- A stepped short tube orifice has been proposed as a replacement for the expansion mechanism in a residential refrigerator that runs on R-290. The present work is primarily concerned with the impacts of stepped short tube orifices on system characteristics such as net refrigeration effect, compressor effort, pull down time, and coefficient of performance. A stepped short tube orifice is made up of two short tube orifices linked serially and having varying sizes. It is used as an extension to the capillary tube in the refrigeration system. A stepped short tube orifice is built and fitted to a home refrigerator in this experiment. The experiments must be done on a home refrigerator equipped with a stepped short tube orifice, R -290 refrigerant, and a 0.5% weight SiO 2 nanoparticle. Following the completion of all trials, the effects of the stepwise short tube orifice on a residential refrigerator were studied using comparison charts. The results indicate that the performance of t he home refrigerator with stepped short tube orifice and SiO 2 nano particle inclusion was much better than the domestic refrigerator without stepped short tube orifice Index ed Terms - stepped short tube orifice, R290 Refrigerant, Nano lubricant, Net refrigeratio n effect. I. INTRODUCTION Compression refrigeration cycles take use of the fact that when strongly compressed fluids at a specific temperature are allowed to expand, they tend to get cooler. If the pressure difference is sufficient, the compressed gas will be hotter than our cooling source (for example, outside air), while the expanded gas will be colder than our targeted cold temperature. Fluid is utilised to cool a low temperature environment and to reject heat to a high temperature environment in this situation. There are two advantages to vapour compression refrigeration cycles. To begin, because it takes a significant quantity of thermal energy to convert a liquid to a vapour, a significant amount of heat may be eliminated from the item being cooled. Second, the isothermal characteristic of vaporisation enables heat to be extracted without raising the working fluid's temperature to that of the object being cooled. This indicates that the heat transfer rate stays high, because the rate of heat transfer dec reases when the working fluid temperature approaches that of the surroundings. Suction line heat exchanger installed between the condenser outlet and compressor intake to maximise net refrigeration effect by subcooling liquid refrigerant at the condenser o utlet and superheating vapour refrigerant prior to entering the compressor. Nanofluids or nano -refrigerants are made by suspending nanoparticles (1 -100nm) in conventional fluids or compressor base oils. The capacity for heat transmission was improved by em ploying nanofluids, since the thermal conductivity of nano lubricants was superior to that of base oils. II. REVIEW OF THE LITERATURE Numerous scientists have examined the vapour compression refrigeration system (VCRS) and the effect of performance paramete rs on the system by modifying or adding components to the cycle, as well as by incorporating nanoparticles into the compressor lubricating oil. [1] Bandgar, M.S., and Kare, R.N. The performance of a vapour compression refrigeration system was tested utilis ing nanoparticles combined with polyol ester (POE) oil / mineral oil (MO) as a nano lubricant and R600a as the refrigerant. To create © JUL 2021 | IRE Journals | Volume 5 Issue 1 | ISSN: 2456 -8880 IRE 170 2875 ICONIC RESEARCH AND ENGINEERING JOURNALS 314 the Nano lubricants, POE Oil / Mineral Oil is combined with Silica (SiO 2) Nano particles using an ultrasonic sonication an d stirring procedure. The compatibility of POE -Mineral oil with Silica (SiO 2) nano powder (concentration of 0.5 percent by mass fraction) as a nano lubricant was investigated. It produces superior outcomes at a mass fraction of 0.5 percent for all Nano -oil combinations. When POE oil is replaced with a combination of (MO+0.5 percent Silica), the time required to lower the temperature of water by 10 oC is reduced and the power consumption is reduced by 12.02 %. When POE oil is replaced with a Nano lubricant ( mineral oil (MO) + 0.5 percent SiO 2), the coefficient of performance increases by 11.66 %. [2] Nilesh S. Desai and P.R. Patil: SiO 2 Nano -oil is presented as a potential lubricant for improving the compressor performance in VCRS systems. Nano -oil is added t o compressor oil at particular quantities of 1%, 2%, and 2.5 % (by mass fraction). The performance of the VCRS was studied with the addition of Nano lubricant, and the results indicated that the system's COP (Coefficient of Performance) rose by 7.61%, 14.0 5%, and 11.9%, respectively, with various mass concentrations of 1%, 2%, and 2.5 percent. Energy savings ranging from 7.03 % to 12.3 % are possible when utilising Nano -lubricant in place of conventional refrigerants. [3] Domanski, P. A., and Didion: By ins talling a suction line/liquid line heat exchanger in a simple vapour compression refrigeration system, the influence of performance parameters is investigated. It evaluates the cycle