Methods based on a semi-empirical model for simulating scroll compressors with HFC and HFO refrigerants

Assuring Reliability of Compressors Using HFC Refrigerants

In Japan, the refrigerant used in room air-conditioners has been changed from HCFC-22 (R-22) to R-410A, a blend of HFC-32 and HFC-125 (50/50 vt%), in order to protect the ozone layer. Generally, the miscibility between the refrigerant and refrigeration oil must be assured, because the oil needs to return to the compressor from the refrigeration cycle and lubricate the sliding parts. Alternative...

Lubrication Analysis of Rotary Compressors for HFC Refrigerants

In this study, a practical numerical analysis has been developed in order to investigate the lubrication characteristics between a rolling piston and a crank of rotary compressors. This analysis is treated as a coupled problem of the momentum equations and the Reynolds equation of oil film. Using this analysis, the lubrication characteristics between the rolling piston and the crank for 2-cylin...

Simulating Scroll Compressors Using a Generalized Conjugate Surface Approach

HFC & HC Blends as Refrigerants

The blends formed mixing hydrofluorocarbons (HFC) and hydrocarbons (HC) can be classified as semi-natural refrigerants since, by optimizing the composition, it is in principle possible to adapt basic features such as GWP, TEWI and flammability to the industrial and environmental requirements. However, the energetic efficiency must be competitive with the traditional refrigerants. To evaluate th...

mortality forecasting based on lee-carter model

over the past decades a number of approaches have been applied for forecasting mortality. in 1992, a new method for long-run forecast of the level and age pattern of mortality was published by lee and carter. this method was welcomed by many authors so it was extended through a wider class of generalized, parametric and nonlinear model. this model represents one of the most influential recent d...