• 제목/요약/키워드: Air Circulation

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A Study on the Ralstonia Solanacearum Inactivation using Improved Plasma Process (개선된 플라즈마 공정을 이용한 Ralstonia Solanacearum 불활성화에 관한 연구)

  • Kim, Dong-Seog;Park, Young-Seek
    • Journal of Environmental Science International
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    • v.23 no.3
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    • pp.369-378
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    • 2014
  • Effect of improvement of the dielectric barrier discharge (DBD) plasma system on the inactivation performance of bacteria were investigated. The improvement of plasma reactor was performed by combination with the basic plasma reactor and UV process or combination with the basic plasma reactor and circulation system which was equipped with gas-liquid mixer. Experimental results showed that tailing effect was appeared after the exponential decrease in basic plasma reactor. There was no enhancement effect on the Ralstonia Solanacearum inactivation with combination of basic plasma process and UV process. The application of gas-liquid mixing device on the basic plasma reactor reduced inactivation time and led to complete sterilization. The effect existence of gas-liquid mixing device, voltage, air flow rate (1 ~ 5 L/min), water circulation rate (2.8 ~ 9.4 L/min) in gas-liquid mixing plasma, plasma voltage and UV power of gas-liquid mixing plasma+UV process were evaluated. The optimum air flow rate, water circulation rate, voltage of gas-liquid mixing system were 3 L/min, 3.5 L/min and 60 V, respectively. There was no enhancement effect on the Ralstonia Solanacearum inactivation with combination of gas-liquid mixing plasma and UV process.

A Case Study on Sea Breeze Circulation and Ozone Concentration due to the Effect of Cold Water in the Southeastern Coastal Area of Korea (한국 남동연안의 냉수대 영향에 의한 해풍순환과 오존농도의 사례연구)

  • Ji, Hyo Eun;Lee, Soon-Hwan;Park, Changhyoun;Lee, Hwa Woon
    • Journal of Environmental Science International
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    • v.23 no.2
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    • pp.261-274
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    • 2014
  • This work investigates the relationship between the sea breeze circulation and ozone concentrations during cold water events in the southeastern coastal area of the Korean Peninsula, where coastal upwelling frequently occur. This analysis was performed based on the classification of two categories, such as cold water and non-cold water events, over the period of 2000-2009. The low air temperature ($0.5^{\circ}C$), low SST ($5^{\circ}C$) and the wind direction(southerly) are the features of the cold water events in the Southeastern coastal area. Moreover, ozone concentrations in the cases of the sea breeze circulation and cold water events were significantly lower (below 30 ppb) than those (70~100 ppb) in the non-clod water events, because of the low air temperature ($10{\sim}20^{\circ}C$) and high wind speed (3~5 m/s) around the southeastern coastal area.

Pressure Drop Characteristics on HTS Power Cables with LN2 Flow (초전도 케이블 냉각유로에서의 압력강하 특성)

  • Koh Deuk-Yong;Yeom Han-Kil;Lee Kwan-Soo
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.1
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    • pp.81-86
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    • 2006
  • High temperature superconducting (HTS) power cable requires forced sub-cooled LN2 flow cooling. Liquid nitrogen is circulated by a pump and cooled back by cooling system. Typical operating temperature range is expected to be between 65 K and 77 K. The HTS power cable needs sufficient cooling to overcome its low temperature heat load. For successful cooling, the hydraulic characteristics of the HTS power cable must be well investigated to design the cables. Especially, the pressure drop in the cable is an important design parameter, because the pressure drop decides the length of the cable, size of the coolant circulation pump and circulation pressure, etc. This paper describes measurement and investigation of the pressure drop of the cooling system. In order to reduce the total pressure drop of the cooling system, the flow rate of liquid nitrogen must be controlled by rotational speed of the circulation pump.

