Background of the Invention
The current invention pertains to pulsating heat pipes in general and,
more specifically, to pulsating heat pipes having flexible artery mesh
inserted within to improve heat dissipation for the heat-generating
components.
Present technologies and the limitations
Present field heat pipes are employed in the cooling electronics. Cooling
of Pentium processors in notebook computers is currently one of the heat
pipe's most popular applications. Heat pipes are ideal for cooling the
powerful CPUs in notebook computers because of the limited space and
power available. Battery life is shortened by fan-assisted heat sinks,
which use electricity. The size of typical metallic heat sinks required to
dissipate the heat load prevents their incorporation into the packaging
for the notebook. However, heat pipes offer a passive, compact heat
transfer technique with high efficiency.
Heat pipes with a diameter of three or four millimeters can efficiently
remove the high flux heat from the CPU, but is difficult. The heat pipe
distributes the heat load over a sizable heat sink region, where the heat
flux is so low that it may be effectively discharged through the notebook
case to ambient air. The heat sink may already be present in the laptop,
such as the metal structural components of the various notebook heat
pipe heat sink layouts shown in Fig.
Pulsating flow of liquid slugs and vapour plugs is actuated due to the
period variation of vapour in the evaporator and condenser during
heating. Natural oscillations of the working fluid between the condenser
and evaporator sections cause convection and phase change heat
transfer. Pulsating Heat Pipes outperform traditional heat pipes in terms
of performance and can be used to solve future intermediate Electronic
cooling problems.
Limitations
 Heat pipes with wicking structures have increased thermal
resistance, reducing the heat transfer rate.
 Low-temperature fluids have dry-out conditions in the pulsating
heat pipe.
An experimental investigation on pulsating heat pipes with multiple
turns will be conducted in order to determine the effect of various
intermediate temperature working fluids, filling ratios, heat input, and
the effect of nanoparticles on heat transport capability. The pulsating
heat pipe consists of 8 turns made up of copper tube having an inside
diameter of 2 mm, a wall thickness of 0.5 mm, and a total length of 5324
mm. The experiment is carried out for different working fluids like
Dowtherm-A, Diethlyne Glycol, Ethylene Glycol, Propylene Glycol, and
DI Water with fill ratios of 45%, and 85% of their volume. The heat input
is varied from 120 watts to 600 watts, with an increment of 120 watts.
From the novelty of the invention, intermediate temperature fluid was
stable based on the experimental results. It is noted that heat input
plays a vital role in thermal performance of the pulsating heat pipe. The
performance of a pulsating heat pipe increases with the supply of heat
input, increasing the heat transfer coefficient.
Descriptions
Impact of the Research
Two-phase gas-liquid (or vapour-liquid) flows are commonly used in
industrial operations and technical applications. Substantial research
has been done on them for many years due to the significance of twophase flows in processes in chemical engineering, nuclear reactors,
refrigeration systems, and heat exchangers. On the ground, significant
experimental data was collected for a variety of flow orientations and flow
passage geometries. Approaches and interactions on flow pattern
changes, pressure reductions, void percentages, heat transfer rates, and
other engineering aspects of gas-liquid flows through conduits have been
developed. However, due to the intricacy of the flow, predictions were
mostly made using qualitative or semi-qualitative interactions that were
established based on particular investigation circumstances, such as the
size and shape of the conduit, adiabatic or boiling flows, and heating
technique, or gas source. It might not be viable to extrapolate these
correlations to other circumstances, especially when gravity is
significantly decreased as well as with the introduction of new types of
technology. The use of two-phase heat management is being studied by
space agencies worldwide to improve astronaut survivability onboard
future spacecraft as well as planetary bases. A heat transfer system
should, according to the Technology Roadmap on Thermal Management
Systems, include: Allow secure, dependable, and well-designed low-
mass transport loops for human missions. This enables the use of less
energy-intensive, more dependable systems that can transport heat over
a greater temperature gradient. As a result, a spacecraft may be operated
in a wider variety of circumstances. Capillary-based heat pipe loops are
one of the technologies that should be further researched in order to
improve planetary exploration missions with crews. More efficient are
heat switches, heat straps, and insulation, allowing for more dependable
and passive thermal efficiency in spacecraft management. Another
emerging topic is the use of pulsating heat pipes to create desktop
applications. For illustration, in hybrid or fully electric cars, cooling the
battery packs will boost dependence and prevent excessive battery
capacity dimensions by lowering parasitic energy use (i.e. pumping
energy in with use for ground two-phase passive systems, as seen in
Figure 1). 38% of the electricity is used for the devices' cooling. To assist
engineers in designing the suitable thermal solution, advancing via
research innovation methodologies and, collecting precise data to back
up the modeling phase, a design tool is needed in both the on-ground
and in-space sectors. This will enable it to be done to advance the Level
of Technology Readiness (TRL), beginning with the Space qualification
production method for a fresh batch of pulsating heat pipes. As a
result, the current effort has had a significant effect.
Constriction and Working Principal Pulsating Heat pipe
Pulsating heat pipes have been widely employed because they have
proven to be capable of meeting traditional standards for high heat flux
dissipation in a variety of applications connected to electronics without
the need for outside assistance and with no mechanical parts (refer to
Figure 1.7). Due to the physical phenomena involved (such as satellites
and spacecraft), HPs and TSs have shown a variety of constraints under
the pressing position experienced in actual compact equipment (such as
the latest version of Ultra Books and cell phones) and non-gravityassisted devices.
