A review on the performance of nanoparticles suspended with refrigerants and lubricating oils in refrigeration systems

doi:10.1016/j.rser.2010.08.018

Renewable and Sustainable Energy Reviews

Volume 15, Issue 1, January 2011, Pages 310-323

https://doi.org/10.1016/j.rser.2010.08.018 Get rights and content

Abstract

Recently scientists used nanoparticles in refrigeration systems because of theirs remarkable improvement in thermo-physical, and heat transfer capabilities to enhance the efficiency and reliability of refrigeration and air conditioning system. In this paper thermal–physical properties of nanoparticles suspended in refrigerant and lubricating oil of refrigerating systems were reviewed. Heat transfer performance of different nanorefrigerants with varying concentrations was reviewed and review results are presented as well. Pressure drop and pumping power of a refrigeration system with nanorefrigerants were obtained from different sources and reported in this review. Along with these, pool boiling heat transfer performance of CNT refrigerant was reported.

Moreover, challenges and future direction of nanofluids/nanorefrigerants have been reviewed and presented in this paper. Based on results available in the literatures, it has been found that nanorefrigerants have a much higher and strongly temperature-dependent thermal conductivity at very low particle concentrations than conventional refrigerant. This can be considered as one of the key parameters for enhanced performance for refrigeration and air conditioning systems. Because of its superior thermal performances, latest upto date literatures on this property has been summarized and presented in this paper as well.

The results indicate that HFC134a and mineral oil with TiO₂ nanoparticles works normally and safely in the refrigerator with better performance. The energy consumption of the HFC134a refrigerant using mineral oil and nanoparticles mixture as lubricant saved 26.1% energy with 0.1% mass fraction TiO₂ nanoparticles compared to the HFC134a and POE oil system. It was identified that fundamental properties (i.e. density, specific heat capacity, and surface tension) of nanorefrigerants were not experimentally determined yet. It may be noted as well that few barriers and challenges those have been identified in this review must be addressed carefully before it can be fully implemented in refrigeration and air conditioning systems.

Introduction

Nanofluids are a relatively new class of fluids which consist of a base fluid with nano-sized particles (1–100 nm) suspended within them. These particles, generally a metal or metal oxide, increase conduction and convection coefficients, allowing for more heat transfer out of the coolant [1]. Serrano et al. [2] provided excellent examples of nanometer in comparison with millimeter and micrometer to understand clearly as can be seen in Fig. 1.

In the past few decades, rapid advances in nanotechnology have lead to emerging of new generation of heat transfer fluids called “nanofluids”. Nanofluids are defined as suspension of nanoparticles in a basefluid. Some typical nanofluids are ethylene glycol based copper nanofluids, water based copper oxide nanofluids, etc. Nanofluids are dilute suspensions of functionalized nanoparticles composite materials developed about a decade ago with the specific aim of increasing the thermal conductivity of heat transfer fluids, which have now evolved into a promising nanotechnological area. Such thermal nanofluids for heat transfer applications represent a class of its own difference from conventional colloids for other applications. Compared to conventional solid–liquid suspensions for heat transfer intensifications, nanofluids possess the following advantages [1]:

•
High specific surface area and therefore more heat transfer surface between particles and fluids.
•
High dispersion stability with predominant Brownian motion of particles.
•
Reduced pumping power as compared to pure liquid to achieve equivalent heat transfer intensification.
•
Reduced particle clogging as compared to conventional slurries, thus promoting system miniaturization.
•
Adjustable properties, including thermal conductivity and surface wettability, by varying particle concentrations to suit different applications.

