ENHANCEMENT IN THERMAL CONDUCTIVITY OF BIO-NANOFLUIDS

Abstract

Annexure 1 TITLE OF THE INVENTION ENHANCEMENT IN THERMAL CONDUCTIVITY OF BIO-NANOFLUIDS ABSTRACT This invention presents a method for synthesising carbon nanospheres (CNS) from various biowaste materials, including Samanea saman, Callerya atropurpurea, Magnolia champaca seed pods, Acacia auriculiformis, oil palm leaves, Caesalpinia Sapan, onion peel, and arecanut, designated as SI to S8. The synthesis focuses on optimizing zeta potential, shape, and carbon content, with CNS exhibiting zeta potentials ranging from -45.6 mV to -17.0 mV. These CNS are dispersed in propylene glycol (PG) to form nanofluids (NFs) with stability up to 45 days. The thermal conductivity of the NFs is significantly enhanced with increased zeta potential and temperature, with the SI nanofluid showing a 118% improvement over the base fluid. This invention also examines the effects of concentration and pH on zeta potential and thermal conductivity, identifying optimal performance at a pH of 8. Emphasising environmental sustainability, the method reduces hazardous chemical use and energy consumption. By optimising zeta potential, the technology improves nanoparticle dispersion and heat transfer efficiency, making it suitable for applications in automobiles, medical devices, air-cooling systems, nuclear reactors, and solar collectors. This invention offers an eco-friendly, innovative approach to enhancing the thermal properties of nanofluids. (1) Kiran Bijapur (2) Dr Gurumurthy Hegde

Specification

FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
and
THE PATENTS RULES, 2003
PROVISIONAL/COMPLETE SPECIFICATION
(See section 10 and rule 13)

TITLE OF THE INVENTION: ENHANCEMENT IN THERMAL CONDUCTIVITY OF BIONANOFLUIDS

2. APPLICANT(S)
Name Nationality Address
Christ University Indian Hosur Road,
Bengaluru -560029,
Karnataka,
India
3. PREAMBLE TO THE DESChJPTION
PROVISIONAL COMPLETE (</)
The following specification describes the invention The following specification particularly describes the
invention and the manner in which it is to be performed
25-N©v-2024/140139/202441091667/Form 2(Title Page)
4. DESCRIPTION (Description shall start from next page.)
Annexure 2
5. CLAIMS (not applicable for provisional specification. Claims should start with the preamble- "1/ We claim" on
separate page)
Annexure 3
6. DATE AND SIGNATURE (to be given at the end of last page of specification)
Date and Signature
(a) Date:
(b) Signature:
(c) Name: Kiran Bijapur
(a) Date:
(b) Signature:
(c) Name: GURUMURTHY HEGDE

7. ABSTRACT OF THE INVENTION (to be given along with complete specification on separate page)
Annexure 1

Annexure 2
TITLE OF THE INVENTION
ENHANCEMENT IN THERMAL CONDUCTIVITY OF BIO-NANOFLUIDS

DESCRIPTION

FIELD OF THE INVENTION
This invention targets the enhancement of thermal conductivity in nanofluids to improve heat transfer efficiency, especially within the automotive industry and other engineering fields. It employs carbon nanospheres derived from biomass to achieve exceptional thermal properties while maintaining environmental sustainability.

BACKGROUND OF THE INVENTION
Nanofluids are advanced heat transfer fluids created by suspending nanoparticles, typically ranging from 1 to 100 nanometers, in conventional base fluids such as water, oil, or glycol. The inclusion of these nanoparticles significantly enhances the thermal conductivity of the base K fluids, leading to improved heat transfer efficiency. This property makes nanofluids highly e valuable in various applications. In the automotive sector, nanofluids enhance the performance of cooling systems and radiators by enabling more effective heat dissipation, which helps maintain optimal engine temperatures, improve fuel efficiency, and reduce emissions. Similarly, in electronics cooling, nanofluids improve the management of heat generated by electronic components, thereby enhancing the reliability and performance of devices. In HVAC systems, they contribute to reduced energy consumption and better climate control. In contrast, in renewable energy systems, they boost the efficiency of heat transfer, aiding in more effective energy harvesting.

