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This paper is mainly concerned with an experimental investigation of the performance enhancement of a vapor compression refrigeration (VCR) system using nano refrigerant (R-134a + ZrO 2 ) at steady-state conditions. The refrigeration system has become a major consumer of energy for many industrial applications. Therefore, there is a need to enhance the refrigeration systems. The performance of a refrigeration system can be improved by either reducing the compressor power or increasing the heat-absorption rate in the evaporator. The use of nano refrigerant can lead to lower power consumption, increased heat transfer capacity, and reduced (pumping, power, and particle clogging). A two-step method was prepared by dispersing ZrO 2 (0.5, 1, and 1.5 % v) in PAG oil. A magnetic stirrer and an ultrasonic homogenizer were used. ZrO 2 nanoparticles were selected owing to their superior thermophysical properties. Through the experiments, the discharge pressure (Pdis) varies from 11.37 bar to 7.618 bar, and the suction pressure (Psuc) changes from 1.06 to o.85 bar, which gives a VCR system pressure ratio (PR) between 6.45 and 8.32. The use of nano refrigerant reduced the compressor energy consumption by 7.68 %. Finally, the result revealed the use of (R-134a/ZrO 2 ) nano refrigerant has also resulted in a significant increase in the cooling capacity and thermal efficiency of the system.

The shift towards environmentally sustainable refrigerants is driven by the need to mitigate the impact of traditional refrigerants like R134a, which have high global warming potential. This study experimentally explores the performance of alternative refrigerants, R1234yf and R600a, when combined with compressor oils enhanced by Al₂O₃ and ZnO nanoparticles. A novel approach of using a hybrid nanofluid, incorporating both Al₂O₃ and ZnO nanoparticles, is proposed to optimise the performance of vapour compression refrigeration systems. The research involved preparing and characterising nano-additive compressor oils and evaluating their effects on key thermodynamic parameters across R1234yf and R600a refrigerants. The main objective of this study is to experimentally evaluate the impact of Al₂O₃ and ZnO nano-enhanced oils on refrigeration system perfor-mance, focusing on net refrigeration effect, compressor work, mass flow rate, theoretical compressor power, and coefficient of performance. The results indicate significant improvements in the coefficient of performance, mass flow rate, and net re-frigeration effect with the inclusion of nanoparticles in the refrigeration lubrication system. Particularly, the coefficient of performance increased from 2.71 to 3.34 for R134a, from 2.46 to 3.26 for R1234yf, and from 2.62 to 3.12 for R600a with the optimal nanoparticle combination (0.15g Al₂O₃ + 0.05g ZnO). Similarly, compressor power and work of compression were notably reduced, demonstrating enhanced energy efficiency. The optimal mixture (COA0.15Z0.05) shows the highest coeffi-cient of performance and reduced work of compression across all refrigerants. The study highlights that the hybrid nanoparticle approach not only boosts the performance of these refrigerants but also contributes to lower energy consumption and improved cooling efficiency.

The focus of this research is to experimentally explore the influence of elliptically configured coil (ECC) condenser dimensional parameters and working conditions on the coefficient of performance (COP) of vapour compression refrigeration systems (VCRS). Four ECC condensers with varying minor and major axes (maintaining the same ratio) were selected for testing various refrigerants utilized in the different internal tube diameters in a counterflow configuration. A total of 32 experiments were carried out using multiple minor and major axes, coil diameters, and refrigerants as parameters. The experimental results demonstrate that increasing the major and minor axes of the elliptical structure, in addition to coil diameter, improves the condenser COP the elliptical major and minor axes have a greater influence on COP than other factors. Experimental results indicated that elliptical condensers enhanced heat transfer and COP from 25% to 33% compared to circular condensers.

