scholarly journals Active thermal insulation as an element limiting heat loss through external walls

2019 ◽  
Vol 205 ◽  
pp. 109541 ◽  
Author(s):  
Tomasz Kisilewicz ◽  
Małgorzata Fedorczak-Cisak ◽  
Tamas Barkanyi
Keyword(s):  
Heat Loss ◽  
Thermal Insulation ◽  
Active Thermal Insulation

scholarly journals Reduction of Heat Losses in a Pre-Insulated Network Located in Central Poland by Lowering the Operating Temperature of the Water and the Use of Egg-shaped Thermal Insulation: A Case Study

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2104 ◽  
Author(s):  
Dorota Anna Krawczyk ◽  
Tomasz Janusz Teleszewski
Keyword(s):  
Heat Loss ◽  
Thermal Insulation ◽  
Heat Losses ◽  
Ecological Effect ◽  
Operation Temperature ◽  
Supply Pipe ◽  
Insulation Thickness ◽  
Network Operation ◽  
Cross Section Geometry

This paper presents possible variants of reducing the heat loss in an existing heating network made from single pre-insulated pipes located in central Europe. In order to achieve this aim, simulations were carried out for five different variants related to the modification of the network operation temperature, replacement of a single network with a double pre-insulated one, and changes in the cross-section geometry of the thermal insulation of the double heating network from circular to egg-shaped. The proposed egg-shaped thermal insulation was obtained by modifying the shape of the Cassini oval, in that the supply pipe has a greater insulation thickness compared to the return pipe. The larger insulation field in the supply pipe contributed to reducing the heat flux density around the supply line and, as a result, to significantly reducing heat loss. The egg-shaped thermal insulation described in the publication in a mathematical formula can be used in practice. This work compares the heat losses for the presented variants and determines the ecological effect. Heat losses were determined using the boundary element method (BEM), using a proprietary computer program written as part of the VIPSKILLS 2016-1-PL01-KA203-026152 project Erasmus+.

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.

Considerations in Design of Centralizers for Pipe-in-Pipe Systems

2018 ◽  
Author(s):  
Soheil Manouchehri
Keyword(s):  
Heat Loss ◽  
Thermal Insulation ◽  
Insulation Material ◽  
Loading History ◽  
Pipe Systems ◽  
Main Components ◽  
Outer Pipe

For un-bonded (sliding) Pipe-In-Pipe (PIP) systems, one of the main components is the centralizers (also called spacers). The main functions of the centralizers are to centralize the inner pipe inside the outer pipe, to transfer the loads between inner pipe and outer pipe and to safeguard the insulation material in the annulus from excessive compression during fabrication, installation and operation. Centralizers must also have good thermal insulation properties so that the heat loss is minimized. Different designs are now available for centralizers but the majority are based on two half shells which are bolted together. During fabrication, installation and operation, centralizers subject to different loads under which they are required to continue functioning properly. This paper provides an overview of centralizer design aspects and then focuses on the loading history during installation using reeling method. The main contributing parameters to centralizer loading during reeled installation technique are discussed and conclusions are drawn. It is believed that this will enable Pipeline Engineers to select the most appropriate material and design for centralizers.

Hair density, wind speed, and heat loss in mammals

1965 ◽  
Vol 20 (4) ◽  
pp. 796-801 ◽  
Author(s):  
R. T. Tregear
Keyword(s):  
Wind Speed ◽  
Temperature Gradient ◽  
Heat Loss ◽  
Thermal Insulation ◽  
Hair Density ◽  
Wind Speeds

