International Journal of Mechanical Engineering and Technology (IJMET)
Volume 10, Issue 01, January 2019, pp. 1044–1051, Article ID: IJMET_10_01_108
Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJMET&VType=10&IType=01
ISSN Print: 0976-6340 and ISSN Online: 0976-6359
© IAEME Publication
Scopus Indexed
ENHANCED HEAT TRANSFER WITH
ALUMINIUM OXIDE MICROPARTICLES
Angelo Jasper Minz and Dr. Ajeet Kumar Rai
Department of Mechanical Engineering,
Sam Higginbottom University of Agriculture, Technology and Sciences, Prayagraj, U.P. India
ABSTRACT
This study aims at experimental investigation on the effect of mixing of Al2O3
microparticles in water fluid on the heat transfer enhancement. The experiment was done
in a 3 channel 1-1 pass corrugated plate heat exchanger. The plates had sinusoidal wavy
surfaces with corrugation angle of 45°. Hot water at different inlet temperature ranging
from 40°C to 70°C was made to flow through central channel to get cooled by water in
outer channels. Experiment was measured in parallel and counter flow arrangement. The
variations of hot fluid outlet temperature and effectiveness of heat exchanger were
measured with rise of inlet hot fluid temperature. The required properties of the Al2O3
water mixture were measured at different concentration of Al2O3 microparticles from
0.0% to 1.275% by volume. It is observed that with volume percentage of Al2O3 increases
in the cold fluid the effectiveness of heat exchanger increases substantially. The addition
of Al2O3 microparticles in cooing water increases the effectiveness of heat exchanger by
0.88 in parallel flow and by 0.96 in counter flow.
Keywords: -Heat Transfer Enhancement, Al2O3 water fluid, volume concentration,
corrugated plate heat exchanger, Effectiveness, mass flow rate, Heat transfer rate.
Cite this Article: Angelo Jasper Minz and Dr. Ajeet Kumar Rai, Enhanced Heat Transfer
with Aluminium Oxide Microparticles, International Journal of Mechanical Engineering
and Technology, 10(01), 2019, pp.1044–1051
http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=10&Type=01
Abbreviations
l: -Length, (m)
m: -mass flow rate, (kg s-1)
Q: -Heat transfer rate, (W)
T: -Temperature, (K)
V: -Average velocity of fluid, (m s-1)
LMTD: -Logarithmic Mean
Temperature Difference
wt: -Weight
Suffixes
e: -Environment, ambient.
max: -Maximum.
min: -Minimum
Thi (°C): -Temperature of Hot Fluid
(water) at inlet.
Greek Symbols
Є: -Effectiveness.
Ψv: -Volume Concentration
μ: -Dynamic Viscosity of Fluid
Tho (°C): -Temperature of Hot Fluid
(water) at outlet.
К: -Thermal Conductivity of Fluid
ρ: - Density of Fluid
TCi (°C): -Temperature of Cold Fluid
at Inlet.
TCo (°C): -Temperature of Cold
Fluid at Outlet.
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Angelo Jasper Minz and Dr. Ajeet Kumar Rai
1. INTRODUCTION
It is well known fact that solids have higher magnitude of Thermal Conductivity at room
temperature than those of fluids. Thermal Conductivity of Aluminium is 400 times greater than
that of water at room temperature. So it is well known that by dispersing these solid particles in
fluid, Thermal conductivity of fluid can be expected to increase significantly. Over the previous
decades many experimental studies have been conducted to investigate the possible effect and
underlying mechanism of increasing thermal conductivity in heat transfer due to the use of solid
particles in different base fluids. Suspension of solid particles in conventional fluids, the most
prominent features of such fluids includes enhanced heat transfer characteristics, such as
convective heat transfer coefficient and thermal conductivity in comparison to the base fluid
without considerable alteration in physical and chemical properties. This considerable increase
in heat transfer may, under appropriate operational conditions load to decreased energy
expenditure and raw material input, reduced size of equipment and consequently reduced
expenses and increased system efficiency.
