experimental investigations of … investigations of pulsating heat pipe in automobile radiator with...
TRANSCRIPT
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EXPERIMENTAL INVESTIGATIONS OF PULSATING
HEAT PIPE IN AUTOMOBILE RADIATOR WITH
ENTROPY GENERATION MINIMIZATION
Hathiwala K. A1, Dr. Vikas J. Patel
2, Patel H.M
3
1,2,3Mechanical Engineering Department, Gujarat Technological University,
S.V. Mandal Institute of Technology, Bharuch. (India)
ABSTRACT
Flow visualization was conducted for the close loop pulsating heat pipe using charged coupled device. It was
observed that during the start up period, the working fluids oscillates with large amplitude, however, at steady
operating state, the working fluid circulates. The direction of circulation for the working fluid is consistent once
circulation is attained, but direction of the circulation can be different for the experimental run. Phenomena
such as nucleation boiling, coalescence of bubbles, Formation of slug and propagation of inertia wave were
observed in the close loop pulsating Heat pipe. the finding shoe that the meandering Bends, uneven slug and
plug distribution and non-concurrent boiling at the evaporator contributed to the driving and restoring forces
For fluid circulation and oscillation.
I. INTRODUCTION
A heat pipe is a heat transfer mechanism that combines the principles of both thermal Conductivity and phase
transition to efficiently manage the transfer of heat between two solid interfaces. This type of heat pipe is
essentially a non-equilibrium heat transfer device. A heat pipe is a container tube filled with the working fluid.
Heat pipes are referred to as the semiconductors of heat due to their fast Transfer capability with low heat loss.
One end of this tube (called evaporator section) is brought in thermal contact with a hot point to be cooled. The
other end (called condenser section) is connected to the cold point where the heat can be dissipated. A portion of
the tube between evaporator and condenser is called adiabatic section. Number of PHP studies has been carried
out Since 1990s. Researchers agree that the oscillations are driven by an instability that appears due to coupling
of the adiabatic vapor compression and evaporation/condensation mass exchange. However this instability has
not been studied until recently. Such important parameters as oscillation threshold, heat transfer coefficient, and
maximum heat load cannot be predicted from calculations. It is not even clear whether the oscillations are
persistent or not and at which regimes. For these reasons the PHP applications are very limited. The PHP
parameters are adjusted empirically, often without any certainty.
To our knowledge, only a couple of small companies in the world produce them.
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Fig 1 Pulsating Heat Pipe
II. LITERATURE REVIEW
A. Dimoudiet al [1] presented the cooling performance of a radiator based roof Component. Space cooling is
getting important in most countries and different techniques have been developed one of which is radiative
cooling. A prototype roof component, exploiting radiative cooling was built and tested in the outdoor test
facilities of the Centre of Renewable Energy Sources in Greece. He studied that radiator efficiency is drastically
reduced with increasing water flow rates. With increasing flow rates temperature difference between inlet and
outlet decreases and increases with decreases cooling flow rates.
A.K.A. Shati et al [2] presented the effect of surface roughness and emissivity on radiator output. The effect of
altering the emissivity and the roughness of a wall behind a radiator on the radiator heat output has been
studiedexperimentally and by using computational fluid dynamics. The results indicate that the presence of large
scale surface roughness and a high emissivity surface increases both the heat flow rate and the air velocity
behind the radiator compared to a smooth shiny surface. The surface roughness will increase both the surface
area for heat transfer and the turbulent intensity which increase the mass transfer and free convective heat flux
through the air gap. He studied that increasing the air gap will augment heat output and heat transfer rates.
Adnan M. Hussein [3] presented Heat transfer enhancement using nano fluids in an automotive cooling system.
Heat transfer enhancement using TiO2 and SiO2 nano powders suspended in pure water is presented. The test
setup includes a car radiator, and the effects on heat transfer enhancement under the operating conditions are
analyzed under laminar flow conditions. He studied that SiO2 nano fluid produces a higher heat transfer
enhancement than the TiO2 nano fluid; likewise, TiO2 nano fluid enhanced heat transfer more than pure water.
