Influence of ZnO nano-refrigerant in R134a on performance compression systems of refrigeration

In the era of technological, advancements in various fields, refrigeration systems have a significant function in meeting human needs, and continuous research must be done by many researchers who are working to enhance the performance of these systems. Here, an attempt was made to enhance system performance. In the present work, the investigational investigations of ZnO nanoparticles at three amounts (O.2 %, 0.4 %, 0.6 %) are dispersed in polyalkylene glycol (PAG) oil with R134a refrigerant and it is test effect of three temps of water in the evaporator (40degree centigrade, 50-degree centigrade, 60-degree centigrade), it is observed that there is a decrease in the evaporator temp, an enhancement in the thermophysical characteristics of the nano-refrigerant, and maximum an enhancement in the performance coefficient is 24.92 percent at the temp of the water in evaporator 40-degree centigrade and 0.6 percent amount of nanoparticles, while, the power usage is reduced by 3 to 19 percent, and the temp is reduced by (40-degree centigrade – 17-degree centigrade). The investigational investigates show that the systems of refrigeration with nano-refrigerant works normally, just like any other system of refrigeration. Thus nano-particles can be applied to enhance the performance of hydrocarbon-based systems of refrigeration under test conditions .


Introduction
Thermo-physical characteristics of matter are very important in cooling and heating applications. It has been discovered that the efficiency of any device is primarily determined by its architecture, depending on the ability to conduction thermal, viscosity, and other factors the basic heat and mass of gases and liquids are integrated into the system [1][2][3][4]. Conventional fluids have a low ability to conduction thermal, and poor heat transfer, capability, limiting their efficiency. As result, there is an ongoing need to produce reliable and fluids capable of dealing with high heat transfer rates. Minor strong additives, usually in the micrometer range, are an excellent option, it has been utilized to enhance the thermal characteristics of fluids [5][6][7]. M.E. Haque, et al. [8] Investigationally, the addition of various sizes of (AL2O3 and TiO2 )of nano-particles to a lubricant (POE) with two various amounts (0.05 -0.1 v percent ) was studied. Then tests of freezing capacity and energy usage of your refrigerator was a performance. The results demonstrated an increase in the performance factor of the refrigerator 19 percent and 22 percent at mentioned amounts, as well as the energy usage at (0.1 percent) amount of AL2O3 and TiO2 (27.73 percent -14.19 percent) less than pure oil. From the results of the experiment, we conclude that the performance of the refrigerator is better with nano-lubrication oil compared to pure oil. R.S. Mishra, et al. [9]Studied the investigation of the added various nano-particles of (AL2O3, TiO2, CuO)in various refrigerants (R407c, R134a, R404A) and study the Thermophysical characteristics of nano refrigerant and the performance's coefficient of the system. the result demonstrates the thermal characteristics of the system increases by 15 percent to 94 percent, 20 percent, and 12 to 34 percent respectively and the specific heat is lower in nano-refrigerants compared to the pure refrigerant, the R134a-AL2O3 is highest 34 percent and with utilized various nano-particle and (R404A, R407) refrigerant the resulting enhancement in cop from 3-14 percent and 2 to 12 percent respectively. My work consists of an investigational design model a domestic refrigerator model of vapor compression. Our work focuses on comparing the performance's coefficient, compressor work, and cooling effect by replacing the traditional R134a refrigerant with nano-fluids (PAG + various TiO2 nanoparticle mass fractions) with R134a as a refrigerant. Omer A. Alawi et al. [10]explored the thermal characteristics of nano-particles suspended in refrigerant and lubricating oils. Study the effect of nano-lubricants on phenomena of two phases and boiling. The results demonstrated that nano-refrigerant with TiO2 refrigerators work safely and normally and increase in heat transfer because the nano-particles have a much higher and strengthen the ability to conduction thermal compared with pure refrigerants. In Malaysia, Javari and Saidur [11] looked at the usage of nano-refrigerant in household freezers to decrease Emissions of CO2 and electricity usage. They investigated the impacts of introducing two nanoparticles (AL2O3, TiO2) to the mineral of oil R134arefrigerant with three mass fractions of (0.06 percent,0.1 percent). Their findings indicate the highest savings for energy of 25percent once 0.1 percent TiO2 nanoparticles are applied onto mineral oil R134a, as well as a decrease of almost seven million tons of Carbon dioxide by 2030. The theoretical and practical effects of adding AL2O3-particles with nano-size to the refrigerant were investigated by Soliman et al. [12]. The investigational findings show a 9.11 percent rise in theoretical police and a 10.53 percent increase in real cops. Once nano-particles were utilized as a cooling load, the evaporator heating transfer coefficient expanded by 50percent, and power losses has been decreased by 28 percent. The water heating transfer coefficient increased by 70.83 percent, and energy usage has been decreased by 13.30 percent, according to the theoretical results obtained. The performance pool AL2O3-particles that have a nano size with R134a/polyester was studied by Kedzierski [13]. Three various volume percentages of the mixed lubricant were employed, and R134a has been added to the mixture in a varied mass fraction. Since agglomeration of nano-particles exhibited heat transfer deterioration of about 14 percent, amounts increased by roughly 13 percent, 10 percent, and 9 percent for various combinations. Kuljeett Singh and colleagues [14]. A study of the performance of nano refrigerant (AL2O3+R134a) systems of refrigeration was conducted. With 0.5 percent AL2O3, the performance's coefficient has been shown to increase the most (7.2to 8.5 percent). Once the mass fraction of nanoparticles in the refrigerant cop has been raised to 1percent, it is lower than pure R134a.