Recently scientists used nanoparticles in refrigeration systems because of its remarkable improvement in thermo-physical, and heat transfer capabilities to enhance the efficiency and reliability of refrigeration and air conditioning system. Elcock [3] found that TiO₂ nanoparticles can be used as additives to enhance the solubility of the mineral oil with the hydrofluorocarbon (HFC) refrigerant. Authors also reported that refrigeration systems using a mixture of HFC134a and mineral oil with TiO₂ nanoparticles appear to give better performance by returning more lubricant oil to the compressor with similar performance to systems using HFC134a and POE oil. Hindawi [4] carried out an experimental study on the boiling heat transfer characteristics of R22 refrigerant with Al₂O₃ nanoparticles and found that the nanoparticles enhanced the refrigerant heat transfer characteristics with reduced bubble sizes.

Eastman et al. [5] investigated the pool boiling heat transfer characteristics of R11 refrigerant with TiO₂ nanoparticles and showed that the heat transfer enhancement reached 20% at a particle loading of 0.01 g/L. Liu et al. [6] investigated the effects of carbon nanotubes (CNTs) on the nucleate boiling heat transfer of R123 and HFC134a refrigerants. Authors reported that CNTs increase the nucleate boiling heat transfer coefficients for these refrigerants. Authors noticed large enhancements of up to 36.6% at low heat fluxes of less than 30 kW/m². Thus, the use of nanoparticles in refrigeration systems is a new, innovative way to enhance the efficiency and reliability in the refrigeration system.

In the literatures a number of reviews on thermal and rheological properties, different modes of heat transfer of nanofluids have been reported by many researchers [7], [8], [9], [10]. However, to the best of authors’ knowledge, there is no comprehensive literature on the nanoparticles as additives with conventional refrigerants and oils used in refrigeration system. It is authors’ hope that this review will be useful to fill identified research gaps and to overcome the challenges of nanorefrigerants.

Section snippets

Thermal conductivity of nanoparticles used in refrigerants

Different concentrations of nanoparticles of CuO, Al₂O₃, SiO₂ diamond, CNT, TiO₂ were used in base refrigerants such as R11, R113, R123, R134a, and 141b as found in the available literatures [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23]. Thermal conductivity enhancement of some refrigerants with nanoparticles is shown in Fig. 2, Fig. 3, Fig. 4.

The nanofluid is a new type of heat transfer fluid by suspending nano-scale materials in a conventional host fluid and has

Thermal conductivities of nanofluids

Thermal conductivity of nanofluids found to be an attracting characteristic for many applications including refrigeration and air conditioning. It represents the ability of material to conduct or transmit heat. Considerable researches have been carried out on this topic. It may be mentioned that it is a driving factor that leads to an idea of considering nanofluids as refrigerant. Eastman et al. [24] found that thermal conductivity of 0.3% copper nanoparticles of ethylene glycol nanofluids is

Pool boiling heat transfer performance

The phase change heat transfer characteristics of the refrigerant-based nanofluids in the heat exchangers, especially in the evaporator, is an important factor to consider. In order to investigate the overall performance of the heat exchangers of refrigeration systems using refrigerant-based nanofluids, the heat transfer characteristics of them must be known. It is reported that the concentration of nanoparticles in nanorefrigerant has influence on the boiling heat transfer coefficient as the

Lubricity and material compatibility

A few investigations were carried out with nanoparticles in refrigeration systems to use advantageous properties of nanoparticles to enhance the efficiency and reliability of refrigerators. For example, Wang and Xie [68] found that TiO₂ nanoparticles can be used as additives to enhance the solubility of the mineral oil in the hydrofluorocarbon (HFC) refrigerant. In addition, refrigeration systems using a mixture of HFC134a and mineral oil with TiO₂ nanoparticles appear to give better

Surface roughness

Table 4 shows the surface roughness of fixed plate operated at the orbiting speed of 1000 rpm and the normal force up to 1000 N for 100-min test period. The surface roughness of the fixed plate for raw mineral oil was distinctively high, 0.106 μm in depth at the scratched circle, while those of nano-oil I, II, III, and IV were 0.077, 0.067, 0.052, and 0.048 μm, respectively [72].

