scholarly journals A Review On: Analysis Of The Properties Of Thermal Insulation Materials

2021 ◽  
Vol 03 (05) ◽  
pp. 27-38
Author(s):  
Azim Rasulovich Abdullaev ◽  
◽  
Xayotbek Mansurjon O’g’li Rafiqov ◽  
Isroiljonova Nizomjon Qizi Zulxumor ◽  
◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Comfort ◽  
Thermal Insulation ◽  
Body Position ◽  
Thermal Contact ◽  
Body Parts ◽  
Clothing Insulation ◽  
Human Thermal Comfort ◽  
Object Shapes ◽  
Materials Used

Clothing insulation is one of the important factors of human thermal comfort assessment. Thermal insulation is the reduction of heat transfer (i.e., the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radioactive influence. Thermal insulation can be achieved with specially engineered methods or processes, as well as with suitable object shapes and materials. Heat flow is an inevitable consequence of contact between objects of different temperature. Thermal insulation provides a region of insulation in which thermal conduction is reduced or thermal radiation is reflected rather than absorbed by the lower-temperature body. The term thermal insulation can refer to materials used to reduce the rate of heat transfer, or the methods and processes used to reduce heat transfer. Heat energy can be transferred by conduction, convection, radiation or when undergoing a phase change. For the purposes of this discussion only the first three mechanisms need to be considered. The flow of heat can be delayed by addressing one or more of these mechanisms and is dependent on the physical properties of the material employed to do this. Predicting the pattern of clothing adjustment to climate change can provide important basis for thermal comfort and energy consumption analysis. To achieve reliable results, it is necessary to provide precise inputs, such as clothing thermal parameters. These values are usually presented in a standing body position and scarcely reported locally for individual body parts. Moreover, as an air gap distribution is both highly affected by a given body position and critical for clothing insulation, this needs to be taken into account.

scholarly journals Genetic Algorithm Applied to Multi-Criteria Selection of Thermal Insulation on Industrial Shed Roof

Buildings ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 238 ◽  
Author(s):  
Stamoulis ◽  
Santos ◽  
Lenz ◽  
Tusset
Keyword(s):  
Genetic Algorithm ◽  
Thermal Comfort ◽  
Thermal Insulation ◽  
Optimization Technique ◽  
Building Envelope ◽  
Expanded Polystyrene ◽  
Insulation Material ◽  
Clothing Insulation ◽  
Climate Conditions ◽  
Selection Of

The rational use of energy has motivated research on improving the energy efficiency of buildings, which are responsible for a large share of world consumption. A strategy to achieve this goal is the application of optimized thermal insulation on a building envelope to avoid thermal exchanges with the external environment, reducing the use of heating, ventilation and air-conditioning (HVAC) systems. In order to contribute to the best choice of insulation applied to an industrial shed roof, this study aims to provide an optimization tool to assist this process. Beyond the thermal comfort and cost of the insulation, some hygrothermic properties also have been analysed to obtain the best insulation option. To implement this optimization technique, several thermo-energetic simulations of an industrial shed were performed using the Domus software, applying 4 types of insulation material (polyurethane, expanded polystyrene, rockwool and glass wool) on the roof. Ten thicknesses ranging from 0.5 cm to 5 cm were considered, with the purpose of obtaining different thermal comfort indexes (PPD, predicted percentage dissatisfied). Posteriorly, the best insulation ranking has been obtained from the weights assigned to the parameters in the objective function, using the technique of the genetic algorithm (GA) applied to multi-criteria selection. The optimization results showed that polyurethane (PU) insulation, applied with a thickness of 1 cm was the best option for the roof, considering the building functional parameters, occupant metabolic activity, clothing insulation and climate conditions. On the other hand, when the Brazilian standard was utilized, rock wool (2 cm) was considered the best choice.

Transient Human Thermal Comfort Response in Convective and Radiative Environments

2008 ◽  
Author(s):  
Mohamad Al-Othmani ◽  
Nesreen Ghaddar ◽  
Kamel Ghali
Keyword(s):  
Thermal Comfort ◽  
Thermal Conditions ◽  
Activity Level ◽  
Convective Heating ◽  
Convective System ◽  
Clothing Insulation ◽  
Indoor Space ◽  
Human Thermal Comfort ◽  
Walking Activity ◽  
Local Thermal Comfort

In this work, human transient thermal responses and comfort are studied in non-uniform radiant heating and convective heating environments. The focus was on a change from walking activity of human in outdoor cold environment at high clothing insulation to warm indoor environment at sedentary activity level associated with lower clothing insulation. A transient multi-segmented bioheat model sensitive to radiant asymmetry is used to compare how fast the human body approaches steady state thermal conditions in both radiative and convective warm environments. A space thermal model is integrated with the bioheat model to predict the transient changes in skin and core temperature of a person subject to change in metabolic rate and clothing insulation when entering conditioned indoor space. It was found that overall thermal comfort and neutrality were reached in 6.2 minutes in the radiative environment compared to 9.24 minutes in convective environment. The local thermal comfort of various body segments differed in their response to the convective system where it took more than 19 minutes for extremities to reach local comfort unlike the radiative system where thermal comfort was attained within 7 minutes.