Working principles of Pulsating Heat pipe
A pulsating heat pipe operates similarly to a system of liquid plugs and
vapour bubbles in a spring-mass damper. Within the pulsating heat
pipe, there is a complex system in which the working fluid is oscillating.
The input of heat generates a rise in vapour volume and pressure as the
liquid plug travels to the evaporating region. The bubble velocity will not
match the slug velocity in Taylor bubble train flow conditions because of
the reduced friction brought on by the thin liquid film's presence. When
the liquid plug reaches the evaporation section, there is an exciting start
to the oscillating motion. This force aids in the beginning of the
oscillating motion when the liquid plug reaches the evaporation section.
Where it comes to a halt and begins to travel back. The pulsating heat
pipe’s oscillating motion will come to a halt when this spring-mass
system vanishes. On the one hand, the length of the liquid plugs
reduces, while the vapour velocity reaches a critical point and, the flow
pattern changes to annular flow as a result of the vapour penetrating the
liquid plug. This can occur when the rate of heat transfer increases,
increasing the oscillating movement, heat transfer, as well as the velocity
field. The stream of bubbles and plugs disappears, and the oscillations
vanish as well. The Pulsating Heat Pipe reaches its maximum heat
transmission capacity, which is referred to as the Pulsating Heat Pipe's
functional limit. To form the oscillation or circulation motion, the liquid
slug must be driven by the vapour plugs; the Taylor bubble train flow is
the appropriate flow pattern for this type of behaviour. Surface tension at
the solid-liquid-vapour interface results in the formation of a meniscus
zone on both ends of a slug. The phase transition takes place at the pipe
wall, where the vapour plug is covered by a thin liquid film. The phase
transition occurs at the pipe wall, where a thin liquid film covers the
vapour plug. The lateral area between slugs and plugs also helps with
phase change heat transmission. As a result, many parameters must be
examined when investigating. Despite the fact that there are several
pulsating heat pipe designs, the basic classification in the literature
consists of three planar layouts. The pipe's ends are not joined to create
an open loop and are instead sealed off. Closed circuit with linked ends
that allows the fluid to circulate and oscillate. A chuck valve is used to
close the loop. A situation in which the fluid is forced to flow in a specific
direction by one or more chuck valves. Because of the complexities of the
disappearance and condensation phenomena, as well as the dynamics of
internal fluxes. To depict the heat transmission characteristics of a
pulsating heat pipe accurately is a challenging job. However, the
observed operating regimes can now be described as follows: Pure
conduction occurs when we gradually increase the heat power input to a
pulsating heat pipe from cold to hot. Pure conduction: This describes the
warmth transfer mode of a pulsing heat pipe that has not been activated
before commencing, or a pulsing heat pipe that's within the latter stages
of turning off. Once the facility demand is increased, the evaporator
temperature rises, but there's no fluid fluctuation, leading to no
movement of vapour bubbles and liquid slugs.
• Weak Pulsation: The condenser’s pressure is steady and matches the
saturation temperature, and neither the condenser nor the evaporator
show temperature variations; Key entities pulse rapidly, with only a
small amplitude pressure difference between pulses detectable.
• Full activation: The thermal energy supplied to the system is It is now
enough to cause significant thermal instabilities, resulting in strong
pressure oscillations that are repeated with high time-density: the
evaporator's temperatures are unstable, displaying rapid oscillations in
between periods of increase and drop associated with fluid stop-over;
Given the chaos of the occurrences, an appropriate frequency of
oscillation is not discernible. All the temperatures in the evaporator zone
drop rapidly, indicating a robust two-phase flow motion. This motion can
have two distinct features, or a combination of both. A confined thermal
instability-generated large amplitude change of in straight and turnaround flow is called a fluctuation. Heat transmission is aided by the
fluid's circulation, which moves in a favorable direction. The motion
changes from oscillating to circulating as the power input increases. FF,
A pseudo steady-state can be produced when the system is fully engaged
and the power input is held constant for a sufficient period of time
(thermal transient).
Due to the complex disappearance and condensation phenomena and
the dynamics of internal fluxes, it is challenging to accurately depict the
heat transmission characteristics of a pulsating heat pipe. However, the
observed operating regimes can now be described as follows: if we
progressively increase the heat power input to a pulsating heat pipe from
cold, If a pulsating heat pipe's heat power input is gradually increased
from cold.

CLAIMS
1. Experimental and Numerical Investigation on Thermal Performance of
Pulsating Heat Pipe states it is the groundwork for future research.
2. Experimental and Numerical Investigation on Thermal Performance of
Pulsating Heat Pipe of claim 1, wherein said it is a cutting edge
technology.
3. Experimental and Numerical Investigation on Thermal Performance of
Pulsating Heat Pipe of claim 1, wherein said this paper attempts to
explain the concept, and assess its impact.
4. Experimental and Numerical Investigation on Thermal Performance of
Pulsating Heat Pipe of claim 1, wherein said this paper has many
applications.
5. Experimental and Numerical Investigation on Thermal Performance of
Pulsating Heat Pipe of claim 1, wherein said that this paper discusses
the major advantages and how it can improve.
6. Experimental and Numerical Investigation on Thermal Performance of
Pulsating Heat Pipe of claim 1, wherein said that it spread awareness
about the Pulsating Heat Pipe and security.
7. Experimental and Numerical Investigation on Thermal Performance of
Pulsating Heat Pipe of claim 1, wherein said that we analyzed and
discussed various aspects.
8. Experimental and Numerical Investigation on Thermal Performance of
Pulsating Heat Pipe of claim 1, wherein said that in recent years,
Pulsating Heat Pipe has become hot topic around the world.