ASSESSMENT OF NON-VENTILATED AIR GAP IN SLOPING ROOF WITH THERMAL INSULATION ABOVE WOODEN RAFTERS

2019 ◽  
Author(s):  
Marek Jasek
Keyword(s):  
Thermal Insulation ◽  
Air Gap

Thermal insulations of multilayer clothing systems measured by a bench scale test in low level heat exposures

2014 ◽  
Vol 26 (5) ◽  
pp. 412-423 ◽  
Author(s):  
Ming Fu ◽  
Wenguo Weng ◽  
Hongyong Yuan
Keyword(s):  
Thermal Radiation ◽  
Thermal Insulation ◽  
Protective Clothing ◽  
Air Gap ◽  
Content Type ◽  
Low Level ◽  
Bench Scale ◽  
Scale Test ◽  
Fabric Layer ◽  
Bench Scale Test

Purpose – The purpose of this paper is to measure the thermal insulation of protective clothing with multilayer gaps in low-level heat exposures. Design/methodology/approach – Nine different combinations of protective clothing systems with multiple air gaps are used to measure the thermal insulation by a self-designed bench-scale test apparatus in different levels of an external thermal radiation of 2-10 kW/m2. The outside and inside surface temperatures of each fabric layer are also measured to calculate the local thermal insulation of each fabric layer and each air gap. Findings – The results show that the total thermal insulation of protective clothing under thermal radiation is less than that in normal environments, and the exposed thermal radiation will worsen the total thermal insulation of the multilayer fabric systems. Air gap plays a positive role in the total thermal insulation, and thus provides the enhanced thermal protection. It is also suggested that the local resistance of the air gap closer to the external thermal radiation is more easily affected by the thermal radiation, due to the different heat transfer ways in the fabric system and the external thermal radiation. Originality/value – Effects of air gap on the thermal insulation of protective clothing, and contribution of the local thermal resistance of each fabric layer and each air gap to the total thermal insulation.

scholarly journals Experimental Study of Using Thermal Insulation In Buildings Walls To Reduce Heating Load In Al - Kut City

2019 ◽  
Vol 26 (4) ◽  
pp. 30-40
Author(s):  
Sadiq Abdalnabee Kadhm ◽  
Hassan Kareem Abdullah
Keyword(s):  
Experimental Study ◽  
Thermal Insulation ◽  
Winter Season ◽  
Maximum Energy ◽  
Glass Wool ◽  
Air Gap ◽  
Night Time ◽  
South Wall ◽  
Heating Load ◽  
Room Model

Experimental study has been carried out on a small room model constructed from sandwich panel in Al-Kut city to reduce the heating load in winter season. Three types of thermal insulation were used; (Glass wool, Air gap and Sawdust). The room model dimensions were (2m length x2m width x2.4 m height). Room's south wall includes two openings of 0.3m width, 1m height. The first opening is closed by common bricks only, while the second opening is built with double walls from brick separated by thermal insulation of thickness 2cm. The results show that the maximum energy saving of heating load at night time when using thermal insulation were.69%, 58.4%, and 53.6%for glass wool, sawdust and Air gap respectively.

scholarly journals Studying Energy Performance and Thermal Comfort Conditions in Heritage Buildings: A Case Study of Murabba Palace

2021 ◽  
Vol 13 (21) ◽  
pp. 12250
Author(s):  
Abobakr Al-Sakkaf ◽  
Eslam Mohammed Abdelkader ◽  
Sherif Mahmoud ◽  
Ashutosh Bagchi
Keyword(s):  
Thermal Comfort ◽  
Thermal Insulation ◽  
Architectural Design ◽  
Energy Performance ◽  
Air Gap ◽  
Added Value ◽  
Passive Design ◽  
Heritage Buildings ◽  
Double Wall