Energy performance

The refrigerator performance with the nanoparticles was investigated using energy consumption tests and freezer capacity tests by Ref. [69]. Authors reported that refrigerator's performance was better with 26.1% less energy consumption with 0.1% mass fraction of TiO₂ nanoparticles compared to the HFC134a and POE oil system. The same tests with Al₂O₃ nanoparticles showed that the different nanoparticles properties have little effect on the refrigerator energy performance. Thus, nanoparticles can

Viscosity of nano-oil

Fig. 13 shows the kinematic viscosity of nano-oils as a function of volume fraction of fullerene nanoparticles in suspension for temperature ranging from 40 to 80 °C. There was no considerable change in the kinematic viscosity of nano-oil at the various volume fractions of nanoparticles, indicating that the kinematic viscosity of nano-oils is a weak function of oil temperature considered [72].

Fig. 14 shows the change of kinetic viscosity as a function of volume fraction and temperature of the

Pressure drop performance of nanorefrigerant

In the modern avenue of research, refrigerant-based nanofluids formed by suspension of nanoparticles in pure refrigerants have been used as a new kind of working fluid to improve the performance of refrigeration systems [68], [69], [74]. Presence of nanoparticles in suspension form may change the pressure drop characteristics of the fluid, so this characteristic needed to be understood in selecting the refrigerant. Liquid solid phase pressure drop characteristics and liquid solid and vapor

Binary nanofluids in absorption system

The binary mixture of NH₃/H₂O with nanoparticles of CNT or Al₂O₃ was used as a working fluid to investigate heat transfer performance along with the stability of nanorefrigerant by Ref. [86]. Authors reported that binary nanofluids are potential candidate for next generation working fluid of absorption systems [65]. Authors found that the heat transfer and absorption rate with 0.02 vol% CNT particles are about 17% and 16% higher than those without nanoparticles, respectively. Heat transfer and

Challenges of nanofluids

Many interesting properties of nanofluids have been reported in the review. In the previous studies, thermal conductivity has received the maximum attention, but many researchers have recently initiated studies on other thermo-physical properties as well. The use of nanofluids in a wide variety of applications appears promising. But the development of the field is hindered by (i) lack of agreement of results obtained by different researchers; (ii) poor characterization of suspensions; (iii)

Conclusions

•
Based on the literatures, it has been found that the thermal conductivities of nanorefrigerants are higher than traditional refrigerants. It was also observed that increased thermal conductivity of nanorefrigerants is comparable with the increased thermal conductivities of other nanofluids.
•
Thermal conductivities of refrigerant with carbon CNT found to be higher than refrigerant without CNT. It was observed that maximum thermal conductivity enhancement was found to be about 46%. It was also

Recommendations for future work

The heat transfer results show that nanofluids have significant potential for improving the flow boiling heat transfer of refrigerant/lubricant mixtures. However, the reasons behind this marked improvement with nanoparticle volume fractions at different concentrations are not clearly understood. It is unclear why a large increase in heat transfer is observed with an insignificant increase in pressure. Moreover, obvious challenges with particle circulation and unknown effects on the compressor

Acknowledgements

The authors would like to acknowledge the financial support from the Vice Chancellor, University of Malaya. This research was carried under the High Impact Research Grant (HIRG) scheme.

References (94)

