Prof. Ing. Jiri Miltky, CSc., EURING doc. Rajesh Mishra, Ph.D., B. Techimage.silikaty.cz/prezentace/5_Venkataraman.pdf · 2016-05-18 · 6 • “Mesoporous” refers to a material

Mohanapriya Venkataraman

Department of Material Engineering Faculty of Textile Engineering

Prof. Ing. Jiri Miltky, CSc., EURING doc. Rajesh Mishra, Ph.D., B. Tech

2

Background

Research Objectives

Materials & Methods

Results & Discussion

Conclusion

Future Direction

Research Outputs

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In extreme cold applications, the role of

the middle layer, in multilayer clothing, is

to protect the human body against

chilling.

Thermal insulation properties are

determined by the physical as well as

structural parameters of fabrics.

Heat transfer normally occurs through

three modes namely; conduction,

convection and radiation.

In general, the heat transport properties can be divided into two groups:

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Steady-state thermal

properties such as thermal

conductivity and resistance

which provide the

information on the warmth

of a fabric.

Transient-state thermal

properties such as thermal

absorptivity which provides

the information of warm–

cool feeling when fabric is

first handled.

Samples

No.

Sample

Description

Thickness

(mm)

Weight

(g/m2)

Density

(kg/m3)

S1

Silica aerogel treated

nonwoven fabrics

(Polyester +Polyethylene)

3.424 272.56 79.66

S2 6.212 499.46 80.42

S3 6.608 440.7 66.73

S4 8.06 535.1 66.39

S5 11.12 733.7 65.99

S6 13.8 942.7 68.33

H1 Needle punched

ROTIS nonwoven structure 9.336 402 43.06

H2 Needle punched

ROTIS nonwoven structure 8.048 407.5 50.64

M1 Elastic Gros Braun patent no. M123A2046

1.848 101.8 55.20

M2 POLARTEC with 100% polyester 1.522 104.1 68.384

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• “Mesoporous” refers to a material that contains pores ranging from 2 to 50 nm in diameter. Most of the pores in an Aerogel fall within this size range.

Aerogels exhibit somewhere between 90 to 99.8+% porosity and also contain a significant amount of microporosity (pores less than 2 nm in diameter).

An aerogel is an open-celled, mesoporous, solid foam that is composed of a network of interconnected nanostructures and that exhibits a porosity

(non-solid volume) of no less than 50%.

S. No. Properties Value range

1 Particle size range 0.1–0.7mm

2 Pore diameter ~20 nm

3 Particle density 120–140 kg/m3

4 Surface chemistry Fully hydrophobic

5 Thermal conductivity 0.012W/mK at 25oC

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8

Transparency allows use in lighting

Low thermal conductivity minimizes heat loss

Energy efficiency is an important path forward to helping solve our energy crisis

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The micro spacing between fibers is filled with aerogel

particles

Aerogel is covering surface of individual

fibers and is well distributed in the

structure

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Waves maker

Quasi-yarns maker

Input Output

Figure 2: Schematic diagram of a device for manufacturing products being

vertically pleated from thin nonwoven fabrics

2D 3D

PP web

(Top & Bottom layer)

Melt blown polyamide

nanofibres on both sides of

spunbond PP web (Middle layer)

Oldrich Jirsak, Thermo-Insulating Properties of Perpendicular-Laid Versus Cross-Laid Lofty Nonwoven Fabrics, Textile Research Journal February 2000 70: 121-128.

Particle Image Velocimetry

(PIV)

Custom Built Thermal

Measurement Instrument

Custom Built Thermal

Convection Instrument

P.K.Teknik Thermal

Manikin

KES Thermolabo II Alambeta C-Therm (TCi) Thermal

Conductivity Analyzer Air Permeability Tester

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12

Correlation of Thermal Conductivity Correlation of Thermal Resistance

Mohanapriya Venkataraman, Rajesh Mishra, Jiri Militky, Lubos Hes, Aerogel based nanoporous

fibrous materials for thermal insulation, Fibers and Polymers, Vol 15, No. 7, pp. 1444-1449, 2014,

(Impact factor: 0.881).

