Performance Analysis of Pure Iron Nanofluid-Based Refrigerants in Cooling Applications

Abstract

In the present work, the thermal efficiency of pure iron-based nanofluids has been explored as a possible refrigerant in refrigeration applications. Pure iron nanoparticles were prepared via chemical reduction technique and suspended in a typical base fluid to achieve stable nanofluids of different concentrations (0.05–0.5 wt%). Detailed characterization through methods like XRD, TEM, and DLS was carried out to identify nanoparticle structure, crystalline nature, and size distribution. Thermo-physical properties of the nanofluids such as thermal conductivity, viscosity, and specific heat were measured and analyzed experimentally. The performance of the nanofluid refrigerants was tested in a modified vapor compression refrigeration system. Results showed considerable improvement in the COP of the system with thermal conductivity improvements of up to 18% and little negative impact on viscosity. These studies indicate that pure iron nanofluids can be used as effective and ecologically friendly substitutes for conventional refrigerants, providing enhanced heat transfer for emerging technologies in cooling.

Introduction

The study focuses on developing and evaluating Fe?O? (magnetite) nanofluids synthesized from iron ore waste for enhanced thermal management applications. Conventional fluids like water and ethylene glycol have limited thermal conductivity, prompting interest in nanofluids. Iron oxide nanoparticles, particularly magnetite, offer both thermal and magnetic advantages, and using industrial waste for synthesis is both eco-friendly and cost-effective.

Methodology

1. Material Preparation: Iron ore waste was cleaned and processed into fine powder.

2. Nanoparticle Synthesis: Fe?O? nanoparticles were produced via co-precipitation, characterized using XRD, SEM, and FTIR.

3. Nanofluid Preparation: Nanoparticles (0.1%, 0.3%, 0.5%, and 1% concentrations) were dispersed in distilled water with SDS surfactant using sonication.

4. Thermo-physical Testing:

   • Thermal conductivity: Measured using transient hot-wire method.

   • Viscosity: Measured using a Brookfield viscometer.

   • Stability: Assessed via zeta potential, UV–Vis spectroscopy, and visual observation.

Heat Exchanger System

A CAD model of a nanofluid-based refrigeration unit was designed, incorporating typical components such as a compressor, liquefier, vaporizer, and manometers.

Results

The addition of Fe?O? nanoparticles significantly improved heat transfer performance:

• Increasing nanoparticle concentration led to higher thermal energy exchange (Q-cond & Q-evap) and better Coefficient of Performance (COP).

• At 1% concentration, the system achieved the highest performance:

  • Q-cond = 4.308 kW

  • Q-evap = 3.504 kW

  • COP-HP = 5.90

  • COP-R = 4.80

Conclusion

Based on the thermal performance data of iron oxide nanofluids with varying mass fractions, it is evident that the inclusion of iron significantly enhances the heat transfer characteristics of the base fluid (pure water). With increasing iron content from 0.1% to 1%, there is a consistent rise in condenser heat output (Q-cond), evaporator heat input (Q-evap), and Coefficient of Performance for both heat pump (COP-HP) and refrigeration (COP-R) systems. At 1% iron mass fraction, the highest COP-HP (5.90) and COP-R (4.80) were achieved, indicating improved energy efficiency. Compared to pure water, the system\'s performance is markedly enhanced with even minimal iron additions, demonstrating the potential of iron oxide nanofluids in thermal management applications. This study confirms that iron oxide nanofluids, derived from iron ore mines, can be effectively utilized to improve the thermal dissipation and operational efficiency of heat pump and refrigeration systems.

References

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Copyright

Copyright © 2025 Amar Kumar Das, Sudhir Chandra Giri, Pratyush Kumar Sahoo, Smruti Ranjan Lenka, Hemanta Kumar Sahoo. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.