parameters and thermodynamic characteristics of the refrigerant to determ ine if the installation improves the COP and volumetric capacity. Suction line/liquid line heat exchangers are used to sub cool high -pressure refrigerant at the price of superheating vapour entering a compressor. [4] Domola S. Adelekan: They experimented w ith varying the mass charge of LPG gas in a home refrigerator's R -134a compressor. At steady state, performance tests were conducted. The results indicate that all tested nano lubricant mixtures operate safely and effectively in home refrigerators without modifying the capillary tube length, but require appropriate optimization. [5] Senthilkumar D: The effect of silicon carbide nanoparticles on the R134a refrigerant used in VCRS is studied in this study. The refrigeration system's coefficient of performance has increased significantly as a result of the nano -improved refrigerant's thermophysical characteristics and heat transfer capabilities. The increase in thermal conductivity of SiC nanoparticles results in a decrease in power usage. As a result, t he system's operating costs decrease. The freezing capacity of the system rises when the rate of cooling is increased. The use of Nano refrigerants reduces the risk for global warming by reducing the refrigerant's overall mass fraction. Suction and deliver y pressures increase when nanoparticles are added to the refrigeration process. [6] Redhwan: The viscosity and thermal conductivity of SiO 2 nanoparticles dispersed in polyalkylimide glycol (PAG) lubricants were examined and compared to those of Al 2O3 nano particle lubricant at 0.2 -1.5 percent volume concentrations and 303 -353 K operating temperatures. This paper proposed correlations for the viscosity and thermal conductivity of SiO 2 nano lubricants at various concentrations and temperatures. Volume concentrations of SiO 2 and Al2O3 nano lubricants are permitted in car air conditioning compressors of up to 1% and 0.3%, respectively. Thermal conductivity of SiO 2 nano lubricants at a concentration of 1% is greater than that of Al 2O3 nano lubricants at a concentration of 0.3 %. [7] R.RejiKumar: The performance improvement of a home refrigerator using R600a and mineral oil/Al 2O3 nanoparticles was tested in this study. It was discovered that when POE oil is replaced with a combination of mineral oil and alum inium oxide (Al 2O3) nanoparticles, freezing capacity increases and power consumption decreases by 11.5 %. It is conceivable to use aluminium oxide nanoparticles in refrigeration systems, and the refrigeration system's coefficient of performance (COP) rises by 19.6 % when standard POE oil is substituted with nano - refrigerant. III. EXPERIMENTAL SETUP In a vapour compression refrigeration cycle, refrigerant expands in a capillary tube from the condenser to the evaporator. It is proposed in this experiment to a dd a stepped short tube orifice as an expansion extension to the capillary tube. A stepped short tube orifice is a passive device that transfers pressure energy to kinetic energy without the addition of external labour. The current study proposes to © JUL 2021 | IRE Journals | Volume 5 Issue 1 | ISSN: 2456 -8880 IRE 170 2875 ICONIC RESEARCH AND ENGINEERING JOURNALS 315 expand the refrigerant from the condenser pressure to the evaporator pressure using both a stepped short tube orifice and a capillary tube in order to determine the effect of the stepped short tube orifice. The following steps were taken during the course of the current experimental activity. • Nano lubricant preparation: In refrigeration systems, SiO 2 nanoparticles are added to the compressor lubricant. POE (Polyol ester) oil is the most often used lubricant in refrigeration systems. This nano lubricant will be prepared in two steps. To begin. By direct mixing, 5% weight SiO 2 nanoparticles are introduc ed to the Poe oil. After direct mixing, the mixture is agitated for 10 hours using a magnetic stirrer. The mix is then vibrated for 15 hours in an ultrasonic homogenizer. This is to avoid clustering of nanoparticles within the mix. To get a homogeneous and stable combination, adequate stirring using an ultrasonic vibrator is required. The produced nano lubricant is then injected into a home refrigerator's compressor. • Incorporating the nozzle in the vapour compression system: The compressor, condenser , expansion device, stepped short tube orifice, and evaporator are all combined into a modified VCRS. Pressure and temperature gauges are fitted to monitor the functioning of the vapour compression system. At the condenser's output, a stepped short tube or ifice is included. • Experimental design: This stepped short tube orifice will be machined in two stages. In the first stage, a 15mm copper rod will be machined to a length of 13mm by the facing operation. Following the facing operation, the component will be turned to decrease the diameter from 1 0mm to 7.5mm. This copper rod must be faced and turned on a lathe machine. Orifices of 4mm and 2mm diameter will be drilled into copper rods of 6mm and 3mm lengths using a drilling machine. Attach this produced stepped short