BazTech - Yadda

1

Modelowanie procesów wymiany ciepła w dzianinach futerkowych

Więzowska Anna

Zeszyty Naukowe. Włókiennictwo / Politechnika Łódzka

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2019

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z. 75

39--75

PL

Ciepłochronność jest podstawowym parametrem determinującym praktyczne zastosowanie dzianin futerkowych. Analiza wymiany ciepła oraz metodyka określenia podstawowych parametrów struktury do optymalizacji konstrukcji z uwagi na wymagany poziom izolacyjności cieplnej nie zostały jeszcze dotychczas opisane dla dzianin futerkowych. Brak rozwiązań problemów ciepłochronności dla tego typu dzianin wskazuje na celowość podjęcia rozważanej tematyki. Celem prac prowadzonych w ramach dysertacji doktorskiej było opracowanie modelu przepływu ciepła, który może być wykorzystany do projektowania dzianin futerkowych o wymaganych właściwościach termofizycznych. Zaprezentowany model opisu zjawiska przepływu ciepła ma uzasadnienie praktyczne w odniesieniu do dzianin futerkowych. Przyjęta metoda pozwala uniknąć badań wielu parametrów, ograniczając je do minimum: udział objętościowy poszczególnych składników w stosunku do każdej warstwy oraz stosunek grubości poszczególnych warstw do grubości całego wyrobu. Do badań wykorzystuje się powszechnie dostępne urządzenia pomiarowe. Uzyskuje się ponadto możliwość symulacji eksperymentu, bez konieczności wytwarzania dzianiny futerkowej. Metoda ta pozwala na dowolne modelowanie warunków brzegowych i początkowych, co nie zawsze jest możliwe dla metod empirycznych ze względu na ograniczenia sprzętowe. Opracowany model obliczeniowy przepływu ciepła przez dzianiny futerkowe umożliwia uzyskanie rozkładu temperatury w tej konstrukcji oraz może stanowić punkt wyjścia doboru optymalnego struktury dla osiągnięcia 40 Anna Więzowska wymaganych właściwości wyrobów. Projektowanie dzianiny futerkowej o wymaganym poziomie izolacyjności cieplnej, z zastosowaniem przedstawionego modelu, może posłużyć do powstania rzeczywistego materiału o określonych właściwościach ciepłochronnych.