E. Serrano et al.
Nanotechnology for sustainable energy
Renewable and Sustainable Energy Reviews
(2009)
W. Duangthongsuk et al.
An experimental study on the heat transfer performance and pressure drop of TiO₂–water nanofluids flowing under a turbulent flow regime
International Journal of Heat and Mass Transfer
(2010)
V. Trisaksri et al.
Nucleate pool boiling heat transfer of TiO₂–R141b nanofluids
International Journal of Heat and Mass Transfer
(2009)
G. Paul et al.
Techniques for measuring the thermal conductivity of nanofluids: a review
Renewable and Sustainable Energy Reviews
(2010)
L. Godson et al.
Enhancement of heat transfer using nanofluids—an overview
Renewable and Sustainable Energy Reviews
(2010)
W. Jiang et al.
Measurement and model on thermal conductivities of carbon nanotube nanorefrigerants
International Journal of Thermal Sciences
(2009)
K.J. Park et al.
Enhancement of nucleate boiling heat transfer using carbon nanotubes
International Journal of Heat and Mass Transfer
(2007)
K.J. Park et al.
Boiling heat transfer enhancement with carbon nanotubes for refrigerants used in building air conditioning
Energy and Buildings
(2007)
S.K. Das et al.
Pool boiling characteristics of nano fluids
International Journal of Heat and Mass Transfer
(2003)
S.K. Das et al.
Pool boiling of nano-fluids on horizontal narrow tubes
International Journal of Multiphase Flow
(2003)

P. Vassallo et al.

Pool boiling heat transfer experiments in silica–water nanofluids

International Journal of Heat and Mass Transfer

(2004)

I.C. Bang et al.

Boiling heat transfer performance and phenomena of Al₂O₃–water nanofluids from a plain surface in a pool

International Journal of Heat and Mass Transfer

(2005)

Y.J. Hwang et al.

Investigation on characteristics of thermal conductivity enhancement of nanofluids

Current Applied Physics

(2006)

D.-H. Yoo et al.

Study of thermal conductivity of nanofluids for the application of heat transfer fluids

Thermochimica Acta

(2007)

S. Jana et al.

Enhancement of fluid thermal conductivity by the addition of single and hybrid nano-additives

Thermochimica Acta

(2007)

S. Zeinali Heris et al.

Experimental investigation of convective heat transfer of Al₂O₃/water nanofluid in circular tube

International Journal of Heat and Fluid Flow

(2007)

J.-H. Lee et al.

Effective viscosities and thermal conductivities of aqueous nanofluids containing low volume concentrations of Al₂O₃ nanoparticles

International Journal of Heat and Mass Transfer

(2008)

R.S. Vajjha et al.

Experimental determination of thermal conductivity of three nanofluids and development of new correlations

International Journal of Heat and Mass Transfer

(2009)

D. Wen et al.

Review of nanofluids for heat transfer applications

Particuology

(2009)

Y. Xuan et al.

Conceptions for heat transfer correlation of nanofluids

International Journal of Heat and Mass Transfer

(2000)

Y. Xuan et al.

Heat transfer enhancement of nanofluids

International Journal of Heat and Fluid Flow

(2000)

S.M.S. Murshed et al.

Enhanced thermal conductivity of TiO₂–water based nanofluids

International Journal of Thermal Sciences

(2005)

H. Peng et al.

Heat transfer characteristics of refrigerant-based nanofluid flow boiling inside a horizontal smooth tube

International Journal of Refrigeration

(2009)

P. Naphon et al.

Heat pipe efficiency enhancement with refrigerant–nanoparticles mixtures

Energy Conversion and Management

(2009)

S.S. Bi et al.

Application of nanoparticles in domestic refrigerators

Applied Thermal Engineering

(2008)

J. Lee et al.

Application of fullerene-added nano-oil for lubrication enhancement in friction surfaces

Tribology International

(2009)

J. Li et al.

Thermal performance of nanofluid flow in microchannels

International Journal of Heat and Fluid Flow

(2008)

J. Lee et al.

Assessment of the effectiveness of nanofluids for single-phase and two-phase heat transfer in micro-channels

International Journal of Heat and Mass Transfer

(2007)

M.N. Pantzali et al.

Investigating the efficacy of nanofluids as coolants in plate heat exchangers (PHE)

Chemical Engineering Science

(2009)

H. Peng et al.

Measurement and correlation of frictional pressure drop of refrigerant-based nanofluid flow boiling inside a horizontal smooth tube

International Journal of Refrigeration

(2009)

R. Chein et al.

Experimental microchannel heat sink performance studies using nanofluids

International Journal of Thermal Sciences

(2007)

Y.R. He et al.

