The friction and wear characteristics in an alternative refrigerant HFC 134a were investigated using a ball-on-plate type machine. The lubricants used were polyalkylene glycol (PAG) and polyol ester (PEO), which have excellent mutual solubility with HFC 134a. The results obtained are as follows. (1) With PAG, the HFC 134a formed fluoride on the rubbing surfaces, which improved the friction and wear characteristics. In contrast, POE with its high adsorption ability showed poor friction and wear performance above the transition temperature of about 150°C to prevent the formation of fluoride, although it exhibited excellent friction and wear performance below the transition temperature. (2) TCP of aryll-type phosphate ester improved the friction and wear performance owing to the adsorption film in a low temperature range and the formation of iron phosphate in a high temperature region with PAG. (3) MoDTC of organomolybdenum compound significantly improved the friction and wear performance of the oils used as a result of the formation of MoS2.
A rotary multidisc reactor of immobilized glucoamylase was constructed; and the hydrolysis rates of maltose (Katayama Kagaku Co., Japan) and soluble starch (Katayama Kagaku Co., Japan) were measured. The parameters included in the kinetic equation were estimated for these reaction systems.
The friction and wear characteristics of molybdenum dithiocarbamate (MoDTC) and molybdenum dithiophosphate (MoDTP) were examined under a reciprocating sliding condition by adding them to a pure hydrocarbon. Both MoDTC and MoDTP reduced the friction and wear. MoDTC formed a surface film composed mainly of MoS2. MoDTP formed less molybdenum compounds in the rubbing surfaces, which were composed mainly of MoS2 and FePO4 at 120 degrees C, und MoS2, MoO3 and FePO4 at 200 degrees C. A surface film containing MoS2 was effective in reducing the friction. The coefficient of friction was decreased with increasing the concentration of MoS2 in the surface film. MoDTC had a higher ability to form MoS2 than MoDTP. Therefore, MoDTC was superior in reducing friction to MoDTP.
This paper describes a newly developed technique to measure a volume of gas moving between the air side and the sump side across a narrow gap between radial lip seals and a rotating shaft. The volume of gas moved was determined using a gas chromatograph. Preliminary tests were conducted with standard plane lip seals made of fluororubber and nitrile rubber, and with hydrogen and polyalphaolefin as a test gas and a lubricant, respectively. The hydrogen pump rate was almost zero when the shaft was at a standstill and increased with the shaft speed, which suggested that the gas transportation originated from a dynamic effect of fluid flow between the seal and the shaft. The hydrogen pump rate was of the order of 0.1 to 1 cm 3 /h under the test conditions employed and appeared to have no strong correlation with the pump rate of the oil. From the consideration of several possible driving forces for the gas flow, it was suggested that the gas was conveyed in the oil that flowed in and out across the sealed gap, although not entirely in the form of dissolved gas in the oil.
The influence of dissolved refrigerant HFC134a on tribological performance of lubricants for HFC refrigerants was investigated by measuring the solubility of lubricants, and the viscosity reduction and change in oil film thickness of HFC134a/lubricant mixtures in a reciprocating motion. The wear characteristics of an aluminum alloy for the mixtures were also studied. It was found that HFC134a dissolution was exothermic reaction, and the solubility defined by the saturated concentration of HFC134a in lubricants decreased with an increase in the cohesive energy density of lubricants. The reduction in viscosity was affected not only by HFC134a concentration in the lubricants but also by the mean molecular weight of lubricants. The decrease in oil viscosity by dissolved HFC134a made the wear characteristics worse due to reducing the oil film thickness.
Pumping and leakage of gas in radial lip seal were studied using a radial seal tester. Gas moved in and out across the lip, and the gas pump rate was generally larger than the gas leakage rate. Measurement of the solubility of gas in oil and the generation of cavities in oil indicated that the transportation of gas across the lip depended more on the cavity formation than the solubility. It was concluded that gas moved mainly in the form of cavities entrained in the pumping flow of oil.
Continuous countercurrent ion exchange was studied with the cationic system of magnesium and hydrogen ion, using an exchange column, 2cm in internal diameter and 5 to 30cm in height, where the bed of resin particles moved downward.The data were correlated by an equation so as to relate the overall volumetric coefficient of mass transfer based on fluid film to operating variables and the properties of the ionic system.The results indicated that film resistance of each phase was of the same order of magnitude. Overall volumetric coefficient based on the fluid film was found to be about 0.03 [1/sec].Non-dimensional constants, α and β, appearing in the correlation equation, and related to film resistance of each phase, were 2.4 and 0.2, respectively. These values were smaller than those, 4.7 and 0.9, respcctively, obtained by Hiester et al., for the monovalent system of lithium, potassium and hydrogen ion. These differences may be attributable to the colum diameter differences, i.e., 9cm diameter in the Hiester's equipment and 2cm diameter in the authors'. More studies will be required, however, to know what factors participate in this phenomenon. Some considerations were made on the mutual relation between the degree of the exchange adsorption of magnesium in the solution and the ratio of the fluid flow rate to the resin particles flow rate.
