Types Of Thermal Insulation Research Articles

Proposal for Cryogenic Deburring Equipment’s Design and Thermal Insulation

In the paper are presented elements of the deburring technology of rubber or plastic parts in cryogenic conditions. There is a proposal for deburring equipment that follows: simplicity in use, increased production capacity and reduced consumption of liquid nitrogen. The heat transfer through the insulating layer is calculated using several types of thermal insulation: perlite powder, spray-on polyurethane foam and aerogel blanket. The obtained results are used for the design of a cryogenic deburring equipment where the thermal transfer is minimal.

ИССЛЕДОВАНИЕ ТЕПЛОВОЙ ЭФФЕКТИВНОСТИ ИССЛЕДОВАННЫХ РАНЕЕ ВИДОВ ТЕПЛОИЗОЛЯЦИИ В УПРОЩЕННОЙ ПРОТОЧНОЙ ЧАСТИ ТЕПЛООБМЕННОГО АППАРАТА И ПОЛНОЦЕННОЙ МОДЕЛИ РЕКУПЕРАТИВНОГО ТЕПЛООБМЕННИКА

ИССЛЕДОВАНИЕ ТЕПЛОВОЙ ЭФФЕКТИВНОСТИ ИССЛЕДОВАННЫХ РАНЕЕ ВИДОВ ТЕПЛОИЗОЛЯЦИИ В УПРОЩЕННОЙ ПРОТОЧНОЙ ЧАСТИ ТЕПЛООБМЕННОГО АППАРАТА И ПОЛНОЦЕННОЙ МОДЕЛИ РЕКУПЕРАТИВНОГО ТЕПЛООБМЕННИКА

A transparent insulation façade enhanced with a selective absorber: A cooling energy load and validated building energy performance prediction model

Solar thermal façade concepts for building integration have a relevant contribution in the field of renewable solar energy exploitation. This study is focused on an experimental analysis of a transparent insulation façade (TIF) concept and the options for the prediction of its performance using building energy simulation (BES) modelling. A TIF prototype based on a transparent insulation material (TIM) and a selective absorber is tested and compared with a nonselective type of absorber. An experimental study was conducted involving full-scale climatic chamber and dynamic outdoor tests. The proposed TIF concept with a selective absorber and its solar effective layers provides the same thermal performance as conventional types of thermal insulation. As the TIM integration is potentially limited by overheating phenomena, a maximum cooling energy load obtained by dynamic outdoor conditions provides its real outdoor performance. The results show that a significant difference is measured when compared with the nonselective absorber type. Finally, a detailed comparative investigation of the thermal performance of both TIFs was conducted using the BES method. When applying the low-e functionality of the solar absorber, significant limitations were found specifically concerning the surface radiant heat exchange with the low emissivity surface affecting the air cavity enclosed zone.

Woven Kevlar Fiber/Polydimethylsiloxane/Reduced Graphene Oxide Composite-Based Personal Thermal Management with Freestanding Cu-Ni Core-Shell Nanowires.

Thermotherapy is a widespread technique that provides relief for muscle spasms and joint injuries. A great deal of energy is used to heat the surrounding environment, and heat emitted by the human body is wasted on our surroundings. Herein, a woven Kevlar fiber (WKF)-based personal thermal management device was fabricated by directly growing vertical copper-nickel (Cu-Ni) nanowires (NWs) on the WKF surface using a hydrothermal method. The treated WKF was combined with reduced graphene oxide (rGO) dispersed in polydimethylsiloxane (PDMS) to form composites using vacuum-assisted resin transfer molding (VARTM). This WKF-based personal thermal management system contained a conductive network of metallic NWs and rGO that promoted effective Joule heating and reflected back the infrared (IR) radiation emitted by the human body. It thus behaved as a type of thermal insulation. The Cu-Ni NWs were synthesized with a tunable Ni layer on Cu core NWs to enhance the oxidation resistance of the Cu NWs. The combined effect of the NW networks and rGO enabled a surface temperature of 70 °C to be attained on application of 1.5 V to the composites. The Cu3Ni1-WKF/PDMS provided 43% more thermal insulation and higher IR reflectance than bare WKF/PDMS. The absorbed impact energy and tensile strength was highest for the Cu1Ni3- and rGO-integrated WKF/PDMS samples. Those Cu-Ni NWs having higher Ni contents displayed better mechanical properties and those with higher Cu contents showed higher Joule heating performance and IR reflectivity at a given rGO loading. The composite shows sufficient breathability and very high durability. The high flexibility of the composites and their ability to generate sufficient heat during various human motions ensures their suitability for wearable applications.

