Refrigerant alternatives

Investments in plants to produce refrigeration alternatives have been aimounced by a variety of companies. ICI has an HPC-134a plant built in St. Gabriel, La. and is scheduled for 1993 startup. Their HPC-134a plant in Runcorn, UK is operational another one is plaimed for the Mihara, Japan site. 

Commercial refrigeration - Alternatives to CFCs for new commercial refrigeration equipment include HCFCs (including HCFC mixtures) and HFCs and HFC mixtures. Retrofit of existing equipment is possible by using both HCFCs and HFCs, in conjunction with reduced charges and more efficient compressors. Hydrocarbons are, to a limited extent, applied in hermetically sealed systems. 

Based on the above model for ODP, CH3C1 is removed from the list of refrigerant alternatives together with all other compounds with chlorine. Finally, the two compounds C2H60 and C4H10 are kept for further studies as possible replacements. 

Mobile phases containing phosphate are subject to microbial growth, especially molds. These mobile phases should be filter sterilized and stored in autoclaved or sterile containers under refrigeration. Alternatively, a few milligrams of sodium azide per liter of solution may be added to the aqueous mobile phase. An aqueous salt solution used as a mobile phase may cause crystal... 

Let the petals remain in the methanol overnight in the refrigerator. Alternatively, the tissue can be gently crushed with a glass rod or pipette. 

The plant contains iridoid glycosides asperuloside (120) monotropein and aucubin (19), phenolic acids caffeine, gallic acid, anthraquinone derivatives, flavonoids, coumarins, citric acid and red dye. It has been employed in the form of an infusion, as aperient, diuretic, refrigerant, alternative and antiscorbutic. Extract of leaves used as astringent, plant paste applied on skin disease [69,153]. 

D. O Shaughnessey, Flammability of R134a, R22, and R123 in Chlorine, Chlorine Institute CFC Refrigerant Alternatives Seminar, New Orleans, LA (1993). 

Fig. 1. An amplified outline scheme of the making of various wiaes, alternative products, by-products, and associated wastes (23). Ovals = raw materials, sources rectangles = wines hexagon = alternative products (decreasing wine yield) diamond = wastes. To avoid some complexities, eg, all the wine vinegar and all carbonic maceration are indicated as red. This is usual, but not necessarily tme. Similarly, malolactic fermentation is desired in some white wines. FW = finished wine and always involves clarification and stabilization, as in 8, 11, 12, 13, 14, 15, 33, 34, followed by 39, 41, 42. It may or may not include maturation (38) or botde age (40), as indicated for usual styles. Stillage and lees may be treated to recover potassium bitartrate as a by-product. Pomace may also yield red pigment, seed oil, seed tannin, and wine spidts as by-products. Sweet wines are the result of either arresting fermentation at an incomplete stage (by fortification, refrigeration, or other means of yeast inactivation) or addition of juice or concentrate.

Heat Pumps. A heat pump is a refrigeration system that raises heat to a useful level. The most common appHcation is the vapor recompression system for evaporation (qv) (Fig. 14). Its appHcation hinges primarily on low cost power relative to the alternative heating media. If electricity price per unit energy is less than 1.5 times the cost of the heating medium, it merits a close look. This tends to occur when electricity is generated from a cheaper fuel (coal) or when hydroelectric power is available. 

Y. Takaishi, Seminar on New Technology of Alternative Kefrigerants, Tubricants, and Materials Compatibility,Association of Refrigerants, Tokyo, Japan, 1993, pp. 101-106. 

A. P. Cohen, "Test Methods for the CompatibiHty of Desiccants with Alternative Refrigerants," yiSHEAE Transactions Vol. 99, Part 1, American... 

Jotile-Thomson Valves The principal function of a J-T valve is to obtain isenthalpic coohng of the gas flowing through the valve. These valves generally are needle-type valves modified for cryogenic operation. They are an important component in most refrigeration systems, particularly in the last stage of the liquefac tion process. Joule-Thomson valves also offer an attractive alternative to turboexpanders for small-scale gas-recovery applications. 

Substitution If intensification is not possible, then an alternative is to consider using a safer material in place of a hazardous one. Thus it may be possible to replace flammaole solvents, refrigerants, and heat-transfer media by nonflammable or less flammable (high-boiling) ones, hazardous products by safer ones, and processes which use hazardous raw materials or intermediates by processes which do not. As an example of the latter, the product manufactured at Bhopal (carbatyl) was made from three raw materials. Methyl isocyanate is formed as an intermediate. It is possible to react the same raw materials in a different order so that a different and less hazardous intermediate is formed. 

Attenuation Another alternative to intensification is attenuation, using a hazardous material under the least hazardous conditions. Thus large quantities of liquefied chlorine, ammonia, and petroleum gas can be stored as refrigerated liquids at atmospheric pressure instead of storing them under pressure at ambient temperature. (Leaks from the refrigeration eqmpment should also be considered, so there is probably no net gain in refrigerating quantities less than a few hundred tons.) Dyestuffs which form explosive dusts can be handled as slurries. 

A Neslab LILT-80 refrigerated circulating bath was used. Alternatively, a Dewar condenser cooled with acetone-dry ice can be used. 

Hydroearbon dew point eontrol is aehieved by eooling the gas. There are three eooling alternatives free expansion or Joule-Thomson expansion, external refrigeration, and using a turboexpander. Joule-Thomson expansion does not always produee the needed refrigeration over the life of the plant and, henee, is not eonsidered as a viable... 

For areas where cooling water is either scarce or not available, direct liquid injection may be a possibility. The liquid coolant should be injected near the discharge end of the compressor to minimize lubricant dilution. Alternatively, the liquid can be flashed in a separate exchanger and used to cool the lubricant. While the cooling may appear to decrease the power to the compressor, the net effect is an increase in the power due to the additional weight flow of the extra refrigerant needed to perform the cooling. 

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