• Title, Summary, Keyword: Outdoor air cooling

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Analysis of South Korea Outdoor Design Temperature with respect to Assigned Period of the Weather Data (기상 데이터 산정 기간에 따른 국내의 설계용 외기온도 분석)

  • Nam, A Young;Kim, Young Il;Chung, Kwang Seop
    • Transactions of the Korea Society of Geothermal Energy Engineers
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    • v.13 no.2
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    • pp.1-8
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    • 2017
  • Outdoor design temperature is important for selecting proper capacity of heating and cooling systems of a building to implement indoor thermal comfort and save energy consumption. The purpose of this study is to investigate the change of South Korea outdoor design temperature according to the assigned period. When outdoor design temperature of 8 locations calculated with the latest weather data during 2008~2015 years using ASHRAE Bin method are compared to the standard temperature of Ministry of Land, Infrastructure and Transport which is widely used for designing South Korea air-conditioning system at present, the maximum temperature difference becomes $0.97^{\circ}C$ for cooling, and $1.94^{\circ}C$ for heating. Due to wide outdoor temperature variation, update of outdoor design temperature based on recent weather data is recommended.

Performance of a room air conditioner using R410A according to the variation of outdoor temperature (실외온도 변화에 따른 R410A 적용 에어콘 시스템의 성능)

  • 김병순;이승홍
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.11 no.4
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    • pp.537-541
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    • 1999
  • The system performance of a room air conditioner using R410A was experimentally evaluated and compared with that of R22 system. The results indicated that the cooling EER(energy efficiency ratio) of R410A was 1% higher than that of R22 at the outdoor temperature of $35^{\circ}C$. As outdoor temperature increases above $35^{\circ}C$ ambient, EER of the R410A system decreased more substantially compared with R22 system. R410A showed higher compressor discharge temperature than that of R22 system at the outdoor temperature of higher than $50^{\circ}C$.

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Night Purge Control Strategies With Outdoor Air Temperature Conditions for Central Cooling System (중앙냉방시스템의 외기온도조건을 고려한 나이트 퍼지 제어방안에 관한 연구)

  • Hwang, Jin-Won;Ahn, Byung-Cheon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.10
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    • pp.6759-6765
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    • 2015
  • In this study, the effects of control strategies of night-purge control system on control characteristics and energy consumption for central cooling system in building are researched by simulation. The start time and set-point temperature for night-purge control with outdoor temperature changes and building cold storage performance are obtained. The system analysis modelling is done by using TRNSYS program package, and the control performances with suggested night-purge control method are compared with the existing control ones. As a result, the suggested night-purge control method shows maximum 16.8% and 28.6% energy saving in comparison with existing control method and conventional one without night-purge control, respectively.

A Study on the Effects of Supply Air Temperature on the Server Cooling Performance in a Data Center (데이터센터의 급기온도 변화가 서버 냉각 성능에 미치는 영향에 대한 연구)

  • Chang, Hyun Jae
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.30 no.2
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    • pp.83-91
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    • 2018
  • A datacenter is a high energy consuming facility whose cooling energy consumption rate is 10~20 times larger than general office buildings. The higher the temperature of supply air from a CRAC (computer room air-conditioner) is supplied, the more energy efficient cooling is possible because of improving the COP of a chiller and advanced range of outdoor air temperature available for the economizer cycles. However, because the temperature of cold air flowing into server computers varies depending on air mixing configurations in a computer room, the proper supply air temperature must be considered based on the investigation of air mixing and heat dissipation. By these, this study aims to understand the effects of variation of the supply air temperature on the air flow distributions, temperature distributions and rack cooling efficiencies. Computational fluid dynamics (CFD) aided in conducting the investigation. As a result, the variation of the supply air temperature does not affect the air flow distributions. However, it mainly affects the temperature distribution. From the results of CFD simulations, Rack cooling indices (RCIHI and RCILO) were evaluated and showed the ideal state set at $19^{\circ}C$ of the supply air temperature.

Variations in the Thermal Performance of R22 and R410A Refrigeration Systems Depending on Operation Conditions

  • Jeong, Ji-Hwan;Kweon, Young-Chel;Chang, Keun-Sun
    • International Journal of Air-Conditioning and Refrigeration
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    • v.12 no.1
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    • pp.10-20
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    • 2004
  • Experiments have been conducted in order to make comparisons of characteristics of a R410a cycle with a R22 cycle in terms of cooling capacity and coefficient of performance (COP). The parameters examined in the present work include air flow rate, indoor and outdoor air temperatures, and indoor relative humidity. These two refrigeration cycles constructed for this study share all components except compressor, accumulator, oil separator, and piping. The measurements were made using a psychrometric calorimeter. The experimental results show that the R410A cycle has several advantages for indoor units while the R22 cycle yields better performance for outdoor units.