Over the last few years, the alarming rate of increase in greenhouse emissions across the world due to continuous growth in cooling and heating requirements has caused a rise in the global temperature. The use of energy-efficient systems, devices, and renewable energy systems are need of the hour as these can curtail greenhouse gas (GHG) emissions and will aid in sustainable development. In the cooling sector, most commercial and domestic refrigeration and air-conditioning systems run on the conventional vapour compression refrigeration (VCR) cycle. The irreversibility occurring in the capillary tube leads to significant energy loss. Also, hydrofluorocarbons (HFC) refrigerants, are being used in these systems, consuming more energy for the operation of the system and contributing larger GHG leading to enhanced climate change. The literature has demonstrated that deploying an ejector in lieu of the typical throttling valve can minimize the energy loss. In addition to this, the use of environment-friendly refrigerants in these systems will also keep a check on levels of emissions that lead to environmental change. In the prevailing study, a parametric performance analysis is executed of the ejector-assisted vapour compression refrigeration system (EVCR) employing ammonia(R717), propane(R290), and isobutane(R600a) as refrigerants with a uniform pressure ejector model. Ist law and IInd law analyses of the EVCR system are accomplished for a range of condenser temperature (Tcndr = 30°C to 60°C), evaporator temperature (Tevpr = 5°C, -5°C and -15°C), and pressure drop (δP = 0.01 to 0.50 bar) in the suction chamber. Variations in performance parameters such as coefficient of performance (COPEVCR) & % improvement in COPEVCR (%COPEVCR, imp), volumetric cooling capacity (VCCEVCR) & % improvement in VCC (%VCCEVCR, imp), optimum area ratios (ARopt), pressure lift factor (PLF), total exergy destruction (ED, Total), and IInd law efficiency (ηexergetic) of the EVCR system for the above range of the operating parameters are reported in this study. It is observed from the results that at Tcndr = 40°C and Tevpr = 5°C, R600a yields the maximum COPEVCR of 6.14 whereas the R290 gives the highest % COPEVCR, imp of 12.78% and %VCCEVCR, imp = 9.96% compared to the other two refrigerants. Also, it is observed from the IInd law analysis that R717 gives the maximum ED, Total of 59.64 kW, and ηexergetic of 37.61% whereas R290 and R600a give values of ηexergetic as 36.90% and 37.56%.

Vapour Absorption Refrigeration Systems (ARS), which may efficiently use low-grade energy, are gaining more and more attention because of the primary energy deficit. However, ARS is more difficult to miniaturize and has poorer efficiency when compared to Vapour Compression Refrigeration Systems (CRS). As a result, there are some limitations on the advancement of ARS. Thankfully, though a growing number of attempts are being undertaken to enhance ARS performance, particularly with regard to mass transfer efficiency and heat transfer efficiency, using nanofluids. The stability of nanofluids is examined in this work as it plays a significant part in improving heat transfer for potential future uses. Analytical model’s measurement methods and characterization of nanofluids following one- or two-step method preparation are examined. This paper outlines current findings on synthesis, thermophysical features, heat transmission, pressure drop characteristics, potential uses and difficulties in employing nanofluids in ARS.

To boost the efficacy of a refrigeration system, researchers have imported nanoparticles into refrigerants in recent years. This paper comprehensively reviewed the properties, heat transfer performance, and system performance of nano-added refriger-ants in recent years. This article likewise assists with recognizing the gap in past research works and explores the possibilities for additional work. Refrigerant R134a charged with the nanoparticles TiO2 has the highest value of coefficient of perfor-mance which is 63.5% higher than that of Al2O3 nanoparticle charged R134a. Charging of the nano-refrigerants has enhanced the heat transfer performance of vapour compression refrigeration systems, particularly in the pool and nucleate boiling heat transfer. The heat transfer coefficient of R134a-based nano-refrigerant is enhanced by 42% and 30.2% with CuO and TiO2 nanoparticles respectively. The inclusions of nanomaterials, concerning their physical phenomena, influencing the vapour compression refrigeration system are confined in this paper

The present study elucidates the design and experimentation of a minichannel evaporator in an R134a vapour compression refrigeration system for electronics cooling applications. In the current study, a calculation module was developed to design a minichannel evaporator to keep the surface temperature of the chip below a certain value for reliable operation conditions in electronic cooling applications. In the calculation module, the conventional-scale heat transfer correlation was used to predict the surface temperature of the chip. On the other hand, the conventional-scale and microscale pressure drop correlations were tested to assess the pressure drop in the minichannel evaporator. The proposed calculation module was verified using experimental tests for different heat loads. It was found that the proposed calculation model predicted very well the experimental data of the surface temperature of the chip for all heat input. The calculation module with micro-scale pressure drop correlation predicted well the experimental pressure drop data in the minichannel evaporator for all heat loads. Moreover, the effects of the degree of subcooling, superheating degree and condensation temperature on the surface temperature of the chip and pressure drop in the minichannel evaporator were investigated to determine optimum operating conditions at different cooling capacities using the calculation module. The results showed that the increase in the degree of subcooling enhances the performance of the minichannel evaporator. On the other hand, the lower degree of superheating and condensation temperature yielded better performance for the minichannel evaporator. The feasibility of the results for electronic cooling applications is discussed based on the findings.

