Top PDF Effects of microclimate and human parameters on outdoor thermal sensation in the high-density tropical context of Dhaka.

Effects of microclimate and human parameters on outdoor thermal sensation in the high-density tropical context of Dhaka.

Effects of microclimate and human parameters on outdoor thermal sensation in the high-density tropical context of Dhaka.

Received: 6 December 2017 / Revised: 13 July 2018 / Accepted: 25 August 2018 # The Author(s) 2018 Abstract A thermal comfort questionnaire survey was carried out in the high-density, tropical city Dhaka. Comfort responses from over 1300 subjects were collected at six different sites, alongside meteorological parameters. The effect of personal and psychological parameters was examined in order to develop predictive models. Personal parameters included gender, age, activity, profession- type (indoor or outdoor-based), exposure to air-conditioned space and sweat-levels. Psychological parameters, such as ‘the reason for visiting the place’ and ‘next destination is air-conditioned’, had statistically significant effects on thermal sensation. Other parameters, such as ‘body type’, ‘body exposure to sun’, ‘time living in Dhaka’, ‘travelling in last_30 min’, and ‘hot food’ did not have any significant impact. Respondents ’ humidity, wind speed and solar radiation sensation had profound impacts and people were found willing to adjust to the thermal situations with adaptive behaviour. Based on actual sensation votes from the survey, empirical models are developed to predict outdoor thermal sensation in the case study areas. Ordinal linear regression techniques are applied for predicting thermal sensation by considering meteorological and personal conditions of the field survey. The inclusion of personal and weather opinion factors produced an improvement in models based on meteorological factors. The models were compared with the actual thermal sensation using the cross-tabulation technique. The predictivity of the three models (meteorological, thermos-physiological and combined parameter) as expressed by the gamma coefficient were 0.575, 0.636 and 0.727, respectively. In all three models, better predictability was observed in the ‘Slightly Warm’ (71% in meteoro- logical model) and ‘Hot’ (64.9% in combined parameter model) categories—the most important ones in a hot-humid climate. Keywords Outdoor thermal comfort . Questionnaire survey . Thermal sensation vote (TSV) . Predictive model . Tropical climate
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Effects of microclimate and human parameters on outdoor thermal sensation in the high-density tropical context of Dhaka

Effects of microclimate and human parameters on outdoor thermal sensation in the high-density tropical context of Dhaka

‘adaptive behaviour’ and ‘weather opinion’. Personal informa- tion of the respondents, such as gender, age, body type, activity, exposure to direct sunlight and clothing level were also included in the table. These were determined by observation during the survey. Several personal characteristics were noted by directly asking the respondents about their residence status in the city, nature of their profession, interviewees’ sweat-levels (Ng & Cheng 2012 ), exposure to air-conditioned space and travelling situations in the last 30 min, etc. Profession is grouped as Bindoor type^, who work in an indoors environment and Boutdoor type^, who work mostly outdoors (e.g. street traders) (Ahmed 2003 ). Respondents’ psychological factors included visiting purposes to the site and whether the next destination is air conditioned or not. Choice of adaptive behaviour, consump- tion of hot food or cold drinks, etc. were considered under ‘adaptive behaviour’. Additionally, interviewees’ judgement of the prevailing humidity, wind speed and solar radiation condi- tions during the survey were recorded. The reason for consider- ing the ‘visiting purpose’ and ‘next destination is air condi- tioned’ under the psychological category is that both have con- siderable psychological impact on the respondent’s mental situ- ation. Visiting a place for leisure could have a different psycho- logical effect to someone who is present for work. Pantavou and Lykoudis ( 2014 ) and Pantavou et al. ( 2013 ) have shown in their studies that people visiting the site for work felt cooler than those visiting the site for rest, due to both psychological effects and also because the former group had better adaptation due to lon- ger exposure time than those simply passing by. Similarly, peo- ple whose next destination is air-conditioned could be more tolerant to warm situations as they know any discomfort is tem- porary. Regarding ‘weather opinion’, although Pantavou et al. ( 2013 ) have discussed this under psychological parameters, it is discussed separately in this study as these can be broadly treated as comparable to the ASHRAE TSV. This is similarly applicable in the case of adaptive behaviour.
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Effects of microclimatic and human parameters on outdoor thermal sensation in the high-density tropical context of Dhaka

