Heat-transfer Liquids

The classic antifreeze agents in heat-transfer liquids are brine solutions and alcohols. 

Of the commonly used antifreeze agents, brines are the most corrosive to metals of the engines and exhibit scale deposition characteristics that are 

Alcohols such as methanol and ethanol are readily available and are occasionally used despite significant disadvantages, such as low boiling points. During summer months significant amounts of alcohol can be lost due to evaporation. Such losses lead to costly replacement of the additive. Furthermore, alcohols have low flash points, which may cause safety problems. Moreover, methanol is highly poisonous. Therefore, the use of alcohols has ceased almost completely in recent years. 

Ethylene glycol is not as active in depression of the freezing point as methanol, but it has a very low vapor pressure evaporation loss in a coolant system is due more to the evaporation of water than to the evaporazation of ethylene glycol. Furthermore, the flammability problem is literally eliminated. 1 1 mixtures of ethylene glycol and water do not exhibit a flash point at all. 

Alcohols may be corrosive to some aluminum alloys. In an aqueous mixture corrosion may still occur because of dissolved ions from residual salts. At high temperatures and in the presence of residual oxygen from the air, glycols are oxidized slowly to the corresponding acids. These acids can corrode metals. 

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Homogeneous reaction Reaction with heat transfer Liquid-liquid mixtures Liquid-gas mixtures Slumes... 

The cooling effect of a central refrigerating system can be distributed by a heat-transferring liquid or secondary refrigerant. 

The next step involves heating the mold while it is rotating. Molds can be heated by a heated oven, a direct flame, a heat-transfer liquid (either in a jacket around the mold or sprayed over the mold), or electric-resistance heaters placed around the mold. With uniform heat transfer through the mold, the plastic melts to build up a layer of molten plastic on the molds inside surface. 

A chlorinated biphenyl heat-transfer liquid was added to a burning batch of naph-thylsodium to help to extinguish it. An exothermic reaction, followed by an explosion occurred. Sodium is known to react violently with many halogenated materials. 

Uses Heat transfer liquid fungistat for oranges plant disease control manufacture of benzidine organic synthesis. 

Uses Solvent for elastomers, natural rubber, synthetic rubber heat-transfer liquid transformer and hydraulic fluid wash liquor for removing C4 and higher hydrocarbons sniff gas recovery agent in chlorine plants chemical intermediate for fluorinated lubricants and rubber compounds fluid for gyroscopes fumigant for grapes. Not produced commercially in the U.S. 

Uses Dielectric liquids in fixed paper capacitors heat-transfer liquid widely used in transformers and utility transmission lines swelling agents for transmission seals ingredient in lubricants, oils, and greases plasticizers for cellulose products, vinyl, and chlorinated rubbers in polyvinyl acetate to improve fiber-tear properties. In fluorescent and high-intensity discharge ballasts manufactured prior to 1979 (U.S. EPA, 1998) and in electric motors (Monsanto, 1960). 

Uses Heat transfer liquid perfuming soaps resins for laminated electrical insulation organic synthesis. 

Hexachlorobutadiene does not occur naturally in the environment. It is formed during the processing of other chemicals such as tetrachloroethylene, trichloroethylene, and carbon tetrachloride. Hexachlorobutadiene is an intermediate in the manufacture of rubber compounds and lubricants. It is used as a fluid for gyroscopes, a heat transfer liquid, or a hydraulic fluid. Outside of the United States it is used to kill soil pests. 

Hexachlorobutadiene is used as a chemical intermediate in the manufacture of rubber compounds (ERA 1982d). Lesser quantities of hexachlorobutadiene are used as a solvent, a fluid for gyroscopes, a heat transfer liquid, hydraulic fluid, and as a chemical intermediate in the production of chlorofluorocarbons and lubricants (ERA 1980 lARC 1979 Verschueren 1983). Small quantities are also used as a laboratory reagent (ERA 1982d). In the international market, Russia is reported to be one of the major users of hexachlorobutadiene, where it is used as a fumigant on grape crops. 

Electromagnetic Force When the fluid is an electrical conductor, as is the case with molten metals, it is possible to impress an electromagnetic field around the fluid conduit in such a way that a driving force that will cause flow is created. Such pumps have been developed for the handling of heat-transfer liquids, especially for nuclear reactors. 

The chief industrial uses of fusible alloys are for fusible automatic sprinklers, anchoring bearings and bushings, for heat transfer liquids, for glass to metal seals, etc (Ref 2) Refs 1) Hackh s Diet (1944), 363-L 2) CondChemDict (1961), 522-23 (1971),... 

Syltherm Heat Transfer Liquids, Dow Coming Corp., Midland, Mich. 

What Controls Mass/Heat Transfer Liquid or Gas Transfer or Bypassing Either gas side or liquid side of the interface can be controlling. 

Converting Liquid Mass-Transfer Data to Direct Contact Heat Transfer Liquid-limited performance measures are much more commonly given for mass-transfer than for heat transfer. Often mass-transfer data are reported as kLa with units of h-1. This can be converted to hLa with units of Btu/(h°F-ft3) by Eq. (14-188). 

A very interesting approach to process intensification was recently presented by Jachuck and coworkers. The authors described the development and performance of an isothermal CF reactor to be used in a domestic microwave oven [81]. The small (270 p,L) CF reactor consists of two sections, a microwave transparent PTFE part for the reaction side and an alumina part for heat transfer (Fig. 23). The heat generated due to the activation by microwave irradiation was rapidly absorbed by the heat transfer liquid (H20) pumped through the alumina part. Inlet and outlet temperatures of both the reaction mixture and the heat transfer liquid were monitored using a PICO temperature recorder. 

The pot is heated with a heating bath rather than a Thermowell to promote even boiling and make possible accurate determination of the boiling point. The bath is filled with a suitable heat transfer liquid (water. 

The thermostatically controlled heaters formerly used in tray-based freeze-dryers were gradually abandoned as they resulted in inconsistent product temperatures. Most freezers of this type currently use hollow trays through which a heat transfer liquid is passed at a controlled temperature. 

Hexachlorobutadiene is an industrial by-product of tetrachloroethylene, trichloroethylene, and perchloro-ethylene production and is used as a solvent for elastomers, heat transfer liquids, transformer fluids, and hydraulic fluids. Hexachlorobutadiene may still be used in certain countries as a fumigant. It is also released during refuse combustion and is found in fly ash. 

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