The world’s energy needs have become important in the last decades. However, energy consumption in developed countries is increasing every year. Around 40% of the world’s energy consumption comes from buildings. The majority of this rate is due to the energy consumed by heating, cooling, and air conditioning systems. Many detailed studies have been conducted on energy efficiency in these systems where energy consumption is so high. Small improvements in these systems would lead to large energy savings on a global scale. When heating, cooling, and air conditioning systems are examined in detail, compressors consume the largest energy consumption. Interventions that affect compressor performance will yield results that are more positive. The performances of mono and binary nanolubricants acquired from various nanoparticles (Al 2 O 3 , SiO 2, and B) used in different fractions (0.5 mass% and 1 mass%) in the vapor compression refrigeration system (VCRS) were evaluated in this study. As a result, a 14.81% increase in the COP of the system was obtained in 1 mass% Al 2 O 3 -SiO 2 binary nanolubricant compared to POE. The compressor’s energy consumption in the experimental system decreased by 19.53% with 1 mass% Al 2 O 3 -SiO 2 binary nanolubricant referred to POE. An improvement of 13.58% was achieved in 1 mass% Al 2 O 3 -SiO 2 binary nanolubricant when the exergy efficiency of the VCRS was referred with POE. The best exergoeconomic performance was seen in 1% Al 2 O 3 -SiO 2 binary nanolubricant with 13.22% increase compared to POE. The best environmental performance was acquired with 19.53% reduction in 1 mass% Al 2 O 3 -SiO 2 binary nanolubricant. Consequently, the binary nanoparticle positively affects the VCRS performance in many aspects.

Air conditioning and refrigeration have become necessary in modern life, accounting for more than 7.8% of greenhouse gases (GHG) emitted globally. Reducing the environmental impact of these systems is crucial for meeting the global GHG emission targets. Two principal directions must be considered to reduce the environmental impact of air conditioning systems. Firstly, reducing the direct effect by looking at less harmful refrigerants and secondly, reducing the indirect effect by searching for options to improve the system efficiency. This study presents the latest developments in the vapor compression cycle and natural refrigerants, focusing on water as a refrigerant. Natural refrigerants, and especially water, could be the ultimate solution for the environmental problems associated with the operation of vapor compression cycle (VCC) cooling systems, including ozone depletion (OD) and global warming (GW). Reducing the environmental impact of building cooling systems is essential, and the recent system improvements made to enhance the system coefficient of performance (COP) are thoroughly discussed in this paper. Though the cycle improvements discussed in this work are essential and could increase the system efficiency, they still need to solve the direct environmental impact of refrigerants. Accordingly, this paper suggests that natural refrigerants, including water, are the most suitable strategic choice to replace the current refrigerants in the refrigeration and air conditioning industry. Finally, this study reviews the latest VCC system improvements and natural refrigerants in order to guide interested researchers with solutions that may reduce the environmental impact of VCC systems and suggest future research areas.

This study presents a review of advances made in evaporative cooling technologies, emphasizing their application in indoor thermal comfort. It highlights that the rising demand for cooling has primarily been met by conventional mechanical vapor compression systems. However, these systems face two significant issues: high electrical energy requirements and the use of refrigerants like chlorofluorocarbons (CFCs) and hydrofluorocarbons (HFCs), which contribute to ozone layer depletion and global warming. The findings indicate that evaporative cooling technology is a promising alternative due to its low energy demand and potential to integrate renewable energy, therefore enhancing its environmental benefits. The study also details various evaporative cooling technologies, recent improvements in their performance, practical applications, challenges, and opportunities for providing indoor thermal comfort.