• 제목/요약/키워드: CHANGE OF TEMPERATURE

검색결과 9,993건 처리시간 0.044초

상변화 열교환기의 용융특성 연구 (A study on characteristics of melting in a air-PCM heat exchanger)

  • 오창묵;유영준
    • 한국추진공학회:학술대회논문집
    • /
    • 한국추진공학회 2011년도 제36회 춘계학술대회논문집
    • /
    • pp.127-129
    • /
    • 2011
  • 빌딩에서 쾌적한 환경을 유지하기 위해 온도제어가 필요하다. 온도를 제어하기 위해서 적정 온도를 유지시켜주는 매체인 상변화물질을 이용할 수 있다. 상변화물질은 고유의 상변화온도가 있고 상변화물질은 열을 얻고/방출할 때 녹거나/굳게 된다. 이러한 장점이 있으므로 상변화물질은 공기-상변화물질 열교환기에 적용할 수 있다. 본 연구에서는 시스템 성능에 만족하도록 공기-상변화물질 열교환기를 설계하였고 열교환기의 성능을 연구하기 위해서 실험을 수행한다.

  • PDF

Envi-Met.을 이용한 도심 대기경계층 내 확산장 변화 수치 모의 (Diffusion Simulation Using Envi-Met. in Urban Planetary Boundary Layer)

  • 최현정
    • 한국기후변화학회지
    • /
    • 제7권3호
    • /
    • pp.357-371
    • /
    • 2016
  • Buildings in the city acts as a cause of distorted wind direction, wind speed, causing the stagnation of the air flow. In the recent trend of climate change can not but consider the temperature rise of the urbanization. This study was aimed to analyze the thermal comfort of planetary boundary layer in different artificial constructions areas which has a direct impact on urban climate, and estimating the warming phenomena. Envi-met model was used to consider the urban structure associated with urban growth in order to precisely determine the impact of the building on the city weather condition. The analyzed values of thermal comfort index were temperature, wind speed, horizontal and vertical turbulent diffusivity. In particular, analysis of the PPD(Predicted Percentage of Dissatisfied) represents the human thermal comfort. In this study, by adjusting the arrangement and proportion of the top floor building in the urban it was found that the inflow of the fresh air and cooling can be derived low PPD. Vertical heat flux amount of the city caused by climate change was a factor to form a high potential temperature in the city and the accumulation of cold air does not appear near the surface. Based on this, to make the city effectively respond to climate change may require a long-term restructuring of urban spatial structure and density management.

Antarctic Marine Microorganisms and Climate Change: Impacts and Feedbacks

  • Marchant Harvey J.;Davidson Andrew T.;Wright Simon W.
    • Ocean and Polar Research
    • /
    • 제23권4호
    • /
    • pp.401-410
    • /
    • 2001
  • Global climate change will alter many such properties of the Southern Ocean as temperature, circulation, stratification, and sea-ice extent. Such changes are likely to influence the species composition and activity of Antarctic marine microorganisms (protists and bacteria) which playa major role in deter-mining the concentration of atmospheric $CO_2$ and producing precursors of cloud condensation nuclei. Direct impacts of climate change on Antarctic marine microorganisms have been determined for very few species. Increasing water temperature would be expected to result in a southward spread of pelagic cyanobacteria, coccolithophorids and others. Growth rates of many species would be expected to increase slightly but nutrient limitation, especially micronutrients, is likely to result in a negligible increase in biomass. The extent of habitats would be reduced for those organisms presently living close to the upper limit of their thermal tolerance. Increased UVB irradiance is likely to favour the growth of those organisms tolerant of UVB and may change the trophic structure of marine communities. Indirect effects, especially those as a consequence of a diminution of the amount of sea-ice and increased upper ocean stratification, are predicted to lead to a change in species composition and impacts on both trophodynamics and vertical carbon flux.

  • PDF

한지형 마늘 '의성'의 온도구배하우스내 온도상승에 따른 생육 및 생리장해 조사 (Investigation of Physiological and Yield Responses to Temperature Increases in Northern-ecotype Garlic (Allium sativum L. ) 'Uiseong' in Temperature Gradient Tunnels)

