Mechops ppt

A Study and Experimental observations

CH2040-Mechanical Operations

Nanofluids

Department of Chemical Engineering CH2040-Mechanical Operations

Nano Crusaders

-Neha Nathan CH10B042

-Sake Karthik CH10B055

-Mohammed Rhazy CH10B100

-Shivani Patel CH10B101

What are nanofluids?

Nanofluids is a name used to

describe a fluid consisting of

solid nanoparticles with size

less than 100nm suspended on

it with solid volume fractions

typically less than 4%.

Examples :

• Blood (Natural nanofluid)

• CuO nanoparticles in glycol


Why do we need nanofluids?

• Enhance thermal properties like heat transfer

and thermal conductivity, when compared to the

host fluid.

• Size does matter!

unique transport properties:

do not settle under gravity and do not block flow


What gives Nanofluids the edge?

Effect of

Nanoparticle

Interfacial Layer

This enhances the

thermal conductivity!


(M.Reza Azizian- Thermo physical

properties of Nanofluids)


CuO Nanowires

Preparation

And

Trends


SYNTHESIS OF CuO NANOWIRES

• Copper nano-particles are placed in 1 N HCL for one minute.

• Rinse with water thoroughly and finally clean with ethanol.

• Place the samples in a ceramic crucible inside a furnace. The

temperature inside the furnace rises at a rate of around 10 °C/min.

Thermal oxidation can be performed at 400 - 600 °C for 3 - 6 hr.

• Once the holding time is over, slowly reduce the temperature down

to room temperature.

• A thin film with a thickness of about 10 μm splits off from the copper

substrate.

• The film surface is black and fluffy, indicating the formation of dense

CuO nanowires.


SEM TEST ON CuO OBTAINED

• The sample was supposed to be prepared at a temperature of 600 °C, however, at

the end of a holding time of 6 hrs, the tubular furnace unexpectedly displayed a

temperature of 198 °C.

• SEM analysis was performed:

• SEM analysis on this sample revealed that CuO nanowires were not formed. The

images obtained :


TRENDS (CITED FROM LITERATURE)

Effect Of Evaporation Temperature on the Growth

Effect of Evaporation Time on the Growth

At 600 °C, the effect of

evaporation time on the growth

was noted.

At six different temperatures, the

trends in growth of nanowires are

as follows:

Temperature Dimensions of CuO

Rods

300°C Diameter : 40 nm

Length: 1 μm






900°C No nanowires observed

Evaporation Time Length of CuO

rods

0.5 h 5 μm

2 h 10 μm

10 h 20 μm

20 h 35 μm


Preparation of large-scale cupric oxide nanowires by thermal

evaporation method

L.S. Huanga, S.G. Yanga,*, T. Lia, B.X. Gua, Y.W. Dua, Y.N. Lub, S.Z. Shib

SEM IMAGES FOR THE TRENDS SEM images of CuO nanowires prepared

at various temperatures: (a) 300 C, (b)

400 C, (c) 500 C, (d) 600 C, (e) 750 C and

(f) 800 C.

Morphologies of CuO nanowires

prepared at 600°C for different times:

(a) 0.5 h, (b) 2 h,(c) 10 h and (d) 20 h.



evaporation method

L.S. Huanga, S.G. Yanga,*, T. Lia, B.X. Gua, Y.W. Dua, Y.N. Lub, S.Z. Shib

Stability Test-CuO nanofluid

• Prepared a 0.05, 0.15 and 0.25

volume % CuO suspension in

de-ionized water.

• Solutions were checked every

4 hours for a week.

• RESULT: The nanoparticles

did not settle. They were still in

the solution phase. CuO

nanofluid is stable


Photograph taken

after leaving the vial

with 0.05% CuO

suspension in de-

ionozed water for 4

hours

Density Test – CuO

nanoparticles

13 g of 10 % by weight

CuO suspension

x=0 x = 0.025 x = 0.05 x = 0.075 x = 0.1


Using a densitometer, the density of each

of the 5 samples was measured.