The use of nanofluids also supports environmental sustainability by reducing energy consumption and lowering greenhouse gas emissions. The use of biomass-derived carbon nanofluids not only enhances the Thermal conductivity but also converts waste into valuable resources. The carbon nanomaterials produced enhance the thermal conductivity of nanofluids, contributing to their efficiency and performance while promoting sustainability through reduced waste and resource recycling.

BRIEF SUMMARY OF THE INVENTION
The present invention consists of novel nano particles that efficiently increase the thermal conductivity of nanofluids: carbon nanospheres (CNS), which are synthesised from waste Samanea saman, Callerya atropurpurea, Magnolia champaca seed pods, Acacia auriculiformis. Elaeis guineensis, Caesalpinia Sapan, Allium cepa L., and Areca catechu L. This procedure is straightforward and environmentally sustainable as it uses biomass. As demonstrated by many nanoscale characterisation approaches, the resultant CNS exhibits exceptional structural and morphological features. Biomass such as Samanea saman, Callerya atropurpurea, and Magnolia champaca seed pods are abundant and often considered agricultural or industrial by-products. While they offer high carbon content, their disposal can be problematic, leading to waste accumulation and environmental issues. Similarly, Elaeis guineensis leaves, Acacia auriculiformis, and Caesalpinia Sapan are typically discarded as waste during agricultural activities. Allium cepa L., and Areca catechu L. also contribute to significant waste in food processing and agriculture. One of the primary disadvantages of these
- biomass materials is their tendency to-contribute to waste and-environmental pollution if not - properly managed. Their disposal can lead to soil and water contamination, greenhouse gas emissions, and other environmental impacts. By converting these waste materials into valuable carbon nanospheres, the present invention not only addresses the challenge of waste disposal but also transforms these materials into high-performance nanomaterials with enhanced thermal conductivity and stability.

All these selected biomasses have been found to enhance the thermophysical characteristics of nanofluids, particularly the zeta potential and TC, which are essential for effective heat transfer. Nevertheless, their potential in related applications has not yet been fully investigated. The precursors are comprised of 20-25% of hemicellulose, 34-40 % of lignin, and 50-55% of cellulose. '

This invention focuses on synthesising carbon nanospheres from various abundantly produced bio waste materials, contributing to a waste-to-wealth approach. The process is low-cost and sustainable. The synthesised nanospheres exhibit excellent zeta potential values, making them ideal for use in nanofluids to achieve improved heat transfer and enhanced stability. As described in the embodiment, thermal conductivity studies were performed on nanofluids based on biomass-derived carbon nanospheres (CNS). These nanofluids demonstrated outstanding results, with a thermal conductivity enhancement of 118% compared to their base fluid, propylene glycol (PG). This significant improvement is attributed to the high zeta potential value of the nanofluids, which ensures excellent stability. Traditional nanofluids often rely on non-renewable, synthetic nanoparticles, resulting in a significant environmental footprint and higher production costs due to expensive raw materials and complex manufacturing processes. Traditional coolants often face challenges related to stability, particularly when it comes to their long-term performance in various engineering applications. These conventional coolants can suffer from issues like sedimentation, phase separation, and degradation over time, which can significantly impact their effectiveness and reduce their thermal conductivity. These problems arise because traditional coolants may lack the necessary chemical and physical properties to maintain a uniform dispersion of particles, leading to instability during extended use. In contrast, biomass-derived carbon nanospheres offer a superior alternative with inherently high zeta potential, ensuring exceptional stability in nanofluids. This high zeta potential prevents particle agglomeration, maintaining a consistent, homogeneous mixture and enhanced thermal conductivity.