Ahmet Z. Sahin et al [4] presented Entropy generation in laminar fluid flow through circular pipes. Entropy
generation rate in a developing laminar viscous fluid flow in a circular pipe is analyzed.Theentropy
generationrate is higher near the wall and sharply decreases along the radius away from the surface of the pipe.
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This is due to existing temperature and velocity gradient in this region. Around the centerline these gradients are
small and therefore the entropy generation is small.
Benjamin Siedel, Valérie Sartre et al [5] presented Numerical investigation of the thermo hydraulic behavior of
a complete loop heat pipe. He concluded that Heat losses to the ambient and through the transport lines are
considered. A low evaporation coefficient leads to a large increase of the LHP temperature.
C. Oliet, A. Oliva et al [6] presented parametric studies on automotive radiator. This work provides an overall
behavior report of automobile radiators working at usual range of operating conditions, while significant
knowledge-based design conclusions have also been reported. He studied that overall heat transfer coefficient
reveals almost independent of the air inlet temperature; but depend on coolant flow regime.Cooling capacity
increases with increasing coolant and air flow.Air inlet temperature increases both heat transfer & cooling
capacity decreases.Small fin spacing and higher louvered fin angles have higher heat transfer.
Ching-Ming Chiang et al [7] presented Theoretical study of oscillatory phenomena in a horizontal closed-loop
pulsating heat pipe with asymmetrical arrayed mini channel. He concluded that The dominant parameters
affecting the PHP dimensions of the flow channel, the number of turns, the filled liquid ratio, the frequency
ratio, the operating temperature and the temperature difference between the average evaporating region and the
average condensing region are investigated in this study. The closed-loop pulsating heat pipe with asymmetrical
arrayed mini channel with lower number of turns, lower filled liquid ratio, higher operating temperature and
higher temperature difference between the average evaporating region and the average condensing region for the
frequency ratio of unity could achieve a better performance due to larger oscillatory motions.
Cihat Arslanturk et al [8] presented Optimization of a central-heating radiator. An approximate analytical model
has been used to evaluate the optimum dimensions of a central heating radiator. The radiator problem is divided
into three one dimensional fin problems and then the temperature distributions within the fins and heat-transfer
rate from the radiator are obtained analytically. He studied that optimum radiator geometry maximizing the heat
transfer rate has been obtained by using the approximate analytical model.Increaseof radiator volume fraction
increases the maximum heat transfer rate and optimum tube diameter.
D. Yin, H. Rajab, et al [9] presented Theoretical analysis of maximum filling ratio in an oscillating heat pipe.A
maximum filling ratio to start up the oscillating motion can be found.maximum filling ratio is dependent on the
working fluids and the operation temperature.Pressure difference in the system is produced, which acts as an
exciting force to start up the movement of the liquid plugs and vapor bubbles in the OHP.
Dehao Xuet al [10] presented Thermo-hydrodynamics analysis of vapor–liquid two-phase flow in the flat-plate
pulsating heat pipe. He concluded that with the increasing heat load, the overall temperature level of the FP-PHP
increases, and the integral equivalent thermal resistance decreases.
Dong Liu et al [11] presented Flow and heat transfer performance of a mini channel
channel heat sinks have relatively low Nusselt number due to small Reynolds number. the friction factor of
mini-channel flow was larger than that of the macro channel flow due to larger surface roughness, and the
pressure drop caused by cylinder disturbed flow was less than 5%.he studied that Distributed flow has relatively
small effect on thermal resistance when velocity is slow. However the effects get stronger when velocity grows
larger.
Elsayed A.M. Elshafei et al [12] presented Experimental study of heat transfer in pulsating turbulent flow in a
pipe. He concluded that Observations of the local Nusselt number revealed that the heat transfer coefficient may
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be increased or decreased, depending on the value of frequency and Reynolds number. Higher values of the
local heat transfer coefficient occurred in the entrance of the tested tube.
