Search & Filtering
2.1. Classify the following process as batch, continuous, semi – batch and identify if the process is an unsteady or steady state; 2.1.1. A balloon is filled with air at a steady rate of 4 g/ min. (2) 2.1.2. A bottle of milk is taken from the refrigerator and left on the kitchen table. (2) 2.1.3. Water is boiled in an open flask. (2) 2.1.4. Water is boiled in a closed flask. (2) 2.1.5. Filling an empty swimming pool with water. (2)
Suppose each year 60 000 people move into Gauteng province, 85000 people move out, 32000 are born and 18000 die. Write a balance equation on the population in Gauteng province accumulated per year. (Let P denote people)
One thousand kilograms per hour of a mixture of benzene (B) and Toluene (T) containing 60% benzene by mass is separated by distillation into two fractions. The mass flowrate of the benzene (B) in the top stream is 500 kg (B) /h and that of toluene in the bottom stream is 485 kg (T) / h. The unit operates at steady state. 3.1.1. Draw a schematic diagram showing all the relevant streams in the distillation unit. (8) 3.1.2. Write the basis for calculation.
Sulphur dioxide is to be scrubbed from an air stream in a small packed tower by contacting it with an organic amine. The feed gas 3% SO2, by volume, and 95% of it is to be absorbed. The total gas rate is 150 m^{3}/h. at 20^{°}C and 1.1 bar absolute pressure. The liquid enters the column at rate of 1.40 kmol / h. Give:the overall mass transfer coefficient, KG=3.2*10^{-4} kmol/m^{2}.s. bar; the effective gas-liquid contact area =105 m^{2} per m^{3} of packed volume; slope of the equilibrium line, m=0.17 . Determine the number of overall gas-phase mass transfer units and the packed height if the column is 1 ft in diameter.
A metal ball (radius 2.5 cm) initially at a uniform temperature of 450°C is suddenly placed in a controlled environment in which the temperature is maintained at 100°C. The convective heat transfer coefficient is 10 W/(m² -K). Determine the time taken (in hours) for the metal ball to cool to 150 °C ? Clearly mention the suitable assumptions if necessary?. Property data are given below.
Property of all metal ball,unit ___________ value
Density, kg/m³_______7800
Thermal conductivity,W(m-°C)____35
Heat capacity, (J/kg-°C) 460
A composite wall is formed of a 2.5 cm copper plate (k=385 W/m-K). a 3.2 cm layer of
asbestos (k=0.2 W/m-K), and a 5 cm layer of fibreglass (k=0.045 W/m-K). The wall is subjected to an overall temperature drop of 560°C. Calculate the heat flux through the composite wall and also determine the temperature drop across the asbestos layer?
A schedule number 40 standard steel pipe (outer diameter 4.5 in. and wall thickness 0.237 in.) carrying steam is lagged (insulated) with two layers. First layer (near the steel pipe) having 50mm thickness is made of 85% magnesia and second layer having 60 mm thickness is made of cork. The inner surface temperature of the steel pipe is maintained at 150°C and the outer surface temperature of the cork is maintained at 35°C. Determine the individual thermal resistance of each layer and the rate of heat loss per meter length of the pipe. Consider only the conduction heat transfer. Make suitable assumptions if necessary? (Take
1 in.= 2.54 cm)
Material: Thermal.conduct.
Steel pipe. 45(W/(m-°C)
85% magnesia. 0.07 "
Cork 0.043 "
A metal ball (radius 2.5 cm) initially at a uniform temperature of 450°C is suddenly placed in a controlled environment in which the temperature is maintained at 100°C. The convective heat transfer coefficient is 10 W/(m² -K). Determine the time taken (in hours) for the metal ball to cool to 150 °C ? Clearly mention the suitable assumptions if necessary?. Property data are given below.
Property of all metal ball,unit ___________ value
Density, kg/m³_______7800
Thermal conductivity,W(m-°C)____35
Heat capacity, (J/kg-°C) 460
A light fuel oil is used in the tube side of a 2-4 shell-and-tube heat exchanger. Water is heated in the shell side from 10°C to 50°C while the oil is cooled from 90°C to 60°C. The overall heat-transfer coefficient is 53 W/(m²-°C). The LMTD correction factor is 0.975.
Calculate the area of the heat exchanger for a total heat transfer rate of 500 kW. ?
Draw the temperature profiles of hot and cold fluids in a 1-2 shell and tube heat exchanger?
