scholarly journals Thermal efficiency of the building envelope with the air layer and reflective coatings

2019 ◽  
Vol 100 ◽  
pp. 00082
Author(s):  
Adam Ujma ◽  
Nina Umnyakova
Keyword(s):  
Thermal Protection ◽  
Heat Insulation ◽  
Building Envelope ◽  
Air Gap ◽  
Air Gaps ◽  
Number Of Factors ◽  
Air Layers ◽  
The Difference ◽  
Heat Shielding ◽  
Reflective Coatings

Currently, when calculating the heat-shielding qualities of external enclosing structures, the ability of fencing surfaces to reflect the heat flux by radiation is not taken into account. All this leads to an underestimation of heat-shielding characteristics in comparison with reality. Studies have shown. that a number of factors affect the thermal protection of air layers - the difference in temperature on the surfaces of the interlayer, its thickness. But the most important is the coefficient of elimination of the air gap surface. The use of reflective heat insulation with a low emissivity on one of the surfaces of the air gap makes it possible to increase its thermal protection 2.5–3 times. The article presents the calculations of thermal protection of air gaps with different emissivity coefficients of surfaces and conclusions about the effectiveness of the use of reflective insulation.

scholarly journals Problems of thermal protection of two-layer external walls with hinged facade systems

2021 ◽  
Vol 263 ◽  
pp. 02013
Author(s):  
Ekaterina Ibe ◽  
Galina Shibaeva ◽  
Svyatoslav Mironov ◽  
Danil Litvin
Keyword(s):  
Energy Efficiency ◽  
Thermal Protection ◽  
Building Envelope ◽  
Air Gap ◽  
Cold Climate ◽  
Heat Conducting ◽  
Weak Points ◽  
The Republic ◽  
Heat Shielding ◽  
Ventilated Facade

Currently, in the Republic of Khakassia, much attention is paid to research aimed at reducing air pollution due to fuel combustion. In this aspect, the issue of increasing the energy efficiency of buildings is relevant. The use of ventilated facade systems with an air gap makes it possible to improve the energy efficiency class of buildings and modernize the facades. However, these facade systems have weak points that require detailed and high-quality study. Often, design solutions are used that are used in warm climates without taking into account the peculiarities of a cold climate - frequent changes in temperature, humidity, wind loads, and other influences, which can lead to negative manifestations. Facade systems with a ventilated air gap must provide the ability to monitor the operability of all system elements and, if necessary, carry out repair and reconstruction work with minimal operating costs. The article presents an analysis of the thermal properties of an external fence using a hinged facade structure. The influence of installation defects and heat-conducting inclusions on the heat-shielding properties of the building envelope is shown. It was determined that during operation the moisture-windproof membrane loses its vapor-permeable properties.

Unventilated Air Layers with a Reflective Coating in the Building Envelope

2018 ◽  
Vol 931 ◽  
pp. 496-501 ◽  
Author(s):  
Nina P. Umnyakova ◽  
Adam Ujma
Keyword(s):  
Heat Exchange ◽  
Thermal Insulation ◽  
Building Envelope ◽  
Radiative Heat Exchange ◽  
Aluminium Foil ◽  
Reflective Coating ◽  
Air Layers ◽  
Design Calculations ◽  
Reflective Coatings

Heat exchange through infrared radiation in air layers located inside building envelopes may be significantly modified in case of use of aluminium foil coatings therein. The intensity of conductive, convective and radiative heat exchange in these structures depends on the thickness of the air layer and the temperature difference on its surfaces. Generally speaking, application of aluminium foil in air layers of a building envelope improves its thermal insulation capacity. However, assessment of efficiency of such a solution and determination of the thermal resistance value of a given structure is often incorrectly determined and assumed for design calculations. The article analyzes the instructions and principles of determination of thermal insulation capacity of unventilated air layers. Provisions of two standards have been compared with results of tests of air layer parameters. The effect of different factors on heat exchange and insulation capacity of air layers with reflective coatings has been considered and assessed.

