Optimizing Droplet Condensation for Eco-Friendly Cooling: Experimental and CFD Validation

doi:10.21203/rs.3.rs-4908406/v1

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Optimizing Droplet Condensation for Eco-Friendly Cooling: Experimental and CFD Validation

https://doi.org/10.21203/rs.3.rs-4908406/v1

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This study presents a novel cooling system that combines optimum droplet condensation and thermoelectric cooling to reduce energy consumption and environmental impact. With an amalgamation of conventional cooling models, the research adds a new form of nozzle and diffuser layout that increases droplet formation and cooling efficiency. The efficiency of the system was confirmed by experimental tests and modern CFD analysis that proved a 20% enhancement of cooling with a 15% energy saving compared to traditional techniques. The hybrid technique helps the cooler to be environmentally friendly and at the same time points out the possibilities of using the system in high-risk areas like data centers and pharmaceutical facilities. This helps in the development of sustainable cooling technology which goes a long way in providing industries with a probable solution to improving their sustainability and at the same time achieving better performance.

Eco-Friendly Cooling

Environmental-Friendly

CFD Simulation

Droplet Condensation

Energy

Dehumidifiers

Today’s advancing technologies require the best green solutions due to the constantly increasing awareness and an active fight against climate change and environmental pollution (Bradu et al., 2023). HVAC systems which serve as necessities for industries, homes, etc., are major functioning consumers of energy and polluters of the environment. Traditional cooling methods particularly those used in offices involve using huge power-consuming equipment with refrigerants that help in the destruction of the environment.

Researchers and engineers have been designing new ways to introduce green cooling systems to overcome those challenges. From these, the creation of a comprehensive environmental model for droplet condensation in moist air has been recognized as the possible solution. Condensation is the change of phase from water vapor to droplets when cooled and the droplets can help in heat dissipation like dew on plants or fog in the atmosphere (Kumar et al., 2023). Compared to droplet condensation which has garnered interest in recent years as a sustainable cooling technique, the simulation tools used to analyze these systems of have been fairly rudimentary. This research uses state-of-the-art CFD simulation with machine learning to improve the forecast of condensation characteristics under different climate conditions. Through the inclusion of these advanced approaches, this scholar’s study aims to advance the current knowledge as well as the use of droplet condensation in energy-efficient cooling technologies. Droplet condensation has been researched in conventional HVAC systems, nevertheless, its application in sectors such as data centers and pharmaceutical storage or renewable energy facilities is still underutilized. Besides, this study not only advances the design of droplet condensation cooling systems but also explores their viability in supporting the cooling needs of complicated environments, such as data centers, which can be extreme in terms of temperature and humidity requirements for dependable operations.

The specific objectives of this work are as follows: Therefore, the proposed model shall improve the efficiency and use of natural means of cooling, making the systems environmentally friendly. The primary objectives of this research are to:

Tune and fine-tune nozzles and diffusers to affect the most droplet condensation.

Carry out empirical/ experimental research to support the developed theory/model.

The energy consumption as well as the pollution potential of the new system should be compared to that of traditional dehumidifiers.

Through addressing these objectives, this study aims at making the Author’s intended contributions to the development of sustainable cooling technologies a better approach as compared to the conventional techniques and hence promote solutions for combating climate change as cemented globally. New in the past years, condensation by droplets has been proven to be one of the environmentally sound ways of cooling. However, it was observed here that the design of the nozzle and diffuser greatly influenced the condensation efficiency. This research proposes a modification of the geometric layout of the nozzle and diffuser which is intended to greatly improve droplet generation and cooling rates. This innovative design is inserted in the study to fill the gap left between the present models and the necessity for more efficient cooling systems in many industries.

The article is structured as follows: In Section 2, the Literature Review is included which focuses on prior works on eco-friendly cooling systems, droplet condensation, and CFD simulation studies. Section 3 is Methodology, it explains the experimental framework, the simulation model, and data gathering. Section 4 is devoted to the Results where the comparison of the experimental and simulation results is provided; outlet velocity, relative humidity, and pressure distribution are viewed as the key parameters. Section 5 is devoted to the Discussion where the authenticity of the system is evaluated, a detailed explanation of discrepancies is provided, and the model’s correctness is proved. The final Section 6 is devoted to the Conclusion and Future Work where major findings are reviewed and guidance on further study and the improvement of the cooling system is provided.

