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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 26, Issue 12 - Dec 2014
Volume 26, Issue 11 - Nov 2014
Volume 26, Issue 10 - Oct 2014
Volume 26, Issue 9 - Sep 2014
Volume 26, Issue 8 - Aug 2014
Volume 26, Issue 7 - Jul 2014
Volume 26, Issue 6 - Jun 2014
Volume 26, Issue 5 - May 2014
Volume 26, Issue 4 - Apr 2014
Volume 26, Issue 3 - Mar 2014
Volume 26, Issue 2 - Feb 2014
Volume 26, Issue 1 - Jan 2014
Selecting the target year
A Study on Burial Guideline of Horizontal Geothermal Heat Exchanger based on Exit Temperature
Cho, Sung-Woo ; Ihm, Pyeong-Chan ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 26, issue 12, 2014, Pages 553~558
DOI : 10.6110/KJACR.2014.26.12.553
Geothermal energy can be used with a geothermal heat pump or an earth-to-air heat exchange system (EAHES), which is referred to as a "cooling tube" in Korea. In this study, we suggest EAHES burial guidelines in terms of the parameters of buried pipe length and air velocity regarding the exit air temperature of EAHES. The exit air temperature for EAHES in three regions (Changwon, Busan and Seoul) was calculated with variation in buried pipe length and air velocity at
. In conclusion, variation in the buried pipe length is more effective than that of air velocity to achieve the required exit air temperature.
An Experimental Comparison Study of PVT Water and PVT Air Modules for Heat and Power Co-Generation
Lee, Kwang-Seob ; Putrayudha S., Andrew ; Kang, Eun-Chul ; Lee, Euy-Joon ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 26, issue 12, 2014, Pages 559~564
DOI : 10.6110/KJACR.2014.26.12.559
The development of photovoltaic-thermal (PVT) technology has been introduced in recent years specifically to increase PV efficiency. One of the characteristics of PV systems is that the electricity generation increases as the solar radiation increases whereas the efficiency decreases because of high surface temperatures. Using a photovoltaic-thermal system, the surface temperature can be decreased by capturing the excess heat and the efficiency can be increased due to these characteristics. In this paper, three cases are introduced : 1) PV_r as the reference case, 2) PVT_a, which uses air as a heat source, and 3) PVT_w, which uses water as a heat source. Experiments were performed, analyzed, and compared to examine the effect of the PVT type on the efficiency of the system. The results showed that ETC(
) efficiency of the PVT cases was increased versus the reference case due to decreasing surface temperature. Total efficiencies, which are electrical efficiency and thermal efficiency, for each PVT are tested and found to be 12.22% for PV_r, 29.50% for PVT_a, and 68.74% for PVT_w.
A Study on Change in Window Transmitted Solar and the Resultant Wall Surface Convective Heat Gain with Regard to Slat Reflectance of External and Internal Blinds
Hyun, In-Tak ; Lee, Jae-Ho ; Yoon, Yeo-Beom ; Lee, Kwang Ho ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 26, issue 12, 2014, Pages 565~571
DOI : 10.6110/KJACR.2014.26.12.565
Nowadays, to make buildings light weight and aesthetically pleasing, curtain wall structure are commonly used. Therefore, window to wall ratio is increasing, which has caused cooling and heating load in crease in buildings as well. This phenomenon has negative impact from energy point of view. This paper analyzes window and wall convective heat gain when the slat reflectance of external and internal blinds are changed for the better understanding of the fundamentals behind the phenomena. It was observed that, if slat reflectance is increased, window transmitted solar increases and convection heat rate is clearly affected. Among six surfaces including four walls, ceiling and floor, maximum convection heat rate occurs on the south wall in summer. On the other hand, ceiling and floor showed the lowest convection heat gain, since they are shared by adjacent floors.
Measurement and Simulation of Heating Energy for Apartments with District Heating
Lee, Eun Ju ; Lee, Doo Young ; Hong, Hiki ; Kim, Young Kyun ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 26, issue 12, 2014, Pages 572~578
DOI : 10.6110/KJACR.2014.26.12.572
Heating energy was measured in an apartment housing unit with a district heating system, varying the kind of hot water distributors. Ondol coils passing through a living room raised the temperature of the room where the heating was turned off. Including this characteristic of Ondol heating into the modeling, we performed simulations and showed a verification by comparison with the results of measurements. As a result, a main flow control method, which changes hot water flow rate supplied to a housing unit according to the thermal load, can reduce the supplied flow rate and lower the return temperature, compared with a constant flow method. That can result in decreased heat loss in utility-pipe conduits even though the heating energy supplied is almost the same. An outdoor reset control that raises the temperature of the supplied hot water if the outdoor temperature falls has the effect of a quicker response in heating than the reduced flow rate and return temperature.
