FIELD OF INVENTION

[0001]. The present invention relates to difficult phase change materials for high heat storage and transfer or more particularly the phase change materials with varying composition for the energy storage used in the latent heat thermal energy storage (LHTES) system in the dry slag granulation plant.

BACKGROUND OF INVENTION:

[0002]. Since the phase change is an endothermic process, the PCM absorbs heat. Upon storing heat in the storage material, the material begins to melt when the phase change temperature (melting temperature in the case of solid-liquid transformation) is reached. The temperature then stays constant until the melting process is finished. The heat stored during the phase change process (melting process) of the material is called latent heat. Latent heat storage has two main advantages: (i) it is possible to store large amounts of heat with only small temperature changes and therefore this process has a high storage density; (ii) because the phase change at a constant temperature takes some duration to complete which enables the possibility of smooth temperature variations. The comparison between latent and sensible heat storage displays that using latent heat storage increases the storage densities typically 5 to 10 times higher. Latent heat storage can be used in a wide temperature range.
[0003]. In the steel industry, Phase Change Materials can be used to extract the available heat from the output air after the granulation process. These phase change materials store energy during their respective phase transformation i.e. changing from solid to liquid, in the form of latent heat. These materials have high energy density thus energy is stored over small volume changes and at constant temperature which diminishes the containment problem. Unlike in sensible heat storage system, no significant heat loss is observed in a Latent Heat Thermal Energy Storage System. The phase change materials, along with extraction of available heat, are an excellent medium for heat storage. Latent Heat storage gives the advantage of using the thermal energy when the need arises otherwise it can remain stored in a thermally insulated container in the form of

liquid phase change material. It also allows us to transport the heat energy to power generation facility. One disadvantage of using phase change materials is their low thermal conductivity. To overcome this challenge, phase change materials are added with specific nanoparticles of certain weight percentage, which will increase the general phase change material’s conductivity by a significant amount.
Prior Art
[0004]. The Phase Change Materials currently available in the market are affected by two major problems, low thermal conductivity and low energy density. Low thermal conductivity hampers the efficiency of heat transfer in the system in terms of both time of the process and energy output of process. Meanwhile, low energy density corresponds to larger volume of PCM required to generate same amount of energy.
[0005]. Patent Application US20090236079A1 describes about the dispersion of nanoparticles to improve the functionality of phase change materials. The resulting nanoparticle-enhanced phase change materials (NEPCM) exhibit enhanced thermal conductivity in comparison to the base material. Higher rate of heat release in the NEPCM is observed in relation to the conventional PCM due to increase of thermal conductivity and also due to lowering of the latent heat of fusion. The increase of the heat release rate of the NEPCM is a clear indicator of its great potential for diverse thermal energy storage applications.
[0006]. In this document, two classes of nanoparticles are proposed. First, Carbon-based nanoparticles such as Graphene, Graphite, and/or Carbon Nano-Tubes as they have superior thermal conductivity as compared to any other class of nanoparticles. Second, magnetic nanoparticles such as Iron, Cobalt, Nickel and their oxides as their properties are tunable with magnetic field. Nanoparticles were dispersed with the PCM by the means of mechanical dispersion through ball milling.

[0007]. One major issue that needs to be addressed is that most PCMs have an unacceptably low thermal conductivity, and hence, heat transfer enhancement techniques are required for any latent heat thermal storage application. In a latent heat energy storage system, during the phase change process, the solid-liquid interface moves away from the heat transfer surface. During this process, thermal resistance of the growing layer (thickness of the molten / solidified medium) decreases the surface heat flux. At the time of solidification, conduction is the only transport mechanism, and in most cases, it is very slow. But during melting process, natural convection can occur in the molten layer and this generally increases the heat transfer rate as compared to the solidification process (this is possible if the layer is thick enough to allow natural convection to occur). However, suitable heat transfer enhancement techniques can be used to increase this low heat transfer rate. There are various methods to enhance the heat transfer in latent heat storage system. Some of the heat transfer enhancement techniques are the use of thin aluminum plates filled with PCM.
[0008]. But conventionally used phase change materials often does not provide desired latent heat storage and energy density.
[0009]. But the present invention uses different novel combination of different phase change materials, which can fulfilled this long felt need.
OBJECTS OF THE INVENTION
[00010]. It is therefore the principal object for the present invention to provide a novel composite phase change materials for storing and recovering heat in form of latent heat in the dry slag granulation plant.
[00011]. Another object of the present invention is to provide a novel composite phase change materials, which has substantially high latent heat storage and high energy density.
[00012]. Yet another object of the present invention is to provide a novel composite phase change materials, which can utilizes in different combination including lithium nitrate in each.