  • 김병혁;최민선;김천환;신민지;이성은;문경환;한현희
    • 한국농림기상학회지
    • /
    • 제25권4호
    • /
    • pp.276-283
    • /
    • 2023
  • 마늘(Allium sativum L.)은 한국과 많은 나라에서 다양한 음식에 사용되는 가장 중요한 채소 중 하나이다. 마늘 재배시 재배온도, 습도, 최저온도기간 및 광주기 등에 의해 생육이 달라진다. 본 연구는 지구온난화에 따른 재배온도 상승이 한지형 마늘 '의성'의 생육에 미치는 영향을 규명하기위해 온도구배하우스에서 생육을 조사하였다. 그 결과, 재배온도의 상승은 마늘의 인경지름, 인경무게 및 인편수를 감소시키는 것으로 분석되었다. 또한, 재배온도 상승은 한지형 마늘 '의성'의 불완전 추대율을 증가시켰다. 또한, 불완전 추대로 인한 마늘의 생산성 감소와 상품성 있는 마늘 생산을 감소시키는 것으로 분석되어, 온도 상승은 마늘의 인경발달에 영향을 미치는 것을 알 수 있었다. 본 연구의 결과는 재배온도 상승에 따른 한지형 마늘 '의성'의 생육을 이해하고, 작물모형을 설계하는데 기초자료로 활용될 수 있을 것으로 기대한다. 또한, 본 연구의 결과가 온난화에 따른 재배온도 상승과 마늘의 성장과의 상호작용을 이해하는데 기여할 것으로 판단된다.

기온과 봄 식물계절지수와의 관계 (The Relationship Between Temperature and Spring Phytophenological Index)

  • 장정걸;유성태;김병도;손성원;이명훈
    • 한국자원식물학회지
    • /
    • 제33권2호
    • /
    • pp.106-115
    • /
    • 2020
  • 본 연구는 봄 식물계절지수와 기온지표와의 관계를 알아보기 위해 지난 9년간(2010년-2018년) 대구수목원, 팔공산, 주왕산, 가야산에 공통적으로 생육하는 소나무, 일본잎갈나무, 신갈나무, 진달래, 생강나무, 당단풍나무 6종을 대상으로 발아, 개화, 개엽의 봄 식물계절 시기의 변화 경향과 기온간의 관계를 파악하였다. 기온의 변화는 9년동안2월 보다 3~4월의 월평균 기온이 증가하였으며, 지역별로 수목원과 팔공산의 평균기온이 높았다. 발아, 개화, 개엽은 수종별로 생강나무가 가장 빠르며 소나무가 가장 느렸고, 지역별로 수목원에서 가장 빨리 식물계절시기가 도래하였다. 봄 식물계절시기는 -1.267~-6.151일/9년 정도 앞당겨지고 있는 경향을 보이는데 소나무(-6.151일/9년)가 가장 크며, 진달래(-1.267일/9년)의 변화율이 가장 낮았다. 발아, 개화, 개엽에서 모두 유의한 값을 보이는 수종은 진달래와 소나무로서 이들은 1월~3월 평균기온과 상관관계를 보였다. 봄 식물계절지수(SPI)의 시계열 변화를 확인한 결과 4개 지역의 변화율이 모두 음의 값으로 식물계절 시기가 모두 빨라지고 있었다. 그 중 수목원, 팔공산 및 가야산과 같은 내륙지역일수록 변화율이 컸으며, 다소 거리가 떨어진 주왕산의 경우 변화율이 조금 낮게 나타났다.

WRF-UCM을 활용한 수도권 지역의 열환경 변화 연구: 2000년과 2009년의 비교 (Study on Heat Environment Changes in Seoul Metropolitan Area Using WRF-UCM: A Comparison between 2000 and 2009)

  • 이보라;이대근;남경엽;이영곤;김백조
    • 대기
    • /
    • 제25권3호
    • /
    • pp.483-499
    • /
    • 2015
  • This study examined the impact of change of land-use and meteorological condition due to urbanization on heat environment in Seoul metropolitan area over a decade (2000 and 2009) using Weather Research and Forecasting (WRF)-Urban Canopy Model (UCM). The numerical simulations consist of three sets: meteorological conditions of (1) October 2000 with land-use data in 2000 (base simulation), (2) October 2009 with land-use data in 2000 (meteorological condition change effect) and (3) October 2009 with land-use data in 2009 (both the effects of land-use and meteorological condition change). According to the experiment results, the change of land-use and meteorological condition by urbanization over a decade showed different contribution to the change of heat environment in Seoul metropolitan area. There was about $1^{\circ}C$ increase in near-surface (2 m) temperature over all of the analyzed stations due to meteorological condition change. In stations where the land-use type changed into urban, large temperature increase at nighttime was observed by combined effects of meteorological condition and land-use changes (maximum $4.23^{\circ}C$). Urban heat island (UHI) over $3^{\circ}C$ (temperature difference between Seoul and Okcheon) increased 5.24% due to the meteorological condition change and 26.61% due to the land-use change. That is, land-use change turned out to be contributing to the strengthening of UHI more than the meteorological condition change. Moreover, the land-use change plays a major role in the increase of sensible heat flux and decrease of latent heat flux.

