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Sample Topics

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Thermodynamics

Thermodynamics deals with the treatment of solutions or fluids by changing the temperature or heat source. Thermodynamics is the basis for the other chemical engineering subjects (heat and mass transfer and reaction engineering). Thermodynamics includes laws of thermodynamics and their application, concepts of enthalpy and entropy, real and ideal fluids, solution thermodynamics, phase equilibrium, heat engines and heat pumps.

**Sample Questions:-**

1. We are interested in modelling methane gas with the virial equation of state truncated at the second virial coefficient. The Lennard -Jones potential parameters σ =3.783 Å and ε/k =148.9K.(a) Determine the B(T) at 150, 400 and 600 K in units of cm3/mol.(b) At 150K, what is the constant volume heat capacity if Cv(ideal)= 33.4 and pressure is 1bar?

2. Calculate the relative change in saturation vapor pressure of water at 300 K when it is dispersed in droplets (pore) of 0.1 μm radius. Given: γw = 0.073 N/m.

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Mass Transfer

Mass transfer is the subject which deals with the transfer of a mass (or) substance from one phase to another phase on a molecular scale. The phase may be a solid or fluid (gas or liquid).The mass transfer operations include gas-Liquid operations such as absorption, stripping, distillation and humidification, solid- fluid operations such as drying, leaching, adsorption and Ion exchange, liquid-liquid operations such as liquid extraction.

**Sample Questions:**

1. Estimate the mass transfer coefficient, kc, in a wetted-wall column (wetted with benzene) for the transfer of benzene into carbon dioxide at 0o C. The carbon dioxide gas velocity through the column is 1.25 m/s. The diameter of the column is 0.16 m. Assume that the benzene concentration in the carbon dioxide gas is very low.

Mass density of CO2 = 1.966 kg/m3

Viscosity of CO2 = 1.35 x 10-5 kg/m∙s

Diffusivity of benzene in CO2 = 5.28 × 10-6 m2 /s

Molecular weight of CO2 = 44 g/g mol

Molecular weight of benzene = 78 g/g mol

Note that the friction factor, f, can be correlated with the Reynolds number, Re, as follows: f/2 = 0.023Re^(-0.2) for Re between 5,000-200,000for f Calculate kc based on (a) the Reynolds Analogy, (b) the Chilton-Colburn Analogy, (c) mass transfer correlation (use the table given in the class). Which mass transfer coefficient is more accurate and why?

2. The total weight of the basket and the semi-wet clothes before drying was 13.9 kgs. Dr. Blowers’ wife pulled in the laundry that afternoon and weighed it again in the basket and it came in at 20.5 lbs. Estimate the volume of entering air that would have been needed to dry the Blowers’ clothing if they had used their dryer in the utility room instead of sun drying it, and the air coming in to the dryer was at 67% rh and was left with a humidity of 1% at 183 oC

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Heat Transfer

Heat transfer deals with the transfer of heat from higher temperature to a lower temperature by three modes of transfer conduction, convection and radiation.This subject includes conduction, heat transfer in fluids with phase change and without phase change, radiation and heat exchange equipment.

**Sample Questions:**

1. A triple effect evaporator is supplied with saturated steam at 2500F. The temperature at the last effect is 150oF. The overall heat transfer coefficients are 150, 200, and 250 BTU/hr-ft2- oF in the 1st, 2nd, and 3rd effects, respectively. If the total BPR in the three effects is 55oF, what is the area of the first effect if the steam used is 10,000 lb/hr.

2. A turkey at room temperature is placed in a convection oven at 350 F (176.7 C). The turkey can be assumed to be a sphere with radius of 22 cm and thermal conductivity of 0.7 W/(m*K). The heat transfer coefficient between the turkey and the air in the oven is 5 W/(m^2*K). Will a temperature difference reading taken at a radial position of 8 cm be a good approximation to the temperature in the center of the turkey? Provide a quantitative answer.

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Fluid mechanics & Mechanical operations

Fluid mechanics is the subject which deals with the behaviour of fluids. It is divided into fluid statics (at rest) and dynamics (motion).Fluid mechanics includes the concepts flow of fluids through different boundaries and calculation of respective velocity gradients, pressure, friction factors of the fluid throughout the length of the boundary taken with respect to their flow types of laminar or turbulent

**Sample Questions:**

1. A 50 g/l of a solution of a BSA protein with a constant specific filtration resistance of 4 x 1011 m/kg is being filtered in a cross flow set up at a constant rate of 5 x 10-5m/s. In constant rate filtration, the pressure is varied as a function of time. If the membrane resistance is negligible and the reaction rate kr is 0.0015 s-1determine the pressure after 1 hour. If the area of the filter is 0.1 m2, what is the production rate of the clear permeate in litres per hour

2.In a natural gas pipeline at section 1 the pipe diameter is 1.5 ft and the flow conditions are 900 psia, , and 50 ft/sec velocity. At section 2 the pipe diameter is 3.5 ft and the flow conditions are 600 psia, . What is the velocity at section 2 and what is the mass flow rate.

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Chemical process calculations

Chemical process calculations deal with the unit operations involved in manufacturing industries. This subject introduces the fundamental concepts of the system of units and dimensions, mass and energy balances, their application in chemical process industries, Recycle, purge, degrees of freedom, balances on non-reactive and reactive processes.

**Sample Questions:**

1. I need to calculate the enthalpy Hrxn from the combustion of methane gas. Starting with 500kg of methane and 120 percent excess air. The temperature of the reactants are state functions at 25 C and products temp is 450 C.

2. A mixture of gaseous fuels is burned in an experimental furnace by conventional techniques. The combustion gas is analyzed there is no reason to question the dependability of the results. What is the composition of the fuel for the case in which:

a) The fuel is a mixture of CH4 and NH3 and the analysis results are 6.2% CO2, 4.6% O2, and 89.2% N2?

b) The fuel is a mixture of CH4 and HCN and the analysis results are 10.8% CO2, 4.1% O2, and 85.1% N2?

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Reaction Engineering

Chemical reaction engineering subject plays a key role in chemical process industries. It explains complex reactions, and studies how a reaction takes place in a reactor through reaction kinetics, and design of a chemical reactor.This subject introduces analysis of chemical reactors, an ideal flow and non-ideal flow in a chemical reactor, reactor kinetics, chemical reactor design, compartment models, fluid-solid catalytic reactors and biochemical reactor systems.

**Sample Questions:**

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Process dynamics and control

Process dynamics and control is the subject which deals with the disturbances occur in an equipment used in the chemical process and the control mechanisms of that disturbances to avoid undesired products.Process dynamics and control include the concepts of Laplace transforms, different types of disturbances occur in the equipment, order of the different systems, types of controllers, stability of the system, frequency response and design of control system by using frequency response.

**Sample Questions:**

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Transport phenomena

Transport phenomena is a subject which deals with the transport of different quantities such as momentum, energy and mass in a chemical process. It is the combination of fluid mechanics, heat transfer and mass transfer. It gives the idea about the similarities among the three transport quantities.Transport phenomena include the concepts of basics laws of momentum, heat and mass, shell balances of momentum, energy and mass, distributions of velocity in momentum, distributions of temperature in energy and distributions of concentration in mass.

**Sample Questions:**

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Plant design and economics

This topic deals with the designing of chemical plants based on economic evolution (profits and losses) and development of production. Plant design involves design of individual process equipment for the entire production. It includes:Process design development, cost estimation, taxes and insurance, depreciation, material selection and equipment fabrication and statistical analysis in design.

**Sample Questions:**

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