EN

The fundamental function of the knitted fur fabrics, which are commonly used to manufacture the clothes and shoes, is to protect the human body against heat loss in low environmental temperature. Thus, the heat-insulating properties of fur fabrics are the basic criterion for their functional characteristics. The aim of this work is to determine the heat transfer model, which can be applied to design the knitted fur fabrics of the required thermophysical properties. The mathematical model of heat transport within knitted fur fabrics allows to obtain the temperature distribution in the structure and can be a starting point to optimize the structural shape in respect of the requested properties. The available literature does not introduce the heat transport problems in the knitted fur fabrics. A few works describe in general form some parameters of the structure whereas the corresponding standards are inaccessible. To explain the nature of heat transfer inside the knitted fur fabrics, the dissertation describes the basic phenomena of heat transfer. The heat conduction is defined more precisely as the dominant heat transport mechanism in textiles. The material properties influencing the heat flux density transferred in textile product are also described. The particular cases of heat conduction mechanisms in the single layer and the multi-layer structure have been analysed and next applied to determine the heat transfer in the homogenized fur fabric. The solution methodology of simple and complex heat transfer problems has been explained. The literature pertaining to the measurements of heat isolation in textiles has been reviewed in respect of the measurement methods, character of processes, measured parameters and field of their application vs. both structure of examined material as well as the layers arrangement. Assuming the complex structure of knitted fur fabrics (i.e. the multilayer arrangement, participation of glue in bottom layer, air inside the void spaces under inclined fibers), we have rejected the measurements methods influencing the material structure during the test. Heat transport within knitted fur fabrics is described by means of the heat conduction coefficient tested in steady conditions. The measured conduction coefficient is often of substitute nature and can additionally include the convective and radiative heat transport. The thermal properties of knitted fur fabrics are determined by means of the test device Tilmet 75. The preliminary investigations were conducted using the device Tilmet 75 for different knitted fabrics made of homogenous materials with the diversified thickness and surface mass. The fur fabrics were characterized using the same standard indexes which are tested for the knitted fabrics i.e. the thickness and surface mass. There are tested the heat conduction and heat permeability as well as determined the structure of knitted fabrics samples vs. the characteristics of thermal properties. The empirically determined heat conduction coefficient and heat resistances vs. basic structural parameters do not describe the influence of raw material in the knitted fur fabrics on the material heat characteristics. Both growing surface mass and growing fabric thickness does not determine unequivocally the gradation of these features in respect of thermal properties. According to the preliminary test results, it is necessary to change the factors determining the complex knitted fur fabrics in respect of the structure and raw material composition. The description of the knitted fur fabric can cause difficulties in heat transport correlations. Parameters of fur fabrics of the complex, space and multilayer structure are hard to determine and investigate using the standard test methods. The structure consists of the bottom layer and the fleece layer which are made of different raw materials: the yarn, band and glue as well as considerable volume fraction of air inside. Thus, the description of physical model is troublesome. Let us introduce the following assumptions concerning the fur fabric: (i) the same height of fleece layer; (ii) the uniform distribution of fibres density in cover layer; (iii) the uniform distribution of yarn, fibres and air in bottom layer; (iv) the void spaces between the yarn in bottom layer are filled by both air and glue; (v) the glue does not penetrate the cover layer. Under the above assumptions, the space 3D description can be simplified to the plane 2D problem introducing the homogenized particular layer of fabric. The structure is defined by the volume fraction and heat conduction coefficient of each layer. The heat conduction coefficient is determined using the rule of mixture which limits the domain of study of corresponding parameters to the volume fractions of particular component in every layer. The principal investigations were conducted for the knitted fur fabrics of the diversified both length of fleece and basis weight, subjected to the different finishing processes. The test methods applicable for the different textile materials were analysed in respect of the measurement characteristics i.e. applicable for thickness, density, mass related to materials / textile products and their particular layers. The complex structure of knitted fur fabrics can be characterized by the innovative, non-standard test methods as well as the standard methods, which are not usually applied for those materials. The thickness of knitted fur fabric tested for the various pressures strongly depends on the load applied. The presented model of heat transfer description is practically motivated for the knitted fur fabric. The adopted method can avoid the large number of tests of required parameters and restricts the analysis to the following cases: the volume fraction of particular component within each layer and thickness fraction of particular layer to the complete thickness of product. The commonly available test equipment is used during the tests. Additionally, the experiments are simulated which substitute the manufactured knitted fur fabric. This method allows to model 75 optionally the boundary and initial conditions which is not always applicable for empirical methods due to equipment limitations. Design of knitted fur fabric of the requested thermal isolation level, based on the model presented in this work, can help to create the real material of the prescribed heat-insulating properties. The next stage of the current investigations can be focused on determination of indexes characterizing the knitted fur fabrics in presented model vs. technological parameters necessary to manufacture the designed product.

2

Słabe ogniwa W-70. Cz.2 Zakres koniecznych prac remontowych i modernizacyjnych

Piotrowski Jerzy

Builder

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2014

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R.18, nr 9

40--43

EN

Currently, especially thanks to the financial support of EU's development funds and programmes, a major need to start a complex system of modernization of pre-fabricated housing is widely observed.

3

Zmiany w obrazie termograficznym królika domowego (Oryctolagus cuniculus) w zależności od wieku i stanu fizjologicznego

Łapiński S., Augustyn J., Lis M., Kanik W., Niedbała P.

