• Title/Summary/Keyword: indoor airflow

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Survey evaluation of thermal boundary condition in the inside and outside of double skin facade

  • Shin, Hyun-Cheol;Jang, Gun-Eik
    • KIEAE Journal
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    • v.15 no.4
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    • pp.29-35
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    • 2015
  • Purpose: Double skin facade is a representative advantageous passive technology of building skin in the aspect of energy saving and environment improvement, reduces heat loss with buffer space in winter season and enhances indoor air and comfort of residents by activating natural ventilation in mid-season. However, in summer season, temperature increase in the intermediate space due to solar energy from exterior transparent skin could be a potential problem; also, relatively weak buoyancy of air caused by low density difference between double-skin facade could increase cooling load as air of intermediate space in high temperature hangs. However, proof data is insufficient to objectify such phenomenon. Method: In this study, researchers surveyed air temperature of intermediate space and airflow and diagnosed its cause targeting on applied multistory facade in the building which gives thermal uncomfort to residents. Also, the researchers produced Solar-air heat transfer coefficient meter, measured thermal boundary condition of double-skin facade, and presented the result of measurement as an objectified verification material regarding overheating phenomenon in the intermediate space of double-skin facade in summer season. Result: Inefficient condition was verified that total heat increases and overheating due to insufficient natural ventilation in multistory facade. In addition, logic behind preceding research was objectified and verified regarding high temperature phenomenon in the intermediate space which could increase cooling load in summer season.

Optimal air-conditioning system operating control strategies in summer (여름철 공조시스템의 최적 운전 제어 방식)

  • Huh, J.H.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.9 no.3
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    • pp.410-425
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    • 1997
  • Buildings are mostly under part load conditions causing an inefficient system operation in terms of energy consumption. It is critical to operate building air-conditioning system with a scientific or optimal manner which minimizes energy consumption and maintains thermal comfort by matching building sensible and latent loads. Little research has been performed in developing general methodologies for the optimal operation of air-conditioning system. Based on this research motivation, system simulation program was developed by adopting various equipment operating strategies which are energy efficient especially for humidity control in summer. A numerical optimization technique was utilized to search optimal solution for multi-independent variables and then linked to the developed system simulation model within a mam program. The main goal of the study is to provide a systematic framework and guideline for the optimal operation of air-conditioning system focusing on air-side. For given cooling loads and ambient outdoor conditions the optimal operating strategies of a commercial building are determined by minimizing a constrained objective function by a nonlinear programming technique. Desired space setpoint conditions were found through evaluating the trade-offs between comfort and system power consumption. The results show that supply airflow rate and compressor fraction play main roles in the optimization process. It was found that variable setpoint optimization technique could produce lower indoor humidity level demanding less power consumption which will be benefits for building applications of humidity problem.

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Analyzing for Refrigerant Induced Noise for Split Type Air Conditioner Indoor Unit (분리형 에어컨의 실내기 냉매 소음 저감 분석)

  • Aoyama Shigeo;Mo, Jin-Yong;Lee, Jae-Kwon;Song, Yong-Jae;Han, Hyung-Suk
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.3 s.108
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    • pp.240-246
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    • 2006
  • In the air-conditioner, refrigerant induced noise and vibration can be increased when the airflow rate is reduced in order to decrease the noise at the low mode. Through the test and analysis of this kind of noise, it can be verified that the main reasons of refrigerant induced noise are the velocity and flow Induced force of the refrigerant at the inlet of the evaporator, So, in order to reduce this velocity, quality at the evaporator inlet should be minimized. And, in order to reduce flow induced force of the refrigerant, sudden change of fluid flow must not be occurred. So, in this paper, we will review the characteristics of refrigerant cycle and find how the quality and flow induced force can be minimized.

