To Study the Performance of Nano-Refrigerant (R134a+Al2O3) based Refrigeration System

Abstract

An experimental investigation into the performance of a vapour compression refrigeration system using pure refrigerant (R134a) and nanorefrigerant (R134a+Al2O3) has been conducted at the Mechanical Engineering Department, Thapar University, Patiala. The experimental apparatus has been assembled for this purpose which is similar to 165 litre commercial domestic refrigerator. It has already been known that the performance of the refrigeration system depends upon the heat transfer characteristics of the refrigerant being used. Literature review shows that the heat transfer characteristics of refrigerant R134a are poor as far as its thermal performance is concerned. In order to improve the thermal performance of the conventional refrigerant, an attempt has been made by injecting the nanoparticles along with the refrigerant into the refrigeration system. Aluminium Oxide (Al2O3) nanoparticles of 20 nm diameter are used with two different weight fractions (0.5 and 1%) in base refrigerant R134a. Experiments have been conducted with two refrigerant volume flow rates (6.5 and 11 LPH), two evaporator heat fluxes (at 15 ºC and 30 ºC) and at two ambient temperatures (21 ºC and 28 ºC). Addition of Aluminium Oxide (Al2O3) nanoparticles into the refrigerant R134a is found to be effective and a significant improvement in the thermo physical properties and heat transfer characteristics of the refrigerant is observed which results improvements in the performance of the refrigeration system. It has been also found that the refrigerant temperature drop across the condenser and temperature gain across the evaporator is higher when nanoparticles based refrigerant is used. The coefficient of performance (COP) is also found to be improved for 0.5% weight fraction but reduces with high weight fractions (1%) of nanoparticles in refrigerant. Moreover the nanorefrigerant (R134a + Al2O3) increases the cooling capacity (time to achieve a desired temperature) of refrigeration system. The experimental studies indicate that the refrigeration system works well with nanorefrigerant. Thus, using aluminium oxide nanoparticles along with refrigerant in refrigeration system is feasible and within the investigated limits it gives a significant improvement in performance of the system.