FIELD OF THE INVENTION
The present invention relates to a novel material composition of phase change
materials for maximum peak power generation, considering base and peak load
conditions and also phase change material composition is to optimize the power
output to meet various electrical load demands.
BACKGROUND OF THE INVENTION
Man's dependence on fossil fuels as primary sources of energy has resulted in
major environmental repercussions. Thus, a possible solution adopted by the
energy sector has been to exploit renewable energy sources to meet the ever
increasing demand for energy, and therefore, a shift in the energy sector towards
clean and renewable energy resources has been observed, which is essential for
a sustainable future. At present, the utilization of solar energy by photo voltaic
(PV) panels is a prime area of interest for research in the renewable energy sector.
Other emerging technologies, such as thermoelectricity which has a moderate
conversion efficiency are also being taken into consideration for their
applications in various fields such as solar, space, waste heat recovery, micro
power generation, powering sensors etc. Thermoelectricity, invented during the
18th century based on the principle of Seebeck effect, promoted the development
of the Thermoelectric Generator (TEG). The major features of the TEG are its
ability to directly convert thermal energy into electricity while being a solid-state
device, its high reliability, compactness and environmental friendliness.
PRIOR ART SEARCH
US 2012/0152297 A1: An energy harvesting device has been disclosed that
includes a thermoelectric device adapted to produce electricity according to the
Seebeck effect. A thermal gradient is imposed across first and second major
surfaces thereof, which consists of a housing enclosing a phase change material

that is disposed for thermal communication with the first major surface of the
thermoelectric device and a radio transmitter electrically coupled to the
thermoelectric device, the radio transmitter being capable of transmitting
wireless signals. Additionally, the housing includes a conductive fin to provide a
more uniform distribution of heat to the phase change material.
US 4,251,291: Energy storage has been accomplished for future use with a
thermoelectric generator in which thermopiles have been provided. The source
of solar energy irradiates a latent heat storage device to enable the heat to be
stored at a relatively constant temperature, which serves as the source of heat
for a greater period of time than what the solar source provides energy itself. An
apparatus is provided to enhance the temperature gradient, in which the
thermopile is located in order to increase the thermoelectric energy generated.
The aforementioned patents have suggested various devices for storing thermal
energy during daytime. Whereas, the present invention relates the material
composition of phase change materials for different compositions, of two different
PCMs which can adapt to the demands of both base and peak load conditions
by studying the weight percentage of phase change materials. A heat sink acts
as a thermal energy storage system, and the stored heat is released for peak
power generation and the considerations of peak load conditions has not been
claimed in the aforementioned patents. The material composition of the eutectic
mixture at which the maximum peak power generation is obtained has been
hereby disclosed in this present invention. Hence the searched US patent though
similar in nature but not relevant to the present invention.
The complete realization of the potential of the TEG at present is limited, as there
exists a gap between thermoelectric material development and thermal system
engineering, which is yet to be bridged. Though the renewable sector including
PV technology can be adapted during base load operations, but peak load
demands are not compensated during peak demand hours. In addition, PV
technology comes to a standstill during the evening and the night power demand.

Therefore, there has been a necessity to validate the exploration of additional
energy resource in order to make progress in the renewable energy sector to
overcome this issue.
Hence, there is always a need to produce a novel composition which can
compensate during peak demand hours and validate the exploration of
additional energy resource in order to make progress in the renewable energy
sector.
The present invention meets the long felt need.
OBJECTS OF THE INVENTION
It is therefore the primary object of the present invention is to develop the phase
change material (PCM) composition, which can provide maximum thermo electric
peak power generation for solar applications.
Another object of the present invention to develop the phase change material
(PCM) composition, which can generate maximum peak power and eventually
can compensate the peak hour demands.
Yet another object of the present invention to develop the phase change material
(PCM) composition, which is produced from easily available materials.
Further object of the present invention to develop the phase change material
(PCM) composition, which is cheap and environment friendly.
SUMMARY OF THE INVENTION
A novel eutectic composition for thermal energy storage material used in
thermoelectric reverse power generation in solar applications comprises :
i) D-Mannitol
ii) Magnesium Chloride Hexahydrate