[00013]. Further object of the present invention is to provide a novel composite phase change materials, which is economic for use in thermal energy storage systems.
[00014]. Another object of the present invention is to provide a novel composite phase change materials, which is used in latent heat thermal energy storage system in a metal matrix structure without much reduction in energy storage.
[00015]. Yet Another object of the present invention is to provide a novel composite phase change materials, which has substantially high heat transfer efficiency of a latent heat storage system.
SUMMARY OF INVENTION
[00016]. One or more drawbacks of conventional of phase change materials are overcomed, and additional advantages are provided through the method as claimed in the present disclosure, Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be part of the claimed disclosure.
[00017]. A blended phase change material comprising Lithium nitrate as main component alongwith other components such as lithium chloride, sodium nitrate and potassium nitrate in different combinations.
[00018]. Various objects, features, aspects, and advantages of the inventive subject matter will more apparent from the following detailed of preferred embodiments, alongwith the accompanying drawing figures.
[00019]. 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 may be combined to form a further embodiment of the disclosure.
[00020]. 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 will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
[00021]. The illustrated embodiments of the subject matter be best understood by reference to the drawings. The following description is intended only by way of example, and simply illustrates certain selected embodiments of method, systems, that are consistent with the subject matter as claimed herein, wherein:
[00022]. Figure 1 illustrates DSC experiment result of LiNO3 – LiCl mixture.
[00023]. Figure 2 illustrates Factsage simulation for LiNO3 – LiCl mixture for finding eutectic point.
[00024]. Figure 3 illustrates DSC experiment result of LiNO3 – NaNO3 mixture.
[00025]. Figure 4 illustrates Factsage simulation of LiNO3 – NaNO3 mixture for finding eutectic point.
[00026]. Figure 5 illustrates DSC experiment result of LiNO3 – KNO3 mixture.
[00027]. Figure 6 illustrates Factsage simulation for LiNO3 – KNO3 mixture for finding eutectic point.
[00028]. The figures depict embodiments of the disclosure for purposes of only. One skilled in the art will readily from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[00029].While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of 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.
[00030]. It is to be noted that a person skilled in the art would be motivated from the present disclosure to arrive at a novel phase change materials (PCM) composition. Such composition 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.
[00031]. 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.
[00032]. The terms “comprises”, “comprising”, or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a system, coal tar pitch, method, carbon foam, assembly 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. 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.
[00033].The present invention relates to a novel phase change material (PCM) composition used in a latent heat thermal energy storage (LHTES) system for repetitive storing and recovering the latent heat in the dry slag granulation plant in the steel industry.
[00034]. This blended phase change material comprising Lithium nitrate as main component alongwith other components such as lithium chloride, sodium nitrate and potassium nitrate in different combinations.
[00035].The phase change materials used in LHTES system has mainly three combinations such as
[00036]. i) First combination/composition:- Lithium nitrate and Lithium chloride.

[00037]. ii) Second combination/composition:- Lithium nitrate and sodium nitrate.
[00038]. iii) Third combination/composition:- Lithium nitrate and potassium nitrate.
[00039]. In the first eutectic composition, lithium nitrate is used at a concentration of 70 to 95 weight% based on total amount of PCM and lithium chloride is used at a concentration of 5 to 30 wt. % of the total amount of PCM.
[00040]. The first composition includes lithium cataion, nitrate ion, nitrite ion and a chloride ion.
[00041]. Figure 1 illustrates the peak of the graphs corresponds to the melting point of Lithium nitrate and Lithium chloride mixture, based on the data obtained from differential scanning calorimeter.
[00042].Figure 1 was obtained from the Factsage software, the software simulated the eutectic point i.e. the composition at which the LiNO3-LiCl mixture forms a eutectic mixture. The point at which the two curved line meet corresponds to eutectic composition and melting point of the eutectic mixture. Eutectic composition of LiNO3-LiCl is 91.8 - 8.2 (weight ratio). At the eutectic point phase segregation of salt mixtures can be avoided. The melting point of LiNO3-LiCl is 243.1°C for both the simulated and experimental results.
[00043].This graph is an experimental verification (using Factsage simulation) of the melting point of this composite PCM. The melting point of LiNO3-LiCl PCM is 243.1℃ which is relevant for the heat recovered from the molten slag.
[00044]. Figure 2 illustrates the eutectic point at which the LiNO3-LiCl mixture forms an eutectic mixture based on the data obtained from the Facstage software.
[00045].The point at which the two curved line meet correspond to eutectic composition and melting point of the eutectic mixture. Eutectic composition of LiNO3-LiCl is 91.8 - 8.2. At the eutectic point phase segregation of salt mixtures can be avoided. The melting point of LiNO3-LiCl is 243.1°C for both the simulated and experimental results.

