pages 111~120
DOI : 10.6110/KJACR.2012.24.2.111
In this study, to present the data in the internal thermal condition of Double skin facade were measured internal temperature and inlet and outlet openings wind speed of double skin facade. Measurements were similar to temperatures in the upper double skin facade. Especially in summer, temperature stratification is through to be unfulfilled seamlessly despite inlet and outlet openings open. Double skin facade inlet and outlet openings of the air flow rate was slower outlet openings of the air flow rate than inlet openings of the air flow rate.
A Study on the Performance Evaluation of a Hybrid Desiccant Cooling System
Hwang, Won-Baek ; Kim, Young-Chan ; Lee, Dae-Young ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 2, 2012, Pages 121~128
DOI : 10.6110/KJACR.2012.24.2.121
Improvement in the energy efficiency has been studied of the desiccant cooling system by applying a vapor compression type heat pump to modify the system into a hybrid system. The cycle simulation was performed and the results were compared between a reference desiccant cooling system composed of a desiccant rotor, a sensible rotor and a regenerative evaporative cooler, and a hybrid desiccant cooling system with the sensible rotor being replaced by a heat pump. Though the electric consumption increases as much as the compressor power consumption, the total cooling capacity increases and the thermal energy input decreases by the addition of the heat pump. Therefore, the total energy efficiency can be improved if the increase in the electric consumption can be compensated with the increase in the cooling capacity and the decrease in the thermal energy input. The results showed that the total energy efficiency is optimized at a certain heat pump capacity. When the heat from the CHP plant is used for the thermal energy input, the energy consumption of the hybrid system is reduced by 20~30% compared with the reference system when the heat pump shares 30~40% of the total cooling capacity.
Performance Assessment of Refrigerant Vapor-Pressure Equations with Two Adjustable Parameters
Park, Kyoung-Kuhn ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 2, 2012, Pages 129~135
DOI : 10.6110/KJACR.2012.24.2.129
Performance of various temperature-dependent vapor-pressure equations with two adjustable parameters is assessed. These are Antoine, Miller, Zia-Thodos, Mejbri-Bellagi and other 10 equations. The equations are fitted to correlate the data from NIST Chemistry WebBook for 43 pure substance refrigerants from the critical point to the triple point. It was found that the Mejbri-Bellagi equation yields the lowest average absolute deviation of 0.37% compared with that of 0.58% of the Miller equation which is known to give better fit to experimental data than the Antoine equation(1.42%) does.
Study on the Performance Improvement of Roof Fan Used for Local Exhaust System Installed in Apartment
Kwon, Yong-Il ; Jeong, Yeol-Wha ; Ahn, Jung-Hun ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 2, 2012, Pages 136~141
DOI : 10.6110/KJACR.2012.24.2.136
Performance improvement of local exhaust system used in toilet and cooking place are main concern in a field of ventilation. In Korea, There are many high riser residential apartments in recent years. These buildings were not viewed as being major contributors to exhaust pollutants producted in indoor. It was because many engineers thought that exhaust in high riser building depends on stack effect. This study investigates on the performance improvement of terminal device, roof fan, of vertical spiral duct used in high riser residential apartments. This paper focuses mainly on the effect of accessories, number or shape of blades, composed of roof fan with function of exhaust air volume of toilet and cooking place. Roof fan with 10 blades is observed at optimum exhaust performance in this study.
Evaluation of Corrosion Characteristics of Pipeline Material(SUS316) for the Geothermal Power Plant
Han, Ji-Won ; Park, Young-Su ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 2, 2012, Pages 142~146
DOI : 10.6110/KJACR.2012.24.2.142
In the geothermal power, the geothermal fluid such as water or steam is moved from the ground to turbine a pipeline. Because the geothermal fluid with high temperature contains Cl-and SO4-, It cause to diminish the system lifetime due to the increase in the corrosion of pipeline. In the present work, the characteristics of corrosion and its fatigue of the sus316 which is used in the pipeline are evaluated experimentally. From this study, the following results can be obtained; for the case of the corrosion environment, it is found that the corrosion rate is faster than that of the steam environment by 10 to 30 times, and the corrosion fatigue limit is underestimated compared to that of steam state.
Performance Variation with Length of Internal Heat Exchanger in CO
Cooling Cycle Using an Ejector
Kang, Byun ; Cho, Hong-Hyun ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 2, 2012, Pages 147~154
DOI : 10.6110/KJACR.2012.24.2.147
Recently, many researchers have studied the performance of the transcritical
refrigeration cycle in order to improve the system efficiency. In this study, the length of IHX in the
ejector cycle was varied so as to evaluate the performance improvement. As a result, compressor work and cooling capacity was increased by 3% and 5% as the length of internal heat exchanger was changed from 3 m to 15 m. The best COP was appeared at internal heat exchanger length of 12 m, and it was 3.01. Besides, the length of internal heat exchanger has a big effect to pressure lift ratio and entrainment ratio in the ejector
cycle and it may be changed with operating conditions and system specifications.
Performance Prediction of Geothermal Heat Pump(GHP) System with Energy Piles Using Simulation Approach
Sohn, Byong-Hu ; Choi, Jong-Min ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 2, 2012, Pages 155~163
DOI : 10.6110/KJACR.2012.24.2.155
The aim of this study is to evaluate the performance of the GHP system with 150 energy piles for a commercial building. In order to demonstrate the feasibility of a sustainable performance of the system, simulations were conducted over 1-year and 20-year periods, respectively. The 1-year simulation results showed that the maximum and minimum temperatures of brine returning from the energy piles were
, which were in a range of design target temperatures. In addition, after 20 years' operation, these returning temperatures decreased slowly to
, and finally reached to stable state. The results also showed that the energy piles injected heat of 65.6 MWh to the ground and extracted heat of 96.0 MWh from the ground, respectively. Also, it is expected this GHP system with energy piles can operate with average SPF of more than 4.15 for long term.
