Mixtures boiling heat transfer

J. R. Thome, Prediction of Binary Mixture Boiling Heat Transfer Coefficients Using Only Phase Equilibrium Data, Int. J. Heat Mass Transfer (26) 965,1983. 

B Boiling (heat transfer) or M Gas-liquid mixture property... 

Estimate the nucleate-pool-boiling heat-transfer coefficient for a water-26% glycerin mixture at 1 atm in contact with a copper surface and AT, = 15°C. 

An inorganic clay (Claytone, 0.7 g) is added together with a high-boiling heat-transfer fluid (Dowtherm, 200 ml). The mixture is heated to 250°C and stirred vigorously, whereupon liquid (largely acetic acid) is collected in the conical flask. 

An essential basis for the study of boiling heat transfer is the thermodynamics of multiphase systems. Here, it is normal practice to consider systems at thermodynamic equilibrium, in which the temperature of the system is uniform. Of course, as we will see, departures from such thermodynamic equilibrium are important in many instances. In what follows, the thermodynamic equilibrium of a single-component material is first considered. In many applications of boiling (particularly in the process and petroleum industries), multicomponent mixtures (for example, mixtures of hydrocarbons or refrigerants) are important, and the subject of multicomponent equilibrium is dealt with in the final part of this section. 

J. R. Thome, Boiling Heat Transfer in Binary Liquid Mixtures, in NATO Advanced Research Workshop on Advances in Two-Phase Flow and Heat Transfer, Spitzingsee, Germany, August 31-September 3,1982. 

K. Bier, J. Schmedel, and D. Gorenflo, Influence of Heat Flux and Saturation Pressure on Pbol Boiling Heat Transfer to Binary Mixtures, Chem. Eng. Fundam. (1/2) 79,1983. 

N. H. Afgan, Boiling Heat Transfer and Burnout Heat Flux of Ethyl-Alcohol/Benzene Mixtures, in Proc. 3rd Int. Heat Transfer Conf, vol. 3, p. 175,1966. 

R. P. Reddy and J. H. Lienhard, The Peak Boiling Heat Flux in Saturated Ethanol-Water Mixtures, J. Heat Transfer (111) 480-486,1989. 

H. Muller-Steinhagen and M. Jamialahmandi, Subcooled Flow Boiling Heat Transfer to Mixtures and Solutions, in Convective Flow Boiling, J. C. Chen ed., pp. 277-283, Taylor Francis, Washington, DC, 1996. 

L. Zhang, E. Hihara, and T. Satiao, Boiling Heat Transfer of a Ternary Refrigerant Mixture Inside a Horizontal Smooth Tube, Int. J. Heat Mass Transfer (40) 2009-2017,1997. 

D. E. Jung, M. McLinden, R. Rademacher, and D. Didion, Horizontal Flow Boiling Heat Transfer Experiments With a Mixture of R22/R114, Int. J. Heat Mass Transfer (32) 131,1989. 

V. I. Tolubinsky and P. S. Matorin, Forced Convection Boiling Heat Transfer Crisis With Binary Mixtures, Heat Transfer—Soviet Research (5/2) 98-101,1973. 

Wettermann, M. Steiner, D. Flow boiling heat transfer characteristics of wide-boiling mixtures. International Journal of Thermal Sciences, Band 39 (2000) 2, p. 225/ 235... 

In the macroscopic heat-transfer term of equation 9, the first group in brackets represents the usual Dittus-Boelter equation for heat-transfer coefficients. The second bracket is the ratio of frictional pressure drop per unit length for two-phase flow to that for Hquid phase alone. The Prandd-number function is an empirical correction term. The final bracket is the ratio of the binary macroscopic heat-transfer coefficient to the heat-transfer coefficient that would be calculated for a pure fluid with properties identical to those of the fluid mixture. This term is built on the postulate that mass transfer does not affect the boiling mechanism itself but does affect the driving force. 

Likewise, the microscopic heat-transfer term takes accepted empirical correlations for pure-component pool boiling and adds corrections for mass-transfer and convection effects on the driving forces present in pool boiling. In addition to dependence on the usual physical properties, the extent of superheat, the saturation pressure change related to the superheat, and a suppression factor relating mixture behavior to equivalent pure-component heat-transfer coefficients are correlating functions. 