The Energy-Efficient Heat Insulation Thickness for Systems of Hinged Ventilated Facades

2014 ◽  
Vol 941-944 ◽  
pp. 905-920 ◽  
Author(s):  
Nikolai Vatin ◽  
Aleksandr Sergeevich Gorshkov ◽  
Darya Viktorovna Nemova ◽  
Anastasiia Andreevna Staritcyna ◽  
Darya Sergeevna Tarasova
Keyword(s):  
Energy Saving ◽  
Energy Efficient ◽  
Thermal Protection ◽  
Heat Insulation ◽  
Automatic Equipment ◽  
Insulation Thickness ◽  
Shielding Properties ◽  
Heat Shielding ◽  
Definition Of ◽  
The Given

Calculation of payback periods of the energy saving actions directed on increase of level of thermal protection of external enclosure structures of buildings is given. Economic efficiency of investments in energy saving actions is analyzed and the model allowing to carry out the specified analysis is offered. Recommendations about reduction of payback periods are provided.Article also is devoted definition of optimum, economically well-founded thickness of a insulant in systems of rear ventilated facades. Are resulted thermotechnical and economic calculations. The optimum thickness of the insulant in the given systems is offered.A number of the energy saving actions is necessary for economy of thermal energy, allowing to eliminate defects of protecting designs or to reduce their influence on building heatconsumption. Construction of hinged ventilated facades at simultaneous introduction of automated individual thermal points with automatic equipment dependent on weather [1] can become an example of the engineering decision on increase of heat-shielding properties of protecting walls.

scholarly journals Mathematical modeling of thermal technical characteristics of external protections with air layers

2019 ◽  
Vol 97 ◽  
pp. 06007
Author(s):  
Rustam Mansurov ◽  
Tatyana Rafalskaya ◽  
Dmitry Efimov
Keyword(s):  
Mathematical Modeling ◽  
Heat Transfer ◽  
Software Package ◽  
Outer Wall ◽  
Heat Transfer Process ◽  
Building Envelope ◽  
Ansys Software ◽  
Air Gaps ◽  
Transfer Processes ◽  
Air Layers

A screened enclosing structure of the outer wall of the building without the use of thermal insulation materials is proposed. To ensure the required thermal resistance of the outer fence, screens (cement-containing slabs) and closed air gaps between them are used. Using the ANSYS software package, the heat transfer processes were modeled in a shielded building envelope, consisting of the main (carrier) part and screens with air gaps closed between them. The features of the heat transfer process in the thickness of the outer enclosure are revealed.

scholarly journals Do air-gaps behind soft body armour affect protection?

2017 ◽  
Vol 164 (1) ◽  
pp. 15-18 ◽  
Author(s):  
Lee Tilsley ◽  
D J Carr ◽  
C Lankester ◽  
C Malbon
Keyword(s):  
Ceramic Composite ◽  
Air Gap ◽  
The Body ◽  
Gap Size ◽  
Soft Body ◽  
Air Gaps ◽  
Body Armour ◽  
Ballistic Protection ◽  
Back Face ◽  
Full Metal Jacket

IntroductionBody armour typically comprises a fabric garment covering the torso combined with hard armour (ceramic/composite). Some users wear only soft armour which provides protection from sharp weapons and pistol ammunition. It is usually recommended that body armour is worn against the body with no air-gaps being present between the wearer and the armour. However, air-gaps can occur in certain situations such as females around the breasts, in badly fitting armour and where manufacturers have incorporated an air-gap claiming improvements in thermophysiological burden. The effect of an air-gap on the ballistic protection and the back face signature (BFS) as a result of a non-perforating ballistic impact was determined.MethodsArmour panels representative of typical police armour (400x400 mm) were mounted on calibrated Roma Plastilina No 1 and impacted with 9 mm Luger FMJ (9×19 mm; full metal jacket; Dynamit Nobel DM11A1B2) ammunition at 365±10 m/s with a range of air-gaps (0–15 mm). Whether or not the ammunition perforated the armour was noted, the BFS was measured and the incidence of pencilling (a severe, deep and narrow BFS) was identified.ResultsFor 0° impacts, a critical air-gap size of 10 mm is detrimental to armour performance for the armour/ammunition combination assessed in this work. Specifically, the incidences of pencilling were more common with a 10 mm air-gap and resulted in BFS depth:volume ratios ≥1.0. For impacts at 30° the armour was susceptible to perforation irrespective of air-gap.ConclusionsThis work suggested that an air-gap behind police body armour might result in an increased likelihood of injury. It is recommended that body armour is worn with no air-gap underneath.