A Study on the Pilotis as a Space of Flow in Le Corbusier's Works (르 꼬르뷔지에 건축에 나타나는 흐름의 공간으로서의 필로티에 관한 연구)

  • Cho, Joo-Hyun;Shin, Buhm-Shik
    • Korean Institute of Interior Design Journal
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    • v.21 no.6
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    • pp.194-203
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    • 2012
  • The purpose of this study is to look into a Pilotis as a space of flow in Le Corbusier's works. The first of his principals, "pilotis" shown in "5 principals in new architecture" represents the articulated relationship between architecture and site. The study is based on the flow concept of Pilotis regarding especially its functional, environmental, and visual perspective. Le Corbusier describes his architecture as a circulation representing the modern society. The Pilotis space is often reserved for this circulation while this space is also suggested as a place for the leisure or the garden uninterrupted. So it seems to be meaningful to find out the real usage of the Pilotis space in Le Corbusier's work in order to clarify the relationship between the articulated space and its use proposed. The second question is concerning to the Pilotis space as a space of flow of the light and the air. This issue is not only related to the plastic aspects of the buildings, but also caused from the social, or environmental problematic of those days. Finally, the continuity of the regard is one of the most important characteristics derived from the raised volume by Pilotis.

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Prediction of the Heat Exchange Rate for a Horizontal Ground Heat Pump System Using a Ground Heat Transfer Simulation (지중열 이동 시뮬레이션을 이용한 수평형 지열시스템의 채열성능 예측)

  • Nam, Yujin;Chae, Ho-Byung
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.25 no.6
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    • pp.297-302
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    • 2013
  • The ground source heat pump (GSHP) system has attracted attention, because of its stability of heat production, and the high efficiency of the system. However, there are few studies on the prediction method of the heat exchange rate for a horizontal GSHP system. In this research, in order to predict the performance of a horizontal GSHP system, coupled simulation with a ground heat transfer model and a heat exchanger circulation model was developed, and calculation of heat exchange rate was conducted by the developed tool. In order to optimally design the horizontal GSHP system, the flow rate of circulation water, and the depth and buried spaces of heat exchangers were considered by the case study. As a result, the temperature of circulation water and the heat exchange rate of the system were calculated in each case.

Effects of Water Amount in Refrigerant on Cooling Performance of Vehicle Air Conditioner (냉매 내 수분의 혼입량이 차량 에어컨의 냉각성능에 미치는 영향)

  • Moon, Seong-Won;Min, Young-Bong;Chung, Tae-Sang
    • Journal of Biosystems Engineering
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    • v.36 no.5
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    • pp.319-325
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    • 2011
  • This study was conducted to figure out the diagnosis basis of cooling performance depending on water amount in the refrigerant of air conditioner, which can be estimated by the temperatures and pressures along the refrigerant circulation line. A car air conditioner of SONATA III (Hyundai motor Co., Korea) was tested at maximum cooling condition at the engine speed of 1500 rpm in the room controlled at 33~$35^{\circ}C$ air temperature and 55~57% relative humidity conditionally. Measured variables were temperature differences between inlet and outlet pipe surfaces of the compressor, condenser, receive drier and evaporator; and high pressure and low pressure in the refrigerant circulation line; and temperature difference between inlet and outlet air of the cooling vent of evaporator. In this study, changes of the water amount in the refrigerant were correlated to the temperatures and pressure changes and also water amount caused poor cooling performance. As water amount increased in the refrigerant in the air conditioner, the performance of the cooling or the heat transfer became worse. Temporal variations of the surface temperature of the evaporator outlet pipe and the low-side pressure showed various patterns that could estimate the water amount. When the water amount caused bad cooling performance, the patterns of the temperature of the evaporator outlet pipe indicated irregular fluctuation greater than $5^{\circ}C$. When the diagnosis system is using just external sensors of the low-side pressure and the temperatures of inlet and outlet air of cooling vent of the evaporator, the precise pattern of bad cooling performance caused by excess water amount in the cooling line was irregular pressure fluctuation, 25 kPa under 120 kPa, and temperature, $12^{\circ}C$ and less.

Circulation Effect of the Transparent Insulated Opaque Envelopes (투명 단열외피를 통한 환기효과에 관한 연구)

  • Kim, S.H.;Kim, S.J.;Lee, S.
    • Solar Energy
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    • v.20 no.4
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    • pp.31-43
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    • 2000
  • A model house with a "Ondol" heating working with solar energy and supplied by circulation air was investigated both experimentally and theoretically, A calculation method was developed for interpreting the measured values and for comparing several variants, This calculation method together with the measurement result is presented in the following. The gain in energy of the collector(Trombe wall type with TWD) measured on a particularly selected winter day with plenty of radiation amounted to approximately 31 % of the total solar radiation.

