PERFORMANCE ANALYSIS OF A DOMESTIC REFRIGERATOR USING CUO -R600A NANO - REFRIGERANT AS WORKING FLUID

The application of nano refrigerants in refrigeration system is considered to be a potential way to improve the energy efficiency and to make the use of environment-friendly refrigerants. In this paper we report a method that uses natural gas to enhance the energy efficiency of refrigeration retorting method employing CuO - R600a as alternate refrigerants. Thus reliability and performance of nano refrigerant in the working fluid have been investigated experimentally. A new nano refrigerant is employed in the domestic refrigerator. The performances of the nano refrigerant, such as the cooling capacity, energy efficiency ratio were determined. The results indicate that the mixture of R600a with nano particles (CuO) works normally in the domestic refrigerator. The cooling capacity of the domestic refrigerator is increased by 10 - 20% by using nano - refrigerant. The performance calculation of suction pressure, discharge pressure at no-load, part-load, fully-loaded condition, and running time, COP. INTRODUCTION Nano-refrigerant was proposed on the basis of the concept of the nanofluids, which was prepared by mixing the nanoparticles and traditional refrigerant. There were three main advantages followed for the nanoparticle used in the refrigerator. Firstly, nanoparticles can enhance the solubility between the lubricant and the refrigerant. For example, Wang and Xie found that TiO2 nanoparticles could be used as additives to enhance the solubility between mineral oil and hydro fluorocarbon (HFC) refrigerant. The refrigeration systems using the mixture of R134a and mineral oil appended with nanoparticles TiO2, appeared to give better performance by returning more lubricant oil back to the compressor, and had the similar performance compared to the systems using polyol-ester (POE) and R134a. Secondly, the thermal conductivity and heat transfer characteristics of the refrigerants should be increased, which have been approved by a lot of investigations. For instance, Jiang et al measured the thermal conductivities of CNT-R113 nano-refrigerants and found that the measured thermal conductivities of four kinds of 1.0 vol.% CNT- R113 nano-refrigerants increase 82%, 104%, 43% and 50%, respectively. Wang et al. carried out an experimental study of boiling heat transfer characteristics of Al2O3 nanoparticles dispersed in R22 refrigerant, and found that nanoparticles can enhance the heat transfer characteristic of the refrigerant, and the bubble size diminish and move quickly near the heat transfer surface. Wu et al. investigated the pool boiling heat transfer of the R11 refrigerant mixed with nanoparticles TiO2, and the results indicated that the heat transfer enhancement reached 20% at a particle loading of 0.01 g/L. Park and Jung investigated the effect of carbon nanotubes (CNTs) on nucleate boiling heat transfer of halocarbon refrigerants of R123 and R134a. Test results showed that CNTs increase nucleate boiling heat transfer coefficients for these refrigerants. Especially, large enhancement up to 36.6% was observed at low heat fluxes of less than 30 kW/m2. Peng et al. found that the heat transfer coefficient of CuO-R113 was larger than that of pure refrigerant R113, and the maximum enhancement of heat transfer coefficient was 29.7%. Ding et al. investigated the migrated mass of nanoparticles in the pool boiling process of both nano-refrigerant and nanorefrigerant-oil mixture, and found that the migrated mass of nanoparticles and migration ratio in the nano-refrigerant were larger than those in the nano-refrigerant-oil mixture. Finally, nanoparticles dispersed in lubricant should decrease the friction coefficient and wear rate. Lee et al. investigated the friction coefficient of the mineral oil mixed with 0.1 vol.% fullerene nanoparticles, and the results indicated that the friction coefficient decreased by 90% in comparison with raw lubricant, which lead us to the conclusion that nanoparticles can improve the efficiency and reliability of the compressor. Jwo et al. carried out the performance experiment of a domestic refrigerator using hydrocarbon refrigerant and 0.1 wt. % Al2O3-mineral oil as working fluid, the results indicated that the power consumption was reduced by about 2.4%, and the coefficient of performance was increased by 4.4%. In the previous work, the author has investigated the basic characteristics of the TiO2-R134a nano-refrigerants, including the dispersion behavior, thermal conductivity and flow boiling heat transfer. The performance of a domestic refrigerator with nanoparticles added was also investigated. In the former experiment, the nanoparticles were added into the refrigeration system in two different ways. In one way the nanoparticles were added to the refrigeration system by first adding them into the lubricant to make a nanoparticle-lubricant mixture. Then, the mixtures were put into the compressor as the lubricant. In the other way nanoparticles and traditional refrigerant were mixed directly to make nano-refrigerant. The results of both of the ways had showed the better performance of the refrigerator with nanoparticles