A Study on the Applicability of a Scroll Type Compressor to Small Capacity Refrigerators
Kim, You-Chan ; Kim, Woo-Young ; Kim, Hyun-Jin ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 2, 2012, Pages 164~173
DOI : 10.6110/KJACR.2012.24.2.164
To study the applicability of a scroll type compressor to small capacity refrigerators, a R600a scroll compressor with algebraic scroll wrap has been designed. Its size and performance have been compared to a reciprocating type of the same displacement volume. By employing scroll wrap based on algebraic curve, high compression ratio can be accomplished without increasing the wrap angle much so that compact scroll may be obtained. Compared to a reciprocating one, the designed scroll compressor has diameter and height reduced by about 50% and 80%, respectively. By numerical simulation, it has been estimated that the scroll compressor provides 38.6% more cooling capacity than reciprocating type with 8.9% more power consumption, resulting in 27.3% increase in COP for ASHRAE low back pressure condition. With increasing the operating pressure ratio from 9.5 to 15.3, the overall compressor efficiency of the scroll compressor decreases from 72.6% to 65.2%, while that of the reciprocating compressor increases from 55.7% to 59.8%.
An Evaluation on IR Sensor Based Demand Controlled Ventilation Strategies for Multi-zone in the Apartment House
Hong, Sung-Min ; Yoon, Dong-Won ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 2, 2012, Pages 174~182
DOI : 10.6110/KJACR.2012.24.2.174
In previous research, most occupant said that they have not operated ventilation system installed in the house, because of increasing of energy consumption and unconcern of ventilation. Therefore, it is necessary to applied the sensor based demand controlled ventilation for the IAQ(Indoor Air Quality) and improvement of energy efficiency in ventilation strategy. The propose of this study is to present a application method of IR(Infrared) sensor for multi-zone DCV(Demand Controlled Ventilation) in the apartment house. It is possible that IR sensor could be used for DCV, because that could detect the occupant and action. IR sensor based DCV strategies are established to evaluate characteristic of application in the apartment house and simulated by Contam program. As a result, they have some week points though, if they would be applied DCV with optimum strategy, it would be useful to improve IAQ, to reduce energy consumption.
A Study on the Heating Characteristics of Radiant Floor Panel Using Heat Pipes with the Double Wick
Kim, Yong-Ki ; Lee, Tae-Won ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 2, 2012, Pages 183~189
DOI : 10.6110/KJACR.2012.24.2.183
Most of the domestic residential buildings have used the traditional radiant heating system, circulating hot water through the cross-linked polyethylene(PE-X) pipe buried in the floor panel of the heating space. New type of the heating panel was recently developed using heat pipes with double wicks. Some experiments were carried out in this study to verify the thermal characteristics of this heating system at the unit heating space which surrounded by outer space whose temperature of air be maintained scheduled value with time. Through the various experiments with several parameters, such as flow rate, inlet and outlet temperatures of hot water and the heating duration and so on, we found that the floor heating system with heat pipes was able to reduce the pumping power for hot water circulation by 4~31% compared with the conventional panel heating system using PE-X pipe. These results could be used for optimal design and efficient operation of the heating system as well as improvement of thermal comfort.
A Field Measurement Study on Heat Storage/Emission Characteristics of Tower Type Apartment Structures in Winter Season
Chang, Hyun-Jae ; Cho, Keun-Je ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 2, 2012, Pages 190~195
DOI : 10.6110/KJACR.2012.24.2.190
In this study, as a complementary study of the former study on indoor thermal environment in a tower type apartment house at tropical nights, a field measurement was conducted in winter season. Mainly, characteristics of heat storage and heat emission in apartment structures, in this study, were investigated. As results, indoor air temperature was changed in the range of
, and followed not the change of outdoor air temperature but the changed pattern of floor surface temperature. Wall surface temperature was unresponsive to the change of floor surface temperature compared with the change of indoor air temperature because wall structure was composed of concrete which has large heat capacity, and was changed in the range of
. Heat was stored continuously into the structures of wall and ceiling through the measurement term. and this means that a large heat capacity of the apartment structure acts as a disadvantage in winter season, too. As a total review of the study with the former study, a large heat capacity of the apartment structure acts against indoor thermal comfort in winter season as well as in summer season.
Heating and Cooling Performance of a Ground Coupled Heat Pump System with Energy-Slab
Choi, Jong-Min ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 24, issue 2, 2012, Pages 196~203
DOI : 10.6110/KJACR.2012.24.2.196
Energy foundations and other thermo-active ground structure, energy wells, energy-slab, and pavement heating and cooling represent an innovative technology that contributes to environmental protection and provides substantial long-term cost savings and minimized maintenance. This paper focuses on earth-contact concrete elements that are already required for structural reasons, but which simultaneously work as heat exchangers. Pipes, energy slabs, filled with a heat carrier fluid are installed under conventional structural elements, forming the primary circuit of a geothermal energy system. The natural ground temperature is used as a heat source in winter and a heat sink in summer. The geothermal heat pump system with energy-slab represented very high heating and cooling performance due to the stability of EWT from energy slab. However, the performance of it seemed to be affected by the atmospheric air temperature.