An estimation of the energy efficiency of refrigeration systems operating on ammonia with soluble lubricant

The authors have obtained a new synthetic lubricant (XMPA) which is soluble in ammonia. The main tasks of the study were the as follows: experimental and computational studies of the thermophysical properties of ammonia-XMPA-1 solutions, and the estimation of the energy efficiency of ammonia refrigerating systems which contain soluble lubricant. The cubic equations of state were obtained on the basis of our experimental data on the phase in NH3-XMPA-1 and density, heat capacity and saturated vapour pressure of the refrigerating oil. The caloric properties of the mixture in liquid and gaseous phases were calculated, and an estimation of the energy efficiency of the refrigerating cycle for pure NH3 and the mixture NH3-XMPA-1 were made. It was shown that in this case the condensation-and-boiling-pressures ratio was lowered, as the temperature of ammonia at compressor exit does, and the thermophysical coefficient was increased. Boundary problem was formated modelling the process of freezing-on ice in drum ice-generator when the mixture NH3-XMPA-1 worked as a refrigerant. A solution to the boundary problem was obtained. On this basis an output of ice-generator was calculated. It was shown that using ammonia with the soluble lubricant in the flake ice production led to a decrease in energy expenditure of 20-30%. Obtained results show the potential for using the refrigerating oil XMPA-1 as worked out by the authors.