Film thickness and traction measurements of refrigerant R1233zd used as lubricant in elastohydrodynamic conditions

Abstract

International audienceThis study presents film thickness and friction measurements of the refrigerant R1233zd (E-1-chloro-3,3,3,trifluoropropene-1) in a tribological contact. For the film thickness, optical interferometry technique with glass–steel contact is used in a ball-disc configuration, whilst for the traction measurements (Stribeck and traction curves), a contact ceramic ball–steel disc is used. In both cases, the Wedeven Associates Machines-5 tribometer is employed. An attempt to model the film thickness results is also carried out. The model gives a reasonably good prediction with respect to the experiments

An experimental and modeling assessment of the HCFC-R123 refrigerant capabilities for lubricating rolling EHD circular contacts

“…As shown in Figures 5 and 8, this could be due to the occurrence of the minimum film thickness over a very restricted area, compared with classical EHL shape. These results are also consistent with those presented by Morales-Espejel et al 17 where for another refrigerant quite low boundary friction coefficients were measured.…”

“…This leads to consider the regime for most of the experimental cases as a soft mixed lubrication regime, which is a positive point for the use of pure refrigerants in hybrid contacts for instance, e.g., in rolling bearings composed of steel rings and ceramic balls, as suggested by MoralesEspejel et al 15 and studied later for the first time. 17 Furthermore, at low entrainment speed (42 m/s), the central film thickness appears to be much less affected than h m by the occurrence of such regime because h c is fairly well predicted by both the full numerical model and the Hamrock and Dowson expression. At high u e values, another phenomenon can interfere: the combination of a high vapor pressure with a relatively low boiling temperature for the refrigerant, together with high speed at the contact opening should lead to evaporation and thus production of HCFC-R123 vapor in the exit zone, that can be in turn dragged into the contact inlet by the high rotational speed (several thousand revolutions per minute) of the ball.…”

“…Habchi et al 16 provided a numerical analysis and showed that there was no theoretical reason for not lubricating EHD contacts with ultralow viscosity fluids like refrigerants once a certain level of film thickness is guaranteed. Very recently this new concept was experimentally verified by Morales-Espejel et al 17 who reported film thickness and friction results obtained with pure trans-1-chloro-3,3,3-trifluoropropylene (HCFO-1233zd, one of the refrigerants of the last generation). They also compared their measurements with analytical and numerical predictions, but assuming nonmeasured rheological properties of the fluid.…”

Progress in rolling bearing technology for refrigerant compressors

“…Friction properties are difficult to measure in pure refrigerants and there is no extensive literature on the subject. However, in Morales-Espejel et al 19 boundary friction coefficients of bl % 0:07 were reported for HFO-1233zd in a hybrid contact (steel-Si 3 N 4 ). Rheological (non-Newtonian) properties and fluid film friction have not been reported to the knowledge of the authors.…”

“…This was a critical test result, which opened up the possibility to use pure refrigerant as a lubricant for special rolling bearings (PRL technology). Since then, research and application development have continued and lead to several additional product features enabling reliable long-term operation, [17][18][19][20] currently in industrial use.…”