Thermal comfort, skin temperature distribution, and sensible heat loss distribution in the sitting posture in various asymmetric radiant fields

2007 ◽  
Vol 42 (12) ◽  
pp. 3984-3999 ◽  
Author(s):  
Tomonori Sakoi ◽  
Kazuyo Tsuzuki ◽  
Shinsuke Kato ◽  
Ryozo Ooka ◽  
Doosam Song ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Thermal Comfort ◽  
Skin Temperature ◽  
Heat Loss ◽  
Sensible Heat ◽  
Loss Distribution ◽  
Sitting Posture

scholarly journals The Effects on Thermal Efficiency of Yttria-Stabilized Zirconia and Lanthanum Zirconate-based Thermal Barrier Coatings on Aluminum Heating Block for 3d Printer

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 792
Author(s):  
Hasan Demir
Keyword(s):  
Temperature Distribution ◽  
Heat Loss ◽  
Yttria Stabilized Zirconia ◽  
Thermal Barrier ◽  
Print Quality ◽  
Stabilized Zirconia ◽  
Coating Materials ◽  
Lanthanum Zirconate ◽  
Barrier Coating ◽  
Coating Method

Fused filament fabrication is an important additive manufacturing method, for which 3D printers are the most commonly used printing tools. In this method, there are many factors that affect the printing quality, chief among which is temperature. The fusion temperature of the material is created by an aluminum heating block in the extruder. Stability and a constant temperature for the aluminum heating block are inevitable requirements for print quality. This study aims to use the thermal barrier coating method to increase the thermal efficiency and stability of the aluminum heating block by reducing heat loss. Furthermore, it aims to perform steady-state thermal analysis using finite element analysis software. The analyses are carried out in stagnant air environment and at the printing temperature of acrylonitrile butadiene styrene material. In order to examine the effects of different coating materials, blocks coated with two different coating materials, as well as uncoated blocks, were used in the analyses. The coating made with yttria-stabilized zirconia and pyrochlore-type lanthanum zirconate materials, together with the NiCRAl bond layer, prevent temperature fluctuation by preventing heat loss. The effects of the coating method on average heat flux density, temperature distribution of blocks, and temperature distribution of the filament tube hole were investigated. Additionally, changes in flow velocity were determined by examining the effects of the thermal barrier coating method on temperature distribution. The average heat flux density in the coated blocks decreased by 10.258%. Throughout the investigation, the temperature distributions in the coated blocks became homogeneous. It was also observed that both coating materials produce the same effect. This article performs a steady-state thermal analysis of a conventional model and thermal-barrier-coated models to increase print quality by reducing heat loss from the aluminum heating block.

Air movement and heat loss from sheep. II. Thermal insulation of fleece in wind

1980 ◽  
Vol 209 (1175) ◽  
pp. 209-217 ◽  
Keyword(s):  
Thermal Diffusivity ◽  
Heat Loss ◽  
Thermal Insulation ◽  
General Relation ◽  
Windward Side ◽  
Leeward Side ◽  
Sensible Heat ◽  
Bulk Resistance ◽  
Air Movement ◽  
Dimensionless Constant

Penetration of an animal’s coat by wind reduces its thermal insulation and increases heat loss to the environment. From studies of the sensible heat loss from a life-sized model sheep covered with fleece, the average fleece resistance r¯ f (s cm -1 ) was related to windspeed u (m s -1 ) by 1/ r¯ f ( u ) = l/ r¯ f (0) + cu , where c is a dimensionless constant. As c is expected to be inversely proportional to coat depth Î , the more general relation k¯ ( u ) = k¯ (0) + c'u was evaluated, where k¯ = Î / r¯ f is the thermal diffusivity (cm 2 s -1 ) of the fleece and c' = cÎ is another constant (cm). The orientation of the model to the wind had little effect on the bulk resistance of the fleece, but the resistance on the windward side was substantially lower than on the leeward side.