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Numerical Simulation on the Wind Ventilation Lane and Air Pollutants Transport due to Local Circulation Winds in Daegu Districts (대구지역의 국지순환풍의 환기경로 및 대기오염수송에 관한 수치모의)

  • Koo, Hyun-Suk;Kim, Hae-Dong
    • Journal of the Korean earth science society
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    • v.25 no.6
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    • pp.418-427
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    • 2004
  • Recently, urban planning with consideration of urban climate, represented by the concept of urban ventilation lane is widely practiced in many countries. The concept of urban ventilation lane is mainly aimed to improve the thermal comfort within urban area in summer season. It has also the aim to reduce the urban air pollution by natural cold air drainage flows which are to be intensified by a suitable alignment of buildings as well as use zonings based on scientific reasons. In this study, the prevailing wind ventilation lane of a local wind circulation and around Daegu for a typical summer days was investigated by using a numerical simulation. The transport of air pollutants by the local circulation winds was also investigated by using the numerical simulation model, the RAMS (Reasonal Atmospheric Model System).The domain of interest is the vicinity of Daegu metropolitan city (about 900 km2). The horizontal scale of the area is about 30 km. The simulations were conducted under a late spring synoptic condition with weak gradient wind and almost clear sky. From the numerical experiment, the following three conclusions were obtained: (1) The major wind passages of the local circulation wind generated by radiative cooling over the representative mountains of Daegu (Mt. Palgong and Mt. Ap) were found. The winds blow down along the valley axis over the eastern part of Daegu as a gravity flow during nighttime. (2) At the flatland, the winds blow toward the western part of Daegu through the city center. (3) As the results, the air pollutants were transported toward the western part of Daegu by the winds during nighttime.

Solid Circulation Characteristics of Oxygen Carrier for Chemical Looping Combustion System at Ambient Temperature and Pressure (케미컬루핑 연소시스템을 위한 산소전달입자의 상온-상압 고체순환특성)

  • YOON, JOOYOUNG;KIM, HANA;KIM, JUNGHWAN;LEE, DOYEON;BAEK, JEOM-IN;RYU, HO-JUNG
    • Transactions of the Korean hydrogen and new energy society
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    • v.28 no.4
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    • pp.384-391
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    • 2017
  • Effects of operating variables on solid circulation rate were measured and discussed using two-interconnected circulating fluidized bed system at ambient temperature and pressure. OCN 706-1100 particles were used as oxygen carrier. The measured solid circulation rates increased as the lower loop seal gas flow rates and the solid height in the fuel reactor increased. Suitable operating conditions to avoid choking of the air reactor were confirmed. Continuous long-term operations of steady-state solid circulation were also demonstrated at two different conditions based on the operating window.

Effect of Suction Temperature and Compressor Frequency on Oil Circulation Ratio in a $CO_2$ Refrigeration System ($CO_2$ 냉동시스템에서 압축기의 흡입온도와 운전주파수가 오일 순환량에 미치는 영향)

  • Kim, Kyung-Jae;Lee, Ik-Soo;Kang, Byung-Ha;Kim, Suk-Hyun
    • Proceedings of the SAREK Conference
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    • 2009.06a
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    • pp.893-898
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    • 2009
  • The quantity of discharged oil from a compressor is one of the most important issues for proper operation of refrigeration system. If the oil is increased in the system not only pressure drop is increased in other components, such as evaporator and gas cooler but also heat transfer coefficient in the heat exchangers is decreased. In addition, the lack of oil in the compressor may cause a critical of the system failure. In this study, one stage single rotary compressor is used for measuring oil circulation ratio(OCR). Carbon dioxide and PAG oil are used as refrigerant and lubricant. Using a U-tube densimeter, mixture density is measured. Characteristics of oil circulation ratio have been investigated for $CO_2$ rotary compressor in the range of operation frequency 45 Hz to 63 Hz and the suction temperature range of $0^{\circ}C$ to $15^{\circ}C$. The results obtained indicate that the oil circulation ratio is increased as the suction temperature or compressor operating frequency is increased.

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