With the most recent improvements in the field, the views taken concerning cooling systems have tended to be inclined more toward reliability on sustainable sources of power. Of these, droplet condensation has been at the forefront for green cooling systems solutions. A literature survey presentation on the subject of droplet condensation and its efficiency for the development of sustainable cool technology is presented in this segment.

The study by Baghel et al., 2020 found the solution of the integrated environmental model in droplet condensation in moist air. Their research elaborated on the path of how fluid droplets condense and created a model for predictive changes which was inherent in the condensation process. The validity and applicability of their statistical model were further confirmed via their evaluation of the simulation and laboratory test results and referenced by Pachouri et al., 2024, and the subsequent investigation of other feasible practical droplet condensation-based cooling systems began from this foundation.

Thompson, 2021, compared different techniques of domestic cooling, with an emphasis placed on the aspects concerning condensation-based methods. These technologies identified the performance, energy efficiency, and environmental performance of the above technologies in which, the authors concluded that this type of cooling was more effective and environmentally friendly as compared to conventional cooling. It stressed the requirement for the continual assessment of these systems at different phases in the life cycle to create a net total positive impact on the environment. In the area of sustainable cooling systems, Abdullah et al., 2023 deepened the evaluation of condensation-based cooling, thermoelectric cooling, evaporative cooling, and other ones. They also emphasized the fact that one should also consider the life cycle assessments, and additionally carry out the environmental assessments when choosing the cooling systems. This allowed them to outline large research areas in the formation of numerical models for condensation on droplets in moist air and state the need for financing this promising direction.

Ayou and Coronas, 2020 described a strategy for the use of droplet condensation for green cooling in practice. They recommended a more efficient cooling system using droplet condensation, and they applied their design and performed experiments with it and evaluations to show the result. The recommendations they came up with implied that such systems could act as renewable sources of cooling in several industries. Shi et al., 2023 studied the cost-effectiveness and reality of implementing sustainable cooling systems for commercial building applications. Their study compared the one-time and fixed costs with operating and maintenance costs over some time to show the economic viability of sustainable cooling systems while having a lesser impact on the environment. Therefore, this particular case study helped persuade organizations to implement green cooling technologies while taking the costs and benefits, as well as the effects on the environment, into account. In a publication from Galindo et al., 2023, the authors estimated the performance of an ecological model in describing droplet condensation in moist air. They used the experimental and simulation methods that gave strong support to the model. The author's testing and the comparisons of the obtained results to the simulation results go a long way proving the reliability of the implemented model. This validated model has the potential of providing and improving green cooling systems hence being able to provide actual and efficient solutions.

Based on the reviewed literature, droplet condensation could be regarded as a sustainable method of cooling. The establishment of proper predictive models and their verification by proper experimentation is one step closer to the fine-tuning of these unions. Moreover, risks are present in other aspects of the project, including tricky organizational structures and deep hints at flaws in the engineering concepts of the project that place it in contradiction with other economic and environmental benefits that are tied to such technologies to consider its relevance in the global climate challenges. Integrating the two types has been studied in recent work to achieve enhancement of efficiency as well as environmental friendliness of cooling systems. In the absence of prior investigations that analyze the enhancement of droplet condensation with thermoelectric cooling. This research attempts to plug this gap through a proposed hybrid system that incorporates both these technologies – as a more effective means of cooling as compared to other current techniques.

Experimental Setup

Based on the objectives, this study aims to determine the performance of a recently developed environmentally conscious cooling system using experimentation and simulation. The rationale is to establish a systematic environmental model of droplet condensation in moist air as the primary goal. The design of the experimental setup was such that it was aimed at providing a validation study of the cooling system and also an integrity check under actual conditions as would be there in a data center. They involved modification of the parameter to incorporate high heat output and the need to monitor temperature in such areas closely. The CFD simulations of the cooling system were also made according to specific settings for situations where conventional cooling cannot be effective or can only be partially implemented, for instance, in offshore wind farms or chilled industry cold storage pharmaceuticals.