Heat transfer and flow behavior of aqueous suspensions of TiO₂ nanoparticles (nanofluids) flowing upward through a vertical pipe

International Journal of Heat and Mass Transfer

(2007)

Y. Hwang et al.

Thermal conductivity and lubrication characteristics of nanofluids

Current Applied Physics

(2006)

C. Choi et al.

Preparation and heat transfer properties of nanoparticle-in-transformer oil dispersions as advanced energy-efficient coolants

Current Applied Physics

(2008)

S. Wu et al.

Thermal energy storage behavior of Al₂O₃–H₂O nanofluids

Thermochimica Acta

(2009)

S.U.S. Choi

Development and applications of Non-Newtonian flows’

D. Elcock

Potential impacts of nanotechnology on energy transmission applications and needs

(2007)

Hindawi, Special issue on heat transfer in nanofluids;...

J.A. Eastman et al.

Enhanced thermal conductivity through the development of nanofluids

Mater Res Soc Symp Proc

(1996)

M.S. Liu et al.

Enhancement of thermal conductivity with CuO for Nanofluids

Chemical Engineering and Technology

(2006)

S. Witharana

Boiling of refrigerants on enhanced surfaces and boiling of nanofluids

(2003)

M.S. You et al.

Effect of nanoparticles on critical heat flux of water in pool boiling heat transfer

Applied Physics Letters

(2003)

J.H. Kim et al.

Pool boiling heat transfer in saturated nanofluids

J.P. Tu et al.

An experimental study of nanofluid boiling heat transfer

G. Moreno et al.

Pool boiling heat transfer of alumina–water, zinc oxide–water and alumina–water + ethylene glycol nanofluids

D.S. Wen et al.

Experimental investigation into the pool boiling heat transfer of aqueous based γ-alumina nanofluids

Journal of Nanoparticle Research

(2005)

J.A. Eastman et al.

Anomalously increased effective thermal conductivities of ethylene glycol-based nanofluids containing copper nanoparticles

Applied Physics Letters

(2001)

Cited by (243)