Furthermore, the invention encompasses the evolution of various parameters such as the preparation technique, zeta potential, concentration, temperature, measurement time, and viscosity. The nanofluids achieved a uniform and stable suspension in propylene glycol by effectively employing the two-step method. Comprehensive analysis revealed that thermal conductivity was significantly affected by both the zeta potential and temperature of the nanofluids. The experiments, conducted at various temperatures ranging from 30 to 80°C, revealed that the nanofluid with the highest zeta potential nanoparticle, S1, had a zeta potential value of -45.6 mV and demonstrated a maximum thermal conductivity enhancement of 118%. In contrast, nanofluids with zeta potentials ranging from -33.7 to -17.0 mV showed enhancements between 109% and 59%, respectively. These results indicate that both zeta potential and temperature significantly influence the thermal conductivity of nanofluids.

This invention also explores the impact of pH on the thermal conductivity ratio, determining the optimal pH for enhanced heat transfer. Additionally, the selection of measurement time was carefully considered to ensure accurate results. The nanofluid also exhibited satisfactory viscosity, requiring low pumping power, a crucial parameter for various engineering applications. Overall, this invention provides a sustainable and effective method for enhancing the thermal conductivity of nanofluids in diverse heat transfer applications. It has substantial potential for industrial-scale use and tackles the environmental issues related to traditional nanofluids.

CLAIM
We claim,
1. A method comprising of synthesising carbon nanospheres from biomass-based precursors wherein

biomass-based precursor is obtained from the eight different wastes namely Samanea saman, Callerya atropurpurea, Magnolia champaca seed pods, Acacia auriculiformis, oil palm leaves, Caesalpinia Sapan, onion peel, and arecanut and these precursors are labelled as SI to S8.

The procedure for synthesizing carbon nanospheres from precursors SI to S8 involves removing the biomass or biowaste material from the plant, washing it, and then drying it in the sun to remove moisture and create a dried substance.

After drying, the material is ground and passed through a vibratory sieve shaker equipped with a 35-250 pm mesh to obtain a fine powder.

This powder undergoes pyrolysis in a quartz tube furnace with a continuous nitrogen gas flow at approximately 700-900 °C, resulting in a carbon residue.

The carbon residue is then washed with a 0.1 M HC1 solution and neutralized using distilled water. Following this, the material is dried at temperatures between 50 and 100 °C, forming spherical carbon nanoparticles.

These spherical carbon nanoparticles are then used to prepare nanofluids, making them suitable for the intended applications.

2. Claim 1 asserts that the method ensures the production of carbon nanoparticles with a uniform spherical shape and nano size. These nanoparticles exhibit their negative zeta potential values ranging from -45.6 to -17.0 mV for the samples SI to S8, respectively, signifying stability, crucial for enhancing the thermal conductivity of nanofluids. Additionally, a desirable surface area of 120 to 506 m2/g.

3. Claim 1 describes a method for enhancing the thermal conductivity and stability of nanofluids using biomass-derived carbon nanospheres. These nanospheres are synthesised from biomass precursors SI to S8 and are utilized as nano coolants,

4. In claim 1, a method for enhancing the thermal conductivity of nanofluids, comprising the use of carbon nanospheres with zeta potentials ranging from -45.6 to -17.0 mV, wherein the nanofluid exhibits a thermal conductivity enhancement of 118% to 50% compared to a base fluid of propylene glycol, indicating that the nanofluid is stable and possesses high thermal conductivity.

5. In claim 1, the nanofluid composition comprising nanoparticles with a zeta potential of approximately -45.6 mV, wherein the nanofluid demonstrates stability for a period of up to 40 days post-preparation, and wherein the stability is characterized by minimal change in nanoparticle size and consistent dispersion without significant aggregation over the 40-day period.

6. In claim 1, the method specifies that nanofluid exhibits excellent viscosity characteristics with low pumping power requirements. Nanofluids containing a concentration of 0.1 wt% demonstrate a viscosity of 0.002102 mPas

7. The method, as described in claim 1, wherein the experiment is conducted with the base fluid across a range of pH values from 2 to 12 to evaluate the thermal conductivity ratio and wherein the base fluid with a pH of 8 exhibits a significant enhancement in thermal conductivity ratio compared to other pH levels. Which minimizes agglomeration and enhances heat transfer efficiency by increasing the effective surface area for thermal interactions.

