Heat transfer systems

Hydrotherm Molten Salt Heat Transfer System, American Hydrotherm Corp., New York. 

Like brines, alcohols were readily available and widely used as antifreeze Hquids in the early 1900s. Both methanol and ethanol offer exceUent heat transfer and efficient freeze point depression. However, the alcohols have the distinct disadvantage of their low boiling points. During the summer months when the engines operate hot, significant amounts of the alcohols are lost because of evaporation. These evaporative losses result in cosdy make-up requirements. Additionally, the alcohols have very low flash points and potentially flammable vapors. These safety concerns have, particularly in recent years, caused the use of alcohols to be completely discontinued for most heat-transfer systems. 

Besides freeze protection, antifreezes provide many other performance properties that enhance the operation of a heat-transfer system. Because the internal combustion engine is by far the largest antifreeze appHcation, and ethylene glycol is the predorninant antifreeze in use, the following focus on the performance properties of an ethylene glycol-based antifreeze and their relationship to engine cooling. 

Syltheiin XLT (Dow Corning Coiporation). A sihcone polymer (Dimethyl Polysiloxane) recommended temperature range —70°C to 250°C odorless low in acute oral toxicity noncorrosive toward metals and alloys commonly found in heat transfer systems,... 

Use antifouling agents and corrosion inhibitors in heat transfer systems... 

Hinkle, R. E. and J. Friedman, Controlling Heat Transfer Systems for Glass-Lined Reactors, Chem. Eng, p. 101, Jan. 30, (1978). 

Evaluation of loop-test results Although the thermal loop test approximates to the conditions which obtain in a dynamic heat-transfer system, in evaluating the results it is necessary to be aware of those aspects in which the test differs from the full-scale unit, as otherwise unwarranted confidence may be placed in the data. Assuming that adequate attention has been paid to the purity and condition of components, etc., the following factors will, according to ASTM G68 1980, influence the observed corrosion behaviour ... 

The study of the peak temperature sensitivity to the reactor operating parameters and the construction of sensitivity boundary curves for stable reactor operation were previously reported ( l). This paper presents a computer study on conceptual relationships between the conversion-product properties and the reactor operating parameters in a plug flow tubular reactor of free radical polymerization. In particular, a contour map of conversion-molecular weight relationships in a reactor of fixed size is presented and the sensitivity of its relationship to the choice of initiator system, solvent system and heat transfer system are discussed. 

The last category is the pressure-driven gas flows, which are typical in micro gas fluidic and micro heat transfer systems. Because the channel diameter or width in micro gas fluidic systems is in the scale of sub-micrometer or less, ultra-thin gas lubrication theory plays an important role in... 

Seifert, W.F., Jackson, L.L., Sech, C.E. Organic Fluids for High Temperature Heat Transfer Systems, Chemical Engineering, Oct. 30, 1972, p. %. 

Readily peroxidises in air, and explosions have occurred during large-scale distillations [1], particularly towards the end when sufficiently concentrated [2], Use of tetralin as secondary coolant in a molten sodium heat transfer system led to an explosion due to peroxide formation [3],... 

In the second phase searches were made on the system and subsystem level. This is needed for the comparison of process alternatives and for the design of the exothermic reactor and its heat transfer systems. Carbonylation of methanol is an exothermic reaction. Thus only the exothermal reactors were searched. The CBR search found two cases which are general recommendations on the design of exothermic reactors with heat transfer systems. They are shown in Fig. 8 and 9. 

Reactor heat transfer system 6. Reactor safety systems ... 

Heat transfer systems are normally provided to utilize available process heat, to economize heat for distillation purposes or to preheat fuel supplies before usage. They are generally considered a secondary process support system to the main production process, however they may be so critical to the process that they might be considered a single point failure if not adequately designed. 

Most heat transfer systems are of a closed loop design that circulates a heat transfer medium between heaters and heat exchangers. Circulation pumps provide flow and regulating valves are used for process control. The heat transfer medium is usually steam, a high flash point oil, or in process plants flammable liquids and gases. Inherently steam is a safer medium to use and is preferred over other mediums. When steam supplies are unavailable high flash point oils (organic or synthetics) are sometimes used. 

Carbon reinforced products that require less energy to produce and that are ten times stronger than steel, lighter than aluminum, and that conduct more heat than copper can be increasingly used to reduce the weight of vehicles, improve the performance of appliances and tools and increase the efficiency of heat-transfer systems. Other forms of carbon will provide super semiconductors and advanced optics. 

Integrity of components Corrosion (in particular with resulting material overflow from/to heat transfer systems) Mechanical damage ... 

Mass-Transtcr-Controllcd Flcctrodic Reaction Heat-Transfer systems, i.e.. Heat Transler Involved in Cooling Molten Metals... 

Health, Environmental, and Safety Considerationsfor High Temperature Ofganic Heat Transfer Systems, Dow Chemical Co., Midland, Mich. 

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