Effects of microclimatic and human parameters on outdoor thermal sensation in the high-density tropical context of Dhaka

The models show how people’s personal backgrounds and subjective responses can affect their thermal sensation levels. The meteorological model is helpful for predicting comfort situations when no personal data or weather opinion is available. Thermo- physiological model could be applied in places with high-humidity levels where sweat-levels may vary depending on personal circumstances and thus, have a direct impact on the TSV. Depending on the socio-economic context, other personal variables, such as, exposure to air- conditioning may also be a helpful parameter for understanding the TSV levels. Same is applicable for clothing and gender for places where ‘Clo’-value for men is distinctly different from that of women for social reasons. The combined model, on the other hand, could be applicable for medium-rise, medium density, tropical urban areas where pedestrians may be affected by high solar radiation and therefore, may prefer shaded areas.
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Outdoor thermal comfort and summer PET range: A field study in tropical city Dhaka

Outdoor thermal comfort and summer PET range: A field study in tropical city Dhaka

2 research has been conducted regarding the microclimate in tropical cities (Oke, Taesler and Olsson, 1990; Villadiego and Velay-Dabat, 2014; Fong et al., 2019). The majority of the thermal comfort research concentrates on temperate and cold climate, although people in these climates tend to spend most of their times indoors compared to tropical climate. For example, in the United States and Canada, on average people only spend 2 - 4% of their time in outdoors during winter and 10% in summer (Salata et al., 2016). Research on temperate climate include: Nikolopoulou, Baker and Steemers, 2001; Zacharias, Stathopoulos and Wu, 2001, 2004; Thorsson, Lindqvist and Lindqvist, 2004; Nikolopoulou and Lykoudis, 2006, 2007; Eliasson et al., 2007; Thorsson et al., 2007; Taleghani et al., 2014 etc. Numerous studies have been conducted in the hot-dry climate (Ali-Toudert, 2005; Johansson, 2006; Ali-Toudert and Mayer, 2007b, 2007a; Yahia and Johansson, 2013) and some in a subtropical climate (Lin and Matzarakis, 2008; Lin, Matzarakis and Hwang, 2010; Cheng et al., 2012; Ng and Cheng, 2012). Important studies in a tropical climate include Ahmed, 2003; Emmanuel and Johansson, 2006; Emmanuel, Rosenlund and Johansson, 2007; Yang, Wong and Jusuf, 2013; Villadiego and Velay-Dabat, 2014; Ignatius, Wong and Jusuf, 2015 etc. These studies provide an extensive knowledge of the effects of outdoor climatic conditions on people’s thermal sensation. Nevertheless, people’s thermal comfort sensation can be quite diversified depending on the climate and microclimate of the city they live in and their cultural backgrounds (Salata et al., 2016). The context of each city is unique and therefore, it is important to conduct field studies in different cities to complement our existing knowledge towards making healthy cities.
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Effect of Vertical Urban Surfaces on Human Thermal Comfort in Outdoor Environment

Effect of Vertical Urban Surfaces on Human Thermal Comfort in Outdoor Environment

habitable outdoor spaces so that they improve the outdoor activities. User experience of space is greatly affected by the thermal comfort level of that space. Metropolitan cities and city squares are facing challenges of increased heat at microclimatic scale. Cities are facing challenges to mitigate the environmental impact due increased surface area of buildings [2].Due to thermal discomfort people have declined the use of public open spaces. Lots of public spaces became dead spaces during the daytime. Merely because there are not habitable. Which creates cultural gap due to lack of interaction between people in outdoor areas which also affect the neighborhood livability, street life, outdoor activities etc. The professionals such as Architects, landscape architects, urban designers should intervene in these situations to make cities habitable to live. Innovative approaches to urban open spaces will become more important as the Indian population is becoming more urban. Research and solutions are focused mainly on the pollution, greenhouse gases, burning of fossil fuels for urban climate change, whereas the whole surface area of a building contributes to the heat emission in higher quantity. Design of vertical surfaces will show designers how to work to create climatically habitable spaces for human activities. With remarkable clarity, it covers both the scientific background and the design techniques needed for shaping spaces that increase comfort and reduce energy consumption.
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Variability of human behaviour in outdoor public spaces, associated with the thermal environment