Various objects, features, aspects, and advantages of the inventive subject
matter will become more apparent from the following detailed description of
preferred embodiments, alongwith the accompanying drawing figures.
It is to be understood that the aspects and embodiments of the disclosure
described above may be used in any combination with each other. Several of the
aspects and embodiments may be combined to form a further embodiment of the
disclosure.
The foregoing summary is illustrative only and is not intended to be in any way
limiting. In addition to the illustrative aspects, embodiments, and features
described above, further aspects, embodiments, and features will become
apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The illustrated embodiments of the subject matter will be best understood by
reference to the drawings, wherein like parts are designated by like numerals
throughout. The following description is intended only by way of example, and
simply illustrates certain selected embodiments of devices, systems, and
processes that are consistent with the subject matter as claimed herein, wherein:
Fig. 1 shows the process flow during heating phase of reverse thermoelectric
power generation
Fig. 2 shows the process flow during natural/forced cooling phase of reverse
thermoelectric power generation
Fig. 3 shows the average TEG power generated during heating for different D
mannitol weight loadings
Fig. 4 shows the average TEG power generated during natural cooling for
different D mannitol weight loadings

Fig. 5 shows the average TEG power generated during forced cooling for different
D mannitol weight loadings
Fig. 6 shows the peak power generated during natural cooling for different D-
mannitol weight loadings
Fig. 7 shows the peak power generated during forced cooling for different D-
mannitol weight loadings
The figures depict embodiments of the disclosure for purposes of illustration
only. One skilled in the art will readily recognize from the following description
that alternative embodiments of the methods illustrated herein may be employed
without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
While the embodiments of the disclosure are subject to various modifications
and alternative forms, specific embodiment thereof have been shown by way the
figures and will be described below. It should be understood, however, that it is
not intended to limit the disclosure to the particular forms disclosed, but on the
contrary, the disclosure is to cover all modifications, equivalents and alternative
falling within the scope of the disclosure.
It is to be noted that a person skilled in the art would be motivated from the
present disclosure to arrive at a eutectic composition for thermoelectric reverse
power generator. Such a method for evaluating the same may vary based on
configuration of one or more workpieces. However, such modifications should be
construed within the scope of the disclosure. Accordingly, the drawings illustrate
only those specific details that are pertinent to understand the embodiments of
the present disclosure, so as not to obscure the disclosure with details that will
be clear to those of ordinary skill in the art having benefit of the description
herein.

As used in the description herein and throughout the claims that follow, the
meaning of “a”, “an”, and “the” includes plural reference unless the context
clearly dictates otherwise. Also, as used in the description herein, the meaning
of “in” includes “in” and “on” unless the context clearly dictates otherwise.
The terms “comprises”, “comprising”, or any other variations thereof used in the
disclosure, are intended to cover a non-exclusive inclusion, such that a method,
system, assembly, thermoelectric power, generator, thermal energy that
comprises a list of components does not include only those components but may
include other components not expressly listed or inherent to such method, or
assembly, or method. In other words, one or more elements in a system or device
proceeded by “comprises…..a “does not, without more constraints, preclude the
existence of other elements or additional elements in the system, apparatus or
device.
The present invention relates to a novel material composition of phase change
materials used as thermal energy storage material in the thermoelectric
generator (TEG).
This phase change material composition is to optimize the power output to meet
various electrical load demands and also provides maximum peak power
generation upon considering base and peak load conditions.
The eutectic material composition for maximum power generation comprises
granular particles of magnesium chloride hexahydrate and D-mannitol in a
preferred weight percentage of 30% and 70% respectively.
The magnesium chloride hexhydrate is mechanically blended with D-mannitol.

The density of D-mannitol is high and hence once melted, would not touch the
fins present in the setup and this eventually causes the poor heat transfer, which
has been avoided in this case with the help of the base fin plates.
Magnesium Chloride is in semi solid state when exposed to atmospheric
conditions on evaporation of the water of crystallization.
The material composition of 70% of D-mannitol and 30% magnesium chloride
hexahydrate respectively generates maximum peak power during both base and
peak load operations, which can compensate for peak hour demands.
At higher weight percentage, the peak power generated, decreased when
compared to that of material composition of 70% - 30%.
In accordance with one embodiment of the present invention, it provides a
thermoelectric generator (TEG) reverse power generation applications which
consists of an electric heater, a copper heat spreader plate, TEG modules, an
aluminum heat sink, the Thermal Energy Storage (TES) container or phase
change container, a free convection (natural cooling) system and a thermosyphon
passive cooling system for cooling phase. A plurality of TEG devices are
sandwiched between the top copper heat spreader plate and the base aluminum
fin base plate and are electrically connected in series. The base fin plate also acts
as the top plate of the TES or fluid container. The output terminals are evaluated
for the performance of phase change material composition.
The thermal energy storage (TES) container has a cuboidal shape where different
phase change materials are loaded with different composition. Out of this, D-
mannitol and magnesium chloride hexahydrate is the most optimum
composition.