8. The method, as described in claim 1, wherein the experiment is conducted to investigate the effect of concentration on zeta potential, and wherein it is observed that as the concentration of the carbon nanospheres increases from 0.01 wt% to 0.5 wt%, the zeta potential decreases from -31.7 mV to -22 mV, indicating a reduction in electrostatic stability with increasing concentration.

BRIEF DESCRIPTION OF THE DRAWINGS
Carbon nanosphere synthesis can be effectively achieved through pyrolysis, which is carried out in an atmosphere of nitrogen (N2). To synthesize uniformly spherical nanoparticles, this process involves exposing carbon-rich precursors to high temperatures in the absence of oxygen. The inert N2 atmosphere prevents oxidation, ensuring the purity and stability of the resulting carbon nanospheres. This controlled environment allows for precise regulation of particle size, shape and composition, making pyrolysis in nitrogen a preferred method for customising the synthesis of carbon nanospheres with specific properties. FESEM images of the carbon nanospheres synthesized at temperatures between 700°C and 900°C were analyzed using a Thermo Scientific Apreo 2 S. X-ray diffraction (XRD) patterns obtained with the MiniFlex 600 from Rigaku Corporation were used to evaluate the crystallinity of the CNSs. The XRD patterns displayed two theta values at 23° (0 0 2) and 41° (1 0 0), confirming the presence of carbon nanospheres as previously reported. The Fourier Transform Infrared Spectroscopy (FTIR) method, utilizing an IR Spirit-L from Shimadzu, was employed to identify accessible functional groups in pyrolysed CNSs. The FTIR analysis indicated the presence of carbonization-related functional groups. The HOT DISK thermal analyser determines a nanofluid's thermal conductivity. The viscosity of the nanofluid is measured by the discovery of a hybrid rheometer (DHR-3, USA).

The invention will be detailed and elucidated with the aid of the accompanying drawings, in which:
Figure 1: FSEM images of all the samples from SI to S8 at different temperatures of 800 °C
Figure 2: a) XRD pattern and b) Raman pattern of all the samples from SI to S8.
Figure 3: FTIR Spectrum of the Carbon nanosphere of sample SI.
Figure 4: Zeta potential values of S1 to S8
Figure 5: EDS Spectra of samples SI to S8
Figure 6: Thermal conductivity enhancement in bio-nanofluids measured at different time intervals.
Figure 7: The plot of mean number percentage as a function of particle size on the different time periods of 0,10,20,30 and 40 days
Figure 8: Effect of zeta potential and temperature on the thermal conductivity of nanofluid Figure 9: Effect of pH on thermal conductivity
Figure 10: Effect of concentration on zeta potential.
Figure 11: Effect of temperature on nanofluid viscosity at various weight concentrations (0.01, 0.02, 0.05 and 0.1 wt% at a temperature from 30 °C to 90 °C).

DETAILED DESCRIPTION
This invention presents a novel technique for significantly enhancing the thermal conductivity of sustainable nanofluids. These nanofluids are developed using carbon nanospheres from different biowaste (SI to S8). The method employs pyrolysis, which begins with moisture evaporation at approximately l00°C and progresses through the rapid decomposition of hemicellulose between 220°C and 315 °C. Lignin undergoes pyrolysis over a broad temperature range, while cellulose primarily decomposes between 315°C and 400°C. During carbonization, volatile compounds such as CO2, CFL, and CO, along with various organic molecules, are released. The remaining residue predominantly consists of carbon.

The nanoparticles for this experiment were synthesized through an eco-friendly process at temperatures between 700 °C and 900 °C. When these nanoparticles were dispersed in the base fluid, propylene glycol, they exhibited impressive thermophysical properties. Notably, the thermal conductivity improved as the zeta potential of the nanoparticles increased.

The zeta potential of the nanoparticles is influenced by both thermal conductivity and temperature. The nanofluid with the highest zeta potential of -45.6 mV exhibited a thermal conductivity ranging from 0.2102 W/mK to 0.4584 W/mK. As the pH of the nanofluid increased, the thermal conductivity ratio improved up to a pH of 8, beyond which it began to decline. The zeta potential was significantly affected by the concentration of nanoparticles; as the concentration increased, the zeta potential decreased. Additionally, viscosity measurements were conducted at temperatures ranging from 30°C to 90°C, showing a decrease in viscosity from 0.015648 mPa s to 0.002102 mPas.

