Refrigerant oil mixtures

Automotive refrigerant systems are not composed of refrigerant alone. For lubrication purposes, an oil such as Mobil Artie EAL 68 is used. The significance of this is 

FIGURE 9.3 Phase equilibrium diagram of R134A with oil. 

FIGURE 9.4 Vapor/liquid mole fraction diagram. 

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There are limited data to assess the carcinogenic potential of ammonia. Nasal cancer was reported in an individual accidentally exposed to a refrigeration-oil mixture (Shimkin et al. 1954). Animal carcinogenicity data consist of several oral exposure studies. Ammonia was not found to increase the occurrence of tumors following oral exposure to relatively low doses (Toth 1972 Uzvolgyi and Bojan... 

K. Stephan and J. Mitrovic, Heat Transfer in Natural Convective Boiling of Refrigerants and Refrigerant-Oil-Mixtures in Bundles of T-Shaped Finned Tubes, in Advances in Enhanced Heat Transfer—1981, R. L. Webb, T. C. Carnavos, E. L. Park Jr., and K. M. Hostetler eds., HTD vol. 18, pp. 131-146, ASME, New York, 1981. 

A. L. Souza, J. C. Chato, J. P. Wattelet, and B. R. Christoffersen, Pressure Drop During Two-Phase Flow of Pure Refrigerants and Refrigerant-Oil Mixtures in Horizontal Smooth Tubes, ASME HTD-Vol. 243, New York, pp. 35-41,1993. 

R.22 Separates into oil-rich mixture at top and refrigerant-rich mixture at bottom Fully miscible 1177... 

Carcinogenic potential of ammonia by the inhalation route has not been assessed in humans or animals. One case report was found of a white male who developed epidermal carcinoma of the nasal septum 6 months after being badly burned by accidental contact with a refrigeration ammonia-oil mixture (Shimkin et al. 1954). If ammonia played a role in the development of this cancer, it was most likely due to dermal exposure, not inhalation, since the substance was oily. However, some of the ammonia was probably inhaled into the nasal vestibule and absorbed into nasal mucous. No other such reports were located, although other cases of inhalation exposure to ammonia from spills have been followed for more than 6 months after exposure. One of 10 adult male mice exposed to ammonia gas for 15 minutes/day 6 days/week for 8 weeks had mitotic figures with an intact basement membrane and a carcinoma in situ in one nostril and one mouse had an invasive adenocarcinoma of the nasal mucosa (Gaafar et al. 1992). 

Shimkin MB, de Lorimier AA, Mitchell JR, et al. 1954. Appearance of carcinoma following single exposure to a refrigeration ammonia-oil mixture. Arch Ind Hyg Occup Med 9 186-193. 

Veratronitrile, Dissolve 83 g. of veratraldehyde in 200 ml. of warm rectified spirit in a 1 litre bolt-head flask, and add a warm solution of 42 g. of hydroxylamine hydrochloride in 50 ml. of water. Mix thoroughly and run in a solution of 30 g. of sodium hydroxide in 40 ml. of water. Allow the mixture to stand for 2-5 hours, add 250 g. of crushed ice, and saturate the solution with carbon dioxide. The aldoxime separates as an oil allow the mixture to stand for 12-24 hours in an ice chest or refrigerator when the oil will sohdify. Filter off the crystalline aldoxime at the pump, wash well with cold water, and dry in the air upon filter paper. The yield of veratraldoxime is 88 g. 

The cooled mixture is transferred to a 3-1. separatory funnel, and the ethylene dichloride layer is removed. The aqueous phase is extracted three times with a total of about 500 ml. of ether. The ether and ethylene chloride solutions are combined and washed with three 100-ml. portions of saturated aqueous sodium carbonate solution, which is added cautiously at first to avoid too rapid evolution of carbon dioxide. The non-aqueous solution is then dried over anhydrous sodium carbonate, the solvents are distilled, and the remaining liquid is transferred to a Claisen flask and distilled from an oil bath under reduced pressure (Note 5). The aldehyde boils at 78° at 2 mm. there is very little fore-run and very little residue. The yield of crude 2-pyrrolealdehyde is 85-90 g. (89-95%), as an almost water-white liquid which soon crystallizes. A sample dried on a clay plate melts at 35 0°. The crude product is purified by dissolving in boiling petroleum ether (b.p. 40-60°), in the ratio of 1 g. of crude 2-pyrrolealdehyde to 25 ml. of solvent, and cooling the solution slowly to room temperature, followed by refrigeration for a few hours. The pure aldehyde is obtained from the crude in approximately 85% recovery. The over-all yield from pyrrole is 78-79% of pure 2-pyrrolealdehyde, m.p. 44 5°. 

Operated in this manner, the shell-and-tube type is a flooded evaporator (see Figure 7.3) and has oil drainage pots if using ammonia, or a mixture bleed system if the refrigerant is one of the halocarbons. The speed of the liquid within the tubes should be about 1 m/ s or more, to promote internal turbulence for good heat transfer. End cover baffles will constrain the flow to a number of passes, as with the shell-and-tube condenser. (See Section 6.4.)... 

A solution of 5-methoxy-6//-l, 4-diazepine (0.386 g, 3.1 mmol) and benzoyl chloride (0.550 g, 3.9 mmol) in pyridine (5 mL) was kept for 2 d in a refrigerator and ice-water (15 mL) was then added. The mixture was extracted with CH2C12 and the extract was washed with H20. dried and concentrated under reduced pressure. The residue was chromatographed (alumina, benzene) to give the product yield 0.420 g (65%) oil. 

To a solution of 2.31 g (10 mmol) or tert-butyl Ar-(tfr -buloxycarbonyl)glyeinate in 40 mL of dry CC14 is added 1.78 g (10 mmol) of A-bromosuccinimidc and the mixture is irradiated with a 500-W lamp at 20°C (water cooling) for 1 h. The succinimide is filtered off and the filtrate is concentrated to dryness in vacuo. The residual oil crystallizes on drying in vacuo to give the product in nearly analytical purity yield 3.0 g (97%) mp 55 X. The producl is stable when kept under argon in the refrigerator, and can be used in subsequent steps without further purification. 

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