Pomiary Automatyka Kontrola

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2011

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R. 57, nr 10

1154-1156

PL

Celem badań była ocena różnic w emisji ciepła spowodowanych wiekiem i stanem fizjologicznym królików, przy pomocy metody termowizyjnej. Na podstawie wykonanych pomiarów stwierdzono, iż właściwości ciepłochronne futra królików ulegają zmianie zależnie od wieku i stanu fizjologicznego. Obszarem najsilniej emitującym ciepło są okolice płciowe, których temperatura jest najwyższa u samic mających objawy rui a najniższa u samców i samic ciężarnych. Uszy królików pełnią funkcję termoregulacyjną, a ich temperatura wykazuje znaczną zmienność osobniczą.

EN

The aim of the study was to evaluate the differences in heat emission due to age and physiological state of rabbits. The study was conducted in the spring-summer season for 36 adults and 30 young New Zealand White rabbits. Distribution of the surface temperature of animals was recorded using a Flir System Thermovision A20 camera. The study indicates that the thermographic camera is a useful tool in assessing the rabbit fur quality. At a constant external temperature (19 °C) the genital area is about 1.5 °C cooler than the rabbit body temperature (38,5-40,5 °C), while the surface temperature of the body varies depending on a gender and technological group (p ≤ 0.05) (Tab. 1, Figs. 2 and 3). During pregnancy and lactation the female body is exposed to a greater burden than the male body, which affects directly the density and quality of the fur coat [1]. The genital area was characterized by the highest temperature from among all studied areas. Depending on the physiological state of rabbits it had a different temperature (p ≤ 0.05). This is a consequence of the fact that rabbits are polioestrus animals, ready to get pregnant almost throughout the year. One of the signs that does are sexually receptive is better blood circulation and redness of the vulva [2]. This explains the vulva lower temperature of the pregnant does and higher of lactating does, ready to mating almost immediately after birth. In young animals it was found that the surface temperature of ears was increased in subsequent weeks of life (p ≤ 0.001, Fig. 4, Tab. 2), while the surface temperature of the body decreased (p ≤ 0.001, Figs. 4, 5 and 6, Tab. 2).

4

Badania właściwości termoizolacyjnych cienkich tkanin odzieżowych. Cz. II

Matusiak M., Sikorski K.

Przegląd Włókienniczy - Włókno, Odzież, Skóra

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2010

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nr 4

34-36

EN

Thermal insulation is primal and one of the basic functions of clothing. It depends of many factors connected with clothing structure and thermal-insulation properties of material creating particular clothing layers. Innovative measurement devices such as: ,,skin model". Thermo Labo II, Alambeta and Permetest can be applied to measurement of thermal-insulation properties of textile materials. In presented work the woven fabrics made of cotton and Tencel were measured by means of Alambeta. Due to the small thickness of fabrics they were measured both: as single and double layers. Analysis of the result showed that the relations between the results for single and doubled fabrics are different for different thermal-insulation parameters and different fabric structures.

5

Badania właściwości termoizolacyjnych cienkich tkanin odzieżowych. Cz. I

Matusiak M., Sikorski K.

Przegląd Włókienniczy - Włókno, Odzież, Skóra

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2010

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nr 3

42-44

EN

Thermal insulation is primal and one of the basic functions of clothing. It depends of many factors connected with clothing structure and thermal-insulation properties of material creating particular clothing layers. Innovative measurement devices such as: ,,skin model", Thermo Labo II, Alambeta and Permetest can be applied to measurement of thermal-insulation properties of textile materials. In presented work the woven fabrics made of cotton and Tencel were measured by means of Alambeta. Due to the small thickness of fabrics they were measured both: as single and double layers. Analysis of the result showed that the relations between the results for single and doubled fabrics are different for different thermal-insulation parameters and different fabric structures.

6

Parametry izolacyjności cieplnej tkanin. Część I. Przegląd metod i przyrządów pomiarowych

Frydrych I., Porada A., Bilska J., Konecki W.

Przegląd Włókienniczy + Technik Włókienniczy

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2003

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nr 10

12-15

7

Badanie wpływu wielokrotnego prania na izolacyjność cieplną ciepłochronnych wyrobów włókienniczych

Malinowska G., Nowak T.

Przegląd Włókienniczy + Technik Włókienniczy

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2003

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nr 10

7-9