Effects of Clothing Ventilative Designs on Thermal Insulation under Varying Wind Conditions

2011 ◽  
Vol 332-334 ◽  
pp. 1927-1930 ◽  
Author(s):  
Xiang Hui Zhang ◽  
Jun Li
Keyword(s):  
Experimental Investigation ◽  
Thermal Comfort ◽  
Thermal Insulation ◽  
The Body ◽  
Thermal Manikin ◽  
Clothing Insulation ◽  
Vertical Side ◽  
Wind Velocities ◽  
Heat And Moisture ◽  
Body Heat

This paper reports on an experimental investigation of the effects of clothing ventilative designs on thermal comfort measured in terms of thermal insulation. Eight T-shirts with varying areas and locations of mesh fabric were designed and produced for testing on a dry thermal manikin. Clothing thermal insulation of T-shirts was measured under three wind velocities: 0.5, 1 and 2m/s. The results showed that, the areas and locations of ventilation panels affect the total thermal insulation. The T-shirts with larger area of mesh fabric are preferable in terms of releasing more body heat. Among various designs tested, mesh fabrics applied at two vertical side seams can most effectively release heat and moisture from the body. Clothing insulation is also greatly affected by wind.

scholarly journals Role of Clothing Insulation for Thermal Comfort: A Numerical Study using Bio-Heat Transfer Model

2020 ◽  
Vol 16 (1) ◽  
pp. 224-232
Author(s):  
Kabita Luitel ◽  
Dil Bahadur Gurung ◽  
Harihar Khanal ◽  
Kedar Nath Uprety
Keyword(s):  
Heat Transfer ◽  
Thermal Comfort ◽  
Numerical Study ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Clothing Insulation

A Human Energy Balance Model With Clothing Effects for Estimating Human Thermal Comfort

2010 ◽  
Author(s):  
Atsumasa Yoshida ◽  
Yasuhiro Shimazaki ◽  
Shinichi Kinoshita ◽  
Ryota Suzuki
Keyword(s):  
Heat Transfer ◽  
Energy Balance ◽  
Thermal Comfort ◽  
Human Body ◽  
Thermal Load ◽  
Thermal Environment ◽  
Energy Balance Model ◽  
Balance Model ◽  
Comfort Index ◽  
Human Thermal Comfort

There is an increased world attention on environmental issues with the global trend of environmental degradation. Especially thermal environment was highly concerned as human safety. We have been focused on creation of amenity environment with energy-saving way. This study is uncommonly dealing with human feeling for human thermal comfort, that is to say quantification of environment has been done. The feeling of comfort is mixed sense and can be totally easier to improve compared with straightforward way, and this may lead to energy and cost saving way of improvement. Moreover, this is human-oriented and can reflect humans’ wishes. Since thermal comfort index is useful tool for understanding the present state and evaluating the impact of countermeasures, effectiveness of human thermal load which is thermal comfort index based on energy balance of human body was examined. The human thermal comfort around the human body in outdoor is influenced by six dominant factors; air temperature, humidity, solar radiation, wind speed, metabolism and clothing. The difference between indoor and outdoor is expressed mainly as non-uniform and unsteady. Therefore, the unsteady responses of each dominant factors were examined and clarified human thermal load is quite good estimation of human thermal comfort. In steady state and even in unsteady state, thermal comfort can be obtained by using human thermal load on the whole. The reason is human thermal load consider the amount of physiology and also weather parameters. In the process of creating energy balance model of human, clothing material was deeply considered. For establishing better thermal environment, clothing material is of great use, because clothing material has an impact on thermal exchange between exterior environment and human body and more easy way to improve in 6 factors. The traditional treatment of clothing in human science was only resistance of heat transfer and this was not enough for all clothing effects. In daily life, effect of humidity exists and moisture property is required. Moreover color of material has impact on energy balance in clothing material. In order to show a way of better thermal environment, the heat and the moisture transfer coefficients on clothing material, radiative properties, and additional properties such as convection heat transfer coefficient were measured, and energy flow of clothing material was totally investigated. Finally, the effects of clothing material for human thermal comfort were predicted and this energy balance human model has become much better model.

