scholarly journals RETALT_TPS design and manufacturing

2022 ◽  
Author(s):  
Sofia Paixão ◽  
Cláudia Peixoto ◽  
Marta Reinas ◽  
João Carvalho
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Resistance ◽  
Environmental Conditions ◽  
Thermal Protection ◽  
Development Work ◽  
Atmospheric Reentry ◽  
Vehicle Structure ◽  
Design And Manufacturing ◽  
Surface Increase

AbstractThe present document discusses the development of a new trowelable Thermal Protection System (TPS), able of being mixed, applied and cured directly onto the vehicle structure, with the aim to fulfill the requirements of the thermal properties for the re-usable launch vehicle studied in the Retro Propulsion Landing Technology (RETALT) project. During the development of this TPS, several formula optimizations were made to improve or eliminate cracks in the char surface, increase char stiffness, rheological adjustments, and adhesion improvement to different substrates. The most promising material developed is composed by cork and epoxy resin, together with a set of rheological and thermal resistance additives, that makes it possible to be applied with a spatula, while at the same time it is able to withstand the demanding environmental conditions during atmospheric reentry. In terms of thermal properties, the developed material has a higher thermal conductivity than the current P50 TPS commercialized by Amorim Cork Composites (ACC), but it has a better behavior when exposed to flame conditions. It is expected that the absence of cracks improves its structure and resistance to demanding conditions. The development work included a detailed study of the composition and processes required for the development of a TPS material, which were evaluated by several types of flame characterization tests and thermal properties analysis.

Thermal Properties of Thin Metallic Layer Deposited on Insulators: Effect of the Interface on the Independent Determination of the Thermal Diffusivity and Conductivity of the Layer

2008 ◽  
Author(s):  
Danie`le Fournier ◽  
Jean Paul Roger ◽  
Christian Fretigny
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Thermal Resistance ◽  
Thermal Contact ◽  
Heat Diffusion ◽  
Metallic Layer ◽  
Good Thermal Contact ◽  
Lateral Heat

Lateral heat diffusion thermoreflectance is a very powerful tool for determining directly the thermal diffusivity of layered structures. To do that, experimental data are fitted with the help of a heat diffusion model in which the ratio between the thermal conductivity k and the thermal diffusivity D of each layer is fixed, and the thermal properties of the substrate are known. We have shown in a previous work that it is possible to determine independently the thermal diffusivity and the thermal conductivity of a metallic layer deposited on an insulator, by taking into consideration all the data obtained at different modulation frequencies. Moreover, it is well known that to prevent a lack of adhesion of a gold film deposited on substrates like silica, an intermediate very thin (Cr or Ti) layer is deposited to assure a good thermal contact. We extend our previous work: the asymptotic behaviour determination of the surface temperature wave at large distances from the modulated point heat source for one layer deposited on the substrate to the two layers model. In this case (very thin adhesion coating whose thermal properties and thickness are known), it can be establish that the thermal diffusivity and the thermal conductivity of the top layer can still be determined independently. It is interesting to underline that the calculus can also be extended to the case of a thermal contact resistance which has often to be taken into account between two solids. We call thermal resistance a very thin layer exhibiting a very low thermal conductivity. In this case, the three parameters we have to determine are the thermal conductivity and the thermal diffusivity of the layer and the thermal resistance. We will show that, in this case, the thermal conductivity of the layer is always obtained independently of a bound of the couple thermal resistance – thermal diffusivity, the thermal diffusivity being under bounded and the thermal resistance lower bounded. Experimental results on thin gold layers deposited on silica with and without adhesion layers are presented to illustrate the method. Discussions on the accuracy will also be presented.