Effect of Anion Generating Air Cleaner on the Components of ETS in a Closed Room (음이온 발생 공기청정기에 의한 밀폐된 실내공간에서의 ETS성분 변화)

  • Hwang, Keon-Joong;Rhee, Moon-Soo;Ra, Do-Young
    • Journal of the Korean Society of Tobacco Science
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    • v.20 no.1
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    • pp.124-130
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    • 1998
  • This study was conducted to evaluate the ability of anion generating air cleaner to remove gases, vapor and particles from closed room contaminated with environmental tobacco smoke (ETS). The measurements covered particle sizes of 13.8-542.5nm, particle concentration, surface area, volumes UVPM, FPM, solanesol, and the following gases and vapor; carbon dioxide, carbon monoxide, nicotine, and 3-ethenylpyridine. Tobacco smoke was generated and mixed in a closed room in which the airflow rates were in the range of 0.00-0.04 m/s. The anion generating air cleaner was startedl and the decay rates for the gases, vapor and particles were measured, When the use of anion generating air cleaner, solid components of ETS, such as respirable suspended particle (RSP), utraviolet particulate matter (UVPM, fluorescent particulate matter (FPM) and solanesol was sharply decreased, and vapor phase components of ETS, such as nicotines 3-ethenylpyidine were modelately decreased by time elapse. Even the use of anion generation air cleaner, the decreasing rate of carbon dioxide concentration was similar with control, and the decreasing rate of carbon monoxide was slower than that of control. Our results indicated that the use of anion generting air cleaner had an effect on reduction of solid and vapor components from ETs, but it had no effect on gaseous components of ETS.

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Analysis of Airflow Pattern and Particle Dispersion in Enclosed Environment Using Traditional CFD and Lattice Boltzmann Methods

  • Inoguchi, Tomo;Ito, Kazuhide
    • International Journal of High-Rise Buildings
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    • v.1 no.2
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    • pp.87-97
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    • 2012
  • The indoor environments in high-rise buildings are generally well enclosed by defined boundary conditions. Here, a numerical simulation method based on the Lattice Boltzmann method (LBM), which aims to model and simulate the turbulent flow accurately in an enclosed environment, and its comparison with traditional computational fluid dynamics (CFD) results, are presented in this paper. CFD has become a powerful tool for predicting and evaluating enclosed airflows with the rapid advance in computer capacity and speed, and various types of CFD turbulence modeling and its application and validation have been reported. The LBM is a relatively new method; it involves solving of the discrete Boltzmann equation to simulate the fluid flow with a collision model instead of solving Navier-Stokes equations. In this study, the LBM-based scheme of flow pattern and particle dispersion analyses are validated using the benchmark test case of two- and three-dimensional and isothermal conditions (IEA/Annex 20 case); the prediction accuracy and advantages are also discussed by comparison with the results of CFD.

A Theoretical Study for Stack Effect driven Natural Ventilation System in High-rise Building (고층건물에서 연돌효과를 활용한 자연환기시스템 설계를 위한 이론적 고찰)

  • Yoon, Sung-Min;Seo, Jung-Min;Kim, Yang-Soo;Lee, Joong-Hoon;Song, Doo-Sam
    • 한국태양에너지학회:학술대회논문집
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    • 2009.11a
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    • pp.123-129
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    • 2009
  • In these days, the green building movement caused by the energy crisis is increasing, passive design is getting mere and more attention as it provides many possibilities for energy conservation. Moreover, with the increasing social intention for healthy life, the demand for indoor air Quality is increasing in Korea. As result, the ventilation system which can provide the sound outdoor air constantly has been obliged in Korea. So, the hybrid system which using natural power and mechanical power and makes up for the shortage of mechanical and natural ventilation attracts people's attention in Korea. As a hybrid ventilation system, in this study, the stack effect driven hybrid ventilation system in high-rise residential building will be suggested. And in this paper, the theoretical review for hybrid ventilation system suggested in this study will be addressed. Especially, the characteristics of pressure distribution and airflow caused by stack effect in high-rise residential building and the possibility of natural ventilation as results of stack effect will be described.