The objective of the paper
The goal of this research is to test the performance of a vapor compression system using nano-particles ZnO and R134a as the refrigerant. Depending on the specifications of this research paper, a new vapor compression refrigeration test system was constructed. Three amounts (0.2 %, 0.4 %, and 0.6 %) of ZnO nanoparticles with a size of 50 nm were blended with PAG oil as lubricant and R134a as a refrigerant. The goal of the investigation is to demonstrate how nanoparticles blended with PAG oil can reduce compressor power usage and enhance heat transferability in the system. Once comparing the performance of a system with nanoparticles to the performance of a system with pure refrigerant, the performance coefficient of the system with particles that have nano-size comes out on top.

Experiment setup
Design the refrigeration test rig for compression. The test rig is made up of the compressor, a condenser, a capillary tube, and the evaporator. The reciprocating compressor is hermetically sealed, the evaporator is a cylindrical one in the form of a spiral coil and is fully immersed in water and made of copper. A condenser is a finned coil in a heat exchanger that is also made of copper. A sensor was utilized to measure temps at the inlet and outlet of the main parts. A temp scanner was utilized. An energy meter was utilized at the compressor to find out the amount of energy expended in it. Before charging the device with gas and nano-materials, the system was thoroughly checked for leaks. After the leak test, with the help of a vacuum pump, the device was evacuated of moisture to be charged with the nano-fluid and refrigerant. In this case, use R134a refrigerant. Due to its low ozone layer depletion potential and close thermodynamic characteristics [15,16].

Nano-lubricants preparation:
The nanofluid was prepared by adding a nanoparticle (ZnO) to the base liquid is PAG oil. The weight of the nanoparticles for each amount was calculated from Equation 1, and the required weight was estimated using a sensitive balance and the nanoparticle amount was mentioned in Table 1 and the nanoparticle lubricant was prepared in a two-step manner, by adding a nanoparticle size mass (0.2 percent, 0.4 percent, 0.6 percent) to the PAG oil and placing the mixture on a magnetic stirrer for 1 hour, transferring the mixture to an ultrasonic cleaner. For three hours, the steps can be seen in figure1 After the nano-lubricant has been prepared, it is injected into the compressor through the injection device, and then the compressor is charged with refrigerant, and the process of taking readings begins.