2. PARAMETERS WHICH AFFECTS THERMAL CONDUCTIVITY OF
AL2O3 WATER- FLUID
Particle volume fraction: -Most of the research reports increasing thermal conductivity
with increase particle volume fraction and the relation found are usually linear. It was concluded
that despite the fact that particle volume fraction is very small; particles interact with each other
due to very high particle concentration (1011 particles/cm3).
Particle Material: -Particle material is an important parameter that affects the thermal
conductivity of water-fluids. It might be thought that the difference in the thermal conductivities
of particle materials is the main reason for the effect on heat transfer. This happens because of
different chemical bonding, melting and boiling point of the material. Many different particle
materials are used such as Al2O3, CuO, TiO2, SiC, TiC, Ag, Au, Cu and Fe.
Particle Size: -The size of particle is an important factor that affects the thermal
conductivity enhancement which concludes that the thermal conductivity of water-fluids
increases with decreasing particle size. This trend is theoretically supported by two mechanisms
of thermal conductivity enhancement, Brownian motion of particles and liquid layering around
particles.
Particle Shape: -There mainly two particles shapes used in water-fluid research, spherical
particles and cylindrical particles. Cylindrical particles provide higher thermal conductivity
enhancement than spherical particles because of the rapid heat transfer along relatively larger
distances in cylindrical particles have much larger viscosity than those with spherical particles.
Base fluid: -Base fluids mostly used in the preparation of water-fluids are the common
working fluids of heat transfer applications, such as water, ethylene glycol, and engine oil.
Temperature: -In conventional suspension of solid particles (with sizes on the order of
millimetres or micrometres) in liquids, the thermal conductivity of the mixture depends on
temperature only due to dependence of thermal conductivity of base liquid and solid particles on
temperature.
3. ABOUT CORRUGATED PLATE HEAT EXCHANGER
The fluid dynamical and thermal phenomenon occurred in corrugated wall channel have been
studied in different engineering sectors. Corrugated surface are for example utilised in compact
heat exchanger. The corrugation allows the heat transfer surface between dissipaters and coolant
fluids to be extended, maintaining at same time a reduced dissipater volume and weight. The
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Enhanced Heat Transfer with Aluminium Oxide Microparticles
study of heat transfer through corrugation surface is also particularly interesting for the cooling
application in the electronic industry, aeronautic and automobile industry, food and dairy
industry, chemical and cosmetics industry. In general the corrugation of the walls extends the
heat transfer surface of the channels and generates turbulence at low Reynolds number. Moreover
the corrugation of the walls, in some cases can induce the stagnation of the coolant fluid. As a
consequence, the local convection coefficient s so reduced that even of the heat transfer surface
between the wall and the fluids extended. The global heat transfer effectiveness does not
overcome that of the flat wall channel of comparable size. Therefore, the heat transfer
effectiveness of corrugated channel depends on many factors concerning the geometry of walls,
the properties of the coolant fluid, and the nature of the flow. Moreover, it can only be correctly
compared with the heat transfer effectiveness of the flat wall channels y also considering the
external size, the wall volume or weight. Most of the studies performed on the fluid dynamical
and thermal phenomena occurring in corrugated wall channels consider corrugations having a
periodical pattern which is described by simple functions such as rectangular, triangular or
sinusoidal. However due to the variety of thermal and fluid dynamical characteristics described
in the literature under different conditions, the study of more complex corrugation profile can be
useful to better evaluate the convenience of assigning to the channel walls corrugated rather than
flat profiles.
3.1. Evaluation Parameter of Heat Exchanger
Commonly used parameter to evaluate the performance of two-fluid heat exchangers is the heat
transfer effectiveness, which is defined as the ratio of the heat transfer from either stream to the
maximum possible heat transfer in the heat exchanger. Heat transfer effectiveness of a heat
exchanger only indicates the relative magnitude of the heat transfer loading (not exergy transfer
loading) in a process. The efficiency of the process in terms of exergy is completely irrelevant to
the information of its heat transfer effectiveness.