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Research on Odor Analysis Technology to Secure the Reliability of Air Quality Improvement in Air Conditioners (에어컨디셔너 공기질 개선의 신뢰도 확보를 위한 냄새 분석 기술 연구)

  • Kang, Seok-Hyun;Huh, Pil-Ho;Ahn, Young-Chull
    • Journal of Environmental Science International
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    • v.30 no.1
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    • pp.45-55
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    • 2021
  • In this study, the odor of the parts and the odor of the surrounding environment were classified and verified. In order to increase the reliability of odor quantitative/qualitative analysis, the selection criteria for 5 sensory evaluators were established, and the n-Butanol control solution for each odor intensity was periodically trained to recognize the odor intensity before sensory evaluation. In addition, although various odor thresholds have been used through several studies, verification of whether the odor intensity value obtained through GC/MSD analysis is similar to the degree to which a person directly smells and feels it. It is important to select the odor threshold that has the best correlation with the odor intensity calculated by the person smelling the odor. Finally, sampling and measuring flowing airflow and temporary odors such as odor component analysis was experimentally difficult due to limited collection space and differences in concentration of generated components. In this study, a quantitative analysis was made possible by using the low temperature concentration (cooling) trap method. Through this, it was confirmed that the correlation with the actual odor intensity was not caused by the product itself, but by the environmental factor discharged from the product after creating the odor environment.

Control of Suspended Dust in Various Ventilation Systems of Cement Packaging Process (시멘트 포장공정에서 환기시스템에 따른 발생분진의 제어)

  • Lee, Seung-Chul;Kim, Soo-Chang;Noh, Kwang-Chul;Park, Myoung-Ho
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.10 no.3
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    • pp.463-469
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    • 2009
  • We performed the experimental study on the control of suspended dust in a cement packaging process for various ventilation systems. To effectively remove the dust generated in the cement packaging process, three different kinds of ventilation system, such as local exhaust ventilation, electrostatic scrubber, and local air supply system, were adopted. Dust concentrations in the packaging process were measured with the variation of the airflow rate of the ventilation systems and then their ventilation performance were evaluated. From the results, we knew that the ventilation performance was the best when the local exhaust ventilation and the electrostatic scrubber were simultaneously operated in the packaging process. In the electrostatic scrubber system, the effect of the airflow rate on the indoor dust removal efficiency was negligible so hat he system ust be operated at $2,700m^3/h$ for saving power consumption.

Evaluation of Ventilation Performances for Various Combinations of Inlets and Outlets in a Residential Unit through CO2 Tracer-Gas Concentration Decay Method (CO2 추적가스 농도감소법을 이용한 공동주택의 급·배기구 조합에 따른 환기 성능 분석)

  • Sang Yoon Lee;Soo Man Lee;Jong Yeob Kim;Gil Tae Kim;Byung Chang Kwag
    • Land and Housing Review
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    • v.14 no.4
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    • pp.111-120
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    • 2023
  • Indoor air quality has become increasingly important with the increase in time spent in residential environments, impact of external fine dust, yellow dust, and the post-COVID 19 pandemic. Residential mechanical ventilation plays a key role in addressing indoor air quality. The legal standard for residential air changes per hour in Korea is 0.5 ACH. However, there are no standards for the location of supply and return vents. This study atempts to analyze the impact of ventilation performance based on the location of supply and return vents. An experiment was conducted using the CO2 tracer gas concentration decay method in a mock-up house set inside a large chamber to minimize external influences. The experimental results indicated that the commonly used combination of 2 supply and 2 return vents in living room spaces had a lower mean age of air than the combination of 1 supply and 2 return vents. Using multiple supply and return vents had lower mean age of air than using just 1 supply and 1 return vent.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2016 (설비공학 분야의 최근 연구 동향 : 2016년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.6
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    • pp.327-340
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    • 2017
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.