State Equation Modeling and the Optimum Control of a Variable-Speed Refrigeration System
Lee, Dan-Bi ; Jeong, Seok-Kwon ; Jung, Young-Mi ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 26, issue 12, 2014, Pages 579~587
DOI : 10.6110/KJACR.2014.26.12.579
This paper deals with precise analytical state equation modeling of a variable speed refrigeration system (VSRS) for optimum control in state space. The VSRS is described as multi-input and multi-output (MIMO) system, which has two controlled variables and two control inputs. First, the Navier-Stokes equation and mass flow rate were applied to each component of the basic refrigeration cycle to build a dynamic model. The dynamic model, represented by a differential equation, was transformed into the state equation formula. Next, a full-order state observer was built to estimate all of the state variables to compose an optimum control system. Then, an optimum controller was designed to minimize an evaluation function that has input energy and control error. Finally, simulations and experiments were conducted to verify the validity of the proposed modeling and designed optimum controller to regulate target temperature and superheat in a 1RT oil cooler system. The results show that the proposed method, state equation modeling and optimum control, is efficient to ensure optimal control performance of the VSRS.
Applications of a Coupled Multizone and CFD Simulation to Validate Airflow and Influenza A Contaminant Dispersion in Biosafety Laboratory
Hwang, Ji Hyun ; Hong, Jin Kwan ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 26, issue 12, 2014, Pages 588~593
DOI : 10.6110/KJACR.2014.26.12.588
To maintain a negative pressure, the supply, exhaust airvolume are adjusted by setting volume damper and the infiltration through leakage area of the door between rooms in biosafety laboratory. Multizone simulation is useful way to predict room pressure, supply and exhaust air volume. But in a particular room, local change such as airflow and contaminants concentration distribution can not be evaluated unfortunately. Through this study, a coupled multizone and CFD simulation was performed, indoor air flow and local contaminants concentration distribution in a particular room of BSL lab are predicted. The results show that all zones of BSL lab are well ventilated by unidirectional flow without local stagnation. In addition, in case that unexpected biohazard is occured in BSL lab, multizone simulation results about the spread of pollutants along movement of the occupant also show that contaminants concentration is removing totally without the spread of the outside. In conclusion, a coupled multizone and CFD simulation can be applied to interpret differential pressure in room and local change of physical quantity in a particular room such as airflow and Influenza A contaminants concentration distribution. This simulation method is useful to enhance the reliability and accuracy of biosafety laboratory design.
Exhaust Characteristics of Kitchen Hood System with Inclined Air Curtain
Sung, Sun-Kyung ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 26, issue 12, 2014, Pages 594~599
DOI : 10.6110/KJACR.2014.26.12.594
There have been many cases that the air curtain installed in the apartment can not well remove the gases such as carbon dioxide and particles such as smokes, oils and vapors generated during the cooking to disperse the pollutants into the room. This study uses the numerical analysis to show how the pollutant-removing performance of the range hood is changed when the air curtain is installed on the range hood of kitchen. As a result of the study, it turned out that, when the air amount supplied by air curtain through the slot was about 60% of exhaust amount, the capturing efficiency of range hood for pollutants increased by 70~80% more than the case without the air curtain. Even when the exhaust amount was small, the capturing efficiency was improved a lot with the use of air curtain. In case that the air flow velocity of slot was greater than 2 m/s, the capturing efficiency turned out to decrease.
Numerical Analysis on Longitudinal Heat Conduction in Printed Circuit Heat Exchanger
Oh, Dong-Wook ; Kim, Young ; Choi, Jun Seok ; Yoon, Seok Ho ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 26, issue 12, 2014, Pages 600~604
DOI : 10.6110/KJACR.2014.26.12.600
Longitudinal heat conduction is known to be an important factor in the design of a printed circuit heat exchanger(PCHE) for cryogenic applications. Parasitic heat conduction through the heat exchanger frame needs to be considered because it is known to decrease the effectiveness of the heat exchanger. In this paper, a conjugate heat transfer problem in a simple counter-flow PCHE is analyzed by a computational fluid dynamics simulation. The effect of longitudinal conduction in a straight channel is compared with the theoretical effectiveness-NTU relationship that assumes a "thin" heat exchanger frame. The calculation results suggest that the theoretical model is valid in the present calculation conditions where NTU is < 13.
Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013
Lee, Dae-Young ; Kim, Sa Ryang ; Kim, Hyun-Jung ; Kim, Dong-Seon ; Park, Jun-Seok ; Ihm, Pyeong Chan ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 26, issue 12, 2014, Pages 605~619
DOI : 10.6110/KJACR.2014.26.12.605
This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and
-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including
water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.