scholarly journals Calculating human thermal comfort and thermal stress in the PALM model system 6.0

2019 ◽  
Author(s):  
Dominik Fröhlich ◽  
Andreas Matzarakis
Keyword(s):  
Thermal Comfort ◽  
City Planning ◽  
Model System ◽  
Climate Index ◽  
Mean Radiant Temperature ◽  
Clothing Insulation ◽  
Human Thermal Comfort ◽  
Model Based ◽  
Perceived Temperature ◽  
Radiant Temperature

Abstract. In the frame of the project MOSAIK – Model–based city planning and application in climate change, a German-wide research project within the call Urban Climate Under Change ([UC]2) funded by the German Federal Ministry of Education and Research (BMBF), a biometeorology module was implemented into the PALM model system. The new biometeorology module comprises of methods for the calculation of uv-exposure quantities, a human–biometeorologically weighted mean radiant temperature (Tmrt), as well as for the estimation of human thermal comfort or stress. The latter is achieved through the implementation of the three widely–used thermal indices Perceived Temperature (PT), Universal Thermal Climate Index (UTCI), as well as Physiologically Equivalent Temperature (PET) together with a newly developed instationary index instationary Perceived Temperature (iPT) based on PT for use with the multi–agent model. Comparison calculations were performed for the indices PT, UTCI and PET based on the SkyHelios model and showing PALM calculates higher values in general. This is mostly due to a higher radiational gain leading to higher values of mean radiant temperature. For a more direct comparison, the indices PT, PET and UTCI were calculated by the biometeorology module, as well as the programs provided by the attachment to the VDI guideline 3787, as well as by the RayMan model based on the very same input dataset. Results show deviations below rounding precision (less than 0.1 K) for PET and UTCI and some deviations of up to 2.683 K for PT caused by rounding leading to the selection of a different clothing insulation step in very rare cases (0.027 %).

Experimental study on the thermal regulation performance of winter uniform used for high school students

2018 ◽  
Vol 89 (12) ◽  
pp. 2316-2329 ◽  
Author(s):  
Peijing Li ◽  
Yun Su ◽  
Qianqian Huang ◽  
Jun Li ◽  
Jingxian Xu
Keyword(s):  
High School ◽  
High School Students ◽  
Thermal Comfort ◽  
Thermal Insulation ◽  
Thermal Sensation ◽  
Uniform Design ◽  
Outdoor Environment ◽  
Human Thermal Comfort ◽  
School Uniform ◽  
Indoor And Outdoor

To understand the effectiveness of some garment adjustment designs for high school uniform in winter, manikin tests and subjective wear trials were carried out. Five series of school uniform ensembles were involved in the experiments. They were further collocated into 17 ensemble configurations with detachable designs (ensembles A and B) and opening structures (ensembles C, D, and E). As manikin test results showed, the thermal insulation of ensembles A, B and C varied most significantly due to their adjustment design. The possible thermal insulation regulation levels were approximately 68% and 80% for ensembles A and B, and 60% and 90% for ensemble C. Two human trials that simulated students’ daily movements between indoor and outdoor classes were conducted with ensemble A. Two climate chambers were used at the same time for indoor and outdoor environment simulation. In Case X, where ensemble A was assumed to be non-detachable, skin temperatures that were 0.6℃ lower were finally observed compared to Case Y, where ensemble A was detachable. Moreover, significantly ( p < 0.1) better thermal comfort and thermal sensation evaluations were given during low-intensity activities in Case Y, especially for the torso segments. The detachable high school uniform design was finally proved to be efficient in improving human thermal comfort under various class environments. It was also concluded that more protective measures should be adopted for the hands and face in the school uniform design process.

scholarly journals An experiment to assess the heat transfer performance of thermoelectric-driven conditioned mattress

2021 ◽  
pp. 146-146
Author(s):  
Xiaxia Li ◽  
Liming Shen ◽  
Ying Huang
Keyword(s):  
Heat Transfer ◽  
Thermal Comfort ◽  
Temperature Control ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Cooling Performance ◽  
Water Pipes ◽  
Circulating Water ◽  
Human Thermal Comfort ◽  
Control Layer