Variability of human behaviour in outdoor public spaces, associated with the thermal environment

The studies of comfort in outdoors have addressed the thermal perception of users, but “A truly holistic basis of assessing pedestrian’s satisfaction would, however, also consider sociological factors” (Robinson, 2012). Since integrating the social variables to predict behaviours, or, studying the physiological human response to environmental conditions, by itself is insufficient. We need to look at the influence of social factors, as well as, their influence on the behaviour. Therefore, this research is focused on finding the relationship between different environmental conditions and human behaviour, and determining whether it is possible to predict the behaviour associated with certain thermal conditions.
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Effect of Urbanization and Industrialization Processes on Outdoor Thermal Human Comfort in Egypt

Effect of Urbanization and Industrialization Processes on Outdoor Thermal Human Comfort in Egypt

It was found that all people in rural, urban, suburban and industrial areas feel quite uncomfortable due to cold weather (RI < 60) during only four months (December to March) of both study periods exception rural area through the old non-urbanized period (Table 3). January month has maximum number of quite uncomfortable cooling hours through both study periods with greater value of the old period at all districts. This is attributed, as mentioned above, to the northerly cold air invades Egypt during this month as well as the reduction of air temperatures due to the thermal radiant emittance during the long night hours of this month. On the other hand, the total number of quite uncomfortable cooling (RI < 60) hours in rural area is higher than its corresponding hours in urban, suburban and industrial areas during both study periods except the suburban area (Table 3). This is due to rural conditions at Bahtim [9] and [12]. While the ur- ban area of Abbasiya has the lowest number of quite uncomfortable cooling (RI < 60) hours during both study periods with distinctly higher total number of hours dur- ing the old non-urbanized period. This is due to high temperature and low values of both wind speed and rela- tive humidity resulting from severe urban conditions at Abbasiya [9] and [12]. It must be noticed that the differ- ence between the highest (at rural area) and lowest (at urban area) total number of quite uncomfortable cooling hours during the old non-urbanized period (274 hours) is distinctly lower than its corresponding hours during the recent urbanized period (1095 hours). This explains the increase of urbanization effects from the old to recent period especially at the urban area of Abbasiya. It is clear
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A review of researches about human thermal comfort in semi-outdoor spaces

A review of researches about human thermal comfort in semi-outdoor spaces

The enthusiasm of scientists to study on ther- mal comfort condition of semi-outdoor and out- door spaces has been raised since recent decade but it is needed to focus on more details and locations. Through representing a review on the prior stud- ies, it is understood that although the evaluation of thermal comfort in semi-outdoor spaces of various climates has been done up to now, the number of researches which specifically concentrate on to as- sess the human thermal comfort in semi-open ar- eas are few. Particularly, there is a lack of research- es on assessing thermal conditions of semi-outdoor areas in hot-humid regions. Moreover, it is need- ed to find a proper universal thermal index for vari- ous climate conditions. This index can help urban planner to evaluate thermal condition of districts in the world in understandable range. Finally, to pro- pose the practical software for simulation the ther- mal comfort of semi-outdoor spaces in easy and us- er-friendly manner.
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An Integrated Model for Urban Microclimate and Building Energy in High-Density Cities for Early Stage Design

An Integrated Model for Urban Microclimate and Building Energy in High-Density Cities for Early Stage Design

Hong Kong SAR China 2 Architectural Science Group, Welsh School of Architecture, Cardiff University, UK Abstract The energy performance of an urban building depends on its surroundings. Existing building energy models are limited in accounting for micro-scale variations of the surrounding environment, which may significantly modify building energy performance in high-density cities. Modeling of building energy at urban scale remains a nascent field. This paper presents an integrated urban microclimate (UMM) and building energy model (HTB2), which has been developed to assess the energy performance of a cluster of buildings and their external environments in high-density cities. The simulation results were evaluated by comparison with field measurement data collected from the Sai Ying Pun neighbourhood in Hong Kong. The model has potentials to support building design and urban planning at early stage.
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An integrated model for urban microclimate and building energy in high-density cities for early stage design