An increase in the D-Mannitol weight percentage was performed. The base fin
plate was placed such that the fins were immersed into the container, enabling
the base fin plate for effective heat transfer. The passive cooling of thermoelectric
modules was influenced by the principle of thermosyphon, whereas the natural
cooling of thermoelectric modules was influenced by free convection.
Fig 1 and Fig 2 illustrate the process flow during heating and cooling phase of
reverse thermoelectric power generation respectively.
The surface of the copper plate was heated by a plate type solar heat
flux/resistance heater (1) with heat uniformly distributed (2) to plurality of TEG’s
placed equidistantly (3). The cold side of TEG maintains a same temperature as
Phase Change Material (PCM) (6) which stores heat rejected by TEG through fins
(4 and 5). The heating phase (7) was followed by cooling phase (9). During cooling
phase (9), heater/non availability of sun light and insulation was removed from
the top of the heat/cold spreader plate (2). The natural or passive forced cooling
system (8) was kept on the top of the heat/cold spreader plate (2) and allowed to
cool the PCM. During cooling phase (9), the PCM system is cooled upto ambient
temperature.
Fig 3, 4 and 5 also provide graphical representation of TEG average power
generation of different D-mannitol weight percentage during heating, natural
and forced cooling system.
The average power generation during heating and cooling phase is maximum at
70-30 weight percentage of D-mannitol and magnesium chloride for all heat
input of 10W, 30W, 60W and 90W.
Use of magnesium chloride hexahydrate after the heat transfer characteristics of
D-mannitol which eventually effects direct impact on TEG power generation.

The effective heat transfer from the top side of the TEG to the heat sink (PCM
container) results in the rise in average power generation during the heating
phase. Similarly, during the cooling phase, an improvement in the discharging
of material result in an increased average power generation. This resulted in
achieving maximum TEG power for 70-30 weight percentage of D-Mannitol and
magnesium chloride hexahydrate respectively, which was more than that
generated by using the base materials only. In addition, the average power
generation for heating and cooling was lesser for pure materials or the base
materials when compared to a material composition of 70-30 weight percentage
of D-Mannitol and magnesium chloride hexahydrate respectively.
The trend of peak power is not significant during the heating phase as the
heating of modules resulted in gradual increase of peak power, but has a
significant impact was observed during cooling phase. The graph of peak power
generation for natural and forced cooling are shown in Fig. 6 and Fig. 7
respectively. It can be inferred that there is a steep increase in 70-30 weight
percentage of D-Mannitol and magnesium chloride hexahydrate material
composition for heat inputs of 10 W, 30 W, 60 W and 90 W for both the cooling
system. The peak power generation can be adapted for a peak load time, as the
energy shortage at night time (major time for peak loading) cannot be
compensated by the solar photovoltaic (SPV) method unless the energy is stored
in battery or any other means of storage.
The TEG, integrated with TES system stores the available thermal energy for
night use. The trend of phase change material composition on peak TEG power
generation signifies that of all concentrations, a 70-30 weight percentage of D
mannitol and magnesium chloride hexahydrate material composition is capable
of producing a higher peak power than that produced by pure materials and
other composite counterparts. This peak power is generated within a short
duration of time, which results in peak power produced that is not significantly
generated after long durations of operation. It is evident that the system can
effectively produce power output for peak load conditions for 70-30 weight

percentage of D-Mannitol and magnesium chloride hexahydrate material
composition, as the stored thermal energy is released at a faster rate due to a
higher thermal diffusivity than the base materials themselves.
Hence, it can be included that the optimum D-mannitol and magnesium chloride
hydrate material composition is 70% and 30% for peak load operations. But at
higher weight percentages, i.e. higher than 70% of D-mannitol, the TEG power
generation decreases.
Table 1 provide TEG output parameters of TEG at optimized mixture of DM with
MgCl2.6H2O.


In accordance with another embodiment of the present invention:
A temperature difference across TEG modules was maintained for generating
power during the heating and cooling phases of the TEG system and the heat
rejected by the TEG is transferred to material composition of 70% - 30% of D-
Mannitol and magnesium chloride hexahydrate, which stores thermal energy
during the heating phase.
The cold side of the TEG, which is in contact with the optimized novel
composition of the material through fin arrangement. The plurality of TEGs
were maintained in their positions with both the upper and lower surfaces
being in contact with the ambient or external heating device/solar heater and
the eutectic mixture respectively.
The non-limiting advantages are given below :
i) The peak power obtained was extended for a shorter duration of time in
forced cooling phase and during natural cooling phase the power is
available for a longer duration of time.
ii) The maximum output produced by the material composition of 70-30%
magnesium chloride hexahydrate and D-Mannitol has been observed for
both the heating and cooling phases.
iii) The natural cooling conditions could be used for base loading operations
and the forced cooling conditions could be used for peak loading
operations for higher maximum power output for the optimized 70% - 30%
of composition of D-Mannitol and magnesium chloride hexahydrate.
Each of the appended claims defines a separate invention, which for
infringement purposes is recognized as including equivalents to the various
elements or limitations specified in the claims. Depending on the context, all
references below to the “invention” may in some cases refer to certain specific

