The mutual solubilities of f-pentanol-water system were measured as a function of pressure at six temperatures in the range 332.65 to 401.75 K. The solubilities in two liquid phases at equilibrium increase gradually in the direction of contracting the immiscibility region with increasing pressure and with increasing temperature in the range above 352.55 K. The results obtained are thermodynamically analyzed by applying the van Laar equations to the activity coefficients of the components, and the effect of pressure and temperature on the liquidliquid equilibrium in this system is explained in terms of the partial molar properties of the components.
An experimental investigation was performed to study the transition to turbulence in pipe flow started impulsively with a supercritical Reynolds number. The results show that a turbulentnon-turbulent interface propagates downstream by consuming the non-turbulent region where laminar boundary-layer flow is developing with time. For the startup of a completely quieted fluid, the propagation velocity is equal to the maximum velocity of the steady-state turbulent flow. For restarting the fluid flow after a brief shutoff, however, the propagation velocity is larger than the maximum velocity, and the difference increases with shorter quieting times. In the process of interface propagation, a wave of very low frequency appears ahead of the interface centring around the radial position where the smallest change in velocity is observed at the instant of propagation. A study of the mechanism of interface propagation shows that the final break of the abovementioned wave continuously triggers downstream propagation of the turbulent-flow region. In addition, random jumping of the interface in turbulence-decaying flow is concluded to be the main cause for the increase in propagation velocity for short quieting times.
A numerical solution using the conjugate gradient method is presented for the heat transfer problems of fully developed combined free and forced laminar convection with high Prandtl number fluid in horizontal rectangular ducts, where the wall heat flux is axially uniform and the wall temperature is peripherally uniform. The S. O. R. method frequently fails to obtain a stable solution for large values of ReRaPr. However, the proposed method gives a stable converged solution even when the values of ReRaPr are large. Based on the numerical calculation, the relationships of Nu/Nu0 vs. ReRaPr for various aspect ratios are presented in a graph and by the following equation: Nu/Nuo=a(ReRaPr)b where 0 denotes pure forced convection, and a and b are related to the aspect ratio and ReRaPr. In addition, the streamlines and isothermals are obtained for various aspect ratios and ReRaPr.
The rates of absorption of NO into aqueous Na2SO3 solutions containing Fe(III)-EDTA-Na and/or Fe2(SO4)3 as catalysts were measured at temperatures from 8 to 45°C using a baffled agitated vessel with a flat gas-liquid interface. The experimental results were analyzed by chemical absorption theory and it was found that the reaction is first-order with respect to NO and zeroorder with respect to Na2SO3 for solutions containing Fe(III)-EDTA-Na alone or both Fe(III)-EDTA-Na and Fe2(SO4)3. The first-order rate constants for both catalyzed solutions were calculated and correlated as functions of temperature, ionic strength of the solution and concentrations of Fe(III)-EDTA-Na and Fe2(SO4)3.
This paper deals with the transport properties of inorganic solutes through cellulose acetate membranes. The main purpose of the study is to clarify the effect of both pH and other solutes on the rejection of a particular solute, such as alkali and heavy metal ions. Reverse osmosis experiments were carried out with a batchwise apparatus for several kinds of solution systems in which the concentration of each solution was relatively low. It was found that the rejection of a metal ion is strongly influenced by the pH value of a feed solution. It was also found that the rejection of a particular solute in a mixed-salt solution system is different from that in a single-salt solution system. The degree of the change in rejection depends on the species, concentration and permeation of solutes present in aqueous solutions. In particular, it may be affected strongly by exceedingly permeable or impermeable ions. It is recognized that pH dependence of rejection is attributable to the problem of coexisting solute in mixed-salt solution systems.
A modified structural model is proposed for analysis of solid-consuming reactions such as carbon gasification with carbon dioxide. In this model, it is assumed that a solid tablet consists of a number of fine particles and that reaction takes place on the geometrical surface of these particles. The results from the model clarified effects of void fraction change on the overall reaction rates. Also, theoretical results agreed well with experimental ones, which were given by gasification of carbon with carbon dioxide in the temperature range of 990 to 1100°C.
Continuous combustion of coal and char particles was carried out in an experimental fluidized bed of inert particles. The experimental results indicated that the fuel nitrogen dominated the total "NO" emission. The radical reduction of "NO" emission with decreased air feed ratio below 1.0 was observed only in the case of char combustion, while the NH3 emission remained at a certain low level. The significant reductions of "NO" and NH3 emissions found in the combustion of char with reducing atmosphere suggest strongly that "NO" emission may be considerably reduced by employing staged fluidized bed combustion of char. The mechanism of this radical reduction of NO emission was studied by taking account of the steady state concentration of carbon in fluidized bed. Preliminary experiments of staged combustion were carried out, and the results obtained indicated that staged combustion of carbonized char is an effective combustion modification for the abatement of "NO" emission.
Reactive-extractive distillation in a multistage column is numerically investigated to improve the yield of desired intermediate product in a complex reaction combining reversible and consecutive reactions which are of the first order. On the assumption of phase equilibrium, mass balance equations are formulated in terms of a phase-splitting parameter and solved by use of the modified relaxation method. The optimal value of each decision variable is determined for tentatively chosen parameter values. Then the effect of each parameter on yield is evaluated for fixed values of the remaining parameters. The proposed combined process may have advantages over extractive reaction, reactive distillation and reaction without simultaneous separation singly if the system parameters can be chosen favorably.
For the purpose of safety control of chemical plant operations, the system of supervising valve operations is considered on the premise that all the open-or-closed information for important valves can be monitored by a computer. The algorithms consist basically of two parts: finding the particular route of a stream on specification of the starting and terminating points, and evaluating the flow state in each unit of equipment in the stream. For ease of computer processing the structure of the chemical plant is viewed as an assembly of connectors and valves as done by Rudd. In the procedure of searching routes, redundant searching and repetition of searching in loops are avoided. Once the required route is found, the flow state of each connector is evaluated with the aid of information about the topological connections among the connectors which are generated in the route-searching procedure. It is possible to determine, referring to the restrictions or requirements about the states of connectors given as the security conditions, the sequence of valve operations.
The process synthesis problem formulated by using structure parameters becomes, in general, a highly constrained nonlinear programming problem. This paper shows that by the use of a transformation in constrained structure parameters, however, all the constraints on the structure parameters are eliminated from the problem. This transformation makes it possible to ease significantly the computational difficulty of handling constrained structure parameters. Two computational methods are proposed, in which the incorporation of the transformation in constrained structure parameters is presented. The results of synthesis of two examples are presented and compared with other methods of synthesis. Computational experience with examples has indicated that different methods must be adopted depending on the type of problem.