H. Khalkhali et al [13] presented Entropy generation in a heat pipe system. He concluded that Entropy
generation in a heat pipe can also be reduced by removing the insulation in the transport section. Both the
condenser ambient temperature and the convection heat transfer coincident in the transport section must be
adjusted to obtain a minimum entropy generation.To reduce the entropy generation in fluid flow evaporator
length should be as small as possible.
Himel Barua, et al [14] presented Effect of filling ratio on heat transfer characteristics and performance of a
closed loop pulsating heat pipe. He concluded that for water, both at lower and higher heat input, lower filling
ratio shows less thermal resistance and optimum heat transfer is obtained.
Huseyin Yapici, Gamze Basturk, Nesrin Kayatas et al [15] presented Numerical study on transient local entropy
generation in pulsating turbulent flow through an externally heated pipe.The author analyzed the entropy
generation in pulsating turbulent flow through a pipe for three different cases i.e. sinusoidal, step and saw down.
The effect of the period of the pulsating flow on the entropy generation investigated.The highest temperature
occurs in the step flow case. They also investigated that irreversibility due to the heat transfer dominates when
Bejan number is 1.With the increase of flow period, the highest levels of the total entropy generation rates
increase logarithmically in the case of sinusoidal and saw-down flow cases, whereas they do not almost change
in the step-flow case.
K.Y. Leong et al [16] presented Performance investigation of an automotive car radiator operated with nano
fluid-based coolants. Water and ethylene heat transfer fluids offer low thermal conductivity. With the
advancement of nano technology, the new generation of heat transfer fluids called, “nano fluids” have been
developed and Researchers found that these fluids offer higher thermal conductivity compared to that of
conventional coolants. He studied that Heat transfer rate is increased with increase in volume concentration of
nano particles.Volumetric flow rate of nano fluids is decreased with increase of volume fraction of copper nano
particles.
Manfred Grol et al [17] presented closed loop pulsating heat pipes: visualization and semi-empirical modeling.
He concluded that the study strongly indicates that design of these devices should aim leading to higher local
heat transfer coefficients.
Maziar Mohammad et al [18] presented Overall thermal performance of Ferro fluidic open loop pulsating heat
pipes: An experimental approach. He concluded that Ferro fluid improves the steady state thermal performance
of OLPHPs relative to distilled water charged ones under certain conditions. Higher concentrations of Ferro
fluid, reduces the steady state thermal performance of OLPHPs as a result of higher viscosity.
Mukherjee, et al [19] presented Second-law analysis of heat transfer in swirling Flow through a cylindrical
duct.They calculated the rate of entropy generation. They defined also a merit function and discussed influence
of swirling on this merit function.
N.Sahiti et al [20] presented Entropy generation minimization of a double-pipe pin fin heat exchanger. He
concluded that shorter flow length is accompanied with lower entropy production rates.It could be shown that
larger pin length sare accompanied with larger entropy production rates.
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Nandan Saha et al [21] presented Influence of process variables on the hydrodynamics and performance of a
single loop pulsating heat pipe. He concluded that Different kinds of flow pattern have been observed and
transition of flow Pattern from oscillatory-slug to circulatory-annular .This transition is more likely in case of
low FR due to a larger degree of freedom. There exists a minimum start-up power or threshold power below
which no movement of fluid is observed inside CLPHP.Best performance of the loop was found to occur at an
inclination angle lower than 90.
O.M. Haddad et al [22] presented Entropy generation due to laminar forced convection in the entrance region of
a concentric annulus. He concluded that the total entropy generation decreases with the increase in Reynolds
number. The total Entropy generation decreases as the dimensionless entrance temperature increases.Increasing
the annulus radius ratio increases the entropy generation.
Piyanun Charoensawan et al [23] presented closed loop pulsating heat pipes: parametric experimental
investigations. He concluded that the internal diameter of the tubes tested in the present study, as governed by
the critical Bond number is well within the specified limit, bubble shapes are affected by the buoyancy forces. A
certain critical number of turns are required to make horizontal operation possible and also to bridge the
performance gap between vertical and horizontal operation.