Investigating the impacts of using TiO<inf>2</inf>-ZnO/POE hybrid nanolubricant in a heat pump system: An experimental study
2024, Applied Thermal Engineering
Heating, cooling, and ventilation systems have a share in the majority of energy consumption in buildings. The use of heat pumps (HP) is becoming widespread to reduce energy consumption in buildings to improve this circumstance around the world. The slightest improvement in the heating, cooling and ventilation system will provide significant energy savings in total. For this reason, the use of nanoparticles in these systems has become quite common due to the increase in the thermal properties of fluids. In this study, the thermodynamic and economic performances of the system used at different mass flow rates (10 g/s, 30 g/s and 50 g/s) with the addition of mono and hybrid nanoparticles to pure POE (Polyol ester oil) used in an air-to-water HP were compared. TiO₂ and ZnO nanoparticles were used in 0.8 g/L and 1.6 g/L fractions to obtain mono and hybrid nanolubricants. As a result of the experiments, significant improvements were determined in the thermal conductivity and viscosity values of mono and hybrid nanolubricants compared to pure POE. An increase of 4.89 % was observed in the COP value of the system using 1.6 g/L TiO₂-ZnO/POE hybrid nanolubricant compared to pure POE. The exergy efficiency of the HP improved by 8.39 % compared to pure POE in the same nanolubricant. The lowest heating cost was obtained in 1.6 g/L TiO₂-ZnO/POE hybrid nanolubricant as 4.7844 kWh/$ at 50 g/s mass flow rate. It is seen that as the fractions of mono and hybrid nanolubricants increase, the COP and exergy efficiency of the system increases compared to pure POE. Consequently, better results were obtained from mono and hybrid nanolubricants used in the HP compared to pure POE, energetically, exergetically and economically. In addition, better performance was obtained as the mass flow rate of the system and the fraction of hybrid nanolubricants increased.
Analysis of physicochemical and tribological properties of nano alumina-based gear oil developed from effluent of lube oil blending plant
2024, Industrial Crops and Products
Industrial wastewater, also known as effluent has been identified as one of the leading sources of environmental pollutions worldwide. The establishment of lube oil blending plants in Nigeria has led to a continuous discharge of industrial effluent in densely populated areas. This threatens the well-being of humanity, plants, aquatic lives and construction soils. This research paper focused on developing a nano alumina-based effluent gear oil from effluent of lube oil blending plants as an alternative means of mitigating its threats on the environment. Nano lubricant are used in gearboxes for better thermal, friction and anti-wear properties. This is due to the small size and high specific surface area to volume ratio of the nanoparticles. Furthermore, due to their excellent mechanical and thermal properties, easy dispersal in most fluids, inexpensiveness, ease of manufacture, and aspect ratio, the Al₂O₃ nanoparticles are recently being used by researchers as an additive in gear oils to improve tribological properties, increase power efficiency, extend equipment lifetimes, and lower operating cost. In this work, the alumina nanoparticle was synthesized using co-precipitation method, after which it was characterized using Fourier Transform Infrared (FTIR) and X-ray Diffraction (XRD) analysers. After the development of Al₂O₃-based gear oil from the effluent, the physicochemical and tribological properties of the alumina-based effluent gear oil samples were investigated with varied weight percentages of Al₂O₃ nanoparticles. The Differential Scanning Calorimetry (DSC) and Computational Fluid Dynamics (CFD) thermal analyses of nano alumina-based gear sample was investigated after obtaining the suitable sample among the sample blends developed. The dispersion of the nanoparticle in the effluent oil improved the specific gravity and pour point whereas a slight reduction was observed in kinematic viscosity at 100 °C, viscosity index and flash point. However, viscosity index and flash point values are conforming to the minimum requirements of API EP 85W90 and ISO 100 standard values. The anti-wear property was observed to significantly improved by 26.14%, at 0.4 wt% nanoparticles concentration. The results showed that, the pure effluent oil recovered is more thermally stable than the 0.4 wt% nano alumina-based effluent gear oil sample, whereas the nano gear oil sample has a higher thermo-oxidative stability than the pure effluent oil. Finally, temperature profiles from the simulation results also ensured a better performance of the 0.4 wt% alumina-based effluent gear oil developed, at 1500 rpm speed of rotation by 6.7% and 8.9% and at 4000 rpm is by 5.9% and 7.8% than the API EP 85W90 and pure effluent oil samples respectively. Hence, based on the results obtained, the study indicated that the effluent oil from lube oil blending plants can be used as gear oil with the dispersion of alumina nanoparticles.
Current status of refrigerants used in domestic applications: A review
2024, Renewable and Sustainable Energy Reviews