Evaporating system for cryogenic support of long length HTS power cables

The paper deals with an analysis of the results of theoretical and experimental research on an evaporating system for cryogenic support as supplied to long length thermostatting channels of high-temperature superconducting (HTS) cables and hybrid power transmission lines as well as thermal control systems for cryogenic components in aircraft fuel tanks during long-term spaceflights. Experimental evidence for nitrogen and hydrogen are presented here. The importance of such research for practical application in developing modern cryostatting systems has been highlighted.The design of an experimental hybrid power transmission line for studying thermostatting of superconducting power cables has been considered in the paper. The transmission line contains three sections with different types of thermal insulation and current leads providing high current supply to superconducting threads with minimum external heat inflow. The unique experimental data on heat inflows from the outer surface of the transmission line in different sections has been obtained by the authors. It is shown that it may be possible to compensate fully for external heat inflow to a cryogenic line as well as to lower the temperature of a cryogenic coolant in the section with an evaporating system for cryogenic support. In order to determine the possible length of the cryostatting work field of a long length superconducting cable, estimates of using liquid nitrogen and liquid hydrogen as a working fluid for various mass flow rates of the coolant feed have been made via the mathematical model describing physical processes in a thermostatting channel using an evaporating system for cryogenic support. Calculation data on changes in the length of the long length temperature cryostat, pressure and cooling capacity of the evaporating cryostat system has been obtained.

Сравнительный анализ эффективности различных типов теплоизоляции в теплообменнике-утилизаторе системы рекуперации тепловых потерь мобильных компрессорных установок

Сравнительный анализ эффективности различных типов теплоизоляции в теплообменнике-утилизаторе системы рекуперации тепловых потерь мобильных компрессорных установок

Interventions for Ensuring Thermal Comfort Equality in Apartment Buildings

Energy reduction is one of the goals of sustainability. Thermal comfort and sustainability refers to smart dealing with natural resources to be acceptable for people. In order to provide thermal comfort to occupants, it is necessary to prevent excessive thermal transfers from the building’s envelope. To this end thermal insulation is provided and windows with low U values are installed in buildings. However, the orientation of living spaces in a building determines the amount of solar gains from the facades, which in turn influences the thermal conditions within. Thus, spaces facing different directions need different amount of thermal control to achieve thermal equality. On the other hand, the standard practice for reducing the energy loads of a building is to select the same type of thermal insulation and windows for the entire facade, regardless of the direction of the external walls. This state of affairs gives rise to an inequality in the thermal comfort conditions of residential units facing different orientations. The aim of this study was to eliminate this inequality through certain local interventions on the part of the residents themselves; e.g. increasing insulation, reducing U values of the windows and providing solar shading. To this end an apartment building was modelled with the aid of an energy simulation software: DesignBuilder. The heating and cooling loads obtained from the residential units facing North, South, East and West directions were compared for various intervention scenarios, based on the application of various thicknesses of insulation inside the external walls, improved U values for windows and solar shading devices; as well as natural ventilation. The simulated energy loads demonstrate the effectiveness of case based refurbishment interventions for achieving thermal equality and energy expenditures in all units regardless of their orientations. Keywords: Orientation, thermal insulation, U-value, heating load, cooling load

EVAPORATIVE CRYOGENIC SYSTEM FOR HIGH POWER HTS LONG EXTENSION CABLES

The article analyzes the results of theoretical and experimental studies of the evaporative cryogenic system for extended temperature control channels of high-temperature superconducting cables and hybrid power lines as well as systems for maintaining the thermal regime of cryogenic fuel components in the tanks of aircraft during long space flights. Experimental data obtained with nitrogen and hydrogen are presented. The importance of such studies for practical use in the development of modern cryostat systems is shown. The design of the experimental hybrid power line for studying the processes of thermostating of superconducting cable lines of high power is considered. The main line consists of three sections with different types of thermal insulation and current inputs which provide the supply of an electric current of high power to superconducting veins with a minimum external heat input. Unique experimental data on heat inflows from the outer surface of the main line at various sites have been obtained. The article shows it is possible to fully compensate external heat input into the cryogenic line, and, if necessary, to lower the temperature of the cryogenic coolant in the section with the evaporative cryostat system. With the help of a mathematical model describing the physical processes in the thermostatic channel with the evaporative cryostat system, the estimates were made using liquid nitrogen and liquid hydrogen as the working fluid for various mass flow rates of the coolant supply in order to determine the possible length of the cryostat working zone of the extended superconducting cable. Calculated data are obtained on the change in temperature, pressure, and cooling capacity of an evaporative cryostat system along the length of an extended cryostat.