4. EXPERIMENTAL SETUP
The photograph of the experimental setup was fabricated with 22-gauge GI sheets to investigate
the heat transfer characteristics of the plate heat exchanger channels for same flow conditions
with different inlet hot water temperatures are shown in (Figure 1). It includes a hot water loop,
two coolant loop and a measurement system. The hot water loop comprises a water tank, a heater,
and a submersible water pump. The cold-water loop comprises a water tank, and a submersible
water pump. A digital temperature indicator with thermocouples is used to measure temperatures
at inlet and exit of the hot and cold streams. The flow rate is measured by noting down time for
collection of fixed volume of the fluid. The whole system is thermally insulated to minimize the
energy loss.
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Angelo Jasper Minz and Dr. Ajeet Kumar Rai
Figure 1 Photographs of experimental setup
4.1. Specifications of the experimental setup.
Length of the test section =100 cm
Width of the test section = 10 cm
Height of a flow channel, i.e. gap between two successive corrugated plates = 5 cm.
Chevron angle of the plate = 45°
Material of the plate is GI of 22 gauges.
5. EXPERIMENTAL PROCEDURE
Experimental procedure Hot water was made to flow through the central corrugated channel to
maintain the channel surfaces at approximately constant temperature. Cold water is made to flow
in the upper and lower channels. Thermocouples were inserted in the inlet and exit of the hot and
cold streams, were used to record the corresponding fluid temperatures. Thermocouples were
calibrated with ZEAL mercury thermometer And Infrared Digital Thermometer. Experiments
were conducted for 40˚, 45˚, 50˚, 55˚, 60˚, 65˚, 70˚C inlet temperature of hot water in parallel and
counter flow arrangement. The hot and cold water flow rate is maintained constant for all inlet
hot water temperatures and for both parallel and counter flow arrangements. Mass flow rate of
hot fluid (water) is maintained at 0.05 kg/s and that of the cold fluid (water) is 0.16 kg/s.
Details of Aluminium oxide Micro particles/Micro powder
Formula
Al2O3
Density
3.97 g/cm³
Phase
Purity
Average Size
Morphology
solid
99.9%
1000nm
Spherical
Molar mass
Specific heat capacity
Boiling point:
Melting point
101.96 g/mol
880 J/(Kg-K)
2,977 °C
2,072 °C
6. NUMERICAL METHODOLOGY
In the present experiment, the properties of Al2O3 micro particle dispersed in the water fluid was
measured are given below.
The volume concentration of Al2O 3 micro particle in water-fluids Ψv was determined from
equation
= [((1/Ψm)-1) (ρmp/ρbf) +1
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Enhanced Heat Transfer with Aluminium Oxide Microparticles
The Density of water-fluid ρ water-fluid was determined from equation
ρ water-fluid = ρbase fluid - Ψv (ρ base fluid – ρ micro particle)
Specific heat capacity of water fluid Cp, water fluid was determined from equation
Cp, water-fluid=
Viscosity of water fluid µwater fluid was determined by equation
µ Water fluid = [(1-Ψv)-2.5] * µ base fluid
Thermal conductivity of water fluid kwaterfluid was determined by equation
К water fluid=
x kf
Logarithmic mean temperature difference (LMTD) parallel flow and counter flow:
! !
!" =
!
#$
!
The Effectiveness of the PHE is calculated from experimental observations using the
following equation:
Ԑ = [Cc (Tco - Tci]/ [Cmin (Thi - Tci)]
7. RESULTS AND DISCUSSION
60
50
Th1 at 40
Th1 at 45
Th1 at 50
Th1 at 55
Th1 at 60
Th1 at 65
Th2(oC)
40
30
20
10
0
0
0.125
0.25
0.375
0.5
0.625
0.7
Vol % of Al2O3
0.9
1.025
1.15
1.275
Figure-5 Variation of hot fluid outlet temperature at different volume percent of Al2O3 in cold fluid in
parallel flow arrangement
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Th1 at 40
Th1 at 55
Th1 at 70
60
50
Th1 at 45
Th1 at 60
Th1 at 50
Th1 at 65
Th2(oC)
40
30
20
10
0
0
0.125
0.25
0.375
0.5
0.625
0.7
Vol % of Al2O3
0.9
1.025
1.15
1.275
Figure-6 Variation of hot fluid outlet temperature at different volume percent of Al2O3 in cold fluid in
counter flow arrangement
In the above two figures (fig 5 and 6) It is observed that at different inlet temperature of hot
fluid (400 C to 700 C) temperature drop in hot fluid is maximum in counter flow than in parallel.