Charging of set up
To avoid the negative impacts of moisture, it must empty the gadget before charging it. The charging of the system is then finished. The nano-fluid is initially applied to the compressor, where it is injected via the service port into the compressor and made to stable for 15-20 min before being charged with R134a. Once the pressure gauge demonstrates, the charging phase must be terminated.

Work of an investigational test rig
Vapor pressure relies on a flowing liquid refrigerant to absorb and remove heat, reject the cooled area, and then reject heat from elsewhere. Figure 2 depicts a conventional single-stage vapor pressure system. An evaporator, a capillary, a condenser, and a compressor all seem to be components of these systems. The temp increases as a consequence. Its heated vapor has been sent to the condenser, where it is cooled into a liquid by passing thru a coil or tube with cold air. Condensed Refrigerant is a kind of refrigerant that is compressed into. In thermodynamics, a saturated fluid is directed thru a capillary tube in which there is a sudden pressure drop, which decreases pressure in the evaporation of a statical flash of the refrigerant element if the cold blend is then directed through the coil from the evaporator in which it absorbs heat from the environment. The coolant evaporated and returns to the compressors to be cooled, and the cycle is repeated [17].

Theoretical analysis
Nano-refrigerant thermo-physical characteristics are computed in two stages. Firstly is calculated the thermophysical characteristics of the nano-particles oil mixture, and this information is utilized to compute the characteristics of nano-refrigerant, and the equations are utilized to calculate the performance of the system

Calculation of nano-lubricant thermo-physical characteristics
The following correlation is utilized to calculate the thermophysical characteristics of nano-lubricant.

Calculation of thermo-physical characteristics of nano-refrigerant
Density of nano-refrigerant

The results and discussion
During the investigational investigation, four cases were considered. Initially, R134a and PAG oil were utilized in the test, and then three amounts of ZnO (0.2 %, 0.4 %, and 0.6 %) nanoparticles were tested with PAG oil and R134a refrigerant. Experimentation was conducted with a vapor compression systems of refrigeration to enhance the performance. The results of the investigational investigates are described below.

A Difference between the compressor's power usage and various amounts of nanoparticles ZnO at temp 50 degrees centigrade
The difference between the power usage of the compressor and various amounts of nanoparticles ZnO at temp 50 degree centigrade demonstrated in figure 5. The power usage once compressor running with nano-lubricant containing (0.2 %, 0.4 %, 0.6 %) ZnO nano-particles are reduced about 9.633 percent, 11.009 percent, and 13.2467 percent. it is found once compared results with pure refrigerant the power usage is decreased at an amount of ZnO increases.        Figure 10 demonstrates the difference between the ability to conduction thermal of pure refrigerant and nanorefrigerant. It is found the enhancement of the ability to conduction thermal at amounts (0.2 %, 0.4 %, 0.6 %t) nano-particles are (4.108 percent, 11.76 percent, 23.16 percent), from results it is found the ability to conduction thermal of nano-refrigerant increased with increase nano-particle amounts once compared with the ability to conduction thermal of pure refrigerant R134a. ZnO R134a Figure 11. The density and amounts

Conclusion
In this study, an investigational investigation of a Vapour Compression System of refrigeration with ZnO nanoparticles in PAG oil and R134a refrigerant is carried out. The size of the nanoparticles (ZnO) was 50 nm, and three amounts were utilized (0.2 percent,0.4 percent,0.6 percent ). In this study, three water temps (40, 50, and 60 degrees centigrade) were utilized in the evaporator. The enhancement in the performance's coefficient is the greatest rise of the system, at 24.92 percent, according to the findings. and a max enhancement of 15.385 percent in refrigeration impact The compressor consumes 19.048 percent of the total energy utilized. It's accessible at a 0.6 percent nanoparticle amount. Once pure refrigerant R134a is compared to the aforementioned findings, the performance's coefficient and thermophysical characteristics increase.