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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 28, Issue 8 - Aug 2016
Volume 28, Issue 7 - Jul 2016
Volume 28, Issue 6 - Jun 2016
Volume 28, Issue 5 - May 2016
Volume 28, Issue 4 - Apr 2016
Volume 28, Issue 3 - Mar 2016
Volume 28, Issue 2 - Feb 2016
Volume 28, Issue 1 - Jan 2016
Selecting the target year
A Study of Wind Pressure Distribution for a Rectangular Building Using CFD
Shin, Dongshin ; Park, Jaehyun ; Kang, Bomi ; Kim, Eunmi ; Lim, Hyeongjun ; Lee, Jinyoung ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 28, issue 1, 2016, Pages 1~6
DOI : 10.6110/KJACR.2016.28.1.001
This paper studies the wind pressure distribution over the Commonwealth Advisory Aeronautical Council building model (CAARC model) using CFD. We also considered the interaction between the CAARC model and other buildings. The Reynolds number based on the building height was 380,000. The number of sells for the simulation was about 500,000. The wind pressure was lowest when the wind direction was blowing at an angle 45 degrees of the CAARC model. When the gap between the two buildings in front of the CAARC was over 1/2 the horizontal length of the CAARC model, the wind pressure was higher than the pressure without the two buildings. When the distance between the two front buildings and the CAARC was less than 1.5 times the vertical length of the CAARC model, the wind pressure increased. Accordingly, the relative distance between two buildings or the distance from the CAARC model should be considered when extra wind exists due to other buildings.
Feasibility Study of Cold Storage System to Maintaining Cooling Performance for ISG Vehicle
Lee, Daewoong ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 28, issue 1, 2016, Pages 7~14
DOI : 10.6110/KJACR.2016.28.1.007
This study explores the feasibility of a cold storage system to provide thermal comfort for idle stop and go (ISG) vehicles. ISG function is the most valuable and environmental friendly technology in the current automobile industry. However, when an ISG vehicle stops, meaning when the engine standstill, the air-conditioning system does not work, because the compressor also stops. Therefore, passenger thermal comfort is not maintained, as cold air is not provided in the cabin. Consequently, many automakers have studied electric air-conditioning systems based on electrically-driven compressors or cold storage systems using phase-change materials. The experiments herein were conducted for the feasibility testing of different types of cold storage heat-exchangers, cold storage mediums, and thermo-expansion valves with current air-conditioners. The auxiliary cold storage system, filled with phase-change materials, was located behind the evaporator and almost stacked on top of it. In the experimental results, the air discharge temperature rate of increase was better than the conventional air-conditioning system when the compressor stopped and thermal comfort was maintained with
decreases within 60 seconds. The #1 cold storage heat-exchanger (CSH), #2 thermo-expansion valve (TXV) and #2 phase change material (PCM) were chosen because of the best temperature rise delay. It was concluded that a cold storage system is an effective solution for ISG vehicles to maintain thermal comfort during short engine stops.
An Experimental Study on the Heat Transfer Characteristics of a Finned-Tube Heat Exchanger in a PCM Thermal Energy Storage System
Jung, Dong Il ; Chang, Min ; Kim, Yongchan ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 28, issue 1, 2016, Pages 15~20
DOI : 10.6110/KJACR.2016.28.1.015
Phase change materials (PCM) are able to store a large amount of latent heat, and can be applied to thermal energy storage systems. In a PCM, it takes a long time to store heat in the storage system because of the low thermal conductivity. In this study, a finned-tube-in-tank heat exchanger was applied to a PCM thermal energy storage system to increase heat transfer efficiency. The effects of geometric and operating parameters were investigated, and the results were compared with those of the tube-in-tank heat exchanger. The finned-tube-in-tank heat exchanger showed higher heat transfer effectiveness than the tube-in-tank heat exchanger. The heat exchange effectiveness of the storage tank was determined as a function of the average NTU.