An integrated model for urban microclimate and building energy in high-density cities for early stage design

Introduction A building and urban microclimate are highly interconnected in cities. From a thermal perspective, the building modifies its surrounding microclimate, affecting sunlight, wind, and temperature. This modification in turn affects its own energy performance and those buildings nearby. Overshadowing by neighbouring buildings affects solar radiation incident on the buildings facades; temperature fluctuation of external wall surfaces modifies long-wave heat exchanges; wind shadowing affects external heat flux. Air temperature in street canyons can rise 4-6 °C above those of the rural areas (Nichol 2005), which will affect building energy performance as well as external
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Spatial configuration, building microclimate and thermal comfort

Spatial configuration, building microclimate and thermal comfort

courtyard (0.09 m/s) and the point in the living room (0.04 m/s). Figure 6.10(f) shows the hourly average wind velocity at the measured points and the wind velocity recorded by the nearest weather station. The weather station wind velocity was much higher than the measured wind velocity in this specific building microclimate, owning to the location of the weather station in the open field, where it catches more wind. Another finding was that the outdoor wind velocity was irregular compared to the measured points in the building, which followed the temperature trends. Most of the time, the wind velocity in the courtyard was the highest in the building environment due to the fact that it is an outdoor space that easily catches the wind from all directions. The measured wind velocity at the points near patio1 and patio2 was higher than at the point in the living room, indicating both a low level of cross ventilation on the ground floor and that the stack ventilation in the patio contributed to the process of natural ventilation. In other words, the spatial diversity enhanced the natural ventilation. The results show that the wind velocity distribution is varied in the building.
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Impact of Street Canyon Geometry on Outdoor Thermal Comfort and Weather Parameters in Pécs

Impact of Street Canyon Geometry on Outdoor Thermal Comfort and Weather Parameters in Pécs

4. Methodology The importance of new green branches of science aiming to find solutions to environmental challenges has been internationally considered as undisputable [7]. Numerical simulations using ENVI-met code were applied due to its high capabilities and few data entries. The program uses a three-dimensional computational fluid dynamics and energy balance model; the simulation study can analyze unlimited number of points in the model. It is used to simulate the impact of certain urban design strategies on thermal comfort at a certain location [8]. Nonetheless, the study is limited to the moderately warm-wet climate of Pecs. Although some of the findings may be generalized, the conclusions of the study are not necessarily valid throughout moderately warm-wet climate groups, since there are climatic and considerable variations between different cities in terms of size, planning principles, proximity to the sea, and topography, etc. Moreover, visual and acoustical comfort performance is not investigated here. Moreover, due to the diverse scenarios and meteorological conditions, the field measurements could not give the total conclusion. In contrast, the Computational Fluid Dynamics (CFD) simulation method plays an important role in the research because of its means of modeling simplified and optimized. However, the methodology will be divided into four sections first one is describing the selected study site, second analyzing the street canyons of the chosen case, and summarizing the street canyon of the case study features, third, applying the ENVI-met software to simulate the urban microclimate with different street canyon geometries. Nevertheless, fourth section discusses the simulated results as well as draws the related conclusion.
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Variations in household microclimate affect outdoor-biting behaviour of malaria vectors

Variations in household microclimate affect outdoor-biting behaviour of malaria vectors

the exophilic behaviour of Anopheles species The GLMM with a binomial response variable (representing the proportion of mosquitoes caught outside) indicated that the relative difference in microclimatic conditions between indoor and outdoor environments had an impact on the degree of exoph- ily in An. arabiensis. When temperatures were higher indoors compared to outdoors, the odds of exophily increased by ~26% in An. arabiensis for every one unit increase in temperature differential ( Table 5 and Figure 4 ). In contrast, for a one unit increase in the differential between indoor and outdoor humidity, the odds of exophily decreased by 6% ( Table 5 and Figure 4 ), within the limits of our microclimate measurements. There was an interaction between temperature differences ( ΔT) and humidity differences ( ΔRH). This interaction had the impact of increasing the degree to which exophily was enhanced by the indoor vs. outdoor temperature differential, when there was also a bigger difference in humidity between these habitats ( Table 5 ). In contrast, the proportion of An. funestus biting outdoors was not significantly related to temperature ( ΔT) or humidity (ΔRH) difference between indoors and outside ( Table 5 and Figure 4 ). Predictions for the seasonal abundance and biting behaviour of Anopheles mosquitoes
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Ensuring the parameters of microclimate of hothouses during a warm 
		season

Ensuring the parameters of microclimate of hothouses during a warm season

On the basis of justification of the heat and mass transfer processes inside the hothouses during a warm season authors developed methods and means that control dynamics of temperature and humidity parameters and air conditions with the help of complex systems of removal of overheat in hothouses during the all year round and diurnal operations at minimum power inputs.