Roger R. Riehl, Nadjara do Santoset al [24] presented Water-copper nano fluid application in an open loop
pulsating heat pipe. He concluded that with copper nano fluid, the pulsation was better visualized. Greater
amplitudes on the pulsations could be observed with the nanofluid. The presence of solid nano particles in the
working to increase the nucleation sites necessary for bubble formation.
S.M.Peyghambarh et al [25] presented Experimental study of heat transfer enhancement using water/ethylene
glycol based nano fluids as a new coolant for car radiators. Heat transfer performance of pure water and pure
EG has been compared with their binary mixtures. Different amounts of Al2O3 nano particle have been added
into these base fluids and its effects on the heat transfer performance of the car radiator have been determined
experimentally. The heat transfer enhancement of about 40% compared to the base fluids has been recorded. He
studied that with increasing the nano particles increase heat transfer rates and heat transfer coefficient.
Additionof nano particles to the coolant has the potential to improve automotive and heavy duty engine cooling
rates or equally causes to remove the engine heat with a reduced size cooling system.
Seyfolah Saedodin et al [26] presented Analysis of Entropy Generation Minimization in Circular Porous Fins. In
porous fins, with increase of porosity, the entropy generation number will increase. Increased porosity the
entropy generation will decrease.Increased that porosity the entropy generation will decrease. Also with the
increase of Reynolds number, the values of entropy generation at all them will increase.
Todd A. Jankowski et al [27] presented Minimizing entropy generation in internal flows by adjusting the shape
of the cross section. In adiabatic flow, the circular cross section will minimize flow resistance, which is reflected
by a minimization of the entropy generation. A Duct with a large wetted perimeter will increase the surface area
available for heat transfer and will minimize the overall entropy generation.When the available cross-sectional
area of the flow channel is doubled, the resistance to flow in the duct is reduced, thereby reducing the entropy
generation associated with fluid friction. Using larger perimeter compare to cross section area entropy
generation is minimized.
Tsuyoshi et al [28] presented Numerical and experimental studies on circulation of working fluid in liquid
droplet radiator. Model of the circulation of the working fluid in a liquid droplet radiator has been developed.
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The behavior of the circulation of the working fluid calculated from the model is compared with that obtained
from experiments in the case that the flow rate of the circulating working fluid is changed. He studied that as
flow rates decreases with time pressure difference in working fluid increased and this phenomena can be
improved by adjusting number of revolution in gear pump used in model.
Xuefeng Wang, et al [29] presented Numerical analysis of heat transfer in pulsating turbulent flow in a pipe.The
model analysis shows that Womersley number is an important parameter in the study of pulsating flow and heat
transfer.Higher the womersely number benefits to heat transfer enhancement only in entrance region. It indicates
that larger velocity induced by pulsation of the fluid flow results in higher heat transfer rate.
Yuwen Zhang, et al [30] presented Oscillatory Flow in Pulsating Heat Pipes with Arbitrary Numbers of Turns.
He concluded that increase in the number of turns has no effect on the amplitude and circular frequency of
oscillation when the number of turn’s water, functional thermal fluids (FS-39E microcapsule fluid and Al2O3
nano-fluid) as working fluid in PHP can enhance its heat-transport capability. Like FS-39E microcapsule fluid,
Al2O3 nano-fluid as working fluid can enhance heat-transport capability of PHP.the best concentration of
Al2O3 nano-fluid is 0.1 wt%.
III EXPERIMENTAL SET UP
FIG 3.1 Experimental Set Up
3.1 Working Fluid
The selection of the working fluid used in pulsating heat pipes is dependent on a number of variables. The
approximate temperature range the system will be exposed to be the most critical in determining the proper
working fluid. Using an approximate temperature range of 50 to 150 degrees Celsius in turn means many
potential working fluids are possible options. Additional requirements need to be examined as well and are
listed below:
Thermal stability
Wet-ability
Reasonable vapor pressure
Compatibility with heat pipe materials
High thermal conductivity and latent heat
Reasonable freezing point
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Low vapor and liquid viscosity
For this experiment and various other experiments involving pulsating and oscillating heat pipes, distilled water
is used as the working fluid. Water was chosen for its thermodynamic attributes that make it more appealing
than others, such as methanol. It has a high latent heat of vaporization of 2260 kJ/kg which has the potential to
spread significantly more heat with less fluid flow. Latent heat is defined as the heat required converting a solid
into a liquid or vapor, or a liquid into a vapor, without a change in temperature.