In the context of this study, Fig. 1 captures a schematic diagram of the experiment that was conducted to test the eco-friendly cooling system. The elements of the diagram are the nozzle and diffuser sectors, the airflow direction, temperature, humidity, velocity markers, and cooling water inputs and outputs. There is also a pressure gauge which makes a showing of the pressure of internal nature in the system. Such imaginary lines delimit the area of experimentation of the variables in the process.

Materials

The materials used for the experiment include:

Nozzles: Built and crafted through epoxy polymer resin, giving a smooth texture, and roughness of not more than 10 micrometres.
Diffusers: Used to actively increase the effectiveness of the condensation process through the right flow rates.
Measurement Instruments: Temperature, air velocity, and humidity, were measured at the inlet and outlet points, and required instruments included temperature sensors, anemometers, and hygrometers respectively.

Hybrid System Design

To combine the advantages of droplet condensation with those of thermoelectric cooling, the use of a combined system was studied and implemented. Part of the system is a thermoelectric cooler based on the Peltier effect with high accuracy of temperature regulation and a droplet condensation chamber to extract the maximum amount of heat in the latent state. The hybrid system was designed to work in various modes the modes permit the technologies to work synergistically or singularly depending on the conditions. Their design was meant to improve the level of energy efficiency and cooling efficiency.

Procedure

Design and Fabrication: The nozzle and diffuser are specifically intended to enable high droplet condensation. The entry area of the nozzle was 0.4m while the throat area was 0.1m. In this work, a new geometrical configuration of the nozzle and diffuser used in experiments has been employed, which has not been studied before. The nozzle has an aspherical surface that causes an improvement in droplet formation by having a larger surface area to accommodate condensation. Furthermore, the diffuser also contains a dual functionality that enhances the flow rate while at the same time increasing the droplet dispersion resulting in enhanced cooling. This new approach to the design should prove to offer real enhancement over other standard systems.

Experimental Trials: Three sets of trials were carried out with the different inlet conditions as stated below.

Test 1: Inlet temperature of 20, OSHA 30135266 4°C, the temperature was 11°C with a wind speed of 1.9 m/s and relative humidity of 53%.
Test 2: Inlet temperature of 20°C, the wind speed is 3 m/s, and relative humidity is 78%.
Test 3: Inlet temperature of 20°C, the speed of the wind is 1.5 m/s and the relative humidity is 92%.

Data Collection: Outlet temperature, velocity, relative humidity, and pressure drop were recorded at the outlet. These were utilized to confirm the simulation models, which were derived from the following data.

Figure 2 is a detailed arrangement of the nozzle and diffuser along with airflow direction, internal flow passage, and position of sensors. The gradient effects for this system represent the pressure as well as the velocity of the system.

Simulation Model

Simulations in the present study were performed using flow analysis software namely SolidWorks Flow Simulation 2016 under the category of Computational Fluid Dynamics (CFD). All of the simulations were designed to mimic the experiment and demonstrate the conditions in which the environmental model for droplet condensation will occur. In the simulation phase of this study, a high-end approach that is CFD coupled with the machine learning algorithm was applied. This mixed approach made it possible to predict the behavior of droplets in their condensation processes under various environmental conditions; such as those that are very high and very low notch, which would normally require huge resources as in traditional CFD. The machine learning component of the process was trained on the experimental data to allow the model to be refined iteratively. This approach gave more comprehensive and realistic testing to the cooling system – the benefits of using the eco-friendly approach were as a result understood better.

Model Setup: In each simulation, the geometrical model of the nozzle and diffuser was a detailed 3-dimensional model. To ensure a proper simulation of the experimental inlet parameters the boundary conditions were defined.

Simulation Runs: The simulations were deemed as the experimental conditions that were run for the experimental trials. Thus, the outlet parameters were calculated and the obtained values were compared with the experimental results.

Figure 3 graphically shows the configuration of CFD simulation with the nozzle and diffuser, initial and final conditions, together with the computational domain, and areas of refined meshes.

Data Analysis

The post-test and simulation outcomes were evaluated to comprehend the efficiency of the cooling system. Examples of them were outlet velocity, relative humidity, pressure drop, and others. Differences between experimental and simulated values were determined with the view of having an idea of how the model can be improved.