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Air permeability is related to porous

structure of the fabric and is directly

proportional to percentage of porosity

of the fabric.

When the pressure level increased, the

flow rate also increased. Irrespective of

different pressure levels.

Low air permeability may be attributed

to the layered structure and high

porosity.

Mohanapriya Venkataraman, Rajesh Mishra, Jiri Militky, Aerogel based nanoporous fibrous

materials for thermal insulation, Fibers and Polymers, Vol 15, No. 7, pp. 1444-1449, 2014

(Impact factor: 0.881).

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Schematic diagram of custom-built instrument for measuring thermal properties.

Schematic diagram of the newly fabricated instrument (single-plate method).

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Thermal conductivity Thermal resistance

Standard error for all the samples was not more than 0.0002 Confidence Ievel @ 95%

-25 -20 -15 -10 -5 0 5 10 15 20 250.018

0.024

0.030

0.036

0.042

0.048

0.054 S1

S2

S3

S4

S5

S6

H1

H2

Th

erm

al

co

nd

ucti

vit

y (

W.m

-1.K

-1)

Temperature (oC)

-25 -20 -15 -10 -5 0 5 10 15 20 25

160

180

200

220

240

260 S1

S2

S3

S4

S5

S6

H1

H2

Th

erm

al

resis

tan

ce (

m2.

K.

W-1

)

Temperature (oC)

Mohanapriya Venkataraman, Rajesh Mishra, Jakub Wiener, T M Kotresh, Jiri Militky, Miroslav

Vaclavik, Novel techniques to analyze thermal performance of aerogel treated blankets under

extreme temperatures, Journal of the Textile Institute, Accepted, June,

http://dx.doi.org/10.1080/00405000.2014.939808, 2014

(Impact factor: 0.722).

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Set Parameters Velocity of air – 2.5 m/s Climatic chamber temperature - -10oC Temperature of hot plate – 60oC

Mohanapriya Venkataraman, Rajesh Mishra, Guocheng Zhu, Jiri Militky, Dynamic heat flux

measurement for advanced insulation materials, Journal of Industrial Textiles (under review).

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Thermal manikin manufactured by P.K.Teknik systems are used to evaluate whole garments systems (or components of garment systems) for heat and moisture management related to garment insulation and breathability. The parallel method was used to calculate clothing insulation using insulation values from the individual segments operated in UST (Uniform skin temperature) mode.

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Linear model Poly 22:

f(x,y) = p00 + p10*x + p01*y + p20*x^2 + p11*x*y + p02*y^2

Goodness of fit: Coefficients (with 95% confidence bounds):

SSE: 6.798e-010

R-square: 1

Adjusted R-square: 1

RMSE: 1.844e-005

p00 = -0.002523 (-0.0151, 0.01005)

p10 = -7.515e-005 (-0.0005783, 0.000428)

p01 = 5.573 (5.483, 5.663)

p20 = -1.653e-006 (-1.086e-005, 7.556e-006)

p11 = 0.000316 (-0.00167, 0.002302)

p02 = -0.03054 (-0.1919, 0.1308)

Linear model Poly 22:

f(x,y) = p00 + p10*x + p01*y + p20*x^2 + p11*x*y + p02*y^2

Goodness of fit: Coefficients (with 95% confidence bounds):

SSE: 0.000474

R-square: 0.9137

Adjusted R-square:

0.6979

RMSE: 0.01539

p00 = 6.683 (-6.816, 20.18)

p10 = -0.09256 (-0.3402, 0.155)

p01 = -0.1301 (-0.3412, 0.08104)

p20 = 0.000412 (-0.00079, 0.001614)

p11 = 0.0007745 (-0.0009191, 0.002468)

p02 = 0.000713 (-0.0002566, 0.001683)

3D fit model (Thermal manikin) where x= Thickness (mm),

y=R-Value (m2.K/W) & z= Clo value

3D fit model (Thermal manikin) where x= Fabric density (kg/m3)

y=Heat flux (W/m2) & z= R-value (m2.K/W)

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Q-Q plot for residual normality check Q-Q Predicted Residuals

•The L-R plot is an influential scatter plot that is effective in distinguishing between high leverage points and outliers. •The L-R plot combines the leverage values and the residuals in a single scatter plot.

