CONDENSATION RATE ENHANCEMENT OF FLUID IN STEAM … · 2018-05-09 · to lack of collective...

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International Journal of Thermal Engineering (IJTE)

Volume 6, Issue 1, Jan–June 2018, pp. 10–17, Article ID: IJTE_06_01_002

Available online at

http://www.iaeme.com/ijte/issues.asp?JType=IJTE&VType=6&IType=1

ISSN: 2347-3932

© IAEME Publication

CONDENSATION RATE ENHANCEMENT OF

FLUID IN STEAM CONDENSER BY MIXING

NANOPARTICLES

Ajeet Kumar

Assistant Professor, Guru Nanak Institute of Technical Campus, Hyderabad, India

Mukesh Kumar

Lecturer, Assosa University, Ethiopia

Yohannes Feyissa Beyisho

Dean, Assosa University, Ethiopia

Vipul Kumar Sharma

Research Assistant, Drexel University, Philadelphia, PA, US

ABSTRACT

In thermal power plants, the application of a steam condenser is to condense the

exhaust steam from a steam turbine to obtain maximum shaft work, and to change the

turbine exhaust steam into pure water so that it may be reused in the steam

generator boiler as boiler feed water. Condensation rate depends on the physical

properties of steam and the condensate. Condensate properties can be changed

significantly by mixing nanoparticle like Al2O3, SiO2 and CuO. In this paper analysis

of enhancement of condensation rate has been done by changing the thermophysical

properties of condensate by mixing nanoparticle. Mathematically, value of thermal

conductivity, density, absolute viscosity, convective heat transfer coefficient, and mass

condensation rate of fluid at different value of volume fraction has been determined.

Key words: Condenser, condensate, volume fraction and nanoparticle

Cite this Article: Ajeet Kumar, Mukesh Kumar, Yohannes Feyissa Beyisho and

Vipul Kumar Sharma, Condensation Rate Enhancement of Fluid in Steam Condenser

by Mixing Nanoparticles. International Journal of Thermal Engineering, 6 (1), 2018,

pp. 1–9.

http://www.iaeme.com/ijte/issues.asp?JType=IJTE&VType=6&IType=1

NOMENCLATURE

Symbols

kp Thermal conductivity of nanoparticle [W/m°C]

kf Thermal conductivity of fluid [W/m°C]

Greek symbols

φ Volumetric fraction [-]

ρf Density of fluid [kg/m3]

Condensation Rate Enhancement of Fluid in Steam Condenser by Mixing Nanoparticles


keff Thermal conductivity of nanofluid [W/m°C]

h Convective heat transfer coefficient [W/m2°C]

hfg Latent heat of vaporization [W/m2°C]

Q Heat transfer rate [W]

m Mass rate of condensation [gram/meter]

tsat Saturation temperature of fluid [°C]

ts Surface temper of pipe [°C]

D Diameter of condenser pipe [m]

g Acceleration due to gravity [m/s2]

ρp Density of nanoparticle [kg/m3]

ρeff Density of liquid nanofluid [kg/m3]

ρv Density of vapour nanofluid [kg/m3]

µf Viscosity of fluid [Ns/m2]

µeff Viscosity of nanofluid [Ns/m2]

1. INTRODUCTION

Condenser is a heat exchanging device used to convert steam into water. This is a type of heat

exchanger. In heat exchanger phenomena of heat transfer is complicated because at the time

of condensation phase change takes place from vapor to liquid. In condenser heat transfer take

place at constant temperature. Size of condenser depends on compactness of condenser

(surface area per unit volume), properties of material, direction of fluid flow, and properties of

cooling and heating fluids. Thermal conductivity of fluids can be improved substantially by

mixing nanoparticle. Size of nanoparticle, volume concentration and different types of

nanoparticle affect the properties of fluids.

Heat exchanger has been classified in different ways. Based on direction of flow: counter

flow, parallel flow, and cross flow have been classified. Counter flow has more value of log

mean temperature difference compared to remaining two. But crossflow is more compact

compare counter flow. When vapor condenses, there is liquid film formation takes place on

the surface of the condenser. Liquid films cover the surface and avoid direct contact of steam

with cooling surface.

1.1. Nanofluids and its Thermo Physical Property

Thermo physical properties of the nanofluids are very important for prediction of heat transfer

behavior. It becomes exceedingly valuable in the control for energy saving perspectives of the

industrial. There is always a significant industrial interest in nanofluids and nanoparticles.

Especially nanoparticles play immense potential for the improvement of thermal transport

properties compared to conventional micrometer sized particles, millimeter and particles

fluids suspension. In the last decade, due to its enhanced thermal properties, nanofluids have

gained significant attention.

Studies have shown that thermal conductivity of nanofluids depends on many factors such

as particle volume fraction, material, particle size, shape, base fluid material, and temperature.

