Thermal Performance Improvement of Refrigeration Systems Through Nanoparticle-Enhanced Refrigerants and PCM Integration in Condensers

Abstract

The growing demand for energy-efficient and environmentally sustainable refrigeration systems has driven significant research into advanced heat transfer enhancement techniques. This study explores the integration of nanoparticle-enhanced refrigerants and phase change materials (PCMs) within the condenser component of a vapor compression refrigeration system. Specifically, nanoparticles of CuO, SiO?, and MnO? were dispersed in the base refrigerant R134a to assess their impact on thermal performance. Additionally, PCMs were employed in the condenser unit to improve heat storage and dissipation characteristics. Experiments were conducted using a mini ice cream plant setup with varying capillary tube lengths (48?, 52?, 54?) and different nano-refrigerant compositions. The results demonstrated a significant improvement in the coefficient of performance (COP), with CuO–R134a mixtures yielding the highest thermal efficiency. The combined use of nanofluids and PCMs effectively enhanced heat transfer, reduced energy consumption, and improved system stability. These findings underscore the potential of hybrid thermal enhancement strategies for advancing next-generation refrigeration technologies.

Introduction

Refrigeration systems are crucial in sectors such as food preservation, pharmaceuticals, and industrial cooling. As energy demand rises, improving energy efficiency and reducing environmental impact becomes essential. Traditional refrigerants like R134a, while effective, have high global warming potential (GWP). Hence, there's a push to replace or enhance them without compromising performance.

This study explores how nanoparticles (CuO, SiO?, MnO?) and phase change materials (PCMs) can be integrated into refrigeration systems to:

• Improve thermal conductivity and heat transfer.

• Enhance the coefficient of performance (COP).

• Reduce energy consumption and emissions.

2. Literature Review

Past research shows:

• Nano-refrigerants (e.g., CuO-R134a, Al?O?-R600a) improve COP and heat transfer.

• PCMs enhance thermal buffering and load management in condensers.

• However, few studies have explored the combined use of nano-refrigerants and PCMs.

• Capillary tube length, a key design parameter, is also underexplored in this context.

3. Research Objectives & Scope

Objectives:

• Evaluate R134a mixed with CuO, SiO?, MnO? nanoparticles.

• Analyze PCM integration in the condenser for thermal stability.

• Study the effect of capillary tube length (48", 52", 54") on system performance.

• Determine the optimal combination for maximum energy efficiency.

Scope:

• Lab-scale tests on a mini ice cream plant using R134a-based systems.

• Focus on 0.1% nanoparticle concentration, PCMs in the condenser, and various capillary lengths.

4. Materials and Methods

• Refrigerant: R134a, enhanced with nanoparticles (CuO, SiO?, MnO?).

• Nanoparticle Preparation: Uniform dispersion via stirring and sonication.

• Experimental Setup: Closed-loop vapor compression system with:

  • Compressor, air-cooled condenser (with PCM), capillary tube, evaporator.

• Instrumentation:

  • Thermocouples, pressure gauges, energy meter, and refrigerant manifold.

5. Results and Discussion

A. Effect of Capillary Tube Length & Nano-Refrigerants:

• Best performance observed at 52″ capillary tube for all refrigerant types.

• CuO-R134a showed the highest COP (22% improvement) due to superior thermal conductivity.

• SiO? and MnO? followed, also improving efficiency over plain R134a.

B. Observations with 0.81 mm Capillary Tube:

• Experiment tracked temperature, pressure, power consumption, and other parameters.

• Detailed data collected to analyze system behavior and efficiency under consistent conditions.

Conclusion

This study demonstrates the significant potential of combining nanoparticle-enhanced refrigerants and phase change materials (PCMs) to improve the efficiency of vapor compression refrigeration systems. Among the nanoparticles tested—CuO, SiO?, and MnO?—CuO exhibited the highest enhancement in thermal conductivity, resulting in a notable increase in the system’s coefficient of performance (COP). The experimental results showed that the 52? capillary tube length provided the optimal balance for refrigerant flow, maximizing system performance. The incorporation of nanoparticles into R134a increased heat transfer rates in the condenser and evaporator, while PCMs contributed to stabilizing temperature fluctuations by absorbing and releasing latent heat during phase transitions. Overall, the combined approach led to an improvement in COP of up to 22% compared to the base refrigerant, highlighting the effectiveness of hybrid thermal enhancement strategies. These improvements translate into reduced energy consumption and greater operational stability, supporting the development of more sustainable refrigeration technologies. This research validates the practical application of nanoparticle-enhanced refrigerants and PCMs in condenser units and sets the stage for further exploration into optimizing nano-refrigerant formulations and PCM integration in commercial refrigeration systems.

References

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Copyright

Copyright © 2025 Arpit Saxena, Dr Nitesh Kumar Choudhary. 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.