Heritage buildings are significant historical and architecture added value, which requires deep and precise preliminary brainstorming when considering upgrading or retrofitting these valuable buildings. In this study, we opted to highlight some passive design architecture interventions to improve the thermal comfort and the required cooling energy for buildings. The Murabba Palace in Riyadh was selected as a case study. DesignBuilder software was used to evaluate the energy performance of ten passive architectural design alternatives throughout different seasons in an attempt to improve the energy performance and thermal comfort of heritage buildings. The ten passive design scenarios encompassed double low-E glass, double reflected glass, double low-E glass and double wall with an air gap, double low-E glass and double wall with thermal insulation, double low-E glass and double wall with lightweight thermal insulation, double low-E glass and double wall with sprayed foam insulation, double reflected glass and double wall with an air gap, double reflected glass and double wall with thermal insulation, double reflected glass and double wall with lightweight thermal insulation, and double reflected glass and double wall with sprayed foam insulation. The results show that using double low-E glass and applying a double wall with polystyrene thermal insulation can enhance the thermal comfort inside the building and reduce the energy performance and CO2 emissions to 17% and 9%, respectively.

Effects of athletic T-shirt designs on natural ventilation

2016 ◽  
Vol 20 (2) ◽  
pp. 112-123 ◽  
Author(s):  
Chupo Ho ◽  
Jintu Fan ◽  
Edward Newton ◽  
Raymond Au
Keyword(s):  
Thermal Insulation ◽  
Moisture Transfer ◽  
Design Method ◽  
Air Gap ◽  
Thermal Manikin ◽  
Heat And Moisture Transfer ◽  
Content Type ◽  
Heat And Moisture ◽  
Air Circulation ◽  
Moisture Vapour

Purpose Maintaining air circulation between the wearer and garment layer is crucial for activating heat and moisture transfer from the body. If an air gap is trapped, air circulation may become ineffective and the ventilation of the garment is, thus, hindered. To maintain and extend the air gap, this study aims to propose a design method that involves placing spacer blocks underneath the garment to prevent the fabric from clinging directly to the skin. Design/methodology/approach To study the application of this design method, a series of T-shirts were produced and tested using a thermal manikin in standing and walking postures. All the T-shirts were made of fabric ostensibly manufactured to have high air permeability. Porous mesh fabric was used to construct the vented panels on the T-shirts. The test was conducted in a chamber with controlled temperature, relative humidity and wind velocity. Total thermal insulation (Rt) and moisture vapour resistance (Ret) were measured. Findings The test results showed that extension of the air gap between wearer and fabric provided higher ventilation to the wearer if the vented panels were also present on the T-shirts. Different placements of the vented panels on the T-shirts also affected the heat and moisture transfer from the thermal manikin. Research limitations/implications Due to limited resources, the evaluation of total thermal insulation and moisture vapour resistance was based on the testing result from a thermal manikin instead of any subjective wearer trial. Practical implications This research can contribute to the clothing designer who is developing function wear for a better ventilation. Social implications This research can contribute to the clothing designer who is developing function wear for a better ventilation. Originality/value This study aimed to further develop a new design concept in T-shirt design by improving the construction of the spacer blocks. Fabric with higher air and water vapour permeability was used to determine to what extent this design method is applicable to higher performance on heat and moisture transfer.

Estimating the Residual Space between the Surfaces of Clothing and Human Body

2014 ◽  
Vol 556-562 ◽  
pp. 4705-4708
Author(s):  
Yi Jun Zhang ◽  
Yue Qi Zhong ◽  
Ji Ji ◽  
Zhen Wang ◽  
Yu Xiao Ji
Keyword(s):  
Noise Reduction ◽  
Surface Reconstruction ◽  
Thermal Insulation ◽  
Human Body ◽  
Point Cloud ◽  
3D Scanning ◽  
Air Gap ◽  
Fashion Design ◽  
Residual Space ◽  
Geomagic Software

This paper presented a method for measuring the residual space between clothing and human body based on 3D scanning devices. In data collecting procedure, the 3D scanning devices were used to collect original point cloud of apparels and human body. The Geomagic software was used to process the noise reduction and surface reconstruction. In measuring procedure, the volume was calculated by algorithm. Therefore, we can get the value of the residual space between clothing and human body.These residual space is called air gap. Thickness of the air gap is closely related to thermal insulation properties [1] and thermal wet comfort performance of clothing. Meanwhile, the stress levels of apparels on human body can be determined through observation [2], so this technology can be used in the field of fashion design. In addition, 3D virtual try-on system is one of the applications with important value [3].