HFCs that were accepted globally in refrigeration and air conditioning applications may soon be phased out due to environmental concerns. The primary driver behind the phase-out of HFCs is their elevated global warming potential (GWP). As a result, the demand for suitable, environmentally friendly substitutes has been increased. Hydrofluoroolefins (HFOs) are a novel family of environmentally benign refrigerants that have gained popularity in recent years. Moreover, despite their significant flammability, hydrocarbons (HCs) can also serve as viable substitutes for halogenated refrigerants due to their positive environmental impact, energy efficiency, coefficient of performance (COP), refrigerant mass, and compressor discharge temperatures. As possible retrofits for conventional refrigerants, the current review aims to address several pure HCs, HFOs, and HFCs as well as their mixtures. It also addresses their flammability characteristics, such as minimum inerting concentration, critical suppression ratio, inert effect, and flammability, as well as their performance parameters, such as coefficient of performance, compressor power consumption, pulldown time, optimal refrigerant charge, and exergy destruction. Various methods for determining the MIC of the refrigerant mixtures are reported. Cost analysis of different refrigerants and refrigeration with Nano-refrigerants were also discussed. Moreover, this study conducted a comprehensive examination of prior research which helps in identifying the eco-friendly refrigerants for domestic applications.
Performance analysis of ice plant using R134a/POE blended with MWCNTs nano-refrigerant–An experimental approach
2023, International Journal of Refrigeration
Ice plant is used for producing ice at a large scale from water filled in standard cans placed inside rectangular tanks filled with brine solution. Ice plant works on the vapour compression refrigeration (VCR) cycle, the researchers are focusing on minimizing compressor work and improving the cycle's performance by introducing nanoparticles with higher thermophysical properties. In this experimental investigation, the performance analysis of the test rig of an ice plant using varied masses of 0.05 g, 0.10 g, 0.15 g, 0.20 g, and 0.25 g of multi-walled carbon nanotubes (MWCNTs), dispersed in 250 ml polyolester (POE) oil charged with masses 175 g, 200 g, and 225 g of tetrafluoro ethane (R134a) refrigerants is carried out separately. REFPROP 9.1 software is used to obtain the properties of refrigerants. The evaluated parameters are pull-down time, cooling capacity, coefficient of performance (COP), Compressor work input, economic analysis, pressure ratio, thermal conductivity, absolute viscosity, and density. It is observed that in comparison to the pure refrigerant, the refrigerator's pull-down time and compressor work are reduced by 17.9% and 21.46%, whereas, COP and cooling capacity improved by 40.09% and 11.29% for 225 g mass of R134a with 250 ml POE respectively. In addition, thermal conductivity, density, and absolute viscosity improved at both the suction side and discharge side of the compressor.
Performance of hydrocarbon refrigerants in a refrigerator with liquid line magnet and CNT nano-lubricant
2023, Heliyon
The issues of flammability associated with A3-class hydrocarbon-based refrigerants are controllable by limiting their mass charges. However, these reductions in their mass charge below certain limits deteriorate their performance efficiency. In this experimental study, we analyzed the effects of a liquid line magnetic field (Mag), multi-wall carbon nanotube (CNT) nano-lubricant, and the combination of both (Mag-Nano) on the performance of a very low mass charge (i.e., 30 g) of R600a and LPG refrigerants, as a replacement to the 100 g R134a refrigerant in a domestic refrigeration system. The refrigerants were tested with and without CNT nano-lubricant (pure), two pairs of 3000 Gs liquid line mounted O ring N50 permanent magnets (Mag), 0.2 g/L concentration of CNT nano-lubricant (Nano), and in combination with a liquid line magnetic field and CNT nano-lubricant (Mag-Nano). The performance evaluation of the refrigerants includes the determination of coefficient of performance (COP), evaporator air temperature, volumetric refrigeration capacity, instantaneous power consumption, cumulative energy consumption, and energy cost. A reduction in the COP of R600a and LPG was observed to be about 11–42% and 14–26%, respectively, when compared to R134a. The R134a refrigerant had the lowest evaporator air temperature of −24.5 °C and the highest instantaneous power consumption of 74.6 W. The R600a-Mag-Nano refrigerant is the most efficient option, having the lowest instantaneous power consumption, energy cost, and cumulative energy consumption. The adoption of hydrocarbon refrigerants is more cost-effective than using the R134a refrigerant, resulting in a cost saving of about 8–26%. In conclusion, the proposed methods adopted to enhance the performance of refrigeration system, are very safe and effective.
Thermodynamic optimisation of a booster-ejector vapour compression refrigeration system using solar energy and R152a/Cu nano-refrigerant
2023, Applied Thermal Engineering
Conventional vapour compression refrigeration systems require high electrical energy for low temperature applications. For the first time in the literature to reduce this required energy, comprehensive thermodynamic analysis and optimization of booster-assisted ejector expansion vapour compression refrigeration system with R152a/Cu nano-refrigerant are presented for low-temperature applications. Solar panels are used to cover the total compressor work, using the climate data of Izmir, Turkey. According to the thermodynamic optimization findings, the use of nanoparticles in the refrigeration system led to several improvements when compared to the R152a refrigeration system. These enhancements include a reduction of 6.52-11.71% in the main compressor discharge temperature, a decrease of 18.46-34.48% in the total exergy destruction rate, an increase of 3.08-4.04% in the entrainment ratio, a reduction of 0.089-3.25% in the ejector area ratio, a decrease of 8.34-14.27% in the panel area, and an increase of 8.09-14.05% in both the coefficient of performance and exergy efficiency. Another thing worth mentioning is that coefficient of performance and exergy efficiency improved by 2.06% and 1.96%, respectively, while total exergy destruction reduced by 4.83% compared to our previous study. The results obtained from the thermodynamic optimisation provide a useful reference for the design of an experimental system, as they provide evidence of model validity and can guide the implementation of the system.