Outlet Velocity: The measured velocities for the three tests were 10.13, 7.4 m/s, and 7.2 m/s, for sample 1, sample 2, and sample 3 respectively. The level brought a few percent overestimations accompanied by errors of 1.03 m/s, 0.51 m/s, and 1.85 m/s.

Relative Humidity: The relative humidity at the outlet did not change much between the two tests, but there are simulation errors of about 2.65%, 5.90%, and 2.60%.

Pressure Drop: The pressure drops across the system revealed certain deviations concerning the simulation having − 15.0 Pa, 1.0 Pa, and 12.0 Pa.

Figure 4 presents two plots, one that compares the outlet velocities of experimental and the simulation data of three tests with a few variations between them, and the second that compares the relative humidity, and there is a good resemblance between experimental and simulated data specifically in Test 3.

Energy Consumption Analysis

An energy audit was also done to establish the difference and efficiency between the green cooling system and the dehumidifiers normally used. The investigation also established that the new system used far less power than the previous system, at a higher flow rate.

figure 5 illustrates energy consumption between the cooling system and the conventional dehumidifier under four different load inputs and the difference in energy consumption between them proves the superiority of the proposed system for energy-efficient humidity removal.

Experimental Results

Experimental tests of the environmentally friendly cooling system were carried out based on regime indicators such as the outlet velocity, relative humidity, and pressure drop. The experiment found that through the new geometric design of the nozzle and diffuser, there was a significant improvement in the formation of droplets and cooling. As a result of the novelty of the configuration, the design provided a 15% increase in the outlet velocity coupled with a decrease in energy by 10%. Hence, these results confirm the efficiency of the design and propose the idea that it could be used for further manufacturing industries, replacing conventional coolants with a more effective material. The experimental reading results obtained from three trials are given in Table 1.

Table 1

Experimental Results for Outlet Parameters
Test	Inlet Temperature (°C)	Inlet Velocity (m/s)	Inlet Relative Humidity (%)	Outlet Velocity (m/s)	Outlet Relative Humidity (%)	Pressure Drop (Pa)
1	20.4	1.9	53	10.3	53	72
2	20.0	1.3	78	7.4	76	33
3	20.0	1.5	92	7.2	94	33

The outlet velocities that were obtained in the trials include 10.3 m/s, 7.4 m/s, and 7.2 m/s, respectively. The relative humidity at the outlet was not significantly changed and the pressure drop of the system ranged from 33Pa to 72Pa.

Simulation Results

CFD simulations were performed to mimic the experimental conditions and verify the environment model for the condensation of droplets.

CFD simulation and experimental velocity distribution along the flow path have been plotted in Fig. 6 which shows a good correlation between the two. Based on the aforementioned results, CFD velocities are at their highest at 4.00 m/s (Position 3), with the experimental data at 3.90 m/s. The values of the simulated outlet parameters were then checked again by the experimental data and summarized in Table 2.

Table 2

Comparison of Experimental and Simulation Results
Test	Experimental Outlet Velocity (m/s)	Simulated Outlet Velocity (m/s)	Error (m/s)	Experimental Outlet RH (%)	Simulated Outlet RH (%)	Error (%)	Experimental Pressure Drop (Pa)	Simulated Pressure Drop (Pa)	Error (Pa)
1	10.3	10.88	0.58	53	55	2.00	72	60	-12
2	7.4	7.35	-0.05	76	79	3.00	33	34	1
3	7.2	7.35	0.15	94	94	0.00	33	30	-3

The simulation results were also compared with the experimental results and the findings were quite satisfactory though there were some disparities observed. The errors associated with the outlet velocity were from − 0.05 m/s to 0.58 m/s, relative humidity errors varied between 0% and 3% and pressure drop errors varied between − 12 Pa and 1 Pa.

Figure 7 illustrates the pressure drop along the flow path which is further explained. Here, the pressure drop is observed to be decreasing progressively from 101.30 kPa to 97.50 kPa, while the latter two account for pressure drops significant to the droplet condensation conditions.

The simulated application of the optimized cooling system to the data center cooling environment revealed about fifty percent energy savings in contrast to the conventional HVAC systems and with reasonable operating temperatures. This has pointed towards the possibility of using droplet condensation cooling as a possible solution for cooling high-density server racks and environmentally friendly solutions. Likewise, in the case of simulations done for pharmaceutical storage conditions, better control of temperature and relative humidity was observed, the parameter key to preserving the quality of the stored products.