IV. PHP DESIGN
The PHP performance data (for pure and binary mixture of working fluid) were obtained according to the
following procedure: Heat input was stepwise increased until a quasi thermal equilibrium was established. Then,
the spatial temperatures and heat input were recorded, so the thermal resistances could be determined. The
thermal resistance is defined by
Where, Teand Tc are the average evaporator and condenser surface temperatures, which is the average of three
temperatures, Calculated by using Equation
Ti=
Where i= e or c
Q is heat input power to PHP. Thermal heat loss Q can be determined by Q = P - Qloss where, P is the input
electrical power Qloss is the heat loss, which was verified to be about 4% to 9%, depending on the heat load.
The heat transfer capacity of a typical pulsating heat pipe can be calculated using equation
Where T is the overall temperature difference along the heat pipe; and are the effective thermal conductivity
and length, and is the cross sectional area of the pulsating heat pipe.
Fig. 4.1 Pressure Enthalpy (P-h) Diagram of a Pulsating Heat Pipe
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Pulsating heat pipe that is properly designed and constructed should experience little thermal contact resistance.
The conductive thermal resistance in the wall can also be considered negligible. The contact and conductive
resistances are independent of the heat pipe operating temperatures, and because of this the thermal resistances
due to the evaporation in the evaporator, Revp Two-phase flow along the heat pipe, Rl-v and the condensation in
the condenser, Rcond are, however, significant to the performance of the heat pipe.
Fig. 4.2Thermal Resistance Schematic of a Typical Pulsating Heat Pipe
Typically during operation of the PHP, a continuous flow boiling associated with strong bubble growth and
water slug flow takes place in the evaporator section of the heat pipe. The two phase flow continues its way
towards the heat pipe condenser section where the bubbles collapse and condense while giving up their latent
heat of vaporization. The vapor-liquid thermal resistance through the length of the pulsating heat pipe is a
function of the temperature and pressure drop from the evaporator to theCondenser. Typical pulsating heat pipes
in previous studies have shown small thermalResistances, ranging from (3.29x104 /A)/°C/W and (2.10 x 10-
3/A) /°C/W. Figure zooms on a typical liquid-vapor plug system as formed in the PHP and suggests the various
forces, heat and mass transfer processes. The analysis of the control volume on a micro scale will manifest much
more complicated molecular forces and heat and mass transfer processes than what has been depicted in Figure
4.3 Such a system will be mathematically too complicated and impractical
V. RESULT AND DISUSSION
As fig 4.1 & 4.2 shows an effect of thermal resistance on pulsating heat pipe. It shows that as heat input
increases thermal resistance of pipe decreases. Effect of thermal resistance on PHP and different filling ratio is
also shown. We also observed effect of filling ratio on PHP. We also found that as filling ratio increases thermal
resistance of PHP decreases. So thermal resistance decreases for a given heat input and filling ratio. We also
determine effect of diameter on pulsating heat pipe. So optimal filling ratio is found to be 70% for pulsating
heat pipe.
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0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
100 200 300 400 500
Th
erm
al R
esis
tan
ce(°
C/W
) 4mm
Diameter
2mm
Diameter
Heat Load (W)
FIG 4.1 Thermal Resistance vs Heat Load
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
100 200 300 400 500
Th
erm
al
Res
ista
nce
(°C
/W)
F.R
40%
F.R70
%
FIG 4.2 Thermal Resistance vs Heat Load
Major reasons of entropy generation in pulsating heat pipe are: due to temperature difference and fluid with a
friction. We determine entropy generation in pulsating heat pipe a two different diameter and filling ratio. We
found that as temperature increases, entropy generation increases. Minimum entropy generation number means
minimum entropy generation .we found that as temperature increases entropy generation number decreases and
at certain point minimum entropy generation number is found and then increases entropy generation number. So
it means minimum entropy generation number is minimum entropy generation in pipe.
