Utilização de nanopartículas de diamante como aditivo lubrificante em sistema de refrigeração

Abstract

The present work deals with the use of nanolubricants based on synthetic POE oil and Diamond nanoparticles in a refrigeration system. An experimental bench has been developed with a 5-ton (17.58 kW) cooling capacity, in order to evaluate the properties of the system, such as the cooling capacity, the power consumption, the discharge temperature, the oil sump temperature of the compressor and the performance of nanolubricants with of 0.0%, 0.1% and 0.5% diamond nanoparticles mass concentration. The tests have been performed for R410A and R32 refrigerants varying the evaporation temperature from -7 °C to 7 °C and the compressor operation frequency from 45 to 60 Hz. The condensation temperature remained constant at fixed value of 41 °C. The experimentally density, the dynamic viscosity and the thermal conductivity of nanolubricants have also been measured. Linear reciprocating sliding wear tests have been performed in order to evaluate the performance of diamond nanoparticles as lubricant additive. From the R410A experimental results, the addition of diamond nanoparticles to the refrigeration system have slightly increased the cooling capacity and the coefficient of performance, while the discharge temperature and the oil sump temperature of the compressor have reduced. Conversely, R32 refrigerant with POE/Di nanolubricants has not shown remarkable enhances in terms of cooling capacity and compressor temperatures under the evaluated conditions, however, in terms of the compressor power consumption, a slightly tendency to reduce has been noticed.