Discussion

Experimental and simulation studies show that using the newly developed eco-friendly cooling system droplet condensation is quite high and outlet parameters are stable. The slight deviation between the results obtained through the experiment and the simulation could be blamed on the finite simulation model and errors that might have occurred in the measurements. This was made possible by integrating the machine learning algorithms into the CFD simulations thereby improving the model’s dexterity in forecasting droplet condensation behavior, especially under conditions of environmental stress. The novel simulation method uncovered that by optimizing the nozzle and the diffuser design the efficiency would remain stable with normal fluctuating conditions of humidity and temperature. From these results, it can be concluded that the application of an advanced simulation model not only checks the results acquired from experiments but also provides a useful tool for predicting and enhancing cooling systems in a wide range of industrial sectors.

Outlet Velocity: The velocities of the outlet have been simulated with slightly higher velocities than that of experimental values having acceptable errors. This means that it was possible to predict the flow dynamic within the system with high levels of certainty using the model.

Relative Humidity: In experimental and simulation evaluation, there was a good comparison of the relative humidity at the outlet which was relatively less sensitive to errors. The system needs to be stable if it is to perform the function of dehumidifying the air and towards this; it achieves its objective perfectly.

Pressure Drop: The pressure drops across the system varied in some of the experimental and simulations when being compared, due to assumptions made while developing the simulation model. However, the errors were stated within a reasonable range so that the model could be said to be accurate.

In the design of the eco-friendly cooling system highlighted in Fig. 3, the velocity and pressure distributions have been revealed as presented in Fig. 8. The velocity attains a maximum towards the midpoint while pressure decreases, thus illustrating the flow characteristics and pressure distribution of the system, important aspects essential in the confirmation of the droplet condensation process.

Summary

This work was able to prove the feasibility of an energy-efficient cooling method that emphasizes droplet condensation in moist air. The developed environmental model demonstrated a high level of prognosis accuracy in predicting the parameters of the outlet as derived from the experiment and simulation. Lastly, the energy efficiency of the system is another factor that fits a sustainable cooling technique.

The area that should be explored in further studies is the improvement of the design of the nozzle and the diffuser, different environments for the working fluid flow, and the development of the model for larger-scale applications. That will contribute to the improvement of the performance of the system and extend the area of usage across industries.

This work presented a new geometric layout for the nozzle and diffuser where the methods presented herein possess the ability to greatly boost droplet condensation and cooling performance. Thus the results of the experiments confirm the effectiveness of the proposed new design with better results than the previous design layered structure and enhanced with better energy performance. Consequently, this work signifies considerable progress in making cooling with sustainability and pursuing further possibilities of its application in different fields. The study proved that cooling through unused latent heat in moist air is effective and efficient as a droplet condensation cooling system. By developing and validating a comprehensive environmental model through both experimental trials and Computational Fluid Dynamics (CFD) simulations, the research highlighted several key findings:

Performance Validation: The comparison of experimental and simulation results also presented a good agreement, for small differences in the velocity at the outlet, the relative humidity, and the pressure drop. This affirms the correctness of the environmental model with concern for the performance of the system.

Energy Efficiency: The cooling system proposed to be environmentally friendly was more energy efficient compared to the other dehumidifiers especially when the flow rates were high. This implies that there is a great potential of saving on energy and minimizing the pollution of the environment making it a practical solution to the normal forms of cooling.

Model Optimization: These two constitute the droplet condensation areas and were designed and optimized to maximize the condensation of droplets. The model developed and validated here offers a solid foundation for more improvements and process applications.

Sustainability: The proposed system provides a perpetual cooling solution with the help of natural condensation methods, which makes heat dissipation efficient and does not affect the environment at all. This goes in line with international strategies to eliminate climatic change and to encourage the use of technologies that boost environmental sustainability.

This study was able to illustrate how the technology of simulation was applied with higher order using CFD integrated with machine learning optimization for droplet condensation in an environmentally sustainable cooling system. This “hybrid’’ model offered improved predictive accuracy for condensation phenomena and gave a new perspective on the behavior of condensation processes at extreme conditions as compared to the traditional simulation methods. These discoveries emphasize the possibility of the progression of innovative computational approaches to designing and developing efficient cooling technologies that are friendly to the environment.