A Numerical Study on Plate-Type Heat Exchanger Using One-Dimensional Flow Network Model and Porous-Media Model
Park, Jaehyun ; Kim, Minsung ; Min, June Kee ; Ha, Man Yeong ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 28, issue 1, 2016, Pages 21~28
DOI : 10.6110/KJACR.2016.28.1.021
A typical heat exchanger, found in many industrial sites, is made up of a large number of unitary cells, which causes difficulties when carrying out full-scale three-dimensional numerical simulations of the heat exchanger to analyze the aero-thermal performance. In the present study, a three-dimensional numerical study using a porous media model was carried out to evaluate the performance of the heat exchanger modelled in two different ways : full-scale and simplified. The pressure drop in the air side and gas side along with the overall heat transfer rate were calculated using a porous media model and the results were then compared to results obtained with a one-dimensional flow network model. The comparison between the results for two different geometries obtained using a porous media model and a one-dimensional flow network model shows good agreement between the simplified geometry and the one-dimensional flow network model. The full-scale geometry shows reasonable differences caused by the geometry such as sudden expansion and contraction.
A Study of the Friction Factor Unit Considering the Cost of Energy
Shin, Dong-Shin ; Kim, A-In ; Lee, Byung-Hyun ; Jung, Hyueong-Mok ; Lee, Sung-Goo ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 28, issue 1, 2016, Pages 29~34
DOI : 10.6110/KJACR.2016.28.1.029
The friction factor unit was studied to find a more economic alternative compared to the conventional 30 mmAq/m. The pipe and pump for cooling water piping used in a failing were selected, and the friction factor unit was changed to calculate the pipe diameter and the brake shaft power. Based on current electric charges, After the brake shaft power was converted into operational costs based on current electric charges, then an economic analysis was conducted considering that incorporated the initial installation costs and operational costs for the pump. We found that the friction factor unit when using 20 mmAq/m is more economical than that with 30 mmAq/m, if the piping is used for more than 4 years. The small friction factor unit is desirable when the piping is used for quite a long period of time, and the selection of a more economic friction factor unit should considering the period of usage will be important.
Study on Numerical Analysis of Shape and Guidevane Design for Improving a 500 PS SCR Reactor's Flow Uniformity
Seong, Hongseok ; Lee, Chungho ; Suh, Jeongse ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 28, issue 1, 2016, Pages 35~41
DOI : 10.6110/KJACR.2016.28.1.035
With the assumption that the performance of a catalyst is guaranteed and that the performance of an SCR reactor is influenced by the uniformity of fluid flow into the catalyst, this study carried out a numerical analysis of flow uniformity, which is an important design factor in SCR reactors. CFD was used to grasp flow uniformity and flow characteristics inside the SCR reactor. As for the flow uniformity, analysis was carried out on the velocity and direction of the fluid flowing into the front of the first SCR reactor. Numerical analysis was carried out in terms of the area ratios of the mixing evaporator to the catalyst for 500 PS SCR, 1 : 1.9, 1 : 3.1, 1 : 4.5, and 1 : 7.0. The results showed that the larger the area ratio, the smaller the flow uniformity. On the basis of these results, the flow uniformity of the modified SCR reactor is 77%. A guidevane was installed to improve flow uniformity, and attempts were made to grasp the flow uniformity based on the shape of the guide vane. The shape of the guide vane was cylindrical, and numerical analysis was carried out for cases with two cylinders and three cylinders. As a result of the numerical analysis, it was found that while there was no great difference between 82.7% with two cylinders and 81.7% with three cylinders, the effects of the installation of the guide vane on the improvement of flow uniformity were indisputable.
Analysis for Thermal Effect by an Unheated Housing Unit in Apartment
Lee, Eun-Ju ; Koo, Junemo ; Hong, Hiki ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 28, issue 1, 2016, Pages 42~47
DOI : 10.6110/KJACR.2016.28.1.042
Adjacent housing units suffer inevitable thermal losses if an unheated unit exists in an apartment building. Thermal loss of the units adjoining the unheated apartment can be neglected because the contact area is small and insulators are located in the walls. When insulators are not included in the slab between the upper and lower units, 70% of the heat supplied by an Ondol system may be used in the original unit, but 30% is transferred to the unit on the lower floor. Another 30% can be obtained from the ceiling if the upper floor housing unit is heated. This strong thermal connection is a characteristic of Ondol heating in apartment buildings. When there is an unheated unit, the lower floor unit uses 42.3% more heating energy if there is no insulation and 19.5% if a 35 mm insulator is used as in the current guidelines. Therefore, much thicker insulation should be applied to weaken the thermal connection.