scholarly journals Prediction human skin temperature in comfort level

2019 ◽  
Vol 1 (3) ◽  
pp. 1-4
Author(s):  
Zaina Norhallis Zainol ◽  
Masine Md. Tap ◽  
Haslinda Mohamed Kamar
Keyword(s):  
Thermal Comfort ◽  
Skin Temperature ◽  
Human Skin ◽  
Blood Perfusion ◽  
Comfort Level ◽  
Working Environment ◽  
Percentage Error ◽  
Bioheat Equation ◽  
Acceptable Error ◽  
Human Arm

Thermal comfort is the human subject perceive satisfaction to the work environment. The thermal comfort need to be achieve towards productive working environment. The comfort level of the subject is affected by the human skin temperature. To assess the skin temperature with the sorrounding by conducting human experiment in the climatic chamber. It is rigorous and complex experiment.This study was developed to predict human skin temperature in comfort level with the finite element method and the bioheat equation. The bioheat equation is a consideration of metabolic heat generation and the blood perfusion to solve heat transfer of the living tissue. It is to determine the skin temperature focussing at the human arm. From the study, it is found that the predicted skin temperature value were in well agreement with the experimental results. The percentage error insignificant with acceptable error of 1.05%.

scholarly journals Thermal Comfort Modeling of a Church Heated with Static Heaters

2019 ◽  
Vol 9 (1) ◽  
pp. 121-124
Author(s):  
Florin-Emilian Turcanu ◽  
Ana Diana Ancas ◽  
Mihai Profire ◽  
Marina Verdes ◽  
Marius Costel Balan
Keyword(s):  
Temperature Distribution ◽  
Thermal Comfort ◽  
Heating System ◽  
Xviii Century ◽  
Static Heating ◽  
The Impact ◽  
The Church

Abstract This paper evaluates a static heating system from a church. They are presented in almost every church. Temperature distribution in the church is done in 2d plane. The simulation is presented on a particular example, the Dormition of the Mother of God Church from Jassy, Romania. The heating system had been simulated in FLUENT and the consequences over the interior climate in the church are showed. An important issue is the impact of this system over the artwork, the church being rise in XVIII century.

scholarly journals How representative are FLUXNET measurements of surface fluxes during temperature extremes?

2018 ◽  
Author(s):  
Sophie V. J. van der Horst ◽  
Andrew J. Pitman ◽  
Martin G. De Kauwe ◽  
Anna Ukkola ◽  
Gab Abramowitz ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Latent Heat ◽  
Net Ecosystem Exchange ◽  
The United States ◽  
Fair Use ◽  
Heat Fluxes ◽  
Temperature Extremes ◽  
Measured Temperature ◽  
Sensible Heat ◽  
Lower Tail

Abstract. In response to a warming climate, temperature extremes are changing in many regions of the world. Therefore, understanding how the fluxes of sensible heat, latent heat and net ecosystem exchange respond and contribute to these changes is important. We examined 216 sites from the open access Tier 1 FLUXNET2015 and Free-Fair-Use La Thuile datasets, focussing only on observed (non-gap filled) data periods. We examined the availability of sensible heat, latent heat and net ecosystem exchange observations coincident in time with measured temperature for all temperatures, and separately for the upper and lower tail of the temperature distribution and expressed this availability as a measurement ratio. We showed that the measurement ratios for both sensible and latent heat fluxes are generally lower (0.79 and 0.73 respectively) than for temperature, and the measurement ratio of net ecosystem exchange measurements are appreciably lower (0.42). However, sites do exist with a high proportion of measured sensible and latent heat fluxes, mostly over the United States, Europe and Australia. Few sites have a high proportion of measured fluxes at the lower tail of the temperature distribution over very cold regions (e.g. Alaska, Russia) and at the upper tail in many warm regions (e.g. Central America and the majority of the Mediterranean region), and many of the world’s coldest and hottest regions are not represented in the freely available FLUXNET data at all (e.g. India, the Gulf States, Greenland and Antarctica). However, some sites do provide measured fluxes at extreme temperatures suggesting an opportunity for the FLUXNET community to share strategies to increase measurement availability at the tails of the temperature distribution. We also highlight a wide discrepancy between the measurement ratios across FLUXNET sites that is not related to the actual temperature or rainfall regimes at the site, which we cannot explain. Our analysis provides guidance to help select eddy covariance sites for researchers interested in exploring responses to temperature extremes.