HYPOCHROMIC MICROCYTIC ANEMIA OF INFANCY: IRON DEPLETION AS A FACTOR

PEDIATRICS ◽  
1956 ◽  
Vol 18 (6) ◽  
pp. 959-978
Author(s):  
Hugh W. Josephs
Keyword(s):  
Iron Deficiency ◽  
Severe Infection ◽  
Microcytic Anemia ◽  
Severe Anemia ◽  
Iron Depletion ◽  
Hypochromic Microcytic Anemia ◽  
Premature Babies ◽  
Number Of Factors ◽  
The Difference ◽  
Insight Into

In this work the author has attempted to gain insight into the significance of iron depletion by the use of 4 simple calculations, justification for which is found in recent articles. These are: (a) iron with which the infant is born; (b) iron retained from the food; (c) iron being used by the tissues and therefore unavailable for hemoglobin, and (d) iron combined with the total mass of hemoglobin. With these 4 figures it is possible to estimate the iron still potentially available for use (the "reserves" or "stones"). When the difference between a + b and c + d has reached about zero, depletion is considered to exist. The following characteristics of depletion may be emphasized: Depletion is the result of gain in weight and maximum possible usage of iron. It is therefore a normal result of growth and need not be associated with anemia. As soon as depletion has occurred, the organism is thereafter dependent on current absorption of iron. This is ordinarily sufficient, even with a diet of milk alone, to maintain an adequate concentration of hemoglobin after about 8 to 10 months of age. Severe anemia due to depletion alone is practically confined to premature babies whose relative gain in weight is rapid. Severe anemia in other than premature babies is the result of a number of factors by which iron becomes unavailable or is actually diverted from hemoglobin to storage. Response to iron medication is considerably better in infants with depletion than in those in whom some factor is present that interferes with iron utilization, and which is not connected by the mere giving of iron. The dependence on current absorption, whether the result of depletion or non-availability, introduces a certain precariousness which is apparently characteristic of this time of life. The organism gets along from day to day if nothing happens, but may not be able to meet an emergency, whether this appears as a rapid gain in weight, or a necessity to repair damage done by severe infection. If we consider iron deficiency as the cause of anemia, we can think of deficiency as due to a number of factors of which depletion is only one. The development and characteristics of depletion have been considered in this paper; other factors in iron deficiency will be considered in subsequent papers.

scholarly journals Research on Low-Brightness and High-Reflective Coatings Suitable for Buildings in Tropical Areas

Coatings ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 829
Author(s):  
Xian Rong ◽  
Lichao Jiao ◽  
Xiangfei Kong ◽  
Guangpu Yuan
Keyword(s):  
Energy Saving ◽  
Heat Insulation ◽  
Residential Building ◽  
Maximum Temperature ◽  
Kuala Lumpur ◽  
Nano Tio2 ◽  
Insulation Coating ◽  
Tropical Areas ◽  
Saving Effect ◽  
Reflective Coatings

In this article, we mixed hollow glass beads with nano-TiO2 and iron oxide red in a certain proportion to prepare a low-brightness, high-reflective, safe, and durable cooling coating throughout the experiments. The coating is suitable for energy-saving in tropical areas. To discuss the energy saving effects of the coating on an exterior envelope in tropical areas, a comparative analysis for two scenario models of a two-story residential building in Kuala Lumpur, Malaysia was conducted. The results indicated that the heat reflective insulation coating could reduce the exterior envelope surface temperature effectively, and the maximum temperature change was about 6–8 °C. Through calculations, it was found that the annual energy saving rate was 12.9%, which showed that the energy saving effect of the heat insulation coating was obvious in Kuala Lumpur. The brightness of the coating was less than 50%, and its comfort and safety met the requirements.

scholarly journals Behavior and Energy Losses of Cows during the Period of Low Temperatures

2021 ◽  
Vol 24 (5) ◽  
pp. 46-53
Author(s):  
Oleksandr O. Borshch ◽  
Oleksandr V. Borshch ◽  
Yurii Mashkin ◽  
Vasyl Malina ◽  
Maxim Fedorchenko
Keyword(s):  
Low Temperatures ◽  
Heat Insulation ◽  
Energy Losses ◽  
Strong Wind ◽  
The Past ◽  
Air Temperatures ◽  
The Difference ◽  
And Behavior ◽  
Positive Effect ◽  
Moderate Climate

