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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 22, Issue 12 - Dec 2010
Volume 22, Issue 11 - Nov 2010
Volume 22, Issue 10 - Oct 2010
Volume 22, Issue 9 - Sep 2010
Volume 22, Issue 8 - Aug 2010
Volume 22, Issue 7 - Jul 2010
Volume 22, Issue 6 - Jun 2010
Volume 22, Issue 5 - May 2010
Volume 22, Issue 4 - Apr 2010
Volume 22, Issue 3 - Mar 2010
Volume 22, Issue 2 - Feb 2010
Volume 22, Issue 1 - Jan 2010
Selecting the target year
Heating Performance of a Ground Source Multi-Heat Pump for a Greenhouse
Kang, Shin-Hyung ; Choi, Jong-Min ; Moon, Je-Myung ; Kwon, Hyung-Jin ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 22, issue 6, 2010, Pages 337~344
Good plant-growth conditions can be achieved by means of using greenhouses. One of the main issues in greenhouse cultivation is energy savings through the development of high efficient heating and cooling system. GSHPs are one of the recommended systems to cope with this pending need. The aim of this study is to investigate the heating performance of ground source multi-heat pump system installed in a greenhouse under part load conditions. Daily average heating COP of the heat pump unit was very high by at least 7.4, because of relatively large condenser, evaporator, and mass flow rate through ground loop heat exchanger. However, the system COP, overall heating coefficient of the performance of the system with heat pump unit and GLHX, decreased drastically due to relatively large power consumption of circulating pump under part load condition. It is suggested that the technology to enhance the performance of the ground source multi-heat pump system for a greenhouse under part load conditions should be developed.
External Condensation Heat Transfer Coefficients of R1234yf
Park, Ki-Jung ; Lee, Cheol-Hee ; Kang, Dong-Gyu ; Jung, Dong-Soo ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 22, issue 6, 2010, Pages 345~352
In this study, external condensation heat transfer coefficients(HTCs) of R134a and R1234yf are measured on a plain, low fin, and Turbo-C tubes at the saturated vapor temperature of
with the wall subcooling of
. R1234yf is a new alternative refrigerant of low greenhouse warming potential for replacing R134a which is one of the greenhouse gases controlled by Kyoto protocol and is used extensively in mobile air-conditioners. Test results show that the external condensation HTCs of R1234yf are very similar to those of R134a for all three surfaces tested. For the application of condensation heat transfer correlations to the design of condensers charged with R1234yf, thorough property measurements are needed for R1234yf in the near future.
A Study of air Sterilization System in Personalized Office Using Simulation
Choi, Sang-Gon ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 22, issue 6, 2010, Pages 353~360
Recently H1N1(swine flu) and SARS has been infected widely in the world; we have to care about germs and virus in indoor air environment. The air sterilization system investigated in this study allows occupants to turn on/off and to control the incoming air speed and direction. To predict the performance of air sterilization system without real experiment, a simulation is considered to compare and analyze the performance of the air sterilization systems in a typical office space. Multiple system parameters including volume flow rate and velocity of supply air were varied and investigated during the simulation. The investigation result shows that difference (between simulation and experiment) was about 3.5% in case of minimum air flow rate and about 0.2% in case of maximum air flow rate. The results indicate that multi-zone simulation technique can be used to predict the performance of a sterilization system in personalized office.
A Measurement Study of a Dynamic Insulator Thermal Performance
Ko, Seon-Mi ; Kang, Eun-Chul ; Lee, Euy-Joon ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 22, issue 6, 2010, Pages 361~368
Due to the insulation and the air-tightness requirement in modern buildings have resulted NBS(New Building Syndrome) and SBS(Sick Building Syndrome) of IAQ problems. Therefore, energy efficient way of solving such IAQ issues are of major concern in these days and building industries. This paper introduces a method to improve thermal performance with a DI(Dynamic Insulation) concept. The characteristic of the dynamic insulation is that the lower U-value as the higher air velocity through the DI in a micro level. A thermal performance monitoring study has been conducted to show the energy impact of porous DI over the static insulation material. The results show that up to 45% could be improved in the case with DI compared to the conventional insulation.
An Experimental Study on the Performance Characteristics of a Refrigerant-Subcooling Refrigeration System with an Ice Storage Tank
Lee, Eun-Ji ; Lee, Dong-Won ; Kim, Yong-Chan ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 22, issue 6, 2010, Pages 369~374
A refrigerant-subcooling refrigeration system consisted of a typical single vapor-compression refrigeration cycle, a subcooler, and an ice storage tank. The degree of subcooling at the exit of the condenser can be increased by the heat exchange between the subcooler and the ice storage tank. The cold heat in the ice storage tank was stored by using the refrigeration cycle during night time and then used to absorb the heat from the subcooler during daytime. The performance of the refrigerant-subcooling refrigeration system was measured by varying the degree of subcooling. In addition, the performance characteristics of the present system were compared with those of a conventional refrigeration system. The mass flow rate of the present system was higher than that of the conventional system due to the increase in the degree of subcooling. Generally, the refrigerant-subcooling system showed superior performance to the conventional refrigeration system.
Method and Analysis of Dynamic Simulation for Ondol Heating
Hong, Hi-Ki ; Kim, Si-Hwan ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 22, issue 6, 2010, Pages 375~382
Ondol heating, a kind of radiant floor heating, is a main method used in housing units in Korea. Building energy simulation including ondol and relevant facilities has not been performed due to its complexity. For evaluating energy consumption and indoor temperature variation, a new method should be proposed. At the present work, a dynamic simulation on ondol heating was tried by combining TRNSYS and EES. Characteristic functions for a pump, hot water coils and a gas boiler were simultaneously solved by EES, and calculated flow rates and supply temperature of hot water were provided as inputs of the active layer of TYPE 56 in TRNSYS. The results by the simulation on a typical housing unit in Korea shows a good trend in a viewpoint of actual behavior of ondol heating.