This study sets out to describe the design, construction and testing of thermoelectric-driven conditioned mattress intended to reduce the human-mattress interface temperature, in order to satisfy the personal sleep thermal comfort requirements in hot conditions. A prototype of thermoelectric-driven conditioned mattress is constructed and tested. A series of experimental studies related to the temperature of different cushion layers and time from start-up to stable state have been carried out, specifically to analyze the difference in heat transfer performance of two types of temperature control layers (i.e., integral water cushion and circulating water pipes) in cooling operations. The steady-state results showed that, the type of temperature control layer and pre-set temperature exhibited a remarkable influence on the cooling performance of mattress. The mattress with integral water cushion had a superior cooling performance as compared to mattress with circulating water pipes under similar consitons. Specifically, the upper surface temperature of mattress with integral water cushion at the the pre-set temperature of 20?C, 18?C and 16?C were 1.97?C, 2.46?C and 3.08?C lower than indoor air temperature, respectively. Besides, the temperature contour maps of temperature control layer and upper cushion layer for two types of mattresses were constructed using the bilinear interpolation, respectively, thus expected to provide reference for the untested temperatures in this study. This study aims to effectively evaluate the heat transfer performance of the thermoelectric-driven conditioned mattress, and shows highly practical value in further applications of this system in improving human thermal comfort during sleep.

Evaluation of Human Thermal Comfort in Offices in Kuwait and Assessment of the Applicability of the Standard PMV Model

Volume 1 ◽  
2004 ◽  
Author(s):  
Nawaf Al-Mutawa ◽  
Walid Chakroun ◽  
Mohammad H. Hosni
Keyword(s):  
Thermal Comfort ◽  
Psychological Impact ◽  
Activity Level ◽  
Office Buildings ◽  
Clothing Insulation ◽  
Comfort Index ◽  
Human Thermal Comfort ◽  
The State Of Kuwait ◽  
Radiant Temperature ◽  
Velocity Turbulence

It has been known that the human thermal comfort is not exclusively a function of air temperature but also a function of six additional parameters, namely, mean radiant temperature, air velocity, turbulence intensity, humidity, activity level, and clothing insulation. The combined physical and psychological impact of these parameters on thermal comfort is mathematically described in various comfort models. The current comfort models, while use extensive human comfort data, may not be applicable in all world regions due to environmental conditions and people’s expectations. The State of Kuwait has a population of 2.5 million inhabitants with majority of people living in a few populated cities with heavy vehicle traffic, office buildings, factories, petroleum operations, and shopping centers. During the summer months (especially in July and August) the temperature reaches 48 °C in the afternoon, and can sometimes exceed 55 °C requiring extensive use of air conditioning. The traditional clothing (Disdasha) is made of lightweight, white, fabric material to provide some level of comfort. To better understand the regional preferences and assess the applicability of the standard comfort models in Kuwait, important parameters influencing human thermal comfort were measured in ten different government offices and the corresponding PMV indices were calculated. The results were compared with other comfort indices to obtain the most viable comfort index and the appropriate temperature range for local comfort for Kuwait offices. This study is not only important for comfort evaluations but also for evaluation of energy consumption in office buildings.

The effects of using ceiling fans on human thermal comfort in a three-dimensional room with centralized heating including an occupant

2019 ◽  
Vol 29 (10) ◽  
pp. 3976-3993 ◽  
Author(s):  
Mahdi Ashoori ◽  
Ghanbarali Sheikhzadeh ◽  
Soroush Sadripour
Keyword(s):  
Heat Transfer ◽  
Thermal Comfort ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Heating System ◽  
Considerable Effect ◽  
Content Type ◽  
Human Thermal Comfort ◽  
Air Speed ◽  
Comfort Condition

Purpose The purpose of this study is to analyze the effect of using a ceiling fan with central heating system in the winter on thermal comfort and heat transfer rate in a three-dimensional numerically. Design/methodology/approach The geometry had certain dimensions, and an occupant was modeled to be in the room. In models which were used, the flow was turbulent, and turbulence models were used for simulating turbulence. Between all the models, k-ε model had best matching. Findings Results show that using the ceiling fan during the winter had an efficient and considerable effect on improving the thermal comfort and energy saving inside buildings. By the use of ceiling fan, the effective room temperature has increased by 2.5°C. Furthermore, results show that by using ceiling fan in the winter, the predicted mean vote and the predicted percentage dissatisfied indexes improved. At the end, the case Room 11-0.05-15 with temperature of 87°C for radiator and normal fan velocity of o.25m/s were the optimal model that caused the complete thermal comfort and reduced energy consumption up to 28 per cent. Originality/value In the present study, the effects of using the ceiling fans on human comfort condition and heat transfer field during the winter (heating system) are studied. Following are the goals for all models: getting the appropriate temperature for radiator so that thermal comfort condition can be applied at the height of 75 cm of the room, velocity for fan so that air speed can be 0.25m/s at the height of 2 m or lower of the room and position to place the fan.

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