The thermal conductivity enhancement was also shown to be effective in amount and types of

additives and the acidity of the nanofluid. The transport properties of nanofluids: viscosity

and dynamic thermal conductivity are dependent on volume fraction of nanoparticle and is

highly dependent on other parameters such as particle size, shape, mixture combinations and

surfactant, slip mechanisms, etc. Experimental studies showed that by use of nanofluid

compared to base fluid the thermal conductivity and viscosity both increases. Thus far,

different theoretical and experimental studies have been conducted and various correlations

have been proposed for dynamic viscosity and thermal conductivity of nanofluids. So far, due

to lack of collective understanding on mechanism of nanofluid no general correlations have

been established. There are limited rheological studies reported in the literature for viscosity

as compared with the experimental studies on thermal conductivity of nanofluids. To model

Ajeet Kumar, Mukesh Kumar, Yohannes Feyissa Beyisho and Vipul Kumar Sharma


the effective viscosity of nanofluid as a function of volume fraction different models of

viscosity have been used by researchers.

1.2. Application of Nanofluids

The novel and advanced concepts of nanofluids offer fascinating heat transfer characteristics

compared to conventional heat transfer fluids. There are considerable Researches on the

superior heat transfer properties of nanofluids especially on thermal conductivity and

convective heat transfer. Applications of nanofluids in industries such as heat exchanging

devices appear promising with these characteristics. Kostic reported that nanofluids can be

used in following specific are as: Heat-transfer nanofluids.

Tribological nanofluids.

Surfactant and coating nanofluids.

Chemical nanofluids.

Process/extraction nanofluids.

Environmental (pollution cleaning) nanofluids.

Bio-and pharmaceutical-nanofluids.

Medical nanofluids (drug delivery and functional tissue–cell interaction

2. THERMAL CONDUCTIVITY

Maxwell was first to propose model for conductivity of heterogeneous mixture. Thermal

conductivity model is based on continues and discontinues phase. The effective thermal

conductivity has been given by Maxwell [5] as

=

(1)

2.1. Viscosity

Viscosity is an important parameter when dealing with nanofluid. It directly affects the

pressure drop and pumping power of the system. Einstein [6] proposed the viscosity model

which has been used by Brinkmann to calculate viscosity of particles suspended in fluid.

Brinkmann model [7] includes the volume concentration of nanoparticles as shown in

equation.

=

(2)

Where 𝛍eff is the dynamic viscosity of nanofluid and 𝛍f is the dynamic viscosity of the

base fluid.

2.2. Density

Pak and Cho [13] used following equation for calculating density of nanofluids

ρeff = ρp +(1- )ρf (3)

Where ρp and ρf are the density of particle and base fluid respectively

3. CONDENSATION

Condensation is a process in which vapour converted into liquid when it comes to the contact

of liquid surface. Depending on nature of cold surface, condensation is classified in two in



two ways: Film condensation & Dropwise condensation. When condensate tends to wet the

cold surface and thereby makes a liquid film, then condensation process is called film

condensation. In dropwise condensation, the vapour condenses into small liquid droplets of

various sizes which fall down the surface in random fashion.

Figure 1 Dropwise and Filmwise Condensation

3.1. Film heat transfer coefficient

Nusselt’s analysis for laminar filmwise condensation on horizontal tubes leads to the

following relation:

=0.0725[

]

for single horizontal tube.

Here, D=2.5cm, tsat =90°C, ts = 70°C, and hfg = 2309kJ/kgK has been taken. Pressure

inside the inside the condenser is 0.7 bar.

3.2. Rate of Condensation

The rate of condensation for the single tube per meter length is

m =

=

Table 1 Effective thermal conductivity of nanofluid

S.No Fluid

conductivi

ty(Kf)

W/m°C

Thermal conductivity of

nanoparticles(Kp)

W/m°C

Volume

fraction

(φ)

Thermal conductivity of

nanofluids(Keff)

W/m°C

Water

Al2O

3 CuO

SiO

2

TiO

2 Al2O3 CuO SiO2 TiO2

1 0.65 40 33 1.4 8 0.01 0.6561 0.6561 0.6518 0.6551

2 0.65 40 33 1.4 8 0.02 0.6622 0.6620 0.6536 0.6601

3 0.65 40 33 1.4 8 0.03 0.6681 0.6679 0.6554 0.6651

4 0.65 40 33 1.4 8 0.04 0.6739 0.6736 0.6571 0.6699

5 0.65 40 33 1.4 8 0.05 0.6796 0.6793 0.6589 0.6747

6 0.65 40 33 1.4 8 0.06 0.6851 0.6848 0.6607 0.6794

7 0.65 40 33 1.4 8 0.07 0.6906 0.6903 0.6624 0.6841



Table 2 Density of nanofluids

S.No

Fluid

density(ρf)

