thermometer thermometer heated area filter holder check valve temperature sensor stack wall probe silica gel reverse-type pitat tube pitot manometer thermometess inpingers Lice bath vacuum line taypass vatve Grit:ce majn valve dry gas meter airtight pump Figure 1.5

In a counter-current absorption tower, a process gas containing 0.04 (mole fraction) ammonia is scrubbed with pure water. The exit gas contains 0.002 (mole fraction) ammonia.The diameter of the tower is 1m, and the packing has a large area per volume of 200 m2m–3. The overall mass transfer coefficient based on the liquid side driving force, KL, is 1.5×10−5ms–1. The total gas and liquid concentrations are 0.6kmolm–3and 20 kmolm–3respectively and the gas flowrateis 0.03kmols–1. The actual liquid to gas ratio is 1.5 times that of the minimum liquid to gas ratio. The equilibrium for ammonia between the air and water is given by y* = 1.04x. What is the mol fraction of ammonia in the liquid?

8 i. Estimate the dimensions of a drying chamber for a spray dryer that has an output of 1000 kg/h of a heat-sensitive biological material at 60oC containing 5% moisture and having a mean particle size of 100 micrometers. The feed contains 40% solids by weight in an aqueous solution at 4oC. The inlet air has a humidity of 0.01 kg/kg dry air and is at 150oC, while the outlet air is at 80oC.

Forced air at T = 25°C and V = 10 m/s is used to cool electronic elements on a circuit board. One such ele- ment is a chip, 4 mm X 4 mm, located 120 mm from the leading edge of the board. Experiments have revealed that flow over the board is disturbed by the elements and that convection heat transfer is correlated by an expression of the form Nu,= 0.04 Re0.85 P.1/3 V. T uz bog fr dW ninin tol 1 = 4 mm Chip Board 0:00 Wira L= 120 mm Estimate the surface temperature of the chip if it is dis- sipating 30 mW.

P3

The results of air temperature measurement obtained a dry bulb temperature of 37 ° C and a wet bulb temperature of 27.5 ° C. Using a psychrometric chart, determine the properties of the air as follows:a. RH:%b. Water content: kg water / kg airc. Specific volume: m3 / kgd. Enthalpy: kJ / kge. Condensation temperature: ° CIf the air is within 162 m3 space, determinef. Air weight (dry air and water vapor): kgg. the amount of water content in the space: kg

A continuous single-effect evaporator is to be fed with 5000 kg/hr of solution containing 1 wt% solute, the feed is at a temperature of 303 K. it is to be concentrated to a solution of 2 wt% solute. The evaporation is at atmospheric pressure (101.3 kPa) and the area of the evaporator is 69.7 m2 Saturated steam is supplied at 143.3 kPa for heating. It is assumed that the Cp of feed is the same with that of water which is 4.1 kj/kg-K. Assume no BPR. Calculate: overall heat transfer coefficient

Q2\ A- A triple effect backward feed evaporator are used to concentrate NaOH solution of 10. percent and 1.25 Kg/s of feed which is initially at 297 K, using steam at 393 K and a vacuum such that the boiling point in the last effect is 325 K. If the total water vaporized from the three effects was only one kilogram per second, what are the steam consumption, the heat transfer areas, and the concentration for each effect. Assume the heat capacity of liquid 4.187 KJ/ Kg.K and the overall heat transfer coefficients are 2.5, 2, and 1.6 KW/m². K. respectively. Cp= 4.81kg/kg.k

In a counter-current absorption tower, a process gas containing 0.04 (mole fraction) ammonia is scrubbed with pure water. The exit gas contains 0.002 (mole fraction) ammonia.The diameter of the tower is 1m, and the packing has a large area per volume of 200 m2m–3. The overall mass transfer coefficient based on the liquid side driving force, KL, is 1.5×10−5ms–1. The total gas and liquid concentrations are 0.6kmolm–3and 20 kmolm–3respectively and the gas flowrateis 0.03kmols–1. The actual liquid to gas ratio is 1.5 times that of the minimum liquid to gas ratio. The equilibrium for ammonia between the air and water is given by y* = 1.04x. If the operator increases the gas flow by 20% while keeping the liquid flow and the entering gas and liquid compositions constant,what are the new mole fractions of ammonia in the exit gas and the exit liquid? Assume that the overall mass transfer coefficient does not change with the gas flow.