Engineering problems

Although this book may fall into the hands of a practicing engineer, most readers will be college juniors the following is addreped to them. 

Instructors of third-year students would like to assign more complicated or difficult problems but generally cannot because 

The time required is too great— they cannot be done in the time that most students will devote to one homework problem. 

The students would probably get intellectual indigestion. Therefore, at the third-year level most problems and examples in texts like this one are the plug-ins or can be readily reduced to plug-ins. 

In the examples and problems in this book, there are numerous simple plug-in problems. They are included because their solutions give the reader some feel for the numerical values involved in fluid mechanics. There are also more complex problems, in which two or more basic principles are involved (such as the mass balance and the energy balance). In these some manipulation 

Planet abc [6]. On planet abc temperature is measured on the abc scale. If the boiling point of 

Planet abc 2 [6]. On planet abc temperature is measured on the abc scale. If the boiling point of water (212 °F) corresponds to c °abc and the freezing point of water (32 °F) corresponds to a °abc, then find an equation that relates the Fahrenheit scale to the abc scale. 

Reynolds number [5]. The Reynolds number is a DN utilized in fluid mechanics. The Reynolds number is defined as Re = Dvplji, where D is the diameter of a pipe, v the hnear velocity of a fluid, p the density of the fluid, and p the dynamic viscosity of the fluid, (a) Determine Re if D = 3.0 in, / = 62.4 Ib/ft, v = 3.0 m/s, and p = 0.0020 Ibf s/ft. (b) Will the calculation of the Reynolds number depend on the unit system used Why  

2 Fundamentals of Magnitudes, Unit Systems, and Their Applications in Process Engineering 

A (a) A is dimensionless, B has a temperature dimension and in this case degrees Celsius units, and C has temperature as a fundamental magnitude and degrees Celsius units, (b) 760.086 mmHg (0 °C) [recall that the vapor pressure of water at 100 °C is 760 mmHg (0 °C) (1 atm)]. 

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When no experimental data at all are available, activity coefficients can sometimes be estimated using the UNIFAC method (Fredenslund et al., 1977a, b). However, for many real engineering problems it is often necessary to obtain new experimental data. 

Understand the engineering problem and obtain the required information in the most effective way... 

In most engineering problems the boundary of the problem domain includes curved sections. The discretization of domains with curved boundaries using meshes that consist of elements with straight sides inevitably involves some error. This type of discretization error can obviously be reduced by mesh refinements. However, in general, it cannot be entirely eliminated unless finite elements which themselves have curved sides are used. 

The weighted residual method provides a flexible mathematical framework for the construction of a variety of numerical solution schemes for the differential equations arising in engineering problems. In particular, as is shown in the followmg section, its application in conjunction with the finite element discretizations yields powerful solution algorithms for field problems. To outline this technique we consider a steady-state boundary value problem represented by the following mathematical model... 

In the finite element solution of engineering problems the global set of equations obtained after the assembly of elemental contributions will be very large (usually consisting of several thousand algebraic equations). They may also be... 

Acetone cracks to ketene, and may then be converted to anhydride by reaction with acetic acid. This process consumes somewhat less energy and is a popular subject for chemical engineering problems (24,25). The cost of acetone works against widespread appHcation of this process, however. 

Engineering problems involved in the production of TEE seem simple compared with those associated with polymeriza tion and processing of PTEE resins. The monomer must be polymerized to an extremely high molecular weight in order to achieve the desired properties. The low molecular weight polymer does not have the strength needed in end use appHcations. 

Geotextiles are a relatively new concept for solving problems in geotechnical engineering. They have gained wide use as not only an economical solution to these problems, but in many instances as the only viable solution to a complex engineering problem. This is evidenced by the fact that over a seven-year period from 1976 to 1983 sales of geotextiles in North America alone rose from 5 to 115 m (6 to 138 x 10 /yd ). 

The processiag costs associated with separation and corrosion are stiU significant ia the low pressure process for the process to be economical, the efficiency of recovery and recycle of the rhodium must be very high. Consequently, researchers have continued to seek new ways to faciUtate the separation and confine the corrosion. Extensive research was done with rhodium phosphine complexes bonded to soHd supports, but the resulting catalysts were not sufficiently stable, as rhodium was leached iato the product solution (27,28). A mote successful solution to the engineering problem resulted from the apphcation of a two-phase Hquid-Hquid process (29). The catalyst is synthesized with polar -SO Na groups on the phenyl rings of the triphenylphosphine. 

Eigenvalue problems. These are extensions of equilibrium problems in which critical values of certain parameters are to be determined in addition to the corresponding steady-state configurations. The determination of eigenvalues may also arise in propagation problems. Typical chemical engineering problems include those in heat transfer and resonance in which certain boundaiy conditions are prescribed. 

The mathematical treatment of engineering problems involves four basic steps ... 

Vapor/liquid equilibrium (XT E) relationships (as well as other interphase equihbrium relationships) are needed in the solution of many engineering problems. The required data can be found by experiment, but such measurements are seldom easy, even for binaiy systems, and they become rapidly more difficult as the number of constituent species increases. This is the incentive for application of thermodynamics to the calculation of phase-equilibrium relationships. 

Press, 1973. Lee, Y. Y. and G. T. Tsao, Engineering Problems of Immobilized Enzymes, ]. Food Technol, 39, 667 (1974). Messing, R. A., Immobilized Enzymes for Industrial Reactors, Academic Press, 1975. Torry, S., Enzyme Technology, Noyes DataCorp., Park Ridge, New Jersey, 1983. 

A good review of the transient response method in heterogeneous catalysis was published by Kobayashi and Kobayashi (1974). These authors credit Bermett (1967) for applying this previously microcatalytic research technique to recycle reactors and thereby, in view of this author, to engineering problems. 

Methanol synthesis will be used many times as an example to explain some concepts, largely because the stoichiometry of methanol synthesis is simple. The physical properties of all compounds are well known, details of many competing technologies have been published and methanol is an important industrial chemical. In addition to its relative simplicity, methanol synthesis offers an opportunity to show how to handle reversible reactions, the change in mole numbers, removal of reaction heat, and other engineering problems. 

Rules of thumb for ehemical engineers a manual of quick, accurate solutions to everyday process engineering problems/Carl R. Branan, editor.-3 ed. p. cm. 

Many HVAC system engineering problems focus on the operation and the control of the system. In many cases, the optimization of the system s control and operation is the objective of the simulation. Therefore, the appropriate modeling of the controllers and the selected control strategies are of crucial importance in the simulation. Once the system is correctly set up, the use of simulation tools is very helpful when dealing with such problems. Dynamic system operation is often approximated by series of quasi-steady-state operating conditions, provided that the time step of the simulation is large compared to the dynamic response time of the HVAC equipment. However, for dynamic systems and plant simulation and, most important, for the realistic simulation... 

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