Mohanapriya Venkataraman, Rajesh Mishra, Guocheng Zhu, Jiri Militky, Dynamic heat flux

measurement for advanced insulation materials, Journal of Industrial Textiles (under review).

L-R Plot (Areal density, Heat flux & Thermal resistance)- Thermal manikin

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Image of wind column attached

during measurement

Components of KES Thermolabo II

Parameters

Room Temp.– 20oC, R.H – 65% B.T. Box – 30oC, 50 cm2, 10 gf/cm2

T Box – 25 cm2, 10gf/cm2

Velocity of air – 10 to 100 cm/s

Mohanapriya Venkataraman, Rajesh Mishra, T. M. Kotresh, Tomonori Sakoi, Jiri Militky, Effect of

compressibility on heat transport phenomena in aerogel treated nonwoven fabrics, Journal of

Textile Institute - accepted, 2015 (Impact factor: 0.722).

10 20 30 40 50 60 70 80 90 100

24

30

36

42

48

54

60

66

72

78 S1

S2

S3

S4

S5

S6

Th

erm

al

resis

tan

ce (

m2.K

/W)

Wind Velocity (cm/s)

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Thermal conductivity of fabrics (KES Thermolabo II & NT-H1)

Thermal resistance of fabrics (KES Thermolabo II & NT-H1)

10 20 30 40 50 60 70 80 90 100

0.010

0.012

0.014

0.016

0.018

0.020

0.022

0.024 S1

S2

S3

S4

S5

S6

Th

erm

al

co

nd

uc

tiv

ity

(W

/m.K

)

Wind Velocity (cm/s)

10 20 30 40 50 60 70 80 90 1000.010

0.012

0.014

0.016

0.018

0.020

0.022

0.024

0.026

0.028

S1

S2

S3

S4

S5

S6

Th

erm

al

co

nd

ucti

vit

y (

W/m

.K)

Wind Velocity (cm/s)

10 20 30 40 50 60 70 80 90 100

24

30

36

42

48

54

60

66

72

78

S1

S2

S3

S4

S5

S6

Th

erm

al

resis

tan

ce (

m2.K

/W)

Wind Velocity (cm/s)

10 20 30 40 50 60 70 80 90 100-2

-1

0

1

2Residuals

Linear: norm of residuals = 2.1666

10 20 30 40 50 60 70 80 90 10065

70

75

80

Air Velocity (cm/s)

Th

erm

al In

su

lati

on

Ra

te (

%)

y = 0.126*x + 64.6

data 1 linear Y = f(X)

Linear model Poly1: f(x) = p1*x + p2 Coefficients (with 95% confidence bounds): p1 = 0.1209 (0.09574, 0.1461) p2 = 64.85 (63.29, 66.41)

Goodness of fit: SSE: 7.859 R-square: 0.9388 Adjusted R-square: 0.9312 RMSE: 0.9911

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The PIV measurement technique allows obtaining information about the current distribution of velocities in two-dimensional array in a flowing fluid.

Basic Principle

Experimental setup

Conventional methods

• (HWA -Hot wire anemometry, LDV-

Laser doppler velocimetry)

• Single-point measurement

• Traversing of flow domain

• Time consuming

•Only turbulence statistics

Particle Image Velocimetry

•Whole-field method

•Non-intrusive (seeding)

• Instantaneous flow field

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Instantaneous measurement of 2 components in a plane

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• Particles appear from out of laser

plane

• Program assumes false interpolations

• Causes inaccurate vector field

Cross Flow

• Have many different velocities

• The vector field is very sensitive to

the dt choice

Seed particles

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If dt is too small, motion is not detected If dt is too large, the wrong motion will be detected

Look for small but noticeable bulk movement

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Figure 35. Vector and scalar maps for temperature gradient 51.0 C.

21.5 oC

23.8 oC

37.5 oC

51.0 oC

Vector and scalar maps for temperature gradient Distance and air velocity diagram.

Scalar maps are used to display the on-screen multiple data derived from the velocity fields. The x and y axis scales in vector and scalar maps illustrate the magnitude and direction of the out-of-plane velocity component.