In summary, carbon nanospheres produced from various types of biowaste (SI to S8) significantly enhance the thermal conductivity of nano fluids while reducing their viscosity. This sustainable synthesis approach, which uses agricultural waste, underscores the technology's cost-effectiveness and environmental benefits. The research also demonstrates that the prepared nanofluids exhibit good stability due to their high zeta potential. Although the current nanofluids show notable improvements in both thermal conductivity and viscosity. Ongoing research in this area is anticipated to lead to advancements in heat transfer applications, offering scalable and eco-friendly solutions to challenges in thermal enhancement.

From a commercial perspective, the feasibility of these nanoparticles is particularly notable due to their cost-effective production compared to commercially available carbon nanoparticles. Producing about 1 kg of these carbon nanoparticles typically requires just one cylinder of nitrogen, costing around 2000 INR. Additionally, the cost of biomass-derived carbon nanoparticles ranges from 50 to 60 INR per gram. Considering that propylene glycol costs approximately 85 INR per liter. This economical combination makes propylene glycol-
based nanofluids a highly competitive option for industries seeking efficient thermal enhancement solutions.

PERFORMANCE EVALUATION
The efficacy of the Allium Saliva peel-derived carbon nanospheres (CNS) as a Nano coolant with dispersion of propylene glycol is evaluated under various conditions.

1. Selection of measurement time to achieve high thermal conductivity.
The evaluation aimed to optimize measurement time for better thermal conductivity performance by varying durations from 2.5 to 10 seconds with a heating power ranging from 20 to 90 mW. The findings revealed that longer durations resulted in higher temperature increases in the sensor, affecting thermal transport properties. Measurements taken over shorter durations exhibited better thermal conductivities compared to those with longer measurement times. Extended measurement times led to excessively high or low-temperature increments, risking sensor damage and reduced thermal conductivity. Additionally, longer measurement times were associated with heat dispersion into the surrounding air, which could lead to measurement errors.

2. Time-Dependent Size Evolution in Nanofluids and Aggregation
Dynamic Light Scattering (DLS) was used to evaluate the stability of the nanofluids by tracking the average nanoparticle size over 40 days. The nanofluids, synthesized without surfactants, showed no agglomeration or significant size changes at ten-day intervals (0, 10, 20, 30, and 40 days). The consistent average particle size, as shown in Figure X for sample SI (0.1 wt% concentration, zeta potential -45.6 mV), confirms the exceptional long-term stability of the nanofluids, making them suitable for applications requiring reliable performance over extended periods.

3. Effect of zeta potential and temperature on thermal conductivity.
The nanofluid was prepared using nanoparticles with a zeta potential ranging from - 45.6 mV to -17.0 mV, and the thermal conductivity measurements were conducted at temperatures ranging from 20°C to 80°C. The nanofluid with the highest zeta potential exhibited a thermal conductivity enhancement of 118% compared to the base fluid at 80°C. This enhancement is due to the high electrical repulsive force on the nanoparticle surface, which stabilises the nanofluid and leads to increased thermal conductivity. As the temperature increased, the thermal conductivity also increased, which can be attributed to the higher Brownian motion of nanoparticles at elevated temperatures.

4. Effect of concentration on zeta potential.
The evaluation investigated the influence of nanoparticle concentration on the zeta potential in a nanofluid system. Nanofluids were prepared with concentrations ranging from 0.001 to 0.5 wt%. The results indicated a decrease in zeta potential with increasing nanoparticle concentration. Specifically, the zeta potential remained stable at -30.9 mV up to a concentration of 0.1 wt%. Beyond this threshold, a marked reduction in zeta potential was observed, declining to -22.0 mV. This phenomenon is attributed to the aggregation of nanoparticles at higher concentrations, which impedes surface charge and diminishes the repulsive forces among nanoparticles within the suspension.

