03: A wet solid is to be dried in a tray dryer under steady state conditions from a free moisture content of X, -0.4 kgH₂O/kg dry solid 1o X₂= 0.02 kgH₂O/kg dry solid. The dry solid weight is 99.8kg dry solid and the top surface area for drying is 4.645m². the drying rate curve can be represented by Figure below. a- Calculate the time for drying using graphical integration in the falling rate period. b- Repeat but use a straight line through the organic for the drying rate in the falling rate period. Drying rate R 1.2 0.8 0.4 Falling rale D Constant rate 0.1 0,2 0.3 0.4 0.5 06 Free monture X (ke II, O/kg dry solid)

03: A wet solid is to be dried in a tray dryer under steady state conditions from a free moisture content of X₁ =0.4 kgH₂O/kg dry solid to X2 0.02 kgH₂O/kg dry solid. The dry solid weight is 99.8kg dry solid and the top surface area for drying is 4.645m². the drying rate curve can be represented by Figure below. a- Calculate the time for drying using graphical integration in the falling rate period. b- Repeat but use a straight line through the organic for the drying rate in the falling rate period. Drying rate 20 0.8 0.4 Falling rate Constant rate 0.1 0,2 0.3 0.4 0.5 0.6 Free moisture X (kg H, O/kg dry solid)

A moist cement omnes diameter 10 ohm circular cross-section will be dried using air in a tray and, for example, the variation of moisture content over time will be examined. The heat transfer coefficient was calculated as 0.68 cal/min.cm³.C in the fixed still drying arab. Dry and wet chamber temperatures of the air used for drying are 35 and 20°C, respectively. For example, calculate the mass transfer coefficient during the 10-minute constant speed drying interval. (Note: the humidity of the air (Ha) should be calculated with the humidity diagram.) Data Evaporation enthalpy of water: 2454.2 kj/kg at 20°C 2418.6 k/kg at 35C Vapor pressure of water: 17.54 mm Hg at 20°C. 35C is 42.18 mm Hg.

During flour milling, wheat grains are taken at a rate of 4 t/h and goes to the cleaning system. As a result of cleaning, 2% is removed in the form of foreign material and chaff. The cleaned grain is then tempered (moisture adjusted from initial to higher moisture to make the bran layer rubbery) before they pass through roller breaks. If the initial moisture content of of the grain is 13.2%, determine the weight of tempered grains if the tempering moisture is 14.5%. Determine the amount of water adsorbed during tempering per tonne of tempered grain. (Moistures are given in wet basis). Also, determine the amount of foreign material/chaff generated per tonne of tempered grain.

17.5. Identify the following polymer processing techniques as either: (i) Continuous (able to operate for very long periods of time as long as enough polymer is supplied), (ii) Batch or semi-continuous (able to make one material at a time, or possibly operate in a cyclic or fashion for a long time with small breaks between processing) THERMAL EXTRUSION CASTING TO FORM A THERMOSET POLYMER BLOW MOLDING MELT SPINNING OF FIBERS THERMOFORMING - INJECTION MOLDING - BLOW EXTRUSION - CALENDERING - COMPOUNDING - ROTATIONAL MOLDING 17.6. You work at a plant that makes poly(ethylene terephthalate), PET, bottles using blow molding, but the production line is having a problem with lots of rejected bottles, which must be ground up and recycled. The rejected bottles sometimes have holes in the threaded part at the top of the bottle (where the screw-cap goes), or this part is often too thin and not rigid enough for the screw cap to fit snugly. A. Give a likely explanation of what is causing the…

In the dryer models for a belt dryer with throughcirculation and a direct-heat rotary dryer, is the rate of drying based on heat transfer or mass transfer? Why?

Under what drying conditions is the moisture-evaporation temperature equal to the wet-bulb temperature?

4. Polyethylene (HDPE) pipe is used as a strut in a crutch 22 mm assembly. The pipe generally prepared by extrusion followed by external cooling. The attached figure is a plot of variation of density through a PE pipe. a.) What is the % 958- 956 954 1952 bore pipe wall Outside Density (kg m 3)

A 4mx5m wall consists of 3 glass windows of 1.5mx1.0m dimensions. The wall has thickness of 0.125 m and a thermal conductivity of 0.5 W/mK, while the glass windows are 6 mm thick with a thermal conductivity of 1.24 W/mK. The values of Internal and external surface conductance for the wall (including glass) are 8.3 W/m K and 34.4 W/m²K, respectively. The internal and external temperatures are 21°C and -30°C, respectively. Calculate the total heat transfer rate through the wall. What percentage of this heat transfer is through the windows?

Deterioration must be strictly avoided when drying pharmaceutical products. Furthermore, such products are often produced from a nonaqueous solvent such as ethanol, methanol, acetone, etc. Explain why a closed-cycle spray dryer using nitrogen is frequently a good choice of dryer