Mohanapriya Venkataraman, Rajesh Mishra, Darina Jasikova, T M Kotresh, Jiri Militky,

Thermodynamics of aerogel treated nonwoven fabrics at subzero temperatures, Journal of

Industrial Textiles, doi:10.1177/1528083714534711, 2014 (Impact factor: 1.349).

0.1 0.2 0.3 0.40.0

0.1

0.2

0.3

0.4

Exp

eri

men

tal

valu

es (

m2.K

.W-1

)

Theoretical values (m2.K.W

-1)

0.1 0.2 0.3 0.4

0.07

0.14

0.21

0.28

0.35

Exp

eri

men

tal

valu

es (

m2.K

.W-1

)

Theoretical values (m2.K.W

-1)

Alambeta Custom built instrument

0.1 0.2 0.3 0.4

0.05

0.10

0.15

0.20

0.25

0.30

0.35

Exp

eri

men

tal

valu

es (

m2.K

.W-1

)

Theoretical values (m2.K.W

-1)

TCi

Correlation between the theoretical and experimental values of thermal resistance were around R2 = 0.9 for the instruments.

It was concluded that the data generated

from the experiments are theoretically compatible.

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Reference - Oldrich Jirsak and Stanislav Petrik, Recent advances in nanofibre technology: needleless electrospinning, International Journal of Nanotechnology, http://dx.doi.org/10.1504/IJNT.2012.046756

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Equipment – Nanospider (needless electro spinning process) Solution Preparation – 18 wt.% PUR + aerogel , 2 hours stirring

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PUR nanofibre

PUR +Aerogel (powder) PUR +Aerogel (granular)

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Samples Sample description GSM Themal Conductivity

(W.m-1.K-1) Thermal resistance, r

(K.m2.W-1)

NA1 PUR 34.01 0.03362 7.68

NA2 PUR + aerogel (Powder) 33.11 0.03148 8.12

NA3 PUR + aerogel (Granular) 35.28 0.03204 8.88

NA4 PUR + aerogel (Powder) 35.29 0.03262 11.48

NA5 PUR + aerogel (Granular) 38.58 0.03222 11.44

Mohanapriya Venkataraman, Rajesh Mishra, Jaromir Marek, Jiri Militky, Electrospun

nanofibers from PUR and PVDF embedded with SiO2 Aerogel for Advanced Thermal

Properties, Textile Research Journal (under review).

AIR as Insulator | Stagnant Air Conditions

Aerogel as Insulator | Stagnant Air Conditions

The heat retention in the

nonwoven structure with

aerogel is 67% higher than in

the nonwoven structure

without aerogel implying that

aerogel hinders heat transfer,

thus keeping the body warmer.

No.of elements - 13,425

No.of nodes – 2522

Processing time – 6 hours

20 mins

Heat transfer through standard nonwoven without forced convection.

Heat transfer through standard nonwoven with forced convection.

Heat transfer through aerogel treated nonwoven without forced convection

Heat transfer through aerogel treated nonwoven without forced convection

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Aerogel-based fabric samples were found to have considerably lower thermal conductivity and higher thermal resistance even

at extreme temperatures and suitable for thermal insulation under extreme temperature conditions.

The newly fabricated and designed instruments were found to be suitable to measure conductivity and convection at sub-zero

temperatures and convenient for the measurement and evaluation of various temperature variations at different positions of

the fabric.

Electrospun nanofibrous layers from PUR and PVDF embedded with SiO2 Aerogel was found to have application as components

in hybrid battings with high bulk densities.

Simualted results correlated well with the experimental results.

Thermal properties

Thermal resistance

(Rct) of the fabric,

which depends on the

boundary layer of air,

was directly

proportionate to

fabric thickness.

Air permeability was

directly proportional

to percentage of

nanoporosity of the

aerogel based

composite structure.

Thermal insulation is

related to the weight

and compressional

properties of fabric.

High insulation is due

to layered structure

and higher thickness.

The fluid flow motion

accelerated according

to the increasing

temperature gradient.

Mohanapriya Venkataraman

Department of Material Engineering Faculty of Textile Engineering

Thank You