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Analysis of Outdoor Human Thermal Comfort within Three Major Cities in Egypt

Analysis of Outdoor Human Thermal Comfort within Three Major Cities in Egypt

In this study, two thermal comfort indices are employed to investigate outdoor human thermal comfort within three major cities of different climates in Egypt. The indices are: the Discomfort Index (DI), and the Robaa Index (RI). The three considered cities are: Alexandria which is located in the north of Egypt, Cairo which is located in the middle and Aswan city which is located in the south of Egypt. The estimations of the two indices are based on the mean wind data of the three ci- ties, which covers the period from January 2010 to January 2011. The study results show that the thermal comfort indices values can be employed to evaluate climate differences in urban areas. The calculated indices showed that; although extreme climate conditions are not reached in Egypt in general, the climate in the north is milder than in the south. In addition, the study results show that the RI is more practical than DI in assessing the human thermal comfort in the outdoor envi- ronment.
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Neutral thermal sensation or dynamic thermal comfort? Numerical and field test analysis of a thermal chair

Neutral thermal sensation or dynamic thermal comfort? Numerical and field test analysis of a thermal chair

c Department of Mechanical Engineering, University of Sheffield, S10 2TN, UK Abstract Neutral thermal sensation is considered as the measure of thermal comfort in research, as when participants report feeling neutral regarding the thermal environment, they are considered as thermally comfortable. This is taken for granted, and although a few researchers have criticised the matter, still researchers use thermal sensation and the neutral point to assess the thermal conditions in their studies. This study questions the application of thermal neutrality and consequently poses a question on the findings of all the studies that only rely on it. Field studies of thermal comfort were applied in an open plan office in the UK in the winter of 2014. Participants were provided with a thermal chair and before and after using the chair, their views of comfort were recorded, including the ASHRAE seven point scale of thermal sensation, thermal preference, comfort, and satisfaction. The thermal environment was measured and compared against the ASHRAE Standard 55-2013. In addition, numerical modelling was also conducted to investigated the airflow and thermal distribution around the proposed thermal chair with a seated occupant. The results indicated that overall, 72% of the respondents, who did not feel neutral (thermal sensation) before or after using the thermal chair reported to feel comfortable and 65% reported to be satisfied. The results indicated that a neutral thermal sensation does not guarantee thermal comfort of the occupants and that thermal comfort is dynamic and other thermal sensations need to be considered. This study recommends the use of multiple methods (e.g. thermal, preference, decision, comfort, and satisfaction) to assess thermal comfort more accurately. Also, it questions the findings of any research that solely relies on thermal sensation and particularly on the neutral thermal sensation to assess thermal comfort of the occupants. The results also emphasised the importance of the application of numerical modelling in evaluating the thermal performance of the chair.
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Neutral thermal sensation or dynamic thermal comfort? Numerical and field test analysis of a thermal chair

Neutral thermal sensation or dynamic thermal comfort? Numerical and field test analysis of a thermal chair

This study investigated the accuracy of neutral thermal sensation as the measure of thermal comfort through the application of a thermal chair. The prototype of an office chair equipped with heat pads on the seat and the back of the chair with separate temperature controls was designed [23], as illustrated in Figure 2. The application of this thermal chair was examined through field studies of thermal comfort in an open plan office in the University of Leeds in the winter of 2014, where 44 occupants with mainly sedentary activities participated in the research. This was the real context of the office and participants continued with their normal everyday activities during the study. Respondents were mainly in their twenties and thirties and they included 15 females and 19 males. Their views of comfort, satisfaction and thermal comfort (presented in Table 1) were recorded before and after an hour of using the thermal chair, as presented in Figure 2. As explained separate manual control systems were provided for the seat and the back of the chair and occupants were briefed on using them. The temperature settings of the chair for every participant were recorded and the satisfaction of the respondents regarding the use of the thermal chair was investigated. A good practice example of the workplace with a good quality of thermal environment was selected for this study to limit the impact of the thermal environment on occupants’ thermal decision. For this reason, the thermal environment was measured (dry bulb temperature, humidity and mean radiant temperature). Accordingly, the PMV was calculated and it was compared against the ASHRAE Standard 55-2013, which was satisfactory.
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Thermal sensation and comfort model for inhomogeneous indoor environments