scholarly journals An Exploration of Relationships among Thermal Insulation, Area Factor and Air Gap of Male Chinese Ethnic Costumes

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1302
Author(s):  
Ying Ke ◽  
Faming Wang
Keyword(s):  
Thermal Insulation ◽  
Minority Groups ◽  
Body Part ◽  
Air Gap ◽  
Whole Body ◽  
Gap Size ◽  
Body Parts ◽  
Air Volume ◽  
Local Thermal Insulation ◽  
Local Thermal Comfort

The present study investigated total and local thermal insulations of 39 sets of male Chinese ethnic costumes. Total and local clothing area factor, air gap size and air volume were determined by a 3D body scanner. Relationships between thermal insulation and air gap for the whole body, as well as local body parts, were explored. Correlations of both the total and local clothing area factor with the intrinsic insulation were also developed. Results demonstrated that the clothing total thermal insulation first increased with the increasing air gap size/air volume, followed by a decrease when the air gap size/air volume exceeded 37.8 mm/55.8 dm3. Similarly, it was also found that parabolic relationships widely existed between the local thermal insulation and local air gap at each body part. Our research findings provide a comprehensive database for predicting both global and local thermal comfort of male Chinese minority groups.

A Numerical Approach for the Evaluation of the Energy Efficiency in Ventilated Façade

2018 ◽  
Author(s):  
Massimo Milani ◽  
Luca Montorsi ◽  
Matteo Venturelli
Keyword(s):  
Heat Transfer ◽  
Energy Efficiency ◽  
Thermal Insulation ◽  
Radiative Heat ◽  
Fluid Dynamic ◽  
Electric Energy ◽  
Numerical Approach ◽  
Air Gap ◽  
Radiative Heat Exchange ◽  
Ventilated Facade

The paper studies the ventilated façade as a potential alternative to conventional coating technologies for the thermal insulation of building’s external walls. The ventilated façade is modeled by means of a CFD approach that accounts for the full 3D-geometry of the building, the walls thickness and materials’ thermal properties. The effects of the windows on the heat losses and in the performance of the ventilated façade are modeled in order to accurately characterize the thermal behavior of the system. The solar radiative heat transfer during two representative days of the year is considered in the analysis and a multiband thermal radiation is adopted to capture the different nature of radiative heat exchange according to the light wavelengths. The numerical approach enables to estimate the thermo-fluid dynamic behavior of the system and the temperature distribution and the velocity flow field within the air gap between the walls are addressed and their influence on the heat transfer through the building’s external walls is determined. The CFD analysis is employed to compare different configurations of the ventilated façade for improving the thermal insulation of the building; the performance of each scenario is determined in terms of electric energy and fuel consumption for the air conditioning and the heating system. Thus, the potential saving of the energy cost for ambient thermal conditioning is evaluated. The analysis investigates the effects on the energy efficiency of different geometrical features of the system such as the height of the building and the air gap thickness and theoretical correlations are derived in order to estimate the best tradeoff between the energy efficiency of the building and the investment of the ventilated façade configuration.

A novel analytical calculation of magnetic field in the slotted air gap of spoke-type permanent-magnet machines using conformal mapping

2020 ◽  
pp. 1-15
Author(s):  
Jianqi Li ◽  
Yu Zhou ◽  
Jianying Li
Keyword(s):  
Magnetic Field ◽  
Conformal Mapping ◽  
Permanent Magnet ◽  
Flux Density ◽  
Analytical Method ◽  
Electromotive Force ◽  
Analytical Calculation ◽  
Air Gap ◽  
Permanent Magnet Machines ◽  
Peak Value

This paper presented a novel analytical method for calculating magnetic field in the slotted air gap of spoke-type permanent-magnet machines using conformal mapping. Firstly, flux density without slots and complex relative air-gap permeance of slotted air gap are derived from conformal transformation separately. Secondly, they are combined in order to obtain normalized flux density taking account into the slots effect. The finite element (FE) results confirmed the validity of the analytical method for predicting magnetic field and back electromotive force (BEMF) in the slotted air gap of spoke-type permanent-magnet machines. In comparison with FE result, the analytical solution yields higher peak value of cogging torque.

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