The environmental impacts of thermal insulation of buildings including the categories of damage: A Polish case study

Households have a big impact on energy efficiency in Poland. About 80% of final energy in the construction sector is used for heating buildings. Due to the significant role which is assigned to the thermal modernization in European documents, the paper attempts to assess the environmental benefits of the investment consisting of thermal insulation of the building external vertical walls, with the use of LCA analysis and divided into three categories of damage. A methodology for assessing the benefits has been proposed and the analyses for different variants have been performed, including the condition of the building before thermal insulation, the used heat source, the type of thermal insulation and the climatic zone in which the building is located. It has been shown that the investment, for all examined variants, is beneficial for environmental reasons. In the worst case, the reduction of the burden on the environment as a result of the investment occurs after 5 years, while in most cases only after one year. The obtained environmental benefits depend primarily on the condition of the building before thermal insulation and the used heat source. The greater are the advantages, the bigger is the demand for thermal energy of the building that also depends on the climate zone. Because of the thermal insulation material the greatest environmental benefits are found in the case of ecofibre. Taking into account three categories of damage, the greatest benefits were achieved in the Resources category.

Bio-based polyurethane-polyisocyanurate composites with an intumescent flame retardant

Rigid polyurethane and polyisocyanurate (PUR-PIR) foams are one of the most effective thermal insulation materials applied in a wide range of industries. A sustainable solution for the production of these materials is to substitute one of their petrochemical components with a component produced from bio-based resources, like vegetable oils.The biggest disadvantage of this type of thermal insulation is its high flammability which usually is reduced by an addition of halogen-based flame retardants. Halogenated flame retardants are getting out of use due to potential health risks. Two different bio-based polyols obtained from rapeseed oil were applied to develop rigid PUR-PIR foams with isocyanate indices of 150 and 250. Flammability of these materials was decreased using an intumescent expandable graphite (EG) filler; 0%; 3%; 6% and 9% contents of EG were used. Flammability (Cone calorimeter), combustion (limited oxygen index, thermal imaging), thermal stability (TGA/DTG) were studied for the developed PUR-PIR foams. The addition of EG did not change the ignition behaviour of the developed materials but it had a significant influence on other flammability properties. Due to the development of a stable char layer, the peak value of the heat release in the Cone Calorimeter test was reduced from 240 to 136 kW/m2, the released smoke was also reduced from 560 to 288 m2/m2. TGA graphs showed a significant char formation (sample with 9% of EG) that was stable at high temperatures, over 400 °C. The addition of EG to the PUR-PIR system had a positive effect on the burning process which was confirmed by thermal imaging camera results. The formation of the char layer moderated the combustion of the PUR-PIR foams and increased the burning time.

New 30-m Flexible Hybrid Energy Transfer Line With Liquid Hydrogen and Superconducting <inline-formula> <tex-math notation="TeX">$\hbox{MgB}_{2}$</tex-math></inline-formula> Cable—Development and Test Results

In the framework of the second stage of the Russian R&D program for the development of hybrid energy transfer lines (HETLs), the new 30-m $\hbox{MgB}_{2}$ superconducting cable with high voltage insulation has been developed and tested. The superconducting cable was inserted into a newly developed flexible 30-m hydrogen cryogenic line that has three sections with different types of thermal insulation in each section. High-voltage current leads were also developed. The superconducting cable, cryostat, and current leads have been tested in October 2013. Cable critical current was $\sim$ 3500 A at $\sim$ 21 K. Cable and current leads passed a high voltage test with 50-kV dc at liquid hydrogen temperature. The tests were performed at temperatures from 20 to 26 K, hydrogen flow from 70 to 450 g/s, and pressure from 0.25 to 0.5 MPa. It was found that the active evaporating cryostatting system as a thermal insulation practically eliminated heat transfer from room temperature to liquid hydrogen. The flexible 30-m HETL developed is able to deliver $\sim$ up to 60 MW of chemical power and $\sim$ 75 MW of electrical power, i.e., $\sim$ 135 MW in total. $\hbox{MgB}_{2}$ cable design and test results of hybrid energy transfer lines are presented and discussed.