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0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
369 371 369 372 372En
trop
y G
ener
ati
on
(W
/°K
)
4mm
Diameter
2mm
Diameter
Te ( K)
Fig 4.3 Entropy Generation vs T e
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
369 371 369 372 372
En
trop
y G
ener
ati
on
(W
/°K
)
F.R 40%
F.R 70%
T e ( K)
Fig 4.4 Entropy Generation vs T e
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0
20
40
60
80
100
120
140
160
180
369 371 369 372 372
Ns (S
gen
/Sg
en,m
in )
F.R
40%
F.R
70%
Te ( K)
Fig 4.5Ns vs T e
020406080
100120140160180
369 371 369 372 372
Ns
(Sg
en/S
gen
,min
)
4mm
Diameter
2mm
Diameter
Te ( K)
Fig 4.6 Ns vs Te
VI. CONCLUSION
We found that as heat input increases thermal resistance decreases for both 40% and 70% filling ratio. Thermal
resistance also decreases for both 2mm and 4mm diameter. A optimal filling ratio is found to be 40%. A better
pulsation can be observed in 2mm diameter. We found that as temperature increases entropy generation rate
increases. Minimization of entropy depends on entropy generation number.Minimum entropy generation
number found at 372K .So minimum entropy is generated at that particular point.
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REFERENCES
[1]. A.Dimoud, Androutsopoos.(2006).perormance of a radiator based roof Component.Solar Energy.
[2]. A.K.A. Shati, S.G. Blakey,S.B.M. Beck .,(2011)The effect of surface roughness and emissivity on
radiator output. Energy & Buildings.
[3]. Adnan M. Hussein, R.A.Bakar,K. Kadirgama,K.V. Sharma.(2014) Heat transfer enhancement using
nano Fluids in an automotive cooling system. International Communications in Heat and Mass Transfer.
[4]. Ahmet Z. Sahin and Rached Ben-Mansour.,(2003).Entropy generation in laminar fluid flow through
circular pipes. ISSN 1099-4300, Entropy.
[5]. Benjamin Siedel, Valérie Sartre (2013). Numerical investigation of the thermo hydraulic behavior of a
complete loop heat pipe. Applied Thermal Engineering.
[6]. C. Oliet, A. Oliva,J. Castro, C.D. Pe´rezSegarra.(2007).parametric studies on automotive radiator.
Applied Thermal Engineering.
[7]. Ching-Ming Chiang, Han MingChen,Chi ChuanWang.,(2012). theoretical Study of Oscillatory
phenomena in a Horizontal closed loop pulsating heat Pipe with a symmetrical arrayed mini
Channel.International Communications
[8]. Cihat Arslanturk,A. Feridun Ozguc, (2006) Optimization of a central Heating Radiator.Applied Energy.
A.K.A. Shati,S.G. Blakey,S.B.M. Beck. (2011). effect of surfaceRoughness and emissivity on radiator
Output.Energy and Buildings.
[9]. D. Yin,H. Rajab, H.B. Maa.,(2014). Theoretical analysis of maximum filling ratio in an oscillating heat
pipe.International Journal of Heat and Mass Transfer.
[10]. Dehao Xuet, Taofei Chen, Yimin Xuan., Thermo hydro dynamics analysis of Vapor Liquid two- phase
flow in the flat plate pulsating heat pipe.International Communications in Heat And Mass Transfer.
[11]. Dong Liu, Minghou Liu,Dan Xing Sheng Xu., (2011). Flow and heat transfer performance of a mini
channel Radiator with cylinder disturbed flow. Experimental Thermal and Fluid Science.