Influence of Climate Change on the Lifecycle of Construction Projects at Gaza Strip

  • El-Sawalhi, Nabil;Mahdi, Mahdi
    • Journal of Construction Engineering and Project Management
    • /
    • 제5권2호
    • /
    • pp.1-10
    • /
    • 2015
  • There is a high confidence based on scientific evidence that climate is changing over time. Now climate change is considered as one of the challenges facing the construction industry. As no project is risk free and climate change has a strong impact on the different phases of the construction project lifecycle. This research aimed at providing a platform of knowledge for the construction management practitioners about the impacts of climate change on the construction projects lifecycle, identify the most dangerous climate change factors on the construction project lifecycle, and identify the most affected phase by climate change factors through the construction projects lifecycle. The study depended on the opinions of civil engineers who have worked in the construction projects field among the reality of Gaza Strip. Questionnaire tool was adopted as the main research methodology in order to achieve the desired objectives. The questionnaire included 127 factors in order to obtain responses from 88 construction practitioners out of 98 representing 89.79% response rate about the influence of climate change on the generic lifecycle of construction projects. The results deduced that the most significant influence on the construction project lifecycle was related to the extreme weather events, rainfall change, and temperature change respectively. There was a general agreement between the respondents that the most affected phase by temperature, rainfall, and extreme weather events is the execution phase. The results also asserted with a high responses scale on the need to alternative procedures and clear strategies in order to face the climate change within construction industry.

고리형 아민과 이산화탄소의 반응에서 온도와 흡수능이 반응열에 미치는 영향 (Effect on the Heat of Reaction to Temperature and Absorption Capacity in the Reaction of Cyclic Amines with Carbon Dioxide)

  • 최정호;장종탁;윤성희;조원희;정진영;윤여일
    • 한국수소및신에너지학회논문집
    • /
    • 제29권5호
    • /
    • pp.530-537
    • /
    • 2018
  • The effect of temperature and absorption capacity on heat of reaction, which is one of the characteristic studies of $CO_2$ absorption, were investigated in a differential reaction calorimeter (DRC) by using piperazine (PZ) and 2-methylpiperazine (2-MPZ). For all absorbents, $CO_2$ loading capacity decreased with increasing the temperature, while the heat of reaction increased, it figured out that these had a linear correlation between $CO_2$ loading capacity and/or heat of reaction and the temperature. The heat of reaction of all absorbents increased with increasing $CO_2$ loading capacity, especially 2-MPZ rapidly increased at $70^{\circ}C$. The reason for increase in the heat of reaction was occurred the regeneration of $CO_2$, which is a reverse-reaction, simultaneously with the absorption.

겨울철 난방시 탑상형 아파트 구조체의 축·방열 특성에 대한 현장측정 연구 (A Field Measurement Study on Heat Storage/Emission Characteristics of Tower Type Apartment Structures in Winter Season)

  • 장현재;조근제
    • 설비공학논문집
    • /
    • 제24권2호
    • /
    • pp.190-195
    • /
    • 2012
  • In this study, as a complementary study of the former study on indoor thermal environment in a tower type apartment house at tropical nights, a field measurement was conducted in winter season. Mainly, characteristics of heat storage and heat emission in apartment structures, in this study, were investigated. As results, indoor air temperature was changed in the range of $22.5^{\circ}C{\pm}1.0^{\circ}C$, and followed not the change of outdoor air temperature but the changed pattern of floor surface temperature. Wall surface temperature was unresponsive to the change of floor surface temperature compared with the change of indoor air temperature because wall structure was composed of concrete which has large heat capacity, and was changed in the range of $22.3^{\circ}C{\pm}0.6^{\circ}C$. Heat was stored continuously into the structures of wall and ceiling through the measurement term. and this means that a large heat capacity of the apartment structure acts as a disadvantage in winter season, too. As a total review of the study with the former study, a large heat capacity of the apartment structure acts against indoor thermal comfort in winter season as well as in summer season.

유한요소법을 이용한 Super-ROM 디스크 구조의 열 분포 해석 (Simulations of time dependent temperature distributions of Super-ROM disk structure using finite element method)

  • 안덕원;유천열
    • 정보저장시스템학회논문집
    • /
    • 제1권2호
    • /
    • pp.132-136
    • /
    • 2005
  • It is widely accepted that the reading mechanism of Super-RENS(super-resolution near field structure) and Super-ROM(super-resolution read only memory) is closely related with non-linear temperature dependent material properties such as refractive indices, phase change. Furthermore, the dynamic change of the temperature distribution also an essential part of reading mechanism of Super-RENS/ROM. Therefore, the knowledge of the temperature distribution as a function a time is one of the important keys to reveal the physics of reading mechanism in Super-RENS/ROM. We calculated time-dependent temperature distribution in a 3-dimensional Super-ROM disk structure when moving laser beam is irradiated. With a help of commercial software FEMLAB which employed finite element method, we simulated the temperature distribution of ROM structure whose pit diameter is 120-nm with 50-nm depth. Energy absorption by moving laser irradiation, time variations of heat transfer processes, heat fluxes, heat transfer ratios, and temperature distributions of the complicate 3-dimensional ROM structure have been obtained.

  • PDF