Kg/m3

Density of

nanoparticles(ρp)

Kg/m3

Volume

fraction

(φ)

Density

of nanofluids(ρeff)

Kg/m3

Water

Al2O

3 CuO SiO2

TiO

2 Al2O3 CuO SiO2 TiO2

1 1000 3890 6310 2650 4230 0.01 0.6561 0.6561 0.6518 0.6551

2 1000 3890 6310 2650 4230 0.02 0.6622 0.6620 0.6536 0.6601

3 1000 3890 6310 2650 4230 0.03 0.6681 0.6679 0.6554 0.6651

4 1000 3890 6310 2650 4230 0.04 0.6739 0.6736 0.6571 0.6699

5 1000 3890 6310 2650 4230 0.05 0.6796 0.6793 0.6589 0.6747

6 1000 3890 6310 2650 4230 0.06 0.6851 0.6848 0.6607 0.6794

7 1000 3890 6310 2650 4230 0.07 0.6906 0.6903 0.6624 0.6841

Table 3 Convective heat transfer coefficient of nanofluids

S.No Volume

fraction

(φ)

Convective heat transfer coefficient(h)

(W/m2°C)

Rate of condensation (gram/ses-

meter)

Al2O3 CuO SiO2 TiO2 Al2O3 CuO SiO2 TiO2

1 0.01 10002.60 10119.55 9893.23 10007.66 5.91 5.98 5.84 5.91

2 0.02 10145.87 10373.04 9928.41 10154.21 5.99 6.13 5.86 6.00

3 0.03 10286.12 10621.77 9964.07 10299.45 6.07 6.27 5.88 6.08

4 0.04 10424.51 10863.74 9999.01 10441.13 6.16 6.42 5.90 6.17

5 0.05 10554.02 11094.24 10028.80 10574.57 6.23 6.55 5.92 6.24

6 0.06 10680.74 11318.59 10059.23 10705.89 6.31 6.68 5.94 6.32

7 0.07 10786.58 11517.69 10070.06 10815.83 6.37 6.80 5.95 6.39

4. RESULTS AND DISCUSSION

From mathematical analysis it was found that nanoparticle improves significantly physical

properties of fluids. When concentration of nanoparticle increases, thermal conductivity,

density, absolute viscosity and convective heat transfer coefficient of fluid increases. Because

of this improved properties condensation rate of fluid increases. Result is shown in below

figures.

Figure 2 Change of thermal conductivity of nanofluid with nanoparticle volume fraction



Figure 3 Density with change in volume fraction

Figure 4 Dynamic viscosity vs Volume fraction

Figure 5 Convective heat transfer vs Volume fraction



Figure 6 Rate of condensation vs Volume fraction

Among all (Al2O3, CuO, SiO2 and TiO2), CuO is more effective. It shows good impact

on the on the physical properties of fluids.

According to Newton’s law cooling

Q = hA(Tsat-Ts)

So, size of heat exchanger can be reduced by increasing convective heat transfer

coefficient for the same heat rejection, and cost of heat exchanger can be decreased

significantly.

5. CONCLUSIONS

From the above result it is concluded that condensation rate of vapour fluid can be increased

by dispersing nanoparticle in fluid and it also depend on size of particle, material of particle

and volume fraction. And from the compact (low surface area by volume ratio) condenser

more condensation rate can be achieved. Enhancing the condensation rate by extending

surface is obsolete idea.

REFERENCES

[1] I. M. Mahbubul, S. A. Fadhilah, R. Saidur, K. Y. Leong, and M. A. Amalina,

“Thermophysical properties and heat transfer performance of Al2O3/R-134a Nano

refrigerants,” International Journal of Heat and Mass Transfer, vol. 57, no. 1, pp. 100–108,

2013.

[2] D. S. Kumar and R. Elansezhian, “Experimental study on Al2O3-R134a nano refrigerant

in refrigeration system,” International Journal of Modern Engineering Research, vol. 2,

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[3] S. Bi, K. Guo, Z. Liu, and J. Wu, “Performance of a domestic refrigerator using TiO2-

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[4] F. S. Javadi and R. Saidur, “Energetic, economic and environmental impacts of using

nanorefrigerant in domestic refrigerators in Malaysia,” Energy Conversion and

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[5] James Clark Maxwell, A Treatise on Electricity and Magnetism, Unabridged, Dover,1954.



[6] Albert Einstein, A new determination of molecular dimensions, Ann. Phys. 19.2 (1906)

289–306

[7] H.C. Brinkman, The viscosity of concentrated suspensions and solutions, J. Chem.Phys.

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temperature on the Thermophysical properties of CuO/R134a nanorefrigerant."

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CONDENSATION RATE ENHANCEMENT OF FLUID IN STEAM … · 2018-05-09 · to lack of collective...

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