Thermal sensation and comfort model for inhomogeneous indoor environments

2 Human physiology 2.1 Introduction Human physiology has been a topic of interest for a very long time. In the beginning, interest was focussed on a crude understanding of the human body’s thermal state and its boundary condi- tions. Later, internal processes became more important. Alcmaeon of Crotona (6th century B.C.) was the first to suggest that good health is only possible within an equilibrium of forces: wet and dry, cold and hot, bitter and sweet. If one of these forces dominates, it causes disease and de- struction (Chato [1992]). The development of accurate techniques for measuring body temper- ature during the 19th century marked a big step towards a deeper understanding of the human organism. Robert Mayer (1814 - 1878) discovered that heat and mechanical energy are related (Shitzer and Eberhardt [1985]). Max Rubner (1854 - 1932) examined the calorific value of food and proved that animal heat was entirely derived from the metabolism of carbohydrate, fat, and protein (Ihde and Janssen [1974]). Research on the physiological regulation of core temperature also made progress. The groundwork was laid by Bladgen’s discovery (1774) that body tempera- ture remained fairly constant in spite of exposure to extremely dry heat. He postulated that control was exerted through nerves that not only caused vasoconstriction or vasodilation, but also a corre- sponding local decrease or increase in metabolism (Shitzer and Eberhardt [1985]). In the early 20th century, substantial evidence suggesting that heat generation and heat rejection were controlled by the nervous system emerged. Starting from this initial crude mapping, Ranson [1939] identified the hypothalamus as a major site of temperature regulation.
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Microclimate change outdoor and indoor coupled simulation for passive building adaptation design

Microclimate change outdoor and indoor coupled simulation for passive building adaptation design

This paper reports on an initial study of how to deploy passive building design strategy adaptive to climate change scenarios at urban neighbourhood level which is not well understood. To investigate the interaction between them, a microclimate change simulation framework is proposed, showing a series of numerical modelling and prognostic visualization (section 4). It is conducted to show an impact of recent (2012) and future microclimate change (2050) on an existing green building in the University of Sheffield campus as a case study. In addition, a passive building adaptation design strategy in response to the projected microclimate change is conducted. Also, the energy demand to maintain indoor thermal comfort is calculated. Before carrying out the microclimate change modelling tasks, to confirm the methodological appropriateness of the simulation framework and to apply it into passive building adaptation design, a likely performance comparison between simulation result and historical monitored data is presented (section 3).
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The Effects of Design Parameters on the Thermal Response of an LBE Capsule

The Effects of Design Parameters on the Thermal Response of an LBE Capsule

The development of a SFR as one of the advanced reactor systems in Korea requires high temperature irradiation tests of new fuels, claddings, and structural materials. Literature surveys about the system design characteristics of various irradiation devices being developed or used in foreign research reactors were conducted to develop new design concepts. One of the candidate thermal media was selected as an LBE (Lead-Bismuth Eutectic) for the high temperature irradiation devices. Under the current HANARO capsule design practice, in order to evaluate the relative significance of the various parameters on a thermal response, the temperature calculations for the concept of a capsule using an LBE were performed using a finite element analysis program, ANSYS. The analysis model for a circular cylinder with multi specimens is generated by the coupled-field elements of PLANE223 with a 2-D structural-thermal field. The results of these studies indicated that the gap between the LBE container and the external tube can have a great impact on the thermal response. However, variations in the gap size between a specimen and a specimen’s holder and the thickness of a holder material seem to have no significant effect on the specimen temperature. The results could be used for developing a new capsule for a high temperature irradiation test.
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