Questions and Answers of Unit Operations Of Chemical Engineering

Dry gas containing 75 percent air and 25 percent ammonia vapor enters the bottom of a cylindrical packed absorption tower that is 2 ft in diameter. Nozzles in the top of the tower distribute water
Check the dimensional consistency of the following empirical equation for heat transfer between a flowing fluid and the surface of a sphere. where h = heat transfer coefficient Dр = diameter of
An evaporator is fed continuously with 25 t (metric tons)/h of a solution consisting of 10 percent NaOH, 10 percent NaCl, and 80 percent H2O. During evaporation, water is boiled off, and salt
Air is flowing steadily through a horizontal heated tube. The air enters at 40°F and at a velocity of 50 ft/s. It leaves the tube at 140°F and 75 ft/s. The average specific heat of air is 0.24
A flat disk with a central opening of diameter Dᵒ, is set across a pipe of diameter D, and the pressure drop Δp across the opening is measured. It is postulated that Δp is a function of the
A coal-fired power plant with an output of 360 megawatts has an efficiency of 38 percent in converting heat to work. If the coal has a heating value of 30,000 kJ/kg, how many metric tons (1 ton=
At what point is the temperature in degrees Fahrenheit equal to the Celsius temperature? Is there any point where the Kelvin temperature is the same as the Rankine temperature?
Heat-transfer data are sometimes given as a j factor, whereShow that such a correlation can be converted to one that gives the Nusselt number (Nu = hD/k) as a function of the Reynolds number (DG/μ)
In many countries in South America, chunks of cassava root containing 65 percent water are dried to 5 percent water, then ground to make tapioca flour. To make 1,200 kg/h of flour, what would be the
Wet paper pulp containing 66 percent moisture was dried under conditions such that 53 percent of the water originally in the pulp was removed. What was the moisture content of the dried pulp? Per
In making fish meal the oil is first extracted, leaving a wet fish cake containing 82 wt % water. This cake is partially dried to reduce the moisture content to 40 percent, after which the cake is
Explain the difference between Eq. (1.59) and the simple equation that is sometimes shown in thermodynamics texts, ΔE = Q-W. Can the simpler equation be derived from Eq. (1.59)?Eq. 1.59 - [² =
How many molecules of oxygen are there in a pound mole of air at 1 atm and 0°C? How many molecules of O2 are there in a kilogram mole of air at 1 atm and 30°C?
How much error would be introduced in the answer to Prob. 2.2 if the equation for hydrostatic equilibrium [Eq. (2.4)] were used, with the density evaluated at 0°C and an arithmetic average
A simple U-tube manometer is installed across an orifice meter. The manometer is filled with mercury (specific gravity 13.6), and the liquid above the mercury is carbon tetrachloride (specific
The temperature of the earth's atmosphere drops about 5°C for every 1,000 m of elevation above the earth's surface. If the air temperature at ground level is 15°C and the pressure is 760 mm Hg, at
A continuous gravity decanter is to separate chlorobenzene, with a density of 1,109 kg/m3, from an aqueous wash liquid having a density of 1,020 kg/m3. If the total depth in the separator is 1 m and
What should be the volume of the separator in Prob. 2.4 to separate 1,600 kg/h chlorobenzene from 2,100 kg/h of wash liquid. The wash liquid is to be the continuous phase; its viscosity is the same
The liquids described in Prob. 2.4 are to be separated in a tubular centrifuge bowl with an inside diameter of 150 mm, rotating at 8,000 r/min. The free-liquid surface inside the bowl is 40 mm from
A centrifuge bowl with 250-mm ID (internal diameter) is turning at 4,000 r/min. It contains a layer of aniline 50 mm thick. If the density of the aniline is 1,002 kg/m3 and the pressure at the liquid
A U-tube manometer indicates a pressure drop of 10 in. water across an air filter. The air is at 26°C and a gauge pressure of 60 lb,/in2.(a) What is the pressure drop in lb,/in2 and in atm? (b)
A research submarine is designed to operate 3 km below the ocean surface. If the interior pressure is 1 atm, what is the total pressure on a 15-cm-diameter window? The average density of seawater is
A suspension of very fine sand particles in water is used to separate bituminous coal from denser particles of rock. If the desired density of the suspension is 1,500 kg/m3. what are the volume
What is the height, in m, of a column of water at 10°C equivalent to a pressure of I atm? What is this height in ft?
A head of 10 m of ethyl alcohol with a density of 785 kg/m3 is equivalent to what pressure, in kPa?
An oil-water mixture from a pilot-plant reactor is separated in a horizontal decanter 0.6 m in diameter and 3 m long. The residence time needed in the decanter is found to be 20 minutes. (a) If a
Estimate the atmospheric pressure at the summit of Mount Everest, 8,848 m above sea level. Assume an average temperature of 0°C.
A partial oxidation is carried out by bubbling air through a batch of liquid in a pressurized reactor 3 m in diameter and 5 m tall. The initial liquid level is 4.0 m, as shown by a manometer
Compare the change in density with temperature for n-octane and toluene with that of water over the range 0 to 100°C.
For the following situations of steady flow, determine whether flow is laminar or turbulent: (a) Water at 10°C flowing at an average velocity of 2 m/s in a 100-mm pipe;(b) Air at 2-atm pressure and
Approximately how many minutes are there in a microcentury?
Using defined constants and conversion factors for mass, length, time, and temperature, calculate conversion factors for(a) Foot-pounds force to kilowatthours, (b) Gallons (1 gal = 231 in.3) to

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