• Title, Summary, Keyword: Outdoor air temperature

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Sensitivity Analysis of Indoor Environment Factors along with Changes of Outdoor Air Condition (외기상태의 변화에 따른 실내 환경인자의 민감도 분석)

  • Cho, Seok-Ho
    • Journal of Environmental Science International
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    • v.19 no.2
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    • pp.125-136
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    • 2010
  • The most important factors relating to the indoor air environment are temperature, airflow, humidity, and contaminant concentration. A sensitivity analysis of indoor environment factors was carried out to grasp influences along with changes of atmospheric conditions. An integrated multizone model was used to predict these sensitivities. This model was applied to an apartment with six zones. Airflow rates are influenced very seriously by changes of wind direct or wind velocity, but are influenced very slightly by changes of outdoor air temperature and are not influenced at all by changes of outdoor air humidity or contaminant concentration. Indoor air temperatures are influenced very directly by changes of outdoor air temperature, but are influenced very slightly by wind direction or wind velocity and are not influenced at all by changes of outdoor air humidity or contaminant concentration. Indoor air humidities are influenced very directly by changes of outdoor air humidity, but are not influenced at all by changes of outdoor air contaminant concentration and have little or no influence by changes of wind direction, wind velocity, or outdoor air temperature. Indoor air contaminant concentrations are influenced very seriously by changes of wind direct or wind velocity, but are influenced somewhat by changes of outdoor air contaminant concentration and are influenced very slightly by changes of outdoor air temperature and are not influenced at all by changes of outdoor air humidity.

Experimental Study on Energy Saving Performance of Outdoor Temperature Reset Control Strategy for Central Cooling System (중앙 냉방시스템에 대한 외기보상제어의 절약 성능에 관한 실험적 연구)

  • Kim, Dong-Cheol;Song, Jae-Yeob;Ahn, Byung-Cheon
    • Transactions of the Korea Society of Geothermal Energy Engineers
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    • v.7 no.2
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    • pp.30-36
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    • 2011
  • In this study, energy saving performance of outdoor temperature reset control strategy for central cooling system is researched by experiments. Outdoor temperature reset control is the control method to change indoor air set temperature according to outdoor air temperature change. The range of indoor air set temperature is represented by the comfort temperature range of indoor air temperature offered from ASHRAE and indoor air set temperature is programmed between $22^{\circ}C$ and $27^{\circ}C$ by outdoor air temperature $20^{\circ}C{\sim}32^{\circ}C$ in summer. As a result of applying outdoor temperature reset control to central cooling system, the suggested control method shows better performances of energy savings than the conventional method which indoor temperature maintains constantly.

Effects of Control Methods of Outdoor Air Cooling System on Energy Consumption in Building (외기냉방 시스템의 제어방법이 에너지 소비량에 미치는 영향에 관한 연구)

  • Hwang, Jin-Won;Ahn, Byung-Cheon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.6
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    • pp.4253-4259
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    • 2015
  • In this study, the effects of various control methods of outdoor air cooling control system on control characteristics and energy consumption in building are researched by simulation. The system analysis modelling is done by using TRNSYS program package, and the control performances with existing outdoor air cooling methods are compared with the control ones without outdoor air cooling. As a result, appropriate operating temperature conditions of outdoor air cooling system according to outdoor temperature changes are required, and the outdoor air/return air dry bulb temperature comparison control method among the control methods shows best responses in energy savings.

Calculation of Outdoor Air Fraction through Economizer Control Types during Intermediate Season

  • Hong, Goopyo;Hong, Jun;Kim, Byungseon Sean
    • KIEAE Journal
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    • v.16 no.6
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    • pp.13-19
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    • 2016
  • Purpose: In this study, we examined outdoor air fraction using historical data of actual Air Handling Unit (AHU) in the existing building during intermediate season and analyzed optimal outdoor air fraction by control types for economizer. Method: Control types for economizer which was used in analysis are No Economizer(NE), Differential Dry-bulb Temperature(DT), Diffrential Enthalpy(DE), Differential Dry-bulb Temperature+Differential Enthalpy(DTDE), and Differential Enthalpy+Differential Dry-bulb Temperature (DEDT). In addition, the system heating and cooling load were analyzed by calculating the outdoor air fraction through existing AHU operating method and control types for economizer. Result: Optimized outdoor air fraction through control types was the lowest in March and distribution over 50% was shown in May. In case of DE control type, outdoor air fraction was the highest of other control types and the value was average 63% in May. System heating load was shown the lowest value in NE, however, system cooling load was shown 1.7 times higher than DT control type and 5 times higher than DE control type. For system heating load, DT and DTDE is similar during intermediate season. However, system cooling load was shown 3 times higher than DE and DEDT. Accordingly, it was found as the method to save cooling energy most efficiently with DE control considering enthalpy of outdoor air and return air in intermediate season.