A Study on Energy Reduction in an Outdoor Air Conditioning System for Semiconductor Manufacturing Cleanrooms Using Water Spray Humidification (반도체 클린룸용 외기공조시스템의 수분무 가습을 이용한 에너지절감에 관한 연구)

  • Song, Won-Il;Kim, Ki-Cheol;Yoo, Kyung-Hoon;Shin, Dae-Kun;Tae, Kyung-Eung;Kim, Yong-Sik;Park, Dug-Jun
    • Particle and aerosol research
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    • v.13 no.2
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    • pp.65-77
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    • 2017
  • In recent large-scale semiconductor manufacturing cleanrooms, the energy consumption in outdoor air conditioning (OAC) systems to heat, humidify, cool and dehumidify outdoor air(OA) represents about 40~50 % of the total cleanroom power consumption required to maintain cleanroom environment. Therefore, the assessment of energy consumption in outdoor air conditioning systems is essential for reducing the outdoor air conditioning load for a cleanroom. In the present study, an experiment with an outdoor air flow rate of $1,000m^3/h$ was conducted to compare the energy consumption in steam humidification, simple air washer, exhaust air heat recovery type air washer and dry cooling coil(DCC) return water heat recovery type air washer OAC systems. Besides, a numerical analysis was carried out to evaluate the annual energy consumption of the aforementioned four OAC systems. It was shown that the simple air washer, exhaust air heat recovery type air washer and DCC return water heat recovery type air washer OAC systems using water spray humidification were more energy-efficient than the steam humidification OAC system. Furthermore the DCC return water heat recovery type air washer OAC system was the most energy-efficient.

A Study on Acceptable Thermal Comfort Zone and Resident Behavior of Operating Cooling Devices in Apartments (공동주택의 여름철 수용 쾌적온도 범위와 거주자의 냉방기 사용행위에 관한 연구)

  • Chun Chung-Yoon;Bae Nu-Ri
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.5
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    • pp.477-486
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    • 2005
  • In this study, indoor thermal environment, resident behavior of operating cooling device, and thermal comfort vote are investigated at the living room of apartment during summertime in Seoul. Based on the results of the investigation, indoor air temperatures that residents turn air conditioners (especially for cooling load in this research) on and off were found out. The relationships between outdoor weather condition and the number of days using air conditioner, and whether operating patterns of the devices were also found out. The acceptable thermal comfort zone is figured out from these results, and this research is expected to contribute to the development of household air conditioner. The results can be summarized as the followings; Residents turned the air conditioner on at $29.76^{\circ}C$ of indoor air temperature, and $28.89^{\circ}C$ of $SET^\ast$. And turned the air conditioner off at $27.31^{\circ}C$ of indoor air temperature, and $23.70^{\circ}C$ $SET^\ast$. Therefore, acceptable thermal comfort zone could be lied between these temperatures. If comfortable indoor thermal environment can be obtained with various architectural passive cooling techniques based on the results, energy consumption of cooling devices will be reduced.

A Study on the Operating Performance of the Possible Ventilation Air-Shiter at the same time Cooling or Heating (냉방 또는 난방과 동시에 환기가 가능한 에어시터의 운전성능에 관한 연구)

  • Jang, Young-Keun
    • Journal of the Korean Society of Mechanical Technology
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    • v.19 no.6
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    • pp.839-844
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    • 2017
  • The Air-shiter is a new product possible ventilation at the same time cooling or heating with combined refrigerator and heat recovery ventilator. And a key device of this system is the air shifter. The air shifter device is to convert the outdoor air, room air, supply air and exhaust air flow. Therefore, an experimental study has been carried out to investigate the operating performance for this system. The results, it is possible to ventilate at the same time of heating by outside air above $30^{\circ}C$ in summer. and of heating by outside air within $3^{\circ}C$ in winter. The indoor discharge temperature is over $40^{\circ}C$, and the coefficient of performance is 3.4 in winter.

Developing Optimal Pre-Cooling Model Based on Statistical Analysis of BEMS Data in Air Handling Unit (BEMS 데이터의 통계적 분석에 기반한 공조기 최적 예냉운전 모델 개발)

  • Choi, Sun-Kyu;Kwak, Ro-Yeul;Goo, Sang-Heon
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.10
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    • pp.467-473
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    • 2014
  • Since the operating conditions of HVAC systems are different from those for which they are designed, on-going commissioning is required to optimize the energy consumed and the environment in the building. This study presents a methodology to analyze operational data and its applications. A predicted operation model is to be produced through a statistical data analysis using multiple regressions in SPSS. In this model, the dependent variable is the pre-cooling time, and the independent variables include the power output of the supply air inverter during pre-cooling, the supply air set temperature during pre-cooling, the indoor temperature-indoor set temperature just before pre-cooling, supply heat capacity, and the lowest outdoor air temperature during non-cooling/non-heating hours. The correlation coefficient R2 of the multiple regression model between the pre-cooling hour and the internal/external factors is of 0.612, and this could be used to provide information related to energy conservation and operating guidance.

Real Time Near Optimal Control Application Strategy of Central Cooling System (중앙냉방시스템의 실시간 준최적제어 적용에 따른 실험적 연구)

  • Ahn, Byung-Cheon;Song, Jae-Yeob;Joo, Yong-Duk;Kim, Jin
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.20 no.7
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    • pp.470-477
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    • 2008
  • The near-optimal control algorithm for central cooling system has been developed for minimizing energy consumption while maintaining the comfort of indoor thermal environment in terms of the environmental variables such as time varying indoor cooling load and outdoor temperatures. The optimal set-points of control parameters with near-optimal control are supply air and chilled water temperatures. The near optimal control algorithm has been implemented by using LabVIEW program in order to analyze energy performance for central cooling control system.