Future Work

Future research should focus on:

Design Improvements: Even more improvements on the nozzle and diffuser designs to yield better performance.
Environmental Variations: Innovating on how the system works in a specific environmental setup.
Industrial Applications: Extending the model to different industries for further testing of generalization of the suggested approach.

If these areas are tackled hence improving on them, the eco-friendly cooling system can therefore be developed and advanced to offer tremendous support towards sustainable development and environmental conservation. Apart from proving that the droplet condensation cooling system is practical in regular industries as a viable cooling solution, its ability to be developed into an integrated cooling solution for such industries as data centers or storage of drugs points to the future applicability of the technology in contemporary development. This diversification into other sectors also expands the possible uses of the system as well as demonstrates the role the system may play in improving the sustainability of some of the world’s important environments. This paper described a new phase change cooling system that combines droplet condensation and thermoelectric cooling and is nearly 50% more efficient than traditional cooling systems. All in all, the use of the hybrid system also proved more effective than the usual method in cooling, showing a lot of promise for exploitation across several production industries. The innovation also marks a breakthrough in energy-efficient cooling systems and opens up the research for advanced hybrid technology.

Author Contribution

P.K. conceived the study, designed the experiments, and conducted the initial analysis. V.P. developed the hybrid cooling system concept and performed the CFD simulations. I.N.Y. contributed to the experimental setup, data collection, and interpretation of results. P.K., V.P., I.N.Y. participated in writing the manuscript, reviewing, and approving the final version of the manuscript for submission.

Data Availability Statement: The dataset generated and analyzed in the present study will be available from the corresponding author upon reasonable request.

Abdullah, S., Zubir, M. N. B. M., Muhamad, M. R. B., Newaz, K. M. S., Öztop, H. F., Alam, M. S., & Shaikh, K. (2023). Technological development of evaporative cooling systems and its integration with air dehumidification processes: A review. Energy and Buildings, 283, 112805.
Ayou, D. S., & Coronas, A. (2020). New developments and progress in absorption chillers for solar cooling applications. Applied Sciences, 10(12), 4073.
Baghel, V., Sikarwar, B. S., & Muralidhar, K. (2020). Dropwise condensation from moist air over a hydrophobic metallic substrate. Applied Thermal Engineering, 181, 115733.
Bradu, P., Biswas, A., Nair, C., Sreevalsakumar, S., Patil, M., Kannampuzha, S., ... & Gopalakrishnan, A. V. (2023). Recent advances in green technology and Industrial Revolution 4.0 for a sustainable future. Environmental Science and Pollution Research, 30(60), 124488-124519.
Galindo, J., Navarro, R., Moya, F., & Conchado, A. (2023). Comprehensive Method for Obtaining Multi-Fidelity Surrogate Models for Design Space Approximation: Application to Multi-Dimensional Simulations of Condensation Due to Mixing Streams. Applied Sciences, 13(11), 6361.
Kumar, D., Tiwari, A., Agarwal, V., & Srivastava, K. (2023). Investigation of atmospheric water vapour condensation and characteristic analysis as potable water. International Journal of Environmental Science and Technology, 20(5), 4905-4918.
Pachouri, V., Singh, R., Gehlot, A., Pandey, S., Akram, S. V., & Abbas, M. (2024). Empowering sustainability in the built environment: A technological Lens on industry 4.0 Enablers. Technology in Society, 76, 102427.
Shi, Y., Wang, R., & Chen, P. (2023). Multi-criteria decision-making approach for energy-efficient renovation strategies in hospital wards: Balancing energy, economic, and thermal comfort. Energy and Buildings, 298, 113575.
Thompson, T. J. (2021). Modelling Air Source Heat Pump Adoption Propensity and Simulating the Distribution Level Effects of Large-Scale Adoption (Doctoral dissertation, Massachusetts Institute of Technology).

No competing interests reported.

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Optimizing Droplet Condensation for Eco-Friendly Cooling: Experimental and CFD Validation

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Abstract

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1. INTRODUCTION

2. LITERATURE REVIEW

3. METHODOLOGY

4. RESULT AND DISCUSSION

5. CONCLUSION

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Author Contribution

References

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