Effect of weft yarn twist level on thermal comfort of 100 per cent cotton woven fabrics

2018 ◽  
Vol 22 (3) ◽  
pp. 180-194 ◽  
Author(s):  
Desalegn Atalie ◽  
Addisu Ferede Tesema ◽  
Gideon K. Rotich
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Resistance ◽  
Surface Properties ◽  
Close Contact ◽  
Woven Fabrics ◽  
Weft Yarn ◽  
Human Comfort ◽  
Content Type ◽  
Yarn Twist

Purpose Fabrics’ thermal properties greatly influence human comfort during wear. For this reason, fabrics with optimum thermal properties need to be developed. This paper aims to investigate the effect of weft yarn twist levels on thermal and surface properties of 100 per cent cotton woven fabrics. Design/methodology/approach Five types of plain woven cotton fabrics were manufactured using weft yarns with 900, 905, 910, 915 and 920 twists/meter (Tpm). The other parameters of the samples as count, thread density and fabric structures were kept constant. Fabric thermal properties were evaluated by measuring its thermal conductivity, thermal resistance, actual insulation, water permeability, air permeability and wicking ability. The fabric compression and surface properties were also evaluated because they contribute to the overall clothing comfort. Findings The results showed that actual insulation and thermal resistance property decreased with an increase in twists/meter of the weft yarn. However, thermal conductivity does not significantly change while fabric compression reduced with an increase in twist as the surface roughness increased. Originality/value Comfort is a fundamental requirement in human daily existence, and it is greatly influenced by clothing, which comes in close contact with the human skin. Fabrics’ thermal properties greatly influence human comfort during wear. For this reason, fabrics with optimum thermal properties need to be developed.

Thermal properties of thermal insulation chambers

2020 ◽  
pp. 004051752096671
Author(s):  
Dubravko Rogale ◽  
Snježana Firšt Rogale ◽  
Goran Majstorović ◽  
Goran Čubrić
Keyword(s):  
Thermal Properties ◽  
Thermal Resistance ◽  
Thermal Insulation ◽  
Thermal Protection ◽  
Cold Weather ◽  
Thermal Manikin ◽  
Functional Dependencies ◽  
Starting Point ◽  
Wide Range ◽  
Intelligent Clothing

The paper presents the investigation of thermal properties of thermal insulation chambers as an actuator in intelligent clothing, having the property of automatically adjusting the thermal protection level. The chambers are designed to vary their thickness based on the pressure of the inflated air in them. The pressure value measured in the thermal insulation chamber gives the microcomputer information on the thickness of the chamber. The paper presents the investigation of the functional dependencies of changes in the thickness of the chambers on the air pressure in them and the thermal resistance depending on the thickness of the thermal insulation chamber. Experimental thermal insulation chambers were made and integrated into an intelligent article of clothing and filled with air of 0–50 mbar, whereby chamber thicknesses of 0–25 mm were measured. Next, thermal resistance of 0.1876–0.5022 m2 k/W was measured on the thermal manikin. It was found that the ratio of thermal insulation of non-activated to maximally activated chambers was 1:2.7. Research has shown good results for the area where intelligent clothing can automatically adjust its thermal insulation properties. The technical systems described represent a suitable basis for experiments and scientific research during the introduction of intelligent clothing with active thermal protection into human life. The third-generation prototype shows very good properties from the aspect of automatic control of thermal protection in intelligent clothing. This forms the basis for further research. Cold protection has always been carried out by wearing garments with higher or lower thermal protection as well as wearing multiple layers of clothing. The conceptual starting point of the development of intelligent clothing is the development of an adaptive insulation layer with changeable thickness in the form of thermal insulation chambers filled with air. In this way, layered clothing as well as the use of several clothing layers can be avoided. Thus, one intelligent article of clothing regulating its thermal insulation properties can be used in a wide range of cold weather in the environment of the wearer.

Thermal Properties of Thin Films

1992 ◽  
Vol 284 ◽  
Author(s):  
J. C. Lambropoulos ◽  
S.-S. Hwang
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Resistance ◽  
Interfacial Thermal Resistance ◽  
Bulk Solid ◽  
Ceramic Films ◽  
Film Substrate ◽  
Conductivity Of Thin Films

ABSTRACTWe summarize various measurements of the thermal conductivity of thin ceramic films which show that the thermal conductivity of thin films with thickness in the micron and sub-micron range may be up to two orders of magnitude lower than the thermal conductivityof the corresponding bulk solid. The reduction in the thin film effective thermal conductivity is attributed to the interfacial thermal resistance across the film/substrate interface.