tube orifice to the system at t he condenser's output. Pressure gauges and thermocouples will be installed at the schematic diagram's designated places. After that, put 40g of R -290 refrigerant into the compressor of an experimental home refrigerator. Following refrigerant charge, a leak test must be done to identify any leaks. If no leaks are discovered, operate the system from ambient to -10oC evaporator temperature. Simultaneously record temperature and pressure readings. Continue running the system until the evaporator reaches -10oC and record the pull -down time. Now, replace the lubricating oil (POE oil) with a © JUL 2021 | IRE Journals | Volume 5 Issue 1 | ISSN: 2456 -8880 IRE 170 2875 ICONIC RESEARCH AND ENGINEERING JOURNALS 316 nano lubricant POE -SiO 2 at a concentration of.5% by weight, or.2g/L SiO 2. Again, make a note of the relevant pressure temperature and pill down time measurements in the system. Collect all pressure and temperature readings, then create a P -h chart and extract enthalpy values for calculating purposes. IV. RESULTS AND DISCUSSIONS • Net Refrigeration Effect Comparison (NRE): The net cooling effect of a vapour compression refrigerat ion system operating on R -290 with a stepped short tube orifice has been enhanced by 5.76%, which is more than the cycle R290 without the stepped short tube orifice. Additionally, when SiO 2 nanoparticles are used as a lubricant, the net refrigeration effec t is enhanced to 7.11%, compared to the vapour refrigeration system without stepped short tube aperture. This increase in net refrigeration effect is accomplished by converting the refrigerant's available pressure energy to kinetic energy. • Comparison of C ompression work: Compression work in a vapour compression refrigeration system operating on R -290 has been reduced by 6.32 % with the addition of a stepped short tube orifice. That compressor effort is less than that required in the R290 cycle without th e Stepped short tube orifice. Additionally, when SiO 2 nanoparticles are used as a lubricant, the compression effort is reduced by 10.1 % compared to the vapour refrigeration system without stepped short tube orifice. Compression work will be reduced as a r esult of reduced friction in the compressor components owing to the introduction of nanoparticles. • Comparison of Pull -down time: Pull-down time in a vapour compression refrigeration system operating on R -290 has been reduced by 3.77% with the addition of a stepped short tube orifice. This time is shorter than the time required for cycle R290 without the Stepped short tube orifice. Additionally, when SiO 2 nanoparticles are used as a lubricant, the pull-down time is enhanced by 9.43% compared to the vapour refrigeration system without stepped short tube aperture. This improvement in pull -down time is accomplished by converting the refrigerant's available pressure energy to kinetic energy, which increases the refrigerant flow velocity and therefore decreases the pull-down time. © JUL 2021 | IRE Journals | Volume 5 Issue 1 | ISSN: 2456 -8880 IRE 170 2875 ICONIC RESEARCH AND ENGINEERING JOURNALS 317 • Comparison of Coefficient of Performance (COP) The coefficient of performance of a vapour compression refrigeration system operating on R - 290 has been improved by 15.9% by including a stepped short tube orifice. This performance coeffi cient is greater than the performance coefficient of cycle R290 without the Stepped short tube orifice. Additionally, the addition of SiO 2 nanoparticles to the lubricant increases the coefficient of performance to 19.19%, compared to the vapour refrigerati on system without stepped short tube aperture. After all calculations are completed, it is noticed that the net refrigeration effect is enhanced while the compressor effort is lowered, therefore increasing the coefficient of performance. CONCLUSION Experiments has been performed to investigate the effects of stepped short tube orifice which is incorporated as extension to the expansion device capillary tube to the domestic refrigerator running on the principle of vapour compression refrig eration system with refrigerant R -290. The results have been obtained for the experiments are followed as stated below. 1. The vapour compression refrigeration system, using refrigerant R -290, the Net refrigeration effect is increased to 5.76% with SSTO t han the system without SSTO. The Net refrigeration effect is further increased to 7.1% with SSTO and inclusion of SiO 2 nano particle than the without SSTO. 2. The Compressor work is decreased by 6.3% with SSTO than the system without SSTO. The Compressor work is further decreased by 10.1% with SSTO and inclusion of SiO 2 nano particle than the without SSTO. 3. The Pull -down time is decreased by 3.7% with SSTO than the system without SSTO. The Pull - down time is further decreased by 10.1% with SSTO and inclu sion of SiO 2 nano particle than the without SSTO. 4. The Coefficient of performance is increased to 15.9% with SSTO than the system without SSTO. The coefficient of performance is further increased to 19.19% with SSTO and inclusion of SiO 2 nano particle t han the without SSTO