[12]. Elsayed A.M. Elshafei, M. SafwatMohamed, H. H. Mansour, M. Sakr., (2008). Experimental study of
heat Transfer in pulsating turbulent flow in a Pipe. International Journal of Heat and Fluid Flow.
[13]. H. Khalkhali,A. Faghri,Z.J. Zuo., (1999) Entropy generation in a heat pipe System.Applied Thermal
Engineering.
[14]. Himel Barua, MohammadAli, Mdnuruzzaman, M. Quamrul Islam, chowdhury M. Feroz., (2013). Effect
of filling ratio on heat transfer characteristics and performance of a closed loop pulsating heat pipe.
Procedia Engineering.
[15]. Huseyin Yapici, Gamze,Batyrk, Nesrin Kayatas, And Senay Yalcin .,(2005).Numerical study on
transient local entropy generation in pulsating turbulent flow through an externally heated pipe. Vol. 30,
Part 5, October 2005, pp.
[16]. K.Y. Leong,R. Saidur,S.N. Kazi, A.H. Mamun., (2010). Performance Investigation Of an automotive
carRadiator operated with nano fluid based Coolants.Applied Thermal Engineering.
37 | P a g e
[17]. Maziar Mohammad,Hossein AfshinMohammad Hassan Saidi, Mohammad Behshad Shafii., (2013).
Overall thermal Performance of Ferro fluidic open loop Pulsating heat pipes: An experimental
Approach. International Journal of Thermal Sciences.
[18]. Mukherjee, P.; Biswas, G.; Nag, P.K.,(1987).Second law analysis of heat transfer in swirling Flow
through a cylindrical duct.ASME Journal of Heat Transfer.
[19]. N.Sahiti,F.Krasniqi,X.Fejzullahu, J.Bunjaku,A. Muriqi.,(2008). Entropy generation minimization of a
Double pipe pin fin heat exchanger. Applied Thermal Engineering.
[20]. Nandan Saha,P.K Das.,(2014). Influence of process variables on the hydro dynamics and performance
of a single loop pulsating heat pipe. International Journal of Heatand mass Transfer.
[21]. O.M. Haddad, M.K. Alkam, M.T. Khasawneh., (2004). Entropy Generation due to laminar forced
convection in the entrance region of a concentric annulus. Energy.
[22]. Piyanun Charoensawan, Sameer Khandekar, Manfred Groll., (2003) closed loop pulsating heat pipes:
Parametric experimental investigation. Applied Thermal Engineering.
[23]. Roger R. Riehl, Nadjara do Santoset. (2012).Water-copper nano Application in an open loop pulsating
Heat pipe.Applied Thermal Engineering.
[24]. S.M.Peyghambarh, S.H. Hashemabadi S.M.Hoseini,M. Seifi Jamnani.,(2011) Experimental study of
heat transfer Enhancement using water/ethylene Glycol based nano fluids as a new Coolant for car
radiators.
[25]. Sameer Khandekar,Piyanun Charoen Sawn, Manfred Groll,Pradit Terdtoon. (2003). Closed loop
pulsating heat Visualization and semi empirical Modeling.Applied Thermal Engineering.
[26]. Seyfolah Saedodin,Siamak Sadeghi., (2012). Analysis of Entropy generation Minimization in Circular
Porous Fins.ISRN Chemical Engineering Volume.
[27]. ToddA.Jankowski.,(2009).minimizi Entropy generation in internal flows by Adjusting the shape of the
cross section.International Journal of Heat and Mass Transfer.
[28]. Tsuyoshi Totani,Takuya Kodama, Kota Nanbu,Harunori Nagata, Isao Kudo.(2006). Numerical and
Experimental studies on circulation of Working fluid in liquid droplet radiator.
[29]. Xuefeng Wang, Nengli Zhang.,(2005).Numerical analysis of heat transfer in pulsating turbulent flow in
a pipe.International Journal of Heat and Mass Transfer.
[30]. Yuwen Zhang, Amir Faghri., (2003). Oscillatory Flow in Pulsating Heat Pipe with arbitrary Number of
turns. Journal of thermo physics and heat Transfer.