Application Study on the Outdoor Air Temperature Prediction Control for Continuous Floor Heating System (연속바닥난방시스템에 대한 외기예측제어적용 연구)

  • 태춘섭;조성환;이충구
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.9
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    • pp.836-844
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    • 2001
  • For the radiant floor heating system, the possibility of suboptimal prediction control was investigated by computer simulation and experiment. For this study, TRANSYS program was used and an experimental facility consisting of two rooms (3$\times$4.4$\times$2.8m) was built. The facility enabled simultaneous comparison of two different control strategies which implemented in a separate room. Results showed that outdoor air temperature prediction control was superior to the conventional outdoor air temperature compensation control for radiant floor heating system. However, more research for fine prediction of outside air temperature was required in the future.

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Actual Energy Consumption Analysis of Temperature Control Strategies for Secondary Side Hot Water District Heating System with an Inverter (인버터시스템 적용 지역난방 시스템의 2차측 공급수 온도 제어방안에 따른 에너지사용량 실증 비교)

  • Cho, Sung-Hwan;Hong, Seong-Ki
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.4
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    • pp.179-186
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    • 2015
  • In this study, the actual energy consumption of the secondary side District Heating System (DHS) with different hot water supply temperature control methods is compared. The two methods are Outdoor Temperature Reset Control and Outdoor Temperature Predictive Control. While Outdoor Temperature Reset Control has been widely used for energy savings of the secondary side system, the results show that the Outdoor Temperature Predictive Control method saves more energy. In general, the Outdoor Temperature Predictive Control method lowers the supply temperature of hot water, and it reduces standby losses and increases the overall heat transfer value of heated spaces due to more flow into the space. During actual energy consumption monitoring, the Outdoor Temperature predictive Control method saves about 6.6% of energy when compared to the Outdoor Temperature Reset Control method. Also, it is found that at partial load condition, such as during daytime, the fluctuation of hot water supply temperature with Outdoor Temperature Reset Control is more severe than that with Outdoor Temperature Predictive Control. Thus, it proves that Outdoor Temperature Predictive Control is more stable even at partial load conditions.

A Study on Building Energy Saving using Outdoor Air Cooling by Load Prediction (부하예측 외기냉방에 의한 건물에너지 절약에 관한 연구)

  • Kim, Tae-Ho;Yoo, Seong-Yeon;Kim, Myung-Ho
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.2
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    • pp.43-50
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    • 2017
  • The purpose of this study is to develop a control algorithm for outdoor air cooling based on the prediction of cooling load, and to evaluate the building energy saving using outdoor air cooling. Outdoor air conditions such as temperature, humidity, and solar insolation are predicted using forecasted information provided by the meteorological agency, and the building cooling load is predicted from the obtained outdoor air conditions and building characteristics. The air flow rate induced by outdoor air is determined by considering the predicted cooling loads. To evaluate the energy saving, the benchmark building is modeled and simulated using the TRNSYS program. Energy saving by outdoor air cooling using load prediction is found to be around 10% of the total cooling coil load in all locations of Korea. As the allowable minimum indoor temperature is decreased, the total energy saving is increased and approaches close to that of the conventional enthalpy control.

Numerical Analysis on the Performance of a Outdoor Air Cooled Heat exchanger for Cooling Tower (외기이용 하이브리드 냉각탑 성능해석)

  • Kim, Sung-Il;Lee, Wook-Hyun;Lee, Kye-Jung;Chun, Won-Pyo
    • Proceedings of the KSME Conference
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    • pp.2322-2327
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    • 2008
  • This paper is to provide analysis model that can be used to investigate the improvement in energy efficiency for cooling tower by using fresh air. Numerical analysis of Air-cooled heat exchanger for single-phase flow with variations of outdoor air temperature has been performed. A complete set of correlations of the heat transfer in both refrigerant and air sides was employed for predicting the heat transfer rate. The numerical results derived from the correlations were verified with experimental results. The energy consumption for a hybrid cooling tower has been compared for variation of a outdoor air temperature. The results showed that the hybrid cooling tower in low outdoor temperature offers a significant improvement in energy efficiency. The thermal analysis aids significantly in the solution of the design problem of hybrid cooling tower.

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Dynamic Simulation of a Dedicated Outdoor Air-conditioning System (외기 전용 공조기의 동특성 시뮬레이션)

  • Kim, Jung-Min;Kim, Young-Il;Chung, Kwang-Seop;Park, Seung-Tae
    • Proceedings of the SAREK Conference
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    • pp.322-327
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    • 2007
  • Dedicated outdoor air-conditioning(DOA) system that utilizes pre-cooling and desiccant dehumidification can be superior to conventional cooling and reheating system with respect to energy consumption and indoor thermal comfort. In this work, simulation has been conducted to study various factors that affect the performance of DOA. Dynamic simulation shows the transient variation of temperature and humidity as the on/off control logic is imposed. Exit humidity of process air and flow rate are varied to study the effect on exit temperature of process air, dehumidification quantity, required regeneration temperature and exit humidity of regeneration air. For an outdoor air condition of $28.5^{\circ}C$ temperature, 16 g/kg humidity ratio and 2000 cmh flow rate, the dehumidification efficiency is increased by 4.6% as the flow rate is doubled.

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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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