The heat loss from excised pelts of rabbits, horses, and pigs has been measured at various wind speeds. The temperature gradient through the fur was also measured. The thermal insulation of fur is highly dependent on the hair density (i.e., number of hairs/ cm2), and on the wind passing over its surface. If there are less than 1,000 hairs/cm2, an 8-mph wind penetrates deep into the fur, but at higher hair densities an 18-mph wind penetrates only a little way into the fur. fur insulation; obstruction of wind by hair Submitted on September 10, 1964

scholarly journals THE INFLUENCE OF THE METHOD OF LAYING PIPELINES ON THE ENERGY EFFICIENCY OF THE HEATING NETWORK

2019 ◽  
Vol 10 (2) ◽  
pp. 59-66
Author(s):  
E. A Biryuzova ◽  
A. S Glukhanov
Keyword(s):  
Energy Efficiency ◽  
Heat Loss ◽  
Thermal Insulation ◽  
Thermal Energy ◽  
Great Influence ◽  
Temperature Fields ◽  
Insulation Material ◽  
Design Work ◽  
Heat Networks ◽  
Insulation Thickness

Through pipelines of heat networks, due to their large length, a large amount of thermal energy is lost. Identification of technical solutions related to improving the energy efficiency of heating networks is an urgent task at present. The article is devoted to the consideration of options for laying pipelines of heat networks during design work. In the conducted studies, two main methods of underground laying of pipelines of heat networks with the choice of the most energy-efficient, with minimal losses of thermal energy are considered. Channel and channelless laying methods are investigated with the same design features and technological conditions of operation of pipelines of heat networks using the same thermal insulation material. For each option, the required thickness of the thermal insulation is determined by the normalized density of the heat flow, thermal calculations are performed to determine the heat loss and the value of the temperature fields generated around the operating pipelines of the heat networks. The obtained values of the thermal insulation thickness in the channel method of laying pipelines are 30-50 % lower than those in channelless laying. The heat loss values, according to the results of the heat calculation for the options under consideration, in the channel method of laying are reduced by 47-65 %. The temperature fields formed around the pipelines of thermal networks with channelless laying significantly exceed the natural value of the soil temperature at the depth of the pipeline. What has a great influence on the determination of the distance to adjacent pipelines and other utilities, laid underground, in the zone of the thermal network. A comparative analysis of the results obtained makes it possible to single out the choice of the method of laying the pipeline into a group of measures aimed at energy saving and increasing energy efficiency in heating systems.

Effect of pressure on thermal insulation in humans wearing wet suits

1988 ◽  
Vol 64 (5) ◽  
pp. 1916-1922 ◽  
Author(s):  
Y. H. Park ◽  
J. Iwamoto ◽  
F. Tajima ◽  
K. Miki ◽  
Y. S. Park ◽  
...  
Keyword(s):  
Temperature Gradient ◽  
Water Temperature ◽  
Heat Loss ◽  
Thermal Insulation ◽  
Heat Production ◽  
Water Immersion ◽  
The Other ◽  
Body Parts ◽  
Metabolic Heat ◽  
Healthy Males

The present work was undertaken to determine the critical water temperature (Tcw), defined as the lowest water temperature a subject can tolerate at rest for 3 h without shivering, of wet-suited subjects during water immersion at different ambient pressures. Nine healthy males wearing neoprene wet suits (5 mm thick) were subjected to immersion to the neck in water at 1, 2, and 2.5 ATA while resting for 3 h. Continuous measurements of esophageal (T(es)) and skin (Tsk) temperatures and heat loss from the skin (Htissue) and wet suits (Hsuit) were recorded. Insulation of the tissue (Itissue), wet suits (Isuit), and overall total (Itotal) were calculated from the temperature gradient and the heat loss. The Tcw increased curvilinearly as the pressure increased, whereas the metabolic heat production during rest and immersion was identical over the range of pressure tested. During the 3rd h of immersion, Tes was identical under all atmospheric pressures; however, Tsk was significantly higher (P less than 0.05) at 2 and 2.5 ATA compared with 1 ATA. A 42 (P less than 0.001) and 50% (P less than 0.001), reduction in Isuit from the 1 ATA value was detected at 2 and 2.5 ATA, respectively. However, overall mean Itissue was maximal and independent of the pressure during immersion at Tcw. The Itotal was also significantly smaller in 2 and 2.5 ATA compared with 1 ATA. The Itissue provided most insulation in the extremities, such as the hand and foot, and the contribution of Isuit in these body parts was relatively small. On the other hand, Itissue of the trunk areas, such as the chest, back, and thigh, was not high compared with the extremities, and Isuit played a major role in the protection of heat drain from these body parts.