5. Effect of pH on thermal conductivity ratio
The present invention relates to an investigation of how the pH of a nano fluid affects the thermal conductivity of the system. The evaluation was conducted with pH values ranging from 3 to 12. The results demonstrate that at lower pH levels, the zeta potential of the nanoparticles is reduced, leading to insufficient electrostatic repulsion between the particles to counteract the attractive forces between the molecules, thereby resulting in poor dispersion stability. As the pH increases, the absolute value of the zeta potential on the nanoparticle surfaces increases, enhancing the electrostatic repulsion forces between the particles. This repulsion prevents particle attraction and collision due to Brownian motion, leading to an increase in the thermal conductivity ratio up to a certain pH value, defined as the isoelectric point. Beyond this pH, further increases result in stronger electrostatic forces that increase the inter-particle distance, exceeding the hydrogen bonding range and thereby reducing the probability of particle coagulation and settling. Consequently, this causes a decrease in the thermal conductivity ratio.

6. Effect of temperature on viscosity of nanofluid
The present invention relates to an investigation of the effect of temperature on the viscosity of nanofluids. The findings demonstrate that, as the temperature increases, the viscosity of the nanofluid decreases due to weakened molecular adhesion and diminished intermolecular forces. Higher concentrations of nanoparticles result in an increase in viscosity; for example, a nanofluid with 0.1 wt% exhibited a viscosity of 0.01526 mPa s at 30°C, which decreased to 0.002176 mPas at a temperature of 90°C. This decrease in viscosity may be attributed to heightened resistance from the base fluid molecules and the larger surface area of CNS nanoparticles. Furthermore, the increase in viscosity caused by higher nanoparticle concentrations is less significant at elevated temperatures, possibly due to greater molecular separation within the base fluid. At higher temperatures, the reduction in viscosity may also be influenced by changes in the zeta potential. As the temperature rises, the zeta potential often _ decreases, thereby reducing the electrostatic repulsion between nanoparticles. This decrease in repulsion allows the nanoparticles to move more freely, resulting in
reduced viscosity due to decreased resistance to flow.

Based on the inventive aspects of the present invention described above, we submit the following technical differences between the present invention and the cited prior art document.

Al: 201741023910
The referenced prior art Al focuses on synthesizing carbon nanomaterials from Lablab
purpureus seeds, resulting in a yield of approximately 22% porous carbon nanospheres
through pyrolysis. Our investigation surpasses this yield significantly, achieving 35% or more. Additionally, the biomass used in our method is more accessible than Lablab purpureus seeds, enhancing the practicality and scalability of our approach. While Al explores applications in supercapacitors, our invention directs its efforts toward harnessing the high thermal conductivity of nanofluids. Our novel technique not only achieves superior yields but also synthesizes nanoparticles with high zeta potential values, ensuring exceptional stability. This unique approach highlights the versatility and broader potential of our carbon nanomaterials, particularly in improving heat transfer applications, setting it apart from the prior art.

A2:202041021336
In contrast to prior art A2, which explores carbon nanospheres derived from biowaste for supercapacitor applications, our invention represents a notable advancement by utilizing nanoparticles synthesised from eight different biowaste sources with varying lignocellulosic contents. While A2 focuses on energy storage, our research innovates in the development of stable nanofluids with enhanced thermal conductivity.
Additionally, we achieved high zeta potential values for the nanoparticles, ensuring their stability in the nanofluids. This approach not only improves heat transfer efficiency in engineering applications, such as automotive cooling systems but also broadens the scope of biowaste-derived carbon materials. Our invention thus provides a distinct and impactful advancement over the prior art in both application and
performance.

A3:202411057791
Prior art A3 introduces a nanofluid comprising magnetically active gold nanoparticles to enhance thermal conductivity, but this method is costly and suffers from stability issues, leading to nanoparticle aggregation over time. In contrast, our invention synthesizes carbon nanospheres from biowaste, which is economically viable and
sustainable. Our approach not only significantly reduces production costs but also produces highly stable nanoparticles with high zeta potential values, ensuring longterm stability and preventing aggregation. Furthermore, while A3 relies on expensive precious metals, our method repurposes waste materials, enhancing both economic and environmental sustainability. Thus, our invention provides a more cost-effective, stable, and sustainable solution for improving thermal conductivity compared to the prior art.