Batch Mass Fraction

of CuO

Density (g/cc) 1/ρ (g/cc)-1

1 0 0.99814 1.001874

2 0.025 1.00344 0.980132

3 0.05 1.01405 0.961291

4 0.075 1.02341 0.938749

5 0.1 1.02912 0.916708


Density Calculations

1/ ρx=0 = 1/ρsolvent

1/ρx=1 = 1/ρp

1/ρp – 1/ρsolvent = (1/ρx=0.1 - 1/ρx=0)/0.1

= -0.85166 (g/cc)-1

The graph gives 1/ρsolvent = 1.001874 (g/cc)-1

1/ρp = 0.150214 (g/cc)-1

Therefore, the density of CuO particles is calculated to be

6.66g/cc


Inference

• The calculated density of

CuO = 6.66g/cc

• The theoretical density of

CuO = 6.31g/cc

• Therefore, the values are

nearly correct and the

substance taken is CuO

Densitometer


Thermal Conductivity of Nanofluids


Review and Comparison of Nanofluid Thermal Conductivity and Heat Transfer Enhancements

Wenhua Yu a , David M. France b , Jules L. Routbort a & Stephen U. S. Choi b c

Factors affecting thermal

conductivity of nanofluids

1) Particle volume concentration

2) Particle materials

3) Particle size

4) Particle shape

5) Base fluid material

6) Temperature

7) Additive

8) Acidity


Measurement of Thermal

Conductivity

• Dual needle line heat source method

• Transient method or non steady state heat

conduction.

• Measurements done during the process of

heating up.

• Advantage-less experimentation time

• Disadvantage-data analysis


DNL Device


Experimentation Setup Sample

• The primary probe - a

line heater and a

thermocouple

• Secondary probe -

thermocouple only.

• Analysis to be done until

both the probes

temperature reading

becomes same.

• We are more concerned

with the variation of

temperature with time of

primary probe.

Primary

probe

Secondary

probe

DNL Device probes


Calculations

• Thermal conductivity (kW/m◦C) of the medium may be obtained as

k = q/4π S (1)

• where q is heat input (W/m)

• S is a slope determined by linear regression of measured temperatures against the natural logarithm of time (◦C).

Evaluation of Thermal Properties of Food Materials at High Pressures Using a Dual-Needle Line-Heat-Source Method

S. ZHU, H. S. RAMASWAMY, M. MARCOTTE, C. CHEN, Y. SHAO, AND A. LE BAIL


Calculations-What we got

30

31

32

33

34

35

36

37

3.25 3.3 3.35 3.4 3.45 3.5

Temperature v/s log time

Primaryprobe

Linear(Primaryprobe)

Log time

Tem

per

atu

re

0

5

10

15

20

25

30

35

40

45

50

0 50 100

Tte

mp

erat

ure

(.C

)

Time (sec)

Temperature vs Time

Primary probe

Secondary probe


Results-Thermal conductivity SI no Volume fraction Slope Thermal Conductivity (W/

m0C)

1 0 0.97925 0.276736

2 0.05 0.882 0.30717

3 0.15 0.7831 0.34592

4 0.25 0.39 0.694607

0

0.5

1

1.5

2

2.5

3

0 0.1 0.2 0.3

k/ko v/s volume fraction

CuO sample

Volume fraction

k/ko


References



evaporation method

L.S. Huanga, S.G. Yanga,*, T. Lia, B.X. Gua, Y.W. Dua, Y.N. Lub, S.Z.

Shib

Evaluation of Thermal Properties of Food Materials at High Pressures

Using a Dual-Needle Line-Heat-Source Method

S. ZHU, H. S. RAMASWAMY, M. MARCOTTE, C. CHEN, Y. SHAO,

AND A. LE BAIL

Review and Comparison of Nanofluid Thermal Conductivity and Heat

Transfer Enhancements

Wenhua Yu a , David M. France b , Jules L. Routbort a & Stephen U.

S. Choi b c

Acknowledgements


Polymer Lab

• Santhosh

• Ashok

• Venkat

• Gaurav

• Kalpana

• Swami

• Shyam

Last but not the least

Metallurgical Department

• Phani Kumar sir

• Kaushalya

Dr Basavaraja M Gurrappa

Kanan Sir’s URP team

• Deepthi M

• Saranya

Date post:	28-Oct-2014
Category:	Documents
Upload:	shivani-patel
View:	69 times
Download:	0 times

Mechops ppt

Documents