Drop in temperature of hot fluid for Corrugated Plate Heat Exchanger, in parallel & counter flow
increases, as the inlet hot fluid temperature increases. Effect of Th1 from 400 C to700 C is more
significant onTh2 when plain cold water is used. As volume percentage of Al2O3 increases in cold
water from 0.125 to 1.275, the initial temperature of hot fluid becomes less or no significant. This
is clear from fig 4.2 all the lines converge at 1.275 vol % of Al2O3 in the water.
1
Th1 at 40
Th1 at 50
Th1 at 60
Th1 at 70
0.9
Effectiveness
0.8
0.7
Th1 at 45
Th1 at 55
Th1 at 65
0.6
0.5
0.4
0.3
0.2
0.1
0
0
0.125
0.25
0.375
0.5
0.625
0.7
0.9
1.025
1.15
1.275
Vol % of Al2O3
Figure 7 Variation of effectiveness of corrugated pate heat exchanger at different volume percent of
Al2O3 in cold fluid in parallel flow arrangement
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Enhanced Heat Transfer with Aluminium Oxide Microparticles
1.2
Th1 at 40
Th1 at 50
Th1 at 60
Effectiveness
1
Th1 at 45
Th1 at 55
Th1 at 65
0.8
0.6
0.4
0.2
0
0
0.125
0.25
0.375
0.5
0.625
0.7
0.9
1.025
1.15
1.275
Vol% of Al2O3
Figure 8 Variation of effectiveness of corrugated pate heat exchanger at different volume percent of
Al2O3 in cold fluid in counter flow arrangement
In the above two figures (fig 7 and 8) It is observed that counter flow effectiveness is 18%
higher than that in parallel flow in water-water combination of fluid. Counter flow effectiveness
is 0.88 Parallel flow effectiveness is 0.96 as a volume percentage of Al2O3 increases in the cold
fluid the effectiveness of heat exchanger increases substantially. The effectiveness of heat
exchanger is not much affected by inlet hot fluid temperature.
8. SUMMARY AND CONCLUSION
A three channel 1-1 pass corrugated plate heat exchanger with corrugation angle of 45˚ is used
in the present study. Water is taken as cold and hot fluid. The Al2O3 microparticles in different
volume percentage were mixed in the cold fluid (water) in parallel and counter flow
arrangements. The hot water inlet temperature range is selected from 40o C to 70o C. An attempt
has been made in the present study to find the effect of Al2O3 micro particles on the performance
of heat exchanger. The following conclusions are drawn from the present work.
1. Effect of Th1 from 40o C to 70o C is more significant onTh2 when plain cold water is
used. As volume percentage of Al2O3 increases in cold water from 0.125 to 1.275, the
initial temperature of hot fluid becomes less or no significant.
2. Counter flow effectiveness is 18% higher than that in parallel flow in water-water
combination of fluid.
3. Addition of different volume percentage from 0.125 to 1.275 of Al2O3 micro particles
4.
5.
6.
7.
in the cold fluid enhance the heat transfer rate in parallel and counter flow
arrangements.
Counter flow effectiveness is 19.4% higher than that in parallel flow when 0.125% of
Al2O3 micro particles were added in the cold water.
Counter flow effectiveness is 28.57% higher than that in parallel flow when 0.250%
of Al2O3 micro particles were added in the cold water.
As a volume percentage of Al2O3 increases in the cold fluid the effectiveness of heat
exchanger increases substantially.
Counter flow effectiveness is 0.96 when 1.275% of Al2O3 micro particles were added
in the cold water.
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8. Parallel flow effectiveness is 0.88 when 1.275% of Al2O3 micro particles were added
in the cold water.
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