View all citing articles on Scopus

View full text

A review on the performance of nanoparticles suspended with refrigerants and lubricating oils in refrigeration systems

Abstract

Introduction

Section snippets

Thermal conductivity of nanoparticles used in refrigerants

Thermal conductivities of nanofluids

Pool boiling heat transfer performance

Lubricity and material compatibility

Surface roughness

Energy performance

Viscosity of nano-oil

Pressure drop performance of nanorefrigerant

Binary nanofluids in absorption system

Challenges of nanofluids

Conclusions

Recommendations for future work

Acknowledgements

Renewable and Sustainable Energy Reviews

International Journal of Heat and Mass Transfer

International Journal of Heat and Mass Transfer

Renewable and Sustainable Energy Reviews

Renewable and Sustainable Energy Reviews

International Journal of Thermal Sciences

International Journal of Heat and Mass Transfer

Energy and Buildings

International Journal of Heat and Mass Transfer

International Journal of Multiphase Flow

International Journal of Heat and Mass Transfer

International Journal of Heat and Mass Transfer

Current Applied Physics

Thermochimica Acta

Thermochimica Acta

International Journal of Heat and Fluid Flow

International Journal of Heat and Mass Transfer

International Journal of Heat and Mass Transfer

Particuology

International Journal of Heat and Mass Transfer

International Journal of Heat and Fluid Flow

International Journal of Thermal Sciences

International Journal of Refrigeration

Energy Conversion and Management

Applied Thermal Engineering

Tribology International

International Journal of Heat and Fluid Flow

International Journal of Heat and Mass Transfer

Chemical Engineering Science

International Journal of Refrigeration

International Journal of Thermal Sciences

International Journal of Heat and Mass Transfer

Current Applied Physics

Current Applied Physics

Thermochimica Acta

Development and applications of Non-Newtonian flows’

Potential impacts of nanotechnology on energy transmission applications and needs

Enhanced thermal conductivity through the development of nanofluids

Mater Res Soc Symp Proc

Enhancement of thermal conductivity with CuO for Nanofluids

Chemical Engineering and Technology

Boiling of refrigerants on enhanced surfaces and boiling of nanofluids

Effect of nanoparticles on critical heat flux of water in pool boiling heat transfer

Applied Physics Letters

Pool boiling heat transfer in saturated nanofluids

An experimental study of nanofluid boiling heat transfer

Pool boiling heat transfer of alumina–water, zinc oxide–water and alumina–water + ethylene glycol nanofluids

Experimental investigation into the pool boiling heat transfer of aqueous based γ-alumina nanofluids

Journal of Nanoparticle Research

Anomalously increased effective thermal conductivities of ethylene glycol-based nanofluids containing copper nanoparticles

Applied Physics Letters