Energy Transfer with Hydrogen and Superconductivity – The Review of the First Experimental Results

The transfer of massive amounts of both electrical and chemical power over long distances will present a major challenge for the global energy enterprise in future. Attraction of hydrogen is apparent as a chemical energy agent, possessing among the highest energy density content of various common fuels, whose combustive “waste” is simply water. The usage of “gratis” cold to cool a superconducting cable made of proper superconductor permits to deliver extra electrical power with the same line. This, rather old theoretical idea recently found its experimental realization. The team of Russian institutes and organizations with using Italian-produced MgB2 wire has made and successfully tested two hybrid energy transfer lines with liquid hydrogen as a chemical source of power and superconducting cable as a source of electricity. The first line has been tested in 2011. It has length ∼10 m, maximum liquid hydrogen flow ∼250g/s and maximum current of MgB2 superconducting cable 2600 A @ 20K. This test was the first experimental proof of conception of the hybrid energy transfer line. The second line has been tested in October 2013. It has length ∼30 m. The new MgB2 cable has critical current at 21K ∼3500 A and successfully passed high voltage DC test of 50kV. New hydrogen cryostat has three sections with different types of thermal insulation in each section. The idea of hybrid energy transfer is formulated and details of first experiments are reviewed.

Cryogenic Tests of 30 m Flexible Hybrid Energy Transfer Line with Liquid Hydrogen and Superconducting MgB2 Cable

Recently we reported about first in the world test of 10 m hybrid energy transfer line with liquid hydrogen and MgB2 superconducting cable. In this paper we present the new development of our second hybrid energy transfer line with 30 m length. The flexible 30 m hydrogen cryostat has three sections with different types of thermal insulation in each section: simple vacuum superinsulation, vacuum superinsulation with liquid nitrogen shield and active evaporating cryostatting (AEC) system. We performed thermo-hydraulic tests of the cryostat to compare three thermo-insulating methods. The tests were performed at temperatures from 20 to 26 K, hydrogen flow from 100 to 450 g/s and pressure from 0.25 to 0.5 MPa. It was found that AEC thermal insulation practically eliminated completely heat transfer from room temperature to liquid hydrogen in the 10 m section. AEC thermal insulation method can be used for long superconducting power cables. High voltage current leads were developed as well. The current leads and superconducting MgB2 cable have been passed high voltage DC test up to 50 kV DC. Critical current of the cable at ∼21 K was ∼3500 A. The 30 m hybrid energy system developed is able to deliver up to 135 MW of chemical and electrical power in total.

Cryogenic design and test results of 30-m flexible hybrid energy transfer line with liquid hydrogen and superconducting MgB2 cable

In this paper we present the development of a new hybrid energy transfer line with 30m length. The line is essentially a flexible 30m hydrogen cryostat that has three sections with different types of thermal insulation in each section: simple vacuum superinsulation, vacuum superinsulation with liquid nitrogen precooling and active evaporating cryostatting (AEC) system. We performed thermo-hydraulic tests of the cryostat to compare three thermo-insulating methods. The tests were made at temperatures from 20 to 26K, hydrogen flow from 70 to 450g/s and pressure from 0.25 to 0.5MPa. It was found that AEC thermal insulation was the most effective in reducing heat transfer from room temperature to liquid hydrogen in ∼10m section of the cryostat, indicating that it can be used for long superconducting power cables. High voltage current leads were developed as well. The current leads and superconducting MgB2 cable passed high voltage DC test up to 50kV DC. Critical current of the cable at ∼21K was 3500 A. It means that the 30m hybrid energy system developed is able to deliver ∼50–60MW of chemical power and ∼50–75MW of electrical power, i.e. up to ∼135MW in total.