embodiments only. In other cases, it will be recognized that references to the
“invention” will refer to subject matter recited in one or more, but not necessarily
all, of the claims.
Groupings of alternative elements or embodiments of the invention disclosed
herein are not to be construed as limitations. Each group member can be referred
to and claimed individually or in any combination with other members of the
group or other elements found herein. One or more members of a group can be
included in, or deleted from, a group for reasons of convenience and/or
patentability. When any such inclusion or deletion occurs, the specification is
herein deemed to contain the group as modified thus fulfilling the written
description of all groups used in the appended claims.
The present disclosure provides a eutectic composition for thermoelectric reverse
power generator.
Equivalents:
With respect to the use of substantially any plural and/or singular terms herein,
those having skill in the art can translate from the plural to the singular and/or
from the singular to the plural as is appropriate to the context and/or
application. The various singular/plural permutations may be expressly set forth
herein for sake of clarity.
It will be understood by those within the art that, in general, terms used herein,
and especially in the appended claims (e.g., bodies of the appended claims) are
generally intended as “open” terms (e.g., the term “including” should be
interpreted as “including but not limited to”, the term “having” should be
interpreted as “having at least”, the term “includes” should be interpreted as
“includes but is not limited to”, etc.). It will be further understood by those within
the art that if a specific number of an introduced claim recitation is intended,

such an intent will be explicitly recited in the claim, and in the absence of such
recitation no such intent is present. For example, as an aid to understanding,
the following appended claims may contain usage of the introductory phrases
“at least one” and “one or more” to introduce claim recitations. However, the use
of such phrases should not be construed to imply that the introduction of a claim
recitation by the indefinite articles “a” or “an” limits any particular claim
containing such introduced claim recitation to inventions containing only one
such recitation, even when the same claim includes the introductory phrases
“one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a”
and/or “an” should typically be interpreted to mean “at least one” or “one or
more”); the same holds true for the use of definite articles used to introduce claim
recitations. In addition, eve it a specific number of an introduced claim recitation
is explicitly recited, those skilled in the art will recognize that such recitation
should typically be interpreted to mean at least the recited number (e.g., the bare
recitation of “two recitations”, without other modifiers, typically means at least
two recitations, or two or more recitations).
The terminology used herein is for the purpose of describing particular
embodiments only and is not intended to be limiting of the present disclosure. It
will be appreciated that several of the above-disclosed and other features and
functions, or alternatives thereof, may be combined into other systems or
applications. Various presently unforeseen or unanticipated alternatives,
modifications, variations, or improvements therein may subsequently be made
by those skilled in the art without departing from the scope of the present
disclosure as encompassed by the following claims.
The claims, as originally presented and as they may be amended, encompass
variations, alternatives, modifications, improvements, equivalents, and
substantial equivalents of the embodiments and teachings disclosed herein,

including those that are presently unforeseen or unappreciated, and that, for
example, may arise from applicants/patentees and others.
While various aspects and embodiments have been disclosed herein, other
aspects and embodiments will be apparent to those skilled in the art. The various
aspects and embodiments disclosed herein are for purposes of illustration and
are not intended to be limiting, with the true scope and spirit being indicated by
the following claims.

WE CLAIM :
1. A novel eutectic composition for thermal energy storage material used in
thermoelectric reverse power generation in solar application comprises :
i) D-mannitol
ii) Magnesium chloride hexahydrate
2. The eutectic composition as claimed in claim 1, wherein the weight percentage
of D-mannitol and magnesium chloride hexahydrate is 70% and 30%
respectively.
3. The eutectic composition as claimed in claim 1, wherein the density of D-
mannitol is high, so that it would not touch the fins present in the generator.
4. The eutectic composition as claimed in claim 1, wherein the temperature
difference across TEG modules was maintained for generating power during the
heating and cooling phases of the TEG system.
5. The eutectic composition as claimed in claim 1, wherein the rejected heat is
transferred to said composition for storing thermal energy during the heating
phase.
6. The eutectic composition as claimed in claim 1, wherein the said magnesium
chloride is in semi solid state when exposed to atmospheric condition on
evaporation of the water of crystallization.
7. The eutectic composition as claimed in claim 1, wherein the cold side of TEG
is in touch with said composition through the fin arrangement.