Over the past 20 years, dairy farms in Ukraine have been actively introducing the keeping of cows in easy-to-assemble premises. However, in a moderate climate (with four distinct year seasons), the issues of microclimate, energy losses of animals and their behavior during the cold period of the year for keeping in such premises have not been fully studied. The purpose of this work was to study the influence of the heat insulation elements use of side curtains in easy-to-assemble premises during the period of low temperatures on microclimate, energy outgoings for thermoregulation and behavior of cows. The research conducted in the central part of Ukraine (Kyiv region). The research was conducted during January-February (29-43 days of the year) 2021. This period characterized by low average daily temperatures of -12.2– -18.7°С, strong wind gusts and daily precipitation in the form of snow. Two easy-toassemble premises for 400 heads were used for research. Parameters of placements (LxWxH): 150х32х10.5 m. The first one was without the use of curtains heat insulation elements, and the second one was with these elements of heat insulation. It was found that the use of polycarbonate wall heat insulation elements had a positive effect on the microclimate in the placement during the period of low temperatures. Indicators of average daily air temperatures in the placement were 3.2 and 8.8°C higher compared to the temperature in the same premise without the use of heat insulation elements and the environment. The wind speed also differed by 0.18 and 11.04 m/s, respectively. In addition, the heat insulation of the walls affected the temperature under the lying cow (+1.8°C), energy outgoings for thermoregulation (-1.93 MJ) and the number of cows that lay in the period of the lowest temperatures (+3.23-9.83%) compared to the placement without heat insulation elements. The difference in temperature of rubber carpet in the compared premises was significant: +3.3°C in the premises with heat insulation elements compared to the premises without heat insulation

scholarly journals MATHEMATICAL MODELING OF DESTRUCTION OF FIBERGLASS-BASED THERMAL-PROTECTION MATERIAL

2020 ◽  
pp. 71-78
Author(s):  
D.Ya. Barinov ◽  
◽  
P.S. Marakhovskij ◽  
A.V. Zuev ◽  
◽  
...  
Keyword(s):  
Thermal Protection ◽  
Experimental Studies ◽  
Thermophysical Characteristics ◽  
Capsule Type ◽  
Typical Trajectory ◽  
Material Sample ◽  
Heat Shielding ◽  
Physical And Mathematical Models ◽  
The Mathematical Model ◽  
Shielding Material

The paper proposes physical and mathematical models of heat and mass transfer in fiberglass used as a destructive heat-shielding material for capsule type descent vehicles. To provide the mathematical model with the initial data, experimental studies of the thermophysical characteristics of the material and the kinetic parameters of destruction have been carried out. There has been made a simulation of the destruction of a material sample during descent in the Earth's atmosphere along a typical trajectory for various areas of the heat shield; as a result, the dependences of temperatures on the flight time and the depth of the coked layer have been determined.

scholarly journals On the Number of Witnesses in the Miller–Rabin Primality Test

Symmetry ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 890
Author(s):  
Shamil Talgatovich Ishmukhametov ◽  
Bulat Gazinurovich Mubarakov ◽  
Ramilya Gakilevna Rubtsova
Keyword(s):  
Positive Integer ◽  
Euler’S Totient Function ◽  
Number Of Factors ◽  
Primality Test ◽  
Average Probability ◽  
Test Errors ◽  
The Difference

In this paper, we investigate the popular Miller–Rabin primality test and study its effectiveness. The ability of the test to determine prime integers is based on the difference of the number of primality witnesses for composite and prime integers. Let W ( n ) denote the set of all primality witnesses for odd n. By Rabin’s theorem, if n is prime, then each positive integer a < n is a primality witness for n. For composite n, the power of W ( n ) is less than or equal to φ ( n ) / 4 where φ ( n ) is Euler’s Totient function. We derive new exact formulas for the power of W ( n ) depending on the number of factors of tested integers. In addition, we study the average probability of errors in the Miller–Rabin test and show that it decreases when the length of tested integers increases. This allows us to reduce estimations for the probability of the Miller–Rabin test errors and increase its efficiency.

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