A4: 202041028668
Prior art A4 introduces a hybrid nanofluid composed of AhCh-SiC nanoparticles designed to enhance thermal conductivity in heat exchanges for steam power plants, achieving a thermal efficiency of 23%. However, this prior art does not address the stability of the nanofluid. In contrast, our invention involves the synthesis of carbon nanospheres from biowaste, which not only provides a more sustainable and cost- effective material but also ensures long-lasting stability with high zeta potential values. Additionally, our nanofluid demonstrates a significant improvement in thermal conductivity, achieving an enhancement of up to 118% compared to the base fluid. This substantial performance boost, combined with superior stability, highlights the advantages of our invention over A4, making it a more effective and reliable solution for thermal conductivity enhancement.

A5:202441048685
Prior Art A5, which utilises metal oxide nanoparticles (AI2O3) and surfactants to get stable dispersion and heat transfer enhancement, our invention presents a more environmentally friendly and cost-effective solution. A5 is_ the use of metal nanoparticles, which are harmful to the environment also increase the cost, limiting their commercial viability. Additionally, the incorporation of surfactants in A5 can obstruct heat transfer pathways, potentially reducing the thermal conductivity of the nanofluids. Our invention addresses these issues by synthesizing nanoparticles from biomass, eliminating the need for harmful metals and surfactants. The synthesized nanoparticles exhibit excellent zeta potential, indicating inherent stability without the addition of external dispersants. This simplifies the preparation process and ensures better heat transfer performance, making our approach both commercially feasible and environmentally sustainable.

A6: 201941054670
In comparison to Prior Art A6, which prepares a bio-based nanofluid using plant extract combined with carbon nanotubes and various chemical derivatives like AI2O3, NaCuHwSCh, CH3SOCH3, TiCh, and ZnSCU, our approach offers significant improvements in both environmental sustainability and commercial feasibility. A6's use of multiple chemical derivatives and carbon nanotubes complicates the synthesis process and introduces environmental concerns, making it less commercially viable. In contrast, our research simplifies the process by synthesising nanoparticles from biomass without harmful chemicals or surfactants. The nanoparticles demonstrate excellent stability due to their high zeta potential, eliminating the need for additional stabilising agents. This makes our method not only easier to produce but also eco-
friendlier and more cost-effective, offering a better solution for commercial application

REFERENCES
Al: Application Number- 201741023910; Application type- Ordinary Application; Title of Invention-METHOD FOR SYNTHESIZING CARBON NANOMATERIAL; Applicant Name- BMS College of Engineering; Field of Invention- PHYSICS.
A2: Application Number- 202041021336; Application type- Ordinary Application; SUPERCAPACITOR PREPARED FORM A BIOMASS DERIVED CARBON NANOSPHER; Applicant Name- BMS College of Engineering; Field of Invention- CHEMICAL.
A3: Application Number- 202411057791; Application type- Ordinary Application; Title of Invention- UTILIZING GOLD NANOFLUID FOR IMPROVED HEAT TRANSFER IN ENGINEERING AND INDUSTRIAL APPLICATIONS; Applicant Name- University of Engineering & Management (UEM); Field of Invention- MECHANICAL ENGINEERING.
A4: Application Number-202041028668; Application type- Ordinary Application; Title of Invention- ENHANCING THE HEAT TRANSFER RATE OF SPECIALLY DESIGNED SHELL AND TUBE HEAT EXCHANGER BY PROVIDING DIMPLED SURFACE ALONG WITH HYBRID NANOFLUID; Applicant Name- Selvan P; Field of Invention- MECHANICAL ENGINEERING.
A5: Application Number- 202441048685; Application type- Ordinary Application; Title of Invention- HEAT TRANSFER ENHANCEMENT USING SISAL WATER NANOFLUID WITH METAL OXIDE NANOPARTICLES; Applicant Name- Dr. V. ABH1LASH; Field of Invention- CHEMICAL.
A6: Application Number- 201941054670; Application type- Ordinary Application; Title of Invention- BIO-BASED NANOFLUID HEAT TRANSFER MEDIUM; Applicant Name- DINESH KUMAR S; Field of Invention- CHEMICAL.