scholarly journals Design and Verification of a Deep Rock Corer with Retaining the In Situ Temperature

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Zhiqiang He ◽  
Heping Xie ◽  
Mingzhong Gao ◽  
Ling Chen ◽  
Bo Yu ◽  
...  
Keyword(s):  
Thermal Insulation ◽  
Heat Dissipation ◽  
Electric Heating ◽  
Transfer Model ◽  
Hollow Glass Microsphere ◽  
Insulation Material ◽  
Insulation System ◽  
Deep Rock ◽  
Active Thermal Insulation

Deep rock is always under high-temperature conditions. However, traditional coring methods generally have no thermal insulation design, which introduces large deviations in the guidance required for resource mining. Thus, a thermal insulation design that utilizes active and passive thermal insulation was proposed for deep rock corers. The rationale behind the active thermal insulation scheme was to maintain the in situ core temperature through electric heating that was controlled by using a proportional-integral-derivative (PID) chip. Graphene heating material could be used as a heating material for active thermal insulation through testing. In regard to the passive thermal insulation scheme, we conducted insulation and microscopic and insulation effectiveness tests for hollow glass microsphere (HGM) composites and SiO2 aerogels. Results showed that the #1 HGM composite (C1) had an excellent thermal insulation performance (3 mm thick C1 can insulate to 82.6°C), high reflectivity (90.02%), and wide applicability. Therefore, C1 could be used as a passive insulation material in deep rock corers. Moreover, a heat transfer model that considered multiple heat dissipation surfaces was established, which can provide theoretical guidance for engineering applications. Finally, a verification test of the integrated active and passive thermal insulation system (graphene heating material and C1) was carried out. Results showed that the insulating effect could be increased by 13.3%; thus, the feasibility of the integrated thermal insulation system was verified. The abovementioned design scheme and test results provide research basis and guidance for the development of thermally insulated deep rock coring equipment.

Analysis of Heat Loss of Ground Pipeline of Thermal Production Oilfield

2011 ◽  
Vol 90-93 ◽  
pp. 3057-3060 ◽  
Author(s):  
Jian Jun Liu ◽  
Gui Hong Pei ◽  
You Jun Ji
Keyword(s):  
Heat Transfer ◽  
Layer Thickness ◽  
Heat Loss ◽  
Thermal Insulation ◽  
Oil Recovery ◽  
Heavy Oil ◽  
Insulation Layer ◽  
Obvious Effect ◽  
Steam Pipeline ◽  
Heat Transfer Theory

Steam stimulation is one of the main methods used in heavy oil reservoir development. How to inject high temperature and high dryness steam is a key factor to enhance heavy oil recovery. It is significant to evaluate heat transfer of steam pipeline and optimize thermal insulation layer for heavy oil exploitation. Based on fluid mechanics, heat transfer theory, considered phase change, mathematical model to calculate heat transfer and heat loss of steam pipeline was derived. Using COMSOL Multiphysics, a finite element based program for simulating unlimited multiphysics and single physics applications, the author simulated heat transferring in ground steam pipeline and analyzed the effect of thermal insulation layer. From the simulation results, it was known that, (1) Along with the pipeline distance increases, the steam dryness decreases, the decrease rate decreases with the distance increases. (2) At the same transmission distance, the bigger the thermal insulation layer thickness is, the smaller the heat loss of the steam is. The heat loss of steam transmission mainly center on the first half pipeline. (3) With the thickness of thermal insulation layer increases, the heatloss declines. After the thickness of thermal insulation layer increases 90 mm, increasing the thickness has no obvious effect on reducing the heat loss. So, it is suggested that the thermal insulation layer thickness should be 75-80mm.

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