• Title/Summary/Keyword: Effective draft temperature(EDT)

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Comparison of Thermal Comfort Performance Indices for Cooling Loads in the Lecture Room - An Correlation of PMV Bnd EDT - (강의실에서의 냉방부하에 따른 열쾌적성 평가지표 비교 - PMV와 EDT의 연관성 -)

  • Noh Kwang-Chul;Oh Myung-Do
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.7 s.238
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    • pp.868-877
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    • 2005
  • We performed the experimental and the numerical study on the comparison of thermal comfort performance indices for cooling loads in the lecture room for 4 cases: Fan coil unit(FCU) or 4-way cassette air-conditioner is respectively operated with the ventilation system or without. We measured the velocity, the temperature distribution and predicted mean vote(PMV) value in the lecture room for 4 different air-conditioning methods. Effective draft temperature(EDT) and PMV were investigated to analyze the characteristics of two thermal comfort indices in the lecture room and to compare their values each other. From the results we knew that there is the similarity between PMV values and EDTs when the room is air-conditioned for cooling loads. It turned out that definition of the control temperature is very important when the EDT is calculated. Finally EDT should not be used to predict the accurate thermal comfort in case that the temperature and humidity are suddenly varied and the zone affected by the solar and inner wall radiation.

Comparison of Indoor Thermal Environments in Winter depending on Supply Vent Configurations (급기구 형상에 따른 겨울철 실내 온열환경의 비교)

  • Han, Hwa-Taik;Jeong, Young-Kyun
    • Proceedings of the SAREK Conference
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    • 2008.06a
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    • pp.970-975
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    • 2008
  • This study considers indoor thermal comfort in an ondol space by supply vent configurations to prevent cold draft in winter. A specially-designed vent cap has been investigated in comparison with a round pan-type vent and a simple opening without a cap. Numerical simulations have been conducted using CFD to analyze thermal comfort indices such as Predicted Mean Vote (PMV) and Effective Draft Temperature (EDT) as well as air distribution index i.e. Air Diffusion Performance Index (ADPI). Results show the new vent cap provides improved thermal comfort conditions especially near ondol heated floor, as the cold outdoor air spreads upwards along the vertical wall before reaching occupant region near floor. This paper includes discussions on the flow and comfort distributions created by the thermal jets from the vents.

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Simplification of PMV through Multiple Regression Analysis (다중회귀분석을 통한 PMV 모델의 단순화)

  • Moon, Yong-Jun;Noh, Kwang-Chul;Oh, Myung-Do
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.19 no.11
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    • pp.761-769
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    • 2007
  • The purpose of this study is to present a simplified model of predicted mean vote (PMV) using multiple regression analysis. We performed the experiments and the numerical calculations in the lecture room during summer and winter to simplify PMV. And the multiple regression analysis on PMV was conducted to estimate the contribution of independent variables toward PMV. From the multiple regression analysis, we found that the effect of independent variables on PMV followed in order, clo value>air temperatur>air velocity>mean radiant temperature>relative humidity. And the simplified PMV was proposed through a few assumptions and then was compared with original PMV. They had a good agreement with each other. Additionally, we compared the simplified PMV with EDT. We expected that the simplified PMV can be more useful than EDT to evaluate the thermal comfort in the place, where radiation is dominant. But the comfort range of the simplified PMV should be adjusted to predict the exact thermal comfort in the future.

Air Distribution Performance According to the Gap Opening of a Temperature Controlled Diffuser (냉난방 온도감지 디퓨져의 간극변화에 따른 기류분포 특성)

  • Han Hwataik;Shin Min-Woo;Yom Chol-Min;Choi Sun-Ho
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.2
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    • pp.180-185
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    • 2006
  • This study has been conducted in order to develop a temperature-controlled round pan diffuser with variable-openings. Flow visualization was performed to investigate the airflow patterns according to gap openings. The velocity profiles were measured using an omni-directional anemometer for two cases, i.e. a horizontal and a vertical discharge conditions. Numerical simulation also confirms there is a narrow range of gap openings where a horizontal discharge shifts to a vertical discharge. The air distribution performance index increases abruptly when the air discharge shifts from vertical to horizontal direction.

Thermal Comfort and Air Flow Patterns for Indoor Unit Positions and Ventilation Rates in Cooling Operation (냉방조건에서 실내기 위치 및 환기량에 따른 열쾌적성 및 유동 특성)

  • Koh, Jae-Yoon;Kang, Tae-Wook;Park, Yool
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.20 no.4
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    • pp.221-229
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    • 2008
  • This study analyze indoor thermal comfort properties such as PMV, PPD and fluid variables when the cooling loads are light, occupant and ventilation. There are 6 cases to study for the indoor unit installation conditions and ventilation rates. Numerical method is used to study the indoor environmental properties and experimental study is adapted to analyze reaching time by variable cooling load conditions.