Annexure3

TITLE OF THE INVENTION
ENHANCEMENT IN THERMAL CONDUCTIVITY OF BIO-NANOFLUIDS

CLAIMS
We claim,
1. A method comprising of synthesising carbon nanospheres from biomass-based precursors wherein

biomass-based precursor is obtained from the eight different wastes namely Samanea saman, Callerya atropurpurea, Magnolia champaca seed pods, Acacia auriculiformis, oil palm leaves, Caesalpinia Sapan, onion peel, and arecanut and these precursors are labelled as SI to S8.

The procedure for synthesizing carbon nanospheres from precursors SI to S8 involves removing the biomass or biowaste material from the plant, washing it, and then drying it in the sun to remove moisture and create a dried substance.

After drying, the material is ground and passed through a vibratory sieve shaker equipped with a 35-250 pm mesh to obtain a fine powder.

This powder undergoes pyrolysis in a quartz tube furnace with a continuous nitrogen gas flow at approximately 700-900 °C, resulting in a carbon residue.

The carbon residue is then washed with a 0.1 M HC1 solution and neutralised using distilled water.
Following this, the material is dried at temperatures between 50 and 100 °C, forming spherical carbon nanoparticles.

These spherical carbon nanoparticles are then used to prepare nanofluids, making them suitable for the intended applications.

2. Claim 1 asserts that the method ensures the production of carbon nanoparticles with a uniform spherical shape and nano size. These nanoparticles exhibit their negative zeta potential values ranging from -45.6 to -17.0 mV for the samples SI to S8, respectively, signifying stability, crucial for enhancing the thermal conductivity of nanofluids. Additionally, a desirable surface area of 120 to 506 m2 3/g.

3. Claim 1 describes a method for enhancing the thermal conductivity and stability of
nanofluids using biomass-derived carbon nanospheres. These nanospheres are synthesised

from biomass precursors SI to S8 and are utilized as nano coolants.

4. In claim 1, a method for enhancing the thermal conductivity of nanofluids, comprising the
use of carbon nanospheres with zeta potentials ranging from -45.6 to -17.0 mV, wherein the
nanofluid exhibits a thermal conductivity enhancement of 118% to 50% compared to a base
fluid of propylene glycol, indicating that the nanofluid is stable and possesses high thermal
conductivity.

5. In claim 1, the nanofluid composition comprising nanoparticles with a zeta potential of
approximately -45.6 mV, wherein the nanofluid demonstrates stability for a period of up to
40 days post-preparation, and wherein the stability is characterized by minimal change in
nanoparticle size and consistent dispersion without significant aggregation over the 40-day
period.

6. In claim 1, the method specifies that nanoparticles with a small'size ranging from 25 nm to 136 nm exhibit excellent viscosity characteristics with low pumping power requirements. Nanofluids containing a concentration of 0.1 wt% demonstrate a viscosity of 0.006478
mPa-s

7. The method, as described in claim 1, wherein the experiment is conducted with the base fluid across a range of pH values from 2 to 12 to evaluate the thermal conductivity ratio and
wherein the base fluid with a pH of 8 exhibits a significant enhancement in thermal conductivity ratio compared to other pH levels. Which minimizes agglomeration and enhances heat transfer efficiency by increasing the effective surface area for thermal interactions.

8. The method, as described in claim 1, wherein the experiment is conducted to investigate the
effect of concentration on zeta potential, and wherein it is observed that as the concentration
of the carbon nanospheres increases from 0.01 wt% to 0.5 wt%, the zeta potential decreases
from -31.7 mV to -22 mV, indicating a reduction in electrostatic stability with increasing
concentration.

(1) Kiran Bijapur (2) Dr Gurumurthy Hegde

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