Performance evaluation of a nanorefrigerant based vapor compression refrigeration system

Abstract

In the era of technological advancements in various fields, refrigeration systems play a vital role to fulfill the human comfort and industrial needs. The various researches are being carried out by researchers in order to improve the performance of these systems. In the presented work, an attempt has been made to improve the performance of such systems. Our, present study, on experimental investigations into the performance of a nanorefrigerant (hydrocarbon+Al2O3) based refrigeration system, is conducted at the Mechanical Engineering Department, Thapar University, Patiala. A standard experimental setup was build up and made to function under varying load conditions. The performance of the refrigeration system depends upon the various factors like; individual component’s performance, nature and properties of the refrigerant being used, environmental conditions etc. Experiments have been conducted to investigate the effect of nanoparticles on the performance of the refrigeration system. After deliberations & discussion it has been decided to use hydrocarbon as a base refrigerant which is alternative for R134a refrigerant, reason being its ODP and GWP threats if it continued in use for long time. Hydrocarbon R290/R600a refrigerant can be used as a replacement of R134a due to its almost similar properties (thermodynamic and physical properties) and eco-friendly nature. But, it has been found that its heat transfer capacity is limited and it also consumes more power when taken to refrigeration cycle, which is like as that of conventional refrigerants. In addition to this, choice of a particular refrigerant also affects the temperature across condenser and evaporator of the refrigeration system, time taken to reach a particular temperature in the evaporator or freezing capacity. In order to make an enhancement in its performance, an experimental study has been conducted by using nanorefrigerant rather than the conventional refrigerant. Nanoparticles are injected along with the R290/R600a to increase the heat transfer capacity, to reduce the power consumption and thereby to increase the performance of the system. Aluminium oxide (Al2O3) nanoparticles of size (20-30) nm have been used in the refrigeration system with its three different concentrations (0.20, 0.30 and 0.40 gm). Data is collected for 3.4 LPH volume flow rate and for two heat fluxes in evaporator supplied at 25–26 0C and 35–36 0C. It has been found that addition of aluminium oxide (Al2O3) nanoparticles to the refrigerant result in an improvement in the thermo physical properties iv and heat transfer characteristics of the refrigeration system. There is more temperature drop across the condenser for the nanorefrigerant (14.4% – 20%) compared to pure R290/R600a hydrocarbon refrigerant. Similarly, a gain in the evaporator temperature (2.33% –5.55%) has been observed. An improvement in COP (3.68% – 11.05%) is also observed during the investigations. This is achieved under 25–26 0C evaporator temperature load conditions. Similar improvements are also observed when refrigeration system is operated at 35–36 0C evaporator temperature load conditions. A reduction in the power consumption (13.6% - 30.04%) along with faster cooling (from 400C – 250C) is also achieved when nanorefrigerant is used. The experimental studies indicate that the refrigeration system with nanorefrigerant works normal like any conventional refrigeration system. Thus, aluminium oxide (Al2O3) nanoparticles can be used to improve the performance of a hydrocarbon based refrigeration system under investigated conditions.