Enthalpies of formation for three- and eight- membered heterocyclic ethers (15
compounds) in gas state have been determined by different theoretical methods: levels of
theory B3LYP/6-31g(d), MP2/6-31g(d) and chemical composite methods (Gn and CBS)
via two approach’s: atomization energy (AE) and bond separations (BS). Median absolute
deviations (MAD) and standard deviations (SD) of calculated values from experimental
data have been determined for every using method’s. The bond separation method has the
smallest MAD at most of theoretical methods in comparison to the atomization energy
approach. The 6-31g(d,p) basis set doesn’t seen clear effect in the theoretical results.
Enthalpy of formation for three- and seven- membered heterocyclic theoethers (11
compound) in gas state have been determined by different theoretical methods: compo-site
methods (Gn, CBS) and two levels of theory B3LYP/6-31g(d) and MP2/6-31g(d) via
two
approaches: atomization energy (AE) and bond separation (BS). Median abs-lute
deviations (MAD) and standard deviations (SD) of calculation values from experi-ment
data have been determined for every used theoretical method. It has been observed that the
bond separation approach produce lower value of MAD in most of the theoretical methods
in comparison to the atomization energy approach; where the G3MP2 method produce
lower value of MAD, while the deviations corresponding to the two levels of theory
MP2/6-31g(d)//B3LYP/6-31g(d) and MP2/6-31g(d)//B3LYP /6-31g(d) is close to the
deviations of the composite methods. The 6-31g(d,p) basic set doesn't show substantial
effect in the theoretical results.
In this paper, we studied flow and boiling regimes of two-phase forced flow in
vertical tubes to determine the dominated flow and boiling regime at any region of tube.
Studied Ranges of main parameters were: Pressure. Because
of absence an accurat
e method of flow and boiling regimes prediction, some of
experimental equations of two phase flow (liquid-steam) had been used to determine the
dominated flow and boiling regime in vertical tubes and build algorithm written by Matlab
environment describes these regimes. An analytical study was provided of the resulted
diagrams and suggestions were given for next studies .
محتوى البخار الكتلي
نظام الجريان
نظام الغليان
جريان ثنائي الطور
السرعة الكتلية
الغليان السطحي
الغليان النووي
محتوى البخار الحقيقي
الإنتالبي النسبي
Flow regime
boiling regime
Two phase flow
mass velocity
surface boiling
nucleate boiling
actual steam content
mass steam content
relative enthalpy
المزيد..
Kinetic studies were carried out on the reaction between ′4,4-Methylenebis
(2-methylcyclohexylamine) and dimeric fatty acid C36 in molten state by using
a catalyst of sulpheric acid compared with the same kinetic of reaction without
catalyst.
The
reaction was performed at 150, and 160 ˚C and followed by determining
the acid value of the product.The polyamidation reaction was found to be of
overall a second order until equilibrium state. Moreover, the catalyst increases
speed of the reaction. Polyamidation reaction was automatic whereas the value
of free energy was negative and the reaction was endothermic, and this is
shown in change of positive enthalpy values.