scholarly journals Effects of skin heat conduction on aircraft icing process

2020 ◽  
pp. 095441002097257
Author(s):  
Xiaobin Shen ◽  
Yu Zeng ◽  
Guiping Lin ◽  
Zuodong Mu ◽  
Dongsheng Wen
Keyword(s):  
Heat Conduction ◽  
Temperature Distribution ◽  
Skin Temperature ◽  
Accretion Rate ◽  
Skin Surface ◽  
Ice Thickness ◽  
Ice Accretion ◽  
Aircraft Icing ◽  
Outer Skin ◽  
Lateral Heat

During the aircraft icing process caused by super-cooled droplet impingement, the surface temperature and heat flux distributions of the skin would vary due to the solid substrate heat conduction. An unsteady thermodynamic model of the phase transition was established with a time-implicit solution algorithm, in which the solid heat conduction and the water freezing were analyzed simultaneously. The icing process on a rectangular skin segment was numerically simulated, and the variations of skin temperature distribution, thicknesses of ice layer and water film were obtained. Results show that the presented model could predict the icing process more accurately, and is not sensitive to the selection of time step. The latent heat released by water freezing affects the skin temperature, which in turn changes the icing characteristics. The skin temperature distribution would be affected notably by the boundary condition of the inner skin surface, the lateral heat conduction and thermal property of the skin. It was found that the ice accretion rate of the case that the inner surface boundary is in natural convection at ambient temperature is much smaller than that with constant ambient temperature there; due to the skin lateral heat conduction, the outer skin surface temperature increases first and then decreases with uneven distribution, leading to an unsteady ice accretion rate and uneven ice thickness distribution; a smaller heat conductivity would lead to a more uneven temperature distribution and a lower ice accretion rate in most regions, but the maximum ice thickness could be larger than that of higher heat conductivity skin. Therefore, in order to predict the aircraft icing phenomenon more accurately, it is necessary to consider the solid heat conduction and the boundary conditions of the skin substrate, instead of applying a simple boundary condition of adiabatic or a fixed temperature for the outer skin surface.

scholarly journals Determining Favourable and Unfavourable Thermal Areas in Seoul Using In-Situ Measurements: A Preliminary Step towards Developing a Smart City

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2320 ◽  
Author(s):  
You Jin Kwon ◽  
Dong Kun Lee ◽  
Kiseung Lee
Keyword(s):  
Land Cover ◽  
Thermal Comfort ◽  
Thermal Environment ◽  
Smart Cities ◽  
Distribution Data ◽  
Sensible Heat ◽  
Residential Areas ◽  
Coverage Ratio ◽  
Study Results

Urban heat island effects (UHIE) are becoming increasingly widespread, thus, there is an urgent need to address thermal comfort, which significantly influences the daily lives of people. In this study, a means of improving the thermal environment by spatial analysis of heat was implemented to ensure basic thermal comfort in future smart cities. Using Seoul as the study site, the relationship between sensible heat and land cover type was used to identify heat islands in this city. Thereafter, k-means clustering was employed to extract unfavourable and favourable thermal areas. High sensible heat indicates locations where environmental heat needs to be mitigated. Sensible heat distribution data were used for spatial typification to formulate an effective land cover factor to mitigate the UHIE. In-situ net radiation data measured at six sites were utilised to confirm the spatial typification of the thermal environment. It was found that expanding the green space by 1% reduces the sensible heat by 4.9 W/m2. Further, the building coverage ratio and green coverage influence the sensible heat in compact residential areas. The study results can be used to establish spatial planning standards to improve the thermal environments of sustainable cities.

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