The effect of weave pattern on the thermal properties of woven fabrics

2018 ◽  
Vol 30 (4) ◽  
pp. 525-535 ◽  
Author(s):  
Azita Asayesh ◽  
Mehraneh Talaei ◽  
Mohammad Maroufi
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Resistance ◽  
Design Methodology ◽  
Structural Parameters ◽  
Thermal Characteristics ◽  
Woven Fabrics ◽  
Content Type ◽  
Weave Fabric ◽  
Weave Pattern

Purpose Fabric structural parameters play an important role on the thermal comfort of clothing. The purpose of this paper is to investigate the effect of weave pattern and also the length of warp float in each weave pattern on the thermal properties of woven fabrics. Design/methodology/approach Cotton woven fabrics with 23 different weave patterns were produced with identical linear densities of warp and weft yarns as well as constant warp and weft nominal densities. Thereafter, their thermal properties were studied. Findings Statistical analysis demonstrated that the weave pattern significantly influences on the thermal properties of woven fabrics. Plain fabric exhibited the lowest thermal resistance and the highest thermal conductivity, and hopsack 2/2(4) weave fabric demonstrated the highest thermal resistance and the lowest thermal conductivity. Moreover, except hopsack (4) weave fabric, in all weave patterns, the length of warp float had a significant effect on the thermal characteristics of the fabrics, as increasing the warp float led to increase in the thermal resistance of the fabrics. Originality/value Weave pattern as one of the structural parameters of the fabric has a determinant role on the thermal properties of fabric and subsequently, the comfort of clothing produced from it. Owing to the lack of investigation in this area, this research considers the effect of weave pattern and the length of warp float in each weave pattern on the thermal properties of woven fabrics.

scholarly journals Evaluation of thermal properties of insulation systems in pitched roofs

2019 ◽  
Vol 91 ◽  
pp. 02047 ◽  
Author(s):  
Alexey Zhukov ◽  
Armen Ter-Zakaryan ◽  
Ekaterina Bobrova ◽  
Igor Bessonov ◽  
Andrey Medvedev ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Water Vapor ◽  
Thermal Resistance ◽  
Heat Loss ◽  
Thermal Insulation ◽  
Insulating Layer ◽  
Insulation Systems ◽  
Materials Used ◽  
Supporting Structures

The article outlines the basic requirements for pitched roof insulation systems. The analysis of the properties of thermal insulation materials used in insulation systems was conducted. It is substantiated that the thermal resistance of such structures on the surface of the roof is formed taking into account the thermal conductivity of thermal insulation, thermal conductivity of wooden rafters and heat loss through the leakiness of joints and mounting devices. An assessment was made of the effect of loads of various types on the heat-insulating layer, namely: the effect of the air flow in the ventilated gap; the movement of the vapor-air mixture in the material; condensation of water vapor and penetration of drip liquid; exfiltration of air at the joints of the plates and on the surfaces of contact with the supporting structures. The expediency of using products on the basis of unstitched polyethylene foam in the construction of pitched roofs with a wooden roof system, taking into account the advantages and features of this material, as well as taking into account the possibility of creating a seamless insulating shell, is substantiated.

In Situ Testing and Analysis of Thermal Properties of the Ground Formation in Jiangsu, China

2014 ◽  
Vol 933 ◽  
pp. 477-481
Author(s):  
Shuai Chen
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Resistance ◽  
Thermal Response ◽  
Geological Structure ◽  
Ground Source ◽  
In Situ Conditions ◽  
Thermal Conductivity Λ

Ground source heat pump (GSHP) systems exchange heat with the ground, often through a closed-loop, vertical, borehole heat exchanger (BHE). The performance of the BHE depends on the thermal properties of the ground formation, as well as soil or backfill in the borehole. The design and economic probability of GSHP systems need the thermal conductivity of geological structure and thermal resistance of BHE. Thermal response test (TRT) method allows the in-situ determination of the thermal conductivity (λ) of the ground formation in the vicinity of a BHE, as well as the effective thermal resistance (Rb) of this latter. Thermal properties measured in laboratory experiments do not comply with data of in-situ conditions. The present article describes the results of thermal properties of the BHE whose depth is 100m in Yancheng City, Jiangsu Province, China. As shown in these results, λ and Rb of borehole are determined as 1.84(W·m-1·K-1) and 0.121 (m·K·W-1) respectively.