[00046]. The second combination or composition of PCMs is a mixture of lithium nitrate and sodium nitrate.
[00047]. This combination includes lithium nitrate in 48 to 49 wt % based on total amount of PCM and the sodium nitrate is used at a concentration from 51 to 52 wt. % based on total amount of PCM.
[00048].The second combination includes lithium cataion and sodium cataion.
[00049]. Figure 3 illustrates the peak of the graph corresponds to the melting point of LiNO3-NaNO3 mixture based on the data obtained from differential scanning calorimeter.
[00050]. This graph is an experimental verification (for the Factsage simulation) of the melting point of this PCM mixture. The melting point of LiNO3-NaNO3 PCM is 199.0°C. Hence this can recover heat successfully from the molten slag.
[00051]. Figure 3 was obtained from the FactSage software, the software simulated the eutectic point i.e. the composition at which the LiNO3-NaNO3 mixture forms a eutectic mixture. The point at which the two curved line meet corresponds to eutectic composition and melting point of the eutectic mixture. The eutectic composition of LiNO3-NaNO3 is 48.6 - 51.4 (weight ratio). At the eutectic point phase segregation of salt mixtures can be avoided. The melting point of LiNO3-NaNO3 is 199°C for both the simulated and experimental results.
[00052].Figure 4 illustrates the eutectic point at which the LiNO3-NaNO3 mixture forms a eutectic mixture based on the data obtained from the Facstage software.
[00053]. The point at which the two curved line meet correspond to eutectic composition and melting point of the eutectic mixture. The eutectic composition of LiNO3-NaNO3 is 48.6 - 51.4. At the eutectic point phase segregation of salt mixtures can be avoided. The melting point of LiNO3-NaNO3 is 199°C for both the simulated and experimental results.
[00054]. The third combination or composition comprises lithium nitrate and potassium nitrate, where the concentration of lithium nitrate from 20 to 40% and

concentration of potassium nitrate is from 60 to 80 weight% based on the total amount of PCM.
[00055].The third composition includes lithium cation and potassium cataion.
[00056].Figure 5 illustrates the peak of the graph corresponds to the melting point of LiNO3-KNO3 mixture based on the data obtained from differential scanning calorimeter.
[00057]. This graph is an experimental verification (for the Factsage simulation) of the melting point of this PCM mixture. The melting point of LiNO3-KNO3 PCM is 127.4°C.
[00058].Figure 5 was obtained from the FactSage software, the software simulated the eutectic point i.e. the composition at which the LiNO3-KNO3 mixture forms a eutectic mixture. The point at which the two curved line meet corresponds to eutectic composition and melting point of the eutectic mixture. The eutectic composition of LiNO3-KNO3 is 33.5 - 66.5 (weight ratio). At the eutectic point phase segregation of salt mixtures can be avoided. The melting point of LiNO3-KNO3 is 127.4°C for both the simulated and experimental results.
[00059]. Figure 6 illustrates the software simulated the eutectic point at which the LiNO3-KNO3 mixture forms a eutectic mixture based on the data obtained from the Facstage software.
[00060]. The point at which the two curved line meet correspond to eutectic composition and melting point of the eutectic mixture. The eutectic composition of LiNO3-KNO3 is 33.5 - 66.5. At the eutectic point phase segregation of salt mixtures can be avoided. The melting point of LiNO3-KNO3 is 127.4°C for both the simulated and experimental results.
[00061]. In accordance with the another embodiment of the present invention, the LHTES comprises column in form of metallic tubes passed from the interior product of the storage medium comprises:
i) containers filled with different phase change materials selected on the basis of their melting point and energy storage density, arranged in

decreasing order of the melting points of the stored phase change materials in them.
[00062]. These containers are placed in two or more parallel column.
[00063]. A valve is present at the opening of each grid and one batch are closed using valves and only one valve will be open for hot air produced in each slag granulation cycle, while the others remain closed.
[00064]. Table 1 shows the different properties of the different composition of phase change material as claimed hereafter.



[00066]. From table 1 and table 2, it clearly indicates that the new composition of PCMs have substantially higher latent heat consumption and higher energy density than the conventionally used PCMs.
[00067]. 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.
[00068]. 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.
Equivalents:
[00069].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.
[00070]. 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).
[00071].The above description does not provide specific details of the composition of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art are capable of choosing suitable manufacturing and design details.
[00072].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 methods 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.
[00073]. 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.
[00074]. 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 blended phase change material comprising Lithium nitrate as main component alongwith other components such as lithium chloride, sodium nitrate and potassium nitrate in different combinations.
2. The blended phase change material as claimed in claim 1, comprising three different combination/composition such as
i) Lithium nitrate and lithium chloride;
ii) Lithium nitrate and sodium nitrate;
iii) Lithium nitrate and potassium nitrate.


3. The blended phase change material as claimed in claim 1, wherein the first composition/combination comprises lithium nitrate at a concentration of 70-95 weight % and lithium chloride at a concentration of 5-30 weight %.
4. The blended phase change materials as claimed in claim 1, wherein the first composition/combination comprises lithium cation, nitrate ion, and chloride ion.
5. The blended phase change material as claimed in claim 1, wherein the second composition/combination comprises lithium nitrate at a concentration of 48-49 weight % and sodium nitrate at a concentration of 51-52 weight %.
6. The blended phase change material as claimed in claim 1, wherein the second composition/combination comprises lithium cation and sodium cation.
7. The blended phase change material as claimed in claim 1, wherein the third composition/combination comprises lithium nitrate at a concentration of 20-40 weight % and potassium nitrate at a concentration of 60-80 weight %.
8. The blended phase change material as claimed in claim 1, wherein the third composition/combination comprises lithium cation and potassium cation.