Direct contact heat transfer between two immiscible liquids during vaporization: Part II: Total evaporation time

A dilatometric technique was used to determine the total evaporation time of individual drops of furan, isopentane and cyclopentane as they rose in water. The values of total evaporation time were predicted reasonably well for each system by a different equation than was used to correlate the evaporative data for the initial 10% of the evaporative process as reported in Part I of this study. The total evaporation time data were also compared with the correlations given by Klipstein ⁽¹⁾, by Sideman and Taitel ⁽²⁾ and with the correlation which was found by the authors to best fit the total evaporative data for the three systems. In agreement with Klipstein ⁽¹⁾, the correlation for the overall heat transfer coefficient was found to be one of the form, q_A = Cd₁^2.0δt. The rate of rise of an evaporating drop for the conditions used in this study was found to be nearly equal to the instantaneous terminal velocity.     

A comparison of six solvents for the extraction of jojoba seed

Summary Data are presented which show the effects of different solvents on the yield and properties of liquid wax fromSimondsia chinensis (jojoba) and on the characteristics of the hydrogenated waxes obtained from the liquid waxes. Three reagent grade solvents, carbon tetrachloride, benzene, and isopropyl alcohol, and three commercial grade solvents, heptane, hexane, and tetrachloroethylene, were evaluated as extractants for the liquid wax from jojoba. Soxhlet-type of extractions were carried out under conditions in which the solvent was the only significant variable. Four of the solvents extracted essentially the same amount of material from the seed while isopropyl alcohol extracted significantly more material and tetrachloroethylene significantly less. Obviously the difficulties involved in separating the solids recovered from the isopropyl alcohol extraction preclude its use as the extracting solvent for jojoba wax. The density of the liquid waxes varies from 0.8631 to 0.8648; the waxes from the tetrachloroethylene and hexane extractions had the lowest value and the wax from isopropyl alcohol the highest. In each case, regardless of the solvent used, a precipitate developed in the liquid wax after it had been desolventized and stored for 7–10 days. Hydrogenation of clear fractions and precipitate containing fractions of these liquid waxes showed that the precipitate had no apparent effect upon the melting point or hardness of the resulting solid wax. Some of the liquid waxes required a longer hydrogenation time to attain an iodine value of about 1. At this iodine value all of the solid waxes had melting points between 66 and 68°C. Hardness values of all the solid waxes as measured by the Trionic hardness gauge were 90. One of the laboratories of the Southern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.     

Large scale diesel driven vapor compression units

A hybrid plant consisting of a diesel driven vapor compression unit and a steam ejector - vapor compression MES unit will have a very low specific primary energy consumption.This paper discusses results of experiments concerning critical parts of such a concept as well as some results of numerical calculations.The experiments were expecially concerned with brine distribution by sieve trays in the MES-unit and with the behaviour of such units under different but steady state load conditions     

The lipids of krill (Euphausia species) and red crab (Pleuroncodes planipes)

The composition of the lipids of two samples of krill and one of “red crab” was determined by thin layer, column and gas chromatographic procedures. A large number of unusual fatty acids were present.     

Preliminary report on the nutritional significance of bound gossypol in cottonseed meal

Summary A procedure is described by which bound or inactivated gossypol can be removed from cottonseed meal without the application of heat which might damage the protein. The removal of bound gossypol increased the nutritional value of the protein as determined by chick feeding tests, rat protein-repletion tests, and lysine availability tests. A procedure is described for the preparation of a gossypol-cottonseed protein complex without heating the materials. As a result of the combination of the protein with gossypol, marked reduction in nutritional value occurred. The nitrogen solubility of the complex was only about half that of the original protein. The results are in accord with the concept that the inactivation of gossypol during the processing of cottonseed meal is accomplished through the formation of an insoluble, inert gossypol-protein complex which results not only in rendering the gossypol harmless but also in the loss of part of the nutritional value of the protein.     

Thermal analysis of montmorillonites modified with quaternary phosphonium and ammonium surfactants

The thermal stability of seven organically modified montmorillonites (‘organoclays’) has been investigated using differential thermal analysis, differential scanning calorimetry, and thermogravimetry in conjunction with X-ray diffractometry. Six organoclays were synthesised by replacing the interlayer inorganic cations, initially present, with quaternary phosphonium and ammonium surfactant cations. The samples modified with tetrabutylphosphonium (TBP), and butyltriphenylphosphonium (BTPP) ions have an appreciably higher thermal stability than the octadecyltrimethylammonium (ODTMA)-modified clays. Thus, in the case of TBP- and BTPP-modified montmorillonites, the onset temperature of decomposition is close to 300 °C. Samples modified with hexadecyltributylphosphonium (HDTBP) ions have a lower onset temperature of decomposition of 225 °C. In comparison, the onset temperature for ODTMA-montmorillonites (obtained at different concentrations of ODTMA-bromide) ranges from 158 to 222 °C, being highest where the concentration of intercalated surfactant is lowest. The onset temperature for a commercial alkylsilane-treated quaternary ammonium-modified organoclay (S-BEN N-400FP) is 207 °C. The basal spacing of the TBP- and BTPP-modified clays is 1.7–1.8 nm, indicating a monolayer arrangement of quaternary phosphonium ions in the interlayer space, while the value of 2.5 nm for HDTBP-montmorillonite indicates a more open structure. The ODTMA-modified samples have basal spacings ranging from 1.9 to 2.1 nm, indicative of a bilayer to pseudo-trilayer arrangement. The exceptionally high basal spacing of 3.4 nm for the S-BEN N-400FP organoclay might be due to interlayer penetration of organosilane hydrolysis products during synthesis. The thermal properties of organoclays are apparently related to the nature of the surfactants and their arrangement in the interlayer space of montmorillonite.     

Structural condition of martensite in the surface layer of cold rolling rolls

Conclusions The martensitic base of the surface hardened layer is inhomogeneous in phase composition. Despite complicating concepts post-hardening tempering does not cause homogenization of the martensitic phase. Decomposition of the martensite has a heterogeneous character. In the hardened layer and the transition zone together with the low-carbide constituent there is formed a high-carbon one. The presence of high-carbon -martensite may not inpoint of concepts on homogeneous martensite, the degree of tetragonality of which is close to unity, it is difficult to explain the phenomenon of high hardness of rolling mill rolls. Undoubtedly the high-carbon constituent is one of the factors causing an increase in hardness in tempering of type 9KhMF steel. The two martensites manifest themselves differently in rolling. Concepts of the heterogeneous nature of maratensite may be used for improving the service conditions of rolling rolls.Kramatorsk Industrial Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 2, pp. 10–12, February, 1991.     

Catalytic dehydrogenation of isopropanol on La2−xSrxNiO4±y

The series of compounds La_2–xSr_xNiO_4±y (0.0 x 1.0) crystallising in tetragonal K₂NiF₄ structure were prepared and catalytic activity have been investigated using isopropanol decomposition as model reaction. All the catalyst compositions catalyse only the dehydrogenation of isopropanol reaction. The composition La_1.5Sr_0.5NiO₄ showed high activity compared to other compositions in the series. The composition is unique not only in catalytic property but also in other physical properties like structural characteristics, electrical resistivity and metal to semiconductor transition.