The coUigative properties of antifreeze chemicals may also result in boiling point elevation. As the chemical is added to water, the boiling point of the mixture increases. Unlike the freeze depression, the boiling elevation does not experience a maximum the boiling point versus concentration curve is a smooth curve that achieves its maximum at the 100% antifreeze level. The boiling point elevation can be another important characteristic for antifreeze fluids in certain heat-transfer appHcations. 

The solution of sodium methyl sulfide in absolute alcohol is transferred to a 3-I. three-necked flask, which is placed on a steam bath and fitted with a dropping funnel, a reflux condenser, and a mechanical stirrer. The solution is heated until the alcohol begins to boil. Heating is then discontinued and 302 g. (3.7s moles) of ethylene chlorohydrin (Note 5) is added dropwise with efficient stirring over a period of about two hours (Note 6). The reaction mixture is concentrated by distilling as much of the alcohol as possible on the steam bath. The mixture is then allowed to cool and the sodium chloride removed by filtration. The flask is rinsed, and the sodium chloride washed with three loo-cc. portions of 95 per cent alcohol. The combined filtrate and washings are concentrated on the steam bath under reduced pressure until no further distillate passes over. The residue is then transferred to a modified Claisen flask (Org. Syn. Coll. Vol. i, 125) and fractionally distilled under reduced pressure. The yield is 238-265 g. (74-82 per cent of the theoretical amount based on the sodium used) of a product boiling at 68-7o°/20 mm. 

To 40 g. of dry chitin in a 500-ml. beaker is added 200 ml. of concentrated hydrochloric acid (c.p., sp. gr. 1.18), and the mixture is heated on a boiling water bath for 2.5 hours with continuous mechanical agitation. At the end of this time solution is complete, and 200 ml. of water and 4 g. of Norite are added. The beaker is transferred to a hot plate, and the solution is maintained at a temperature of about 60° and is stirred continuously during the process of decolorization. After an hour the solution is filtered through a layer of a filter aid such as Filter-Cel. The filtrate is usually a pale straw color however, if an excessive color persists, the decolorization may be repeated until the solution becomes almost colorless. The filtrate is concentrated under diminished pressure at 50° until the volume of the solution is 10-15 ml. The white crystals of glucosamine hydrochloride are... 

To the cooled reaction mixture, 200 ml. of water is added carefully with stirring. Potassium carbonate is added with continued stirring until the water layer is saturated the mixture is now transferred to a separatory funnel and extracted three times with 60-ml. portions of ether. The combined ether extracts are dried over solid sodium hydroxide and are then transferred to a simple distillation apparatus. Distillation is commenced with a steam bath as source of heat when most of the ether has been removed, the steam bath is replaced by a flame. Distillation is continued until most of the piperidine (b.p. 106°) has been removed. The cooled residue in the distillation flask is recrystallized from petroleum ether (boiling range 30-60°) with the use of charcoal. There is obtained 30.0 g. (71%) of N-/3-naphthyl-piperidine as tan crystals, m.p. 52-56°. An additional recrystallization from the same solvent gives crystals, m.p. 56-58°, with about 10% loss in weight (Note 6). 

Benzene (80 ml) is placed in a suitable pressure vessel (soft drink bottle or hydrogenation bottle) and chilled to 5°. The bottle is weighed, and a gas dispersion tube connected to a cylinder of butadiene is immersed in the benzene. Butadiene is introduced into the flask with continued cooling until a total of 32 g has been transferred. Pulverized maleic anhydride (50 g) is added to the bottle, which is then capped or stoppered with a stopper wired in place. The bottle is allowed to stand at room temperature for 12 hours, then is heated (behind a safety shield) to 100° for 5 hours. The bottle is cooled, then opened, and the contents are transferred to an Erlenmeyer flask. The mixture is heated to boiling, and petroleum ether is added until there is a slight turbidity. After cooling, the product is collected, mp 101-103° (yield 90%). 

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