Performance of HFC152a, HFC134a and HC290 Mixtures as Alternative Refrigerants for HFC134a
Kang, Nam-Koo ; Bae, Guen-Hwan ; Park, Ki-Jung ; Jung, Dong-Soo ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 22, issue 6, 2010, Pages 383~391
In this study, HFC152a, HFC134a/HFC152a and HC290/HFC134a/HFC152a mixtures are studied for the supplementary and alternative refrigerants for HFC134a used in automobile air-conditioners. Due to the high global warming potential of HFC134a, it has to be phased out in the long run. Thermodynamic performance of these refrigerants are measured in a bench tester of 3.5 kW capacity with an open type compressor under both summer and winter conditions. Test results show that the coefficient of performance (COP) and capacity of pure HFC152a and HFC134a/HFC152a mixture are 9.1~12% and 7% higher than those of HFC134a. As for the HC290/HFC134a/HFC152a, the COP is up to 9.5% higher than that of HFC134a with 1~2% of HC290 while that is up to 6.1% lower than that of HFC134a with 5% HC290. The capacity of the ternary mixture, however, is 8.6% higher than that of HFC134a at all compositions tested. The compressor discharge temperatures of all refrigerants tested are
higher than that of HFC134a. For all refrigerants, the amount of charge is reduced up to 32% due to the decrease in liquid density. Overall, these refrigerants provide good performance with reasonable energy savings with less environmental problem and thus can be used as long term alternatives for automobile air-conditioners.
An Analysis of Heating and Cooling Loads by Insulated Shades and Control Method in an Energy Saving Apartment
Park, Sun-Hyo ; Kwon, Kyung-Woo ; Sohn, Jang-Yeul ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 22, issue 6, 2010, Pages 392~397
Energy loss from windows accounts for large scores of heating and cooling loads also in energy saving apartments that is reduced over 30% of total energy consumption. Movable reflective insulations, insulation shutters, blinds, insulated shades are used to reduce energy loads from windows. In this study, energy saving performance of insulated shades was simulated by control methods. According to installation of insulated shades, heating loads were decreased about 10.5~11.3%, and cooling loads are decreased about 29.1~38.3% on an energy saving apartment. The heating peak load was reduced about 9.5% by insulated shades and the cooling peak load was reduced about 25.7~31.5%. In the case of insulated shades with automatic control system, simple time schedule control system would be more efficient than outdoor detection control system that should use several sensors.
A Comparison Study on Drag Reduction Characteristics of Polymer and Surfactant as Drag Reduction Additive
Cho, Sung-Hwan ; Ryu, Jae-Sung ; Kim, Seong-Su ; Jung, Sang-Hoon ; Yoon, Seok-Mann ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 22, issue 6, 2010, Pages 398~403
The drag reduction(DR) of non-ionic surfactant and polymer according to the variation of fluid velocity, temperature and surfactant concentration was investigated experimentally. For this experiment, the kind of surfactant was non ionic amine-oxide and the kinds of polymer were polyacrylamide and xantan gum. An experimental apparatus equipped with one water storage tanks was built and two flow meters, two pressure gauges for data logging system was installed. Results showed that the kinds of polymer, polyacrylamide and xantan gum, had DR of below 20% for below 500 ppm in fluid temperature of
. But the kind of surfactant, amine oxide, had DR of above 40% for 500~1000 ppm in fluid temperature of
. As a result, amin oxide showed better materials to use to the district heating system.
Thermal Performance Evaluation of Apartment Housing Using Infra-red Camera
Choi, Gyeong-Seok ; Sohn, Jang-Yeul ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 22, issue 6, 2010, Pages 404~412
The purpose of this study is to accomplished an in-site evaluation method for existing building insulation status using Infra-red camera and to consider improvement performance to prevent condensation and draw the optimum insulation design method for building using simulation tool. The research contents of this study are to evaluate validity and suitability of building insulation defect survey using Infra-red camera for apartment housing with temperature and heat flow pattern analyze method. Based on this research, the three corners, weak part in condensation, were selected in apartment building and conducted simulation by three-dimensional steady state. From the results, it is required to strengthen insulation design, and it is founded that existing insulation system typically applied to most Korean apartment housings have serious insulation defect that insulation is disconnected by structural components at the joints of wall-slab and wall-wall in envelope. Thus, it is considerate to need a concrete technology improvement.
The Effect of Gasket Shape and Material Properties on Heat Losses in a Refrigerator
Ha, Ji-Soo ; Jung, Kwang-Soo ; Kim, Tae-Kwon ; Shim, Jae-Sung ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 22, issue 6, 2010, Pages 413~418
The amount of heat loss of a refrigerator through the gasket is nearly 30% of total refrigerator heat loss. In this paper, quantitative evaluation for the effects of various effort to reduce heat losses through the gasket. The first trial is to extend the inner gasket to prevent the heat loss flowing from the inner of refrigerator. The effects of thermal conductivity changes of gasket and magnet are investigated by the numerical heat transfer analysis. The position change of hot line is also examined in the present research. From the present result of the numerical simulation of heat transfer, we are able to reduce the heat loss about 20~40% by using inner gasket extension. The reducing of thermal conductivity of gasket is considerable in the heat loss reduction. On the other hand, the thermal conductivity change of magnet has no apparent effect in heat loss reduction. The position change of hot line has considerable positive effect in the reduction of heat loss near gasket region.