A PDF Representation of the STS-2 Self-Noise Obtained from One Year of Data Recorded in the Conrad Observatory, Austria

This paper presents a new, broadband (from 0.2 mHz to 18 Hz) estimate of the self‐noise of the Streckeisen STS‐2 sensor based on the application of the three‐channel correlation technique (Sleeman et al. , 2006) to one year of continuous seismic recordings. A novel presentation of instrumental self‐noise is shown using a probability density function. The measurements were obtained from three collocated sensors in the Conrad Observatory (Austria); the sensors are covered with a new type of thermal insulation consisting of thin layers of neoprene, which significantly reduces noncoherent signals between the sensors. We observe a noise reduction ranging from about 10 dB at 1 mHz to 2 dB at 1 Hz when compared to noise estimates from noninsulated sensors. The new self‐noise estimate for the STS‐2 falls below the new low‐noise model (NLNM; Peterson, 1993) at frequencies above 4 mHz and even reaches the NLNM at frequencies between 0.2 mHz and 4 mHz during optimal conditions. From our observations, we conclude that the broadband STS‐2 sensor can achieve a noise power level of 1.56×10−18 m2/s4/Hz, or −178 dB, at 1000 s. We also show results from synthetic experiments to quantify the effect of sensor misalignment on the self‐noise estimate and to quantify the misalignment between the sensors in our Conrad experiment. The synthetic experiment shows that the three‐channel correlation technique potentially can extract noise from signals with signal‐to‐noise ratio (SNR) up to 140 dB but is in practice limited to signals with 60–80 dB SNR when the alignment errors are on the order of 0.2° and 0.02°, respectively. From the observations, we conclude that the misalignment between the sensors in the Conrad experiment is on the order of 0.2°.

Evaluation of heat flux reduction provided by the use of radiant barriers in clay tile roofs

In Brazilian towns and cities the greatest thermal gain occurs through the roof of single-storey buildings. In this regard, the use of thermal radiation barriers has the function of minimizing the heat flux through the roof. Even though the use of this type of thermal insulation has increased in recent years; there are still no technical standards which address the subject. Thus, many products have become available on the market which have the appearance of a radiant barrier, but without low emissivity, and not functioning properly as thermal insulation. The objective of this study is to analyze the efficiency of some types of radiant barriers found on the civil construction market, as well as to analyze the efficiency of sheets made from the joining together of a solid urban waste, long-live carton packaging, in loco and in the laboratory. The in loco measurements were carried out in a roof of a residence in the city of Florianópolis, where the heat flux, surface temperatures of the tiles and the ceiling, and the internal and external temperatures, were monitored. The laboratory experiments were carried out with an apparatus which simulates the thermal resistances of a real roof. The results allowed the verification of which is the best type of radiant barrier, that is, which achieves the greatest reduction in heat flux through the roof. This study also allowed a comparison between the in loco and laboratory results.

Hypervelocity impacts and damage laws

Space debris are nowadays a recognized threat for any space mission. Hypervelocity impacts of space objects can degrade, or terminate prematurely, costly missions. It is, therefore, necessary to improve the survivability of spacecraft. The first step toward this goal is to characterize the behaviour of different materials and configurations under hypervelocity impacts. The purpose of this paper is to present experimental results covering a fairly wide range of materials. Aluminium, carbon fibre reinforced plastics, carbon-carbon, and various type of thermal insulation are considered. The behaviour of sandwich panels with carbon fibre reinforced facings and aluminium honeycomb cores is also investigated. Considerations are given to hypervelocity impacts on gas filled pressure vessels. On the basis of the available data, damage laws are proposed with remarks about their range of applicability.

Vacuum insulating panel

Theoretical aspects and practical possibilities for realization of a new type of thermal insulation, vacuum panel insulation (VPI), are given. From a functional point of view, it is a flat all metal Dewar flask with an array of supporting beads. They span metal foils at desired distances and limit conduction by internal, near-point contacts. Model studies and first reports show that it can be more energy efficient and environmentally acceptable than mineral or glass wools and blown (CFC) foams, widely used today. Three main contributions to heat transfer are compared: radiation, conductivity of supports and envelope as well as of the residual atmosphere. Some results of our VPI sample preparation and processing are given.

Effective thermal conductivity of reflective multiplate thermal insulation

The roof slab of the sodium-cooled fast breeder reactor must be thermally insulated to reduce the heat flux reaching it from the hot sodium pool of the reactor. The environment, consisting of argon gas laden with sodium vapor and aerosols, does not permit the use of conventional thermal insulation for the roof slab, which comes into contact with the reactor cover gas. This necessitates the development of special types of thermal insulation that can serve inside the reactor cover gas atmosphere. The reflective multiplate thermal insulation concept has been chosen for detailed study. This paper describes initially a theoretical model and its prediction of effective thermal conductivity as a function of various parameters and then gives detailed description of the experimental setup to determine the effective thermal conductivity of multiplate thermal insulation. Some experimental results of the determination of the effective thermal conductivity as a function of temperature and number of plates of insulation are presented.