Acoustic evaluation of Struto nonwovens and their relationship with thermal properties

2016 ◽  
Vol 88 (4) ◽  
pp. 426-437 ◽  
Author(s):  
Tao Yang ◽  
Xiaoman Xiong ◽  
Rajesh Mishra ◽  
Jan Novák ◽  
Jiří Militký
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Resistance ◽  
Strong Correlation ◽  
Sound Absorption ◽  
Structural Parameters ◽  
Airflow Resistance ◽  
Nonwoven Fabrics ◽  
Acoustic Evaluation ◽  
Absorption Performance

This paper presents an experimental investigation on the sound absorption behavior and thermal properties of Struto nonwovens by establishing relationship between these properties. Seven Struto nonwoven fabrics were selected to examine the noise reduction coefficient (NRC) and average values of sound absorption coefficients ([Formula: see text]) as well as thermal properties, including thermal conductivity and thermal resistance. The Brüel and Kjær impedance tube instrument and Alambeta were used for the evaluation of acoustic and thermal properties, respectively. The influence of structural parameters on acoustic and thermal properties of Struto nonwovens were investigated and analyzed. The results showed that Struto nonwovens with higher thickness, finer fibers and higher fabric grams per square meter can provide better sound absorption performance. The effect of specific airflow resistance on sound absorption performance was also investigated. It is observed that sound absorption performance has a strong correlation with specific airflow resistance. The effect of porosity on specific airflow resistance and thermal properties was studied in detail. The result indicated that porosity has a strong correlation with specific airflow resistance and thermal properties. It was also observed that sound absorption, the NRC and [Formula: see text] have an insignificant correlation with thermal conductivity, while they are strongly correlated with thermal resistance. The correlation coefficient of the NRC with thermal resistance is 0.9835, indicating that the NRC is directly proportional to the thermal resistance of Struto nonwovens.

scholarly journals Influence of Silica-Aerogel on Mechanical Characteristics of Polyurethane-Based Composites: Thermal Conductivity and Strength

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1790
Author(s):  
Jeong-Hyeon Kim ◽  
Jae-Hyeok Ahn ◽  
Jeong-Dae Kim ◽  
Dong-Ha Lee ◽  
Seul-Kee Kim ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Cell Morphology ◽  
Environmental Conditions ◽  
Silica Aerogel ◽  
Porous Silica ◽  
Mechanical And Thermal Properties ◽  
Insulation Material ◽  
Wide Range ◽  
Insulation Systems

Polyurethane foam (PUF) has generally been used in liquefied natural gas (LNG) carrier cargo containment systems (CCSs) owing to its excellent mechanical and thermal properties over a wide range of temperatures. An LNG CCS must be designed to withstand extreme environmental conditions. However, as the insulation material for LNGC CCSs, PUF has two major limitations: its strength and thermal conductivity. In the present study, PUFs were synthesized with various weight percentages of porous silica aerogel to reinforce the characteristics of PUF used in LNG carrier insulation systems. To evaluate the mechanical strength of the PUF-silica aerogel composites considering LNG loading/unloading environmental conditions, compressive tests were conducted at room temperature (20 °C) and a cryogenic temperature (−163 °C). In addition, the thermal insulation performance and cellular structure were identified to analyze the effects of silica aerogels on cell morphology. The cell morphology of PUF-silica aerogel composites was relatively homogeneous, and the cell shape remained closed at 1 wt.% in comparison to the other concentrations. As a result, the mechanical and thermal properties were significantly improved by the addition of 1 wt.% silica aerogel to the PUF. The mechanical properties were reduced by increasing the silica aerogel content